1
Q
What are enzymes
A
Enzymes are biological catalysts mostly proteins that speed up biochemical reactions
2
Q
WHAT general role do enzyme they play in biochemical reactions?
A
speed up biochemical reactions by lowering activation energy without being consumed in the process.
3
Q
What are the main properties of enzymes that distinguish them from other biomolecules?
A
They are highly specific, reusable, and efficient catalysts that work under mild physiological conditions (pH, temperature).
4
Q
In what biological or industrial contexts are enzymes particularly useful?
A
Biologically, they’re essential for metabolism, digestion, and DNA replication. Industrially, used in food processing, detergents, pharmaceuticals, and biofuels.
5
Q
Which biomolecules can function as enzymes?
A
Mostly proteins, but some RNA molecules (ribozymes) also act as enzymes.
6
Q
What are prosthetic groups and why are they important for enzyme activity?
A
Non-protein components (like metal ions or organic molecules) tightly bound to enzymes that help them function—e.g., Fe²⁺, Mg²⁺, FAD, heme.
7
Q
Give examples of enzymes that require prosthetic groups.
A
Cytochrome oxidase (heme group), carbonic anhydrase (Zn²⁺), and catalase (Fe³⁺).Cu2+
8
Q
How are enzymes classified according to the Enzyme Commission (EC) system
A
six main classes based on the type of reaction they catalyze
9
Q
six main classes
A
Oxidoreductases
Transferases
Hydrolases
Lyases
Isomerases
Ligases
9
Q
What do the four numbers in an enzyme’s EC name represent?
A
(1) Reaction class, (2) subclass, (3) sub-subclass, and (4) the enzyme’s serial number in that group.
9
Q
How are enzyme names generally derived?
A
Based on their substrate or reaction type, ending in “-ase” (e.g., lactase acts on lactose).
10
Q
What does substrate specificity mean in relation to enzyme function?
A
Each enzyme catalyzes a specific reaction by binding only to a specific substrate at its active site.
11
Q
How do enzymes accelerate biochemical reactions at the molecular level?
A
They stabilize the transition state and lower activation energy, making reactions occur faster.
12
Q
What effect do enzymes have on the activation energy (ΔG‡) of a reaction?
A
They lower ΔG‡, making the reaction kinetically favorable
13
Q
These ions are covalently bound to the corresponding enzyme the enzyme
A
cannot function (is not active) without them!
14
Q
enzyme effect on ΔG or equilibrium.
A
they do not change overall ΔG or equilibrium.
15
Q
What are the main catalytic mechanisms used by enzymes?
A
Acid-base catalysis, covalent catalysis, metal ion catalysis, and proximity/orientation effects.
16
Q
What is binding energy and how does it contribute to catalysis?
A
Binding energy is the energy released when substrate binds the enzyme
16
Q
how does binding energy contribute to catalysis
A
it helps stabilize the transition state and lower activation energy.
17
Q
what strategies do Enzymes use
A
Acid-base:
Covalent:
Metal ion:
Proximity/orientation:
17
Q
Acid-base
A
Donates or accepts protons to stabilize intermediates.
18
Q
Metal ion
A
Stabilizes charges or activates substrates.
18
Q
kcat:
A
Turnover number (substrate molecules converted per enzyme per second).
18
Q
Covalent
A
Forms transient covalent bonds to stabilize transition states.
18
Michaelis-Menten equation
v = (Vmax [S]) / (Km + [S])
19
Proximity/orientation
Brings reactants close in correct orientation.
20
Vmax:
Maximum reaction rate.
20
What is enzyme kinetics and why is it important to study?
study of reaction rates catalyzed by enzymes; it helps understand enzyme efficiency, mechanisms, and regulation.
21
How can kinetic parameters (Km and Vmax) be experimentally determined?
By measuring reaction rates at varying [S] and plotting Michaelis-Menten or Lineweaver-Burk graphs.
21
Km:
Substrate concentration at half Vmax (measures substrate affinity).
21
What does the ratio kcat/Km represent?
Catalytic efficiency , how efficiently an enzyme converts substrate to product.
22
What happens to reaction velocity at low substrate concentrations?
Low [S]: Velocity increases linearly with [S].
23
how do enzyme inhibitors affect enzyme activity?
by blocking substrate binding or catalysis.
23
What happens to reaction velocity at high substrate concentrations?
High [S]: Velocity approaches Vmax (enzyme saturated).
24
Uncompetitive inhibitor
Binds only ES complex; decreases both Km and Vmax.
24
What are enzyme inhibitors
Molecules that reduce or stop enzyme activity
24
How do Lineweaver-Burk plots differ for each type of inhibition?
Each inhibition type alters slope/intercept differently competitive (lines intersect on y-axis), uncompetitive (parallel lines), mixed (intersect left of y-axis).
25
Competitive Inhibitor
Inhibitor binds active site; increases Km, no effect on Vmax.
25
Mixed inhibitor
Binds enzyme or ES complex; decreases Vmax and changes Km variably.
26
lines intersect on y-axis)
competitive
27
(parallel lines)
uncompetitive
28
(intersect left of y-axis)
mixed
28
What are irreversible inhibitors
Covalently bind to enzyme’s active site residues
29
What are allosteric regulators
Molecules that bind non-active sites to change enzyme shape and activity.
29
how do irreversible inhibitors permanently inactivate enzymes?
permanently destroying activity (e.g., aspirin on COX enzyme).
30
What mechanisms exist to regulate enzyme activity in cells?
Allosteric regulation, covalent modification, feedback inhibition, and gene expression control.
31
negative allosteric regulation
Inhibits enzyme activity.
32
Give examples of reversible covalent modifications that regulate enzymes.
Phosphorylation/dephosphorylation, acetylation, methylation.
32
positive allosteric regulation
Enhances enzyme activity.
33
Give examples of irreversible covalent modifications of enzymes.
Proteolytic cleavage (e.g., activation of trypsin from trypsinogen).
34
often used as drugs to slow down a specific enzyme
Reversible inhibitors
34
powerful toxins but also may be used as drugs.
Irreversible inhibitors
35
Chymotrypsin
a pancreatic enzyme that breaks down proteins in the digestive system
36
cuts peptides at specific locations on the peptide backbone
Chymotrypsin
37
The ___________________ the Km the greater the affinity of the enzyme for its substrate !
smaller
38
39
where does Chymotrypsin cleave in amino acids.
peptide bond adjacent to aromatic amino acids.
40
single units of polyhydroxyaldehyde or ketone (e.g. glucose, fructose, erythrose, etc)
monosaccharides
41
few units, linked via ether bonds (e.g. sucrose = disaccharide containing one unit of D-glucose and one unit of D-fructose)
oligosaccharides
42
more than 20 monosaccharide units; some have more than 100.000 units; can be linear (e.g. amylose) or branched (e.g. amylopectin, glycogen)
polysaccharides
43
Carbohydrates role
energy generation and storage
structural role
inactive ingredients (excipients)
potent osmolites ( osmotic pressure )
recognition elements – immunity,
44
polyhydroxyaldehydes
aldoses
45
polyhydroxyketones
ketoses
46
Most of natural sugars are
D relative configuration
47
D configuration
on the right
48
L configuration
on the left
48
; total number of stereoisomers for a sugar
2^n
n= chiral carbons
49
epimers
Two sugars that differ only in the configuration of one chiral carbon atom:
50
two stereoisomers, which differ just on the stereochemistryat the hemiacetalic carbon, are called
anomers
51
the interconversion of the two anomers via the acyclic form is called
MUTAROTATION
52
are different configurations (not conformations)
they are diastereomers and can only be inter-converted by bond cleavage.
alpha and beta
53
equatorial
MORE STABLE
54
glucose is a
reducing sugar
55
Fehling’s reaction
it detects reducing sugars or aldehydes by reacting with them to produce a reddish-brown precipitate of copper(I) oxide
56
Clinitest tablets are used to
test how much sugar (glucose) there is in a person's urine.
57
When are reducing properties displayed in sugars?
Only if the sugar can adopt an acyclic form.
58
For a cyclic sugar to be a reducing sugar, what functional group must be free?
The glycosidic (anomeric) OH group.
59
a widely used enzymatic assay for determining the concentration of glucose in a sample, such as blood or urine
Glucose Oxidase method
60
a highly accurate and precise enzymatic assay used to measure glucose concentration, commonly in plasma or serum
Hexokinase method
61
Reducing
one free anomeric OH
the sugar is a reducing sugar, a carbohydrate with a free anomeric carbon that can open to form an aldehyde or ketone group
62
Non-reducing
anomeric OHs are linked
In a non-reducing sugar, the anomeric carbons of two monosaccharides are linked together
63
To be a reducing sugar________________must be possible !!
mutarotation
64
carbohydrates made of short chains of 3 to 10 monosaccharides and have benefits such as acting as prebiotics to promote a healthy gut microbiome
Oligosaccharides
65
cyclic oligosaccharides made of glucose units that form a cone-like shape with a hydrophilic (water-loving) outer surface and a hydrophobic (water-fearing) inner cavity
Cyclodextrins
66
polymers made of a single type of monosaccharide that serve as a way to store energy for living organisms
Fuel-storage homopolysaccharides
67
a highly branched polysaccharide and a major component of starch, made of many glucose units
Amylopectin
68
a structural polysaccharide that forms the main component of plant cell walls, though humans cannot digest it
Cellulose
68
primary storage form of glucose for energy in animals, composed of branched chains of glucose molecules stored mainly in the liver and muscles
Glycogen
69
a structural polysaccharide, a long-chain polymer of the N-acetylglucosamine molecule, that serves as the main component of arthropod exoskeletons and fungal cell walls
Chitin
70
Glycoconjugates: peptidoglycans
are a specific type of glycoconjugate found in the cell walls of bacteria, distinct from mammalian glycoconjugates like proteoglycans
71
Peptidoglycans ofGram Negativebacteria
Direct links between D-Ala and Lysine (no pentaglycine)
72
Peptidoglycans ofGram Positive bacteria
Pentaglycine link
(NAM)
73
a multi-stage process that starts in the cytoplasm with the creation of nucleotide precursors, then moves to the inner membrane for assembly into lipid-linked monomers, and finally polymerizes in the periplasm
Synthesis of bacterial peptidoglycan
74
Penicillins weaken the bacterial cell wall by
inhibiting the final cross-linking of the peptidoglycan layer, a process that involves peptide chains connecting polysaccharide chains
74
Overcoming bacterial resistance: (Penicillin's)
use a suicide inhibitor of b-lactamase (clavulanic acid) to preserve the potency of an antibiotic:
75
long, unbranched polysaccharides that play vital roles in the body's tissues, including maintaining structural integrity, lubricating joints, and hydrating skin
Glycosaminoglycans
76
are chemical substances that are similar to one another, such as those in the same chemical group or elements on the periodic table. In alcoholic beverages, they are byproducts of fermentation and maturation, aside from ethanol, that give the drink its flavor and color and can contribute to hangovers.
congeners
77
an anticoagulant (a "blood thinner") medication used to prevent and treat blood clots. It is a naturally occurring substance, a glycosaminoglycan, that can also be produced in a laboratory for medical use
Heparin
78
Oligosaccharides link to proteins via
N-linked or O-linked glycosidic bonds
79
a major component of the outer membrane of Gram-negative bacteria that triggers a strong immune response in humans
Lipopolysaccharide (LPS), also known as endotoxin
80
trigger very vigorous immune responses in bacterial infections
Lipopolysaccharides
80
are proteins which bind carbohydrates with high affinity and specificity; oligosaccharides often H-bond to specific areas
Lectins
81
a group of lectins in cell membranes which are involved in processes of cell recognition and adhesion including the movement of T-lymphocytes from blood to tissue during infection or inflammation.
Selectins
82
integrin blocker has utility in preventing platelet aggregation
and blood clots in order to reduce the risk of acute cardiac ischemic events (together with aspirin, heparin). It is approved for use during surgical installation of coronary stents among other uses.
Eptifibatide (Integrilin®)
82
lectins that can serve as “receptors”, conveying information across plasma membranes
Integrins
83
gram negative Helicobacter pylori colony can cause
inflammation of stomach lining, being associated with gastro-duodenal ulcers and stomach cancer
84
enzyme Cannot function without
cofactors!
84
Lyases:
Cleaves Bonds!
- “Bye bonds!”
- “Ly” looks like bye
85
Ligases:
Form bonds!
- “Li” looks like Hi
86
Proton transfer with AA residues happening
within the active site
- Glu, Asp, Cys, His
Acid Base
86
formed between enzyme and
substrate
Requires a nucleophile: serine, thiolate, amine,
carboxylate
Covalent
87
bound to enzyme which facilitate
binding with substrate in oxidation reactions
Metal ion
88
Peptidase that hydrolyzes proteins and uses
multiple of these mechs!
Chymotrypsin
89
Acetylcholinesterase(substrate)
acetylcholine
89
Carbonic anhydrase (substrate)
CO2, HCO3-
90
Catalase(substrate)
H2O2
91
Naming cyclic
structures (anomers)OH above =
beta
92
Naming cyclic
structures (anomers)OH below =
alpha
93
Alternating units of Mur2Ac
and GlcNAc
Gram + bacteria
- Pentaglycine link
94
Building blocks
of NAs
Store and transmit genetic
info
Nucleotides
94
Nucleotides Requirements
Stability
Water couple
Affinity
95
Functions of nucleotides
1. Energy storage
2. Redox coenzymes
3. Regulatory nucleotides
96
encode for ONE amino acid
3 nucleotides
97
Non-enzymatic reactions of nucleotides
1. Deamination
2. Depurination
97
Gene
DNA piece that encodes the primary sequence of some final product (e.g., a peptide)
97
Doxorubicin
acts through two distinct, yet related, mechanisms: DNA intercalation and topoisomerase II stabilization (poisoning).
98
The planar part of the doxorubicin molecule inserts itself between adjacent DNA base pairs, primarily at GC-rich sequences.
Doxorubicin Intercalation
99
Doxorubicin binds to the DNA-topoisomerase II complex, trapping the enzyme at an intermediate stage of its catalytic cycle after it has cut both DNA strands but before it can religate (reseal) them
Doxorubicin is a topoisomerase poison, not a stabilizer in the sense of making the enzyme catalytically better
99
Biotechnology/Genetic
engineering
the use of tissue cultures, living cells or cell enzymes to make a defined product - based on the ability to locate, isolate, prepare, and manipulate small segments of DNA from larger chromosomes by processes of DNA cloning.
100
Genome
total amount of genetic material (DNA/RNA) of a living organism) is the information archive of the cell, encoding all the information needed for cell structure, function and dynamics
101
Restriction endonucleases
accomplished via bacterial enzymes that have been isolated and used for their unique ability to cleave DNA at particular nucleotide sequences
102
c-DNA library
more specialized library which contains only those genes which code for proteins i.e. genes which are transcribed in to mRNA
102
DNA Ligase
can join fragments at the sticky ends produced by the same endonucleases to yield recombinant DNA
103
reverse transcriptases;
used by mRNA of an organism is used to produce complementary DNA
103
genomic library
collection of DNA fragments obtained by digestion of all the DNA of an organisms by restriction endonuclease and recombined to a vector
103
Polymerase
Chain Reaction (PCR)
is a laboratory technique that creates millions to billions of copies of a specific DNA segment, making it easier to analyze. It is a key tool in many fields, including medicine for diagnosing diseases, forensics, and genetic research
103
a molecular biology technique used to detect specific DNA sequences by fragmenting DNA with restriction enzymes, separating the fragments by size using gel electrophoresis, transferring them to a membrane, and then hybridizing them with a labeled probe that is complementary to the target sequence
Southern
Blot
103
steps to
make a cDNA Library
mRNA used as template is destroyed chemically;
A polymerase is used to build the corresponding DNA chain;
the cDNA thus produced is inserted into a vector and cloned forming a cDNA library;
a single strand of cDNA may have a radioactive species attached to it and serve as a probe to find a particular sequence in chromosome.
103
steps in recombinant DNA tech
isolating the desired DNA and a vector (like a plasmid), cutting both with restriction enzymes, joining the DNA fragments using DNA ligase to create recombinant DNA, and then inserting this into a host cell. Finally, selecting and screening the transformed cells is performed to identify those containing the recombinant DNA, which can then be grown to produce the desired gene product.
103
Main characteristics of lipids
Insoluble in water
Soluble in non-polar solvents
104
lipids role in organisms
Dietary
Insulating material
Segregation and dynamic interface,
transport, and signaling
104
a class of lipids that consist of fatty acids and alcohols. They are formed through esterification, a reaction between a fatty acid and an alcohol molecule
Simple lipids
104
a diverse group of lipids that contain fatty acids, glycerol, and additional non-lipid components such as phosphate, sugar, or amino acids
Complex lipids
104
Precursor lipids
acetyl-CoA for fatty acids and cholesterol, and glycerol for triglycerides
105
Derived lipids
fatty acids, steroids, and fat-soluble vitamins. These are formed from the hydrolysis of simple or compound lipids. Other examples are ketone bodies, terpenes, carotenoids, and hormones like estrogen and testosterone
105
a type of fat with a carbon chain that has no double bonds, meaning each carbon atom is bonded to the maximum possible number of hydrogen atoms
saturated fatty acid
106
fatty acids that have at least one double bond between carbon atoms, making them kinked and liquid at room temperature
unsaturated fatty acid
107
a type of fat, primarily from industrially produced, partially hydrogenated oils, that are made to increase shelf life and food stability
trans fatty acids
107
a type of lipid composed of a glycerol molecule bonded to three fatty acid chains
Triacylglycerols
108
essential components of biological membranes, composed of a glycerol backbone, two fatty acids, a phosphate group, and a head group
Glycerophospholipids
108
a major class of lipids found in eukaryotic cell membranes, especially in nerve tissues, that play critical roles in cell signaling, cell growth, and immune responses
Sphingolipids
109
Dipalmitoylphosphatidylcholine
an important surfactant - prevents
Respiratory Distress Syndrome in neonates
109
Atelectasis
the partial or complete collapse of a lung, caused by an airway blockage (such as a mucus plug or foreign object) or pressure on the lung (from a tumor or fluid buildup)
110
IP3 ( inositol trisphosphate)
water soluble, found in cytoplasm
Release of intracellular Ca2+
111
diacylglycerol (DAG)
intracellular messenger
Activates protein kinase C
111
lecithin
not a single chemical, but a group of phospholipids that are crucial for cell function.
It is an emulsifier, meaning it helps combine water and fat.
112
a large and diverse class of organic molecules derived from five-carbon isoprene units
Isoprenoid compounds
112
Lack of vitamin D leads to
Rickets
113
Cholesterol
A steroid that is an essential component of animal cell membranes
114
Vitamins
Vitamin D and parts of Vitamin A are synthesized from isoprenoid precursors.
114
C18
Estrogens(e.g., estradiol)
115
Carbon Count
steroid hormones are often classified by their total carbon count
115
C19
Androgens(e.g., testosterone).
116
C21
Corticosteroids(e.g., cortisol, aldosterone) and progestogens (e.g., progesterone).
116
A1 cleaves the fatty acid at the
(sn-1) position
117
C cleaves the phosphodiester bond
before the phosphate group
117
A2 cleaves the fatty acid at the
sn-2
118
D cleaves
after the phosphate group
119
lysophospholipids
bioactive lipids derived from membrane phospholipids that act as signaling molecules in the body
119
diacylglycerols
a type of lipid with a glycerol backbone attached to two fatty acids, acting as a key intermediate in lipid metabolism and cell signaling
120
phosphatidic acid
a class of lipids with a glycerol backbone attached to two fatty acids and a phosphate group
120
True or False: Enzymes affect the thermodynamics of a reaction
False! They only affect the kinetics. They do not change the free energy (G)
120
Which class of enzymes MAKES bonds via condensation reactions.
Ligases
121
This dictates the overall rate of the reaction
Rate-limiting step
Highest activation energy!
121
What shows the greatest affinity of an enzyme for its substrate?
0.012
122
Remember, the smaller the number
the greater the affinity (Km = k^-1 /
k1) K1 = binding rate
123
The higher the binding rate in the denominator,
the
smaller Km is gonna be.
124
How do irreversible inhibitors work?
Covalently bound to substrate
125
What is the interconversion of the two anomers via the acyclic form?
Mutarotation
126
True or false: CONFIGURATIONs of equatorial positions are more stable
false It should be CONFIRMATIONS. Be careful! ..
127
Alpha and Beta CONFIGURATIONS
are
not confirmations
128
Axial and Equatorial are confirmations with equatorial
being
more stable.
129
These have a toroidal structure: hydrophilic exteriors and hydrophobic interior
Oligiosaccharides (cyclodextrins)
130
Enzyme responsible for crosslinking
Transpeptidase
131
How is B-lactamase resistance overcome?
Using Clavulanic acid in addition to the B-lactam
132
What links the nucleotides together in both RNA and DNA?
Phosphodiesterase linkage
133
(DNA/RNA) is stable at both acidic and basic environments
DNA
134
RNA is
sensitive. Alkaline hydrolysis is rapid in RNA, so not stable in
basic conditions
135
methylators/dialkylatores that can damage DNA, potent carcinogens
a. Nitrogen mustard
b. Dimethylnitrosamine
c. Dimethysulfate
136
T or F: Nucleic acids sequences are read from 3’ to 5’
False, reade 5’ to 3’
137
If DNA sequence A has a higher melting temperature than sequence B, which sequence
is richer in AT pairs>
Sequence B
i. GC pairs (seq A) have higher required melting temp
138
What is the definition of a genome?
The information archive of the cell, encoding all the information needed for
cell structure, function, and dynamics
139
Which of the following statements is false regarding DNA cloning?
a. It involves separating a specific gene or segment from its larger chromosome
b. Uses restriction endonucleases to cut at precise locations
c. Cloning vectors must be linear DNA molecules to replicate efficiently
d. DNA ligase is used to covalently join two DNA segments
Cloning vectors must be linear DNA molecules to replicate efficiently
140
What distinguishes a cDNA library from a genomic library?
cDNA libraries contain only protein-coding genes
141
is essential in the creation of a cDNA library?
Use reverse transcriptase to synthesize DNA from mRNA
142
Which of the following is NOT a step in the Southern blotting procedure?
a. Cleaving DNA with restriction endonucleases
b. Separating DNA fragments by gel electrophoresis
c. Transferring DNA fragments to a nylon membrane
d. Synthesizing complementary DNA using reverse transcriptase
d. Synthesizing complementary DNA using reverse transcriptase
143
Which of the following is a main characteristic of lipids? a. Soluble in water
b. Composed of amino acids
c. Soluble in non-polar solvents
d. Always contain nitrogen
Soluble in non-polar solvents
144
fatty acid is considered essential and cannot be biosynthesized?
Linoleic acid
145
lipid is critical and acts as a surfactant for preventing respiratory distress
syndrome (RDS) in neonates?
Dipalmitoyl phosphatidylcholine
146
most commonly associated with vitamin D deficiency
Rickets
147
intracellular enzyme is activated by DAG following phospholipase C-mediated
cleavage of PIP₂?
Protein kinase C
148
Hydrolases
a class of enzymes that catalyze the breakdown of large molecules into smaller ones by using a water molecule to break a chemical bond
149
isomerases
a class of enzymes that catalyze the rearrangement of atoms within a single molecule to convert a substrate into an isomer, a different structural or spatial form of the same molecule
150
lyases
a class of enzymes (EC 4) that break chemical bonds through elimination reactions, not hydrolysis or oxidation, creating a new double bond or ring
151
are proteins which bind carbohydrates with high affinity and specificity; oligosaccharides often H-bond to specific areas in the
Lectins
152
involves separating a specific gene or segment from its larger chromosome, attaching it to a small carrier DNA molecule and replicating this many times so that a particular gene or segment is selectively amplified (produce many copies).
DNA cloning
153
DNA cloning steps
1.Cut at precise locations (restriction endonucleases or restriction enzymes);
2. Covalently join two DNA segments (DNA ligase);
3. Join the DNA to be cloned to plasmid or viral DNA (cloning vectors) to produce covalently linked segments;
4. Move recombinant DNA into a host which can provide the enzymes needed for DNA replication. The host may be a bacteria, yeast, mammalian cell or a virus;
5. Select/identify host cells that contain recombinant DNA, separate them and isolate the DNA.
154
Humulin
human insulin, the first biotech agent
FDA-approved
155
plasmids:
circular DNA molecules that replicate separately from the host chromosome)
156
restriction endonucleases recognise specific palindromic short DNA nucleotide sequences known as
restriction sites; they cleave DNA to produce a 3’-OH at one end and a 5’-OH at the other end, resulting in either sticky or blunt ends:
157
PCR steps
works by repeatedly cycling through three temperature steps: denaturation (unwinding DNA), annealing (primers bind to DNA), and extension (an enzyme synthesizes new DNA strands).
158
the utility of this process(PCR) is the result of using_________________Thus, the reaction consists of repeating cycles of heating and cooling which denature DNA while the polymerase remains stable.
a thermo-stable DNA polymerase isolated from thermophilic bacteria.
159
Restriction fragment length polymorphism (RFLP)
is a technique that uses restriction enzymes to cut DNA into smaller pieces, which are then separated by size to reveal variations in DNA sequences
159
why is PCR important
millions of copies of a gene or a DNA segment can be produced very efficiently starting from as low as one molecule of DNA
160
heterogenous group actually or potentially related to fatty acids (long C-chain carboxylic acids, saturated or unsaturated)
lipids
161
Main characteristics of lipids
- insoluble in H2O, soluble in non-polar solvents;
- can self-assemble in water due to the hydrophobic
effect forming bilayers, micelles, etc
162
lipids Role in organisms:
dietary
insulating material (adipose tissue
segregation and dynamic interface (membranes), transport, signaling (e.g. lipoproteins)
163
lipids dietary:
high energy value, source of vitamins and essential fatty acids (EFAs C-18 Linolenic (3 unsat) and Linoleic (2 unsat); main energy reserve of the organism
164
lipids insulating material (adipose tissue
thermal insulator, also electrical insulator for nerves)
165
lipids signaling
segregation and dynamic interface (membranes), transport, signaling (e.g. lipoproteins)
166
fatty acid
long chain carboxylic acids; the natural ones usually have an even number of C atoms due to their biosynthesis (from C2 fragments, AcCoA)
167
Eicosanoic fatty acids (EFA), especially arachidonic acid, are important precursors of
prostaglandins, leukotrienes, tromboxanes, prostacyclins – special lipids associated with inflammation and pain;
168
trans fatty acids are
rare in nature; they are produced in small quantities during lipid metabolism and during the manufacture of liquid vegetable oils and margarine. They tend to cause an increase in plasma cholesterol levels
169
are esters formed from long-chain fatty acids and long-chain alcohols, making them hydrophobic and insoluble in water. They serve a protective function in nature by creating waterproof coatings on things like plant leaves and animal feathers, and they are used industrially in products like cosmetics and polishes. Waxes
Waxes
170
primary method for storing energy in the body, insulation, and are essential for cell membranes
Triacylglycerols
171
Nucleotides
constituents of nucleic acids
mediators of energy storage and release in metabolic processes
signaling role
172
Nucleotides as building blocks of
nucleic acids
173
nucleotides requirement
very stable under a diverse range of environmental conditions
water soluble: water is an intrinsic component of life
presence of recognition (affinity) structural features that can mediate their self-association (self-assembling)
174
Nucleotides: structure
a five-carbon sugar, a phosphate group, and a nitrogenous base
175
purines
nitrogenous compounds that are essential for building DNA and RNA, with adenine and guanine being the two main examples. They are found naturally in the body and in certain foods, and are broken down into uric acid.
176
pyrimidines
Pyrimidine is the parent compound for the pyrimidine bases cytosine, thymine, and uracil.
Cytosine and thymine are found in DNA.
Cytosine and uracil are found in RNA.
176
DNA is resistant because it lacks
the 2’-OH’s; DNA fragments
of old fossils, mummies can be retrieved intact → anthropology, history
177
Nucleosides
organic molecules essential for life, composed of a nitrogenous base (a purine or pyrimidine) and a five-carbon sugar (ribose or deoxyribose)
178
DNA became the preferred molecule for storing genetic information due
to its superior stability
179
which is older DNA or RNA
RNA
180
a non-coding RNA molecule that acts as an adapter in protein synthesis, linking messenger RNA (mRNA) codons to their corresponding amino acids
transfer –RNA (tRNA)
181
is a single-stranded RNA molecule that carries genetic information from DNA in the nucleus to the cytoplasm to direct protein synthesis
Messenger–RNA (mRNA)
182
Reversible denaturation of DNA
called renaturation or reannealing, which occurs when the denaturing agent is removed and the temperature is slowly decreased
183
DNA hybridization
the process where two single-stranded DNA molecules with complementary sequences bond to form a double helix.
184
Non-enzymatic reactions of nucleotides
template-directed primer extension for synthesizing RNA and DNA, and spontaneous reactions like the hydrolysis of activated nucleotides or the formation of cyclic intermediates
185
Alkylation of DNA, alkylating agents and DNA damage
alkyl group is added to DNA, caused by alkylating agents, which are found in the environment, the body, or used as chemotherapy drugs
186
DNA polymerase____________repair the alkylated strands
cannot
187
Xeroderma pigmentosum:
lack of UV-specific endonuclease which repairs thymine dimers
188
Other functions of nucleotides
1. Energy storage
2. Redox coenzymes
3. Regulatory Nucleotides
189
acts as an anticancer agent by several mechanisms, primarily through intercalating into DNA to cause breaks and inhibit DNA replication and transcription. It also inhibits the enzyme topoisomerase II, which is crucial for DNA repair, and generates free radicals that cause oxidative damage to DNA, cell membranes, and proteins.
Doxorubicin
190
benign
non cancerous
190
affected tissues:
malign(ant), malignancies, neoplasms, tumors
191
drugs
oncologic drugs, oncolytics, antineoplastics, cytotoxic agents, chemotherapeutic agents (Chemo), anti-cancer agents;
191
Mechlorethamine
also known as nitrogen mustard, is an anticancer chemotherapy drug and the prototype of the alkylating agents class. It works by damaging the DNA of cancer cells to slow or stop their growth, eventually destroying them.
192
the process of making multiple, identical copies of a specific piece of DNA, such as a gene. The general process involves cutting a DNA fragment, inserting it into a "vector" like a bacterial plasmid, and then introducing this recombinant DNA into a host cell (like bacteria) to be copied as the host replicates. This technique is used in biotechnology for applications like creating insulin for treating diabetes.
DNA clonning
193
The glucose and galactose are:
A. Ketoses
B. Epimers
C. Tetroses
D. Anomers
B. Epimers
193
Niacin deficiency, also known as ________________________________, is caused by an inadequate intake of niacin or tryptophan, an amino acid that can be converted to niacin in the body.
pellagra
193
How many stereoisomers have ribose?
A. 2
B. 4
C. 6
D. 8
E. 16
D. 8
194
Which statement is true about nucleic acids?
A. The nucleotides are linked via carboxylic bonds
B. The sequence is read from 3′ to 5′
C. They are neutral compounds at physiologic pH (7.4)
D. RNA is not resistant to alkaline hydrolysis because of the presence of 2′-OH
group
RNA is not resistant to alkaline hydrolysis because of the presence of 2′-OH
group
195
Which of the following statements about the structure of lipids is true:
A. Waxes do not contain any alcohol
B. Sphingolipids contain an amide bond
C. Fats contain only saturated fatty acids
D. Phospholipids always contain disaccharides
E. Sphingolipids may contain glycerol
B. Sphingolipids contain an amide bond
195
Which statement is false about arachidonic acid:
A. It is usually freed from lipids by phospholipase A₂
B. It is an omega-6 unsaturated fatty acid
C. It can be transformed into thromboxanes
D. It is a trans fatty acid
E. It can be found in the structure of membrane phospholipids
D. It is a trans fatty acid
195
Which of the following statements about fatty acids is true:
A. Melting point of fatty acids decreases with the increase of chain length
B. All fatty acids can be biosynthesized by humans
C. The unsaturated natural fatty acids always have cis double bonds
D. There are no fatty acids in the structure of natural waxes
C. The unsaturated natural fatty acids always have cis double bonds
196
The process of Southern blotting does not involve:
A. Gel electrophoresis of DNA fragments
B. Radiolabeled DNA probes
C. Restriction endonucleases
D. Alkaline digestion of RNA strands
E. An X-ray film
D. Alkaline digestion of RNA strands
197
The process of making a cDNA library does not involve:
A. A treatment with alkali (base)
B. A reverse transcriptase
C. Oligo dA primers
D. A DNA polymerase
D.A DNA polymerase
197
DNA cloning does not require:
A. A restriction endonuclease
B. A ligase
C. A cloning vector
D. A host that will receive the recombinant plasmid DNA, such as a bacterium
E. mRNA
E. mRNA
198
Which of the following nucleotides is not present in RNA:
A. G
B. A
C. C
D. T
D. T
199
Which of the following processes does occur in cells spontaneously:
A. Depurination of DNA
B. Alkylation of DNA with nitrogen mustards
C. Deamination of DNA following nitrosylation
D. Denaturation of DNA
A. Depurination of DNA
199
If a DNA has a CG repeating sequence (e.g., CGCGCGCGCG) then this DNA
will be (in cross-section):
A. Thicker than normal DNA
B. Thinner than normal DNA
C. No change in cross section of DNA would be observed
D. Curved or bent
B. Thinner than normal DNA
199
What statement is false about enzymes as catalysts?
A) Enzymes increase the rate of both direct and inverse reactions
B) Enzymes help to reach thermodynamic equilibrium faster
C) Enzymes increase reaction rates without being used up
D) Enzymes increase activation energy of the reactions they catalyze
D) Enzymes increase activation energy of the reactions they catalyze
199
Which of the following statements is false:
A. Deamination of DNA
B. Depurination of DNA
C. Methylation of DNA
D. UV cross-linking of nitrogen bases in DNA
C. Methylation of DNA
199
Which statement is false about allosteric regulation of enzymes?
A) Allosteric regulators bind in a site different from the substrate
B) Allosteric regulation can be positive or negative
C) Allosteric regulation can modify the enzyme fold
D) Allosteric regulators can denature the enzyme
D) Allosteric regulators can denature the enzyme
199
The affinity of an enzyme for its substrate is defined by:
A) Kcat
B) Km
C) Vmax
D) kcat/Km
D) kcat/Km
199
The Michaelis-Menten equation of enzyme kinetics does not involve:
A) Km
B) Vmax
C) [S] (substrate concentration)
D) [E] (enzyme concentration)
D) [E] (enzyme concentration)
199
Which statement is true related to the involvement of enzymes in biochemical
reactions?
A) Enzyme active sites are not complementary to the transition state of the
reaction catalyzed
B) Enzymes bind transition states best
C) Activation energy of a biochemical reaction does not change when an enzyme
catalyzes it
D) Enzymes bind substrate better than transition states
B) Enzymes bind transition states best
199
Which ion cannot serve as an enzyme cofactor?
A) Fe²⁺
B) Mg²⁺
C) Zn²⁺
D) Li⁺
D) Li⁺
199
Which of the following statements is false about the catalytic activity of
enzymes?
A) Catalytic activity depends on the integrity of the native fold
B) All primary, secondary, tertiary, and quaternary structures are important for
catalysis
C) Sometimes catalytic activity depends on the presence of prosthetic groups
D) Only proteins can catalyze reactions and display catalytic activity
D) Only proteins can catalyze reactions and display catalytic activity
199
Which statement is false about biocatalysis with enzymes compared with
catalysis with inorganic catalysts?
A) Enzymes ensure higher reaction rates
B) Enzymes have a lower reaction specificity
C) Enzymes require milder reaction conditions
D) Enzymes ensure capacity for regulation and control of biological pathw
B) Enzymes have a lower reaction specificity
199
Polymerization of nucleotides does not involve:
A. A pyrophosphate leaving group
B. NTPs
C. Hydrolysis of a pyrophosphate into two phosphate groups
D. Hydrolysis of ATP
D. Hydrolysis of ATP
200
What would be the approximate Keq for the biosynthesis of DNA and RNA
from NTP (per 1 nucleotide elongation):
A. 1,000
B. 100,000
C. Reaction is not thermodynamically possible
D. 10
E. Over 1,000,000
E. Over 1,000,000
200
One reason for which ATP likes to lose its terminal phosphate cannot be:
A. Ionization of products
B. Resonance stabilization of products
C. Charge attraction in ATP
D. Solvation of products
C. Charge attraction in ATP
201
If the Keq of a reaction is 100 then that reaction:
A. Proceeds forward
B. Proceeds backward
C. Is at equilibrium
D. It does not matter
A. Proceeds forward
201
Which of the following reactions does not occur in biochemistry:
A. Group transfer reactions
B. Redox reactions
C. Nuclear reactions
D. Isomerization reactions
E. Reactions with C–C bond breakage
C. Nuclear reactions
202
Kcat
The maximum number of substrate molecules that can be converted into product per enzyme molecule per second when the enzyme is saturated with substrate.
202
Which process uses S-adenosylmethionine?
A. Catabolism generates highly reduced species with long hydrocarbon chains
B. Anabolism occurs with consumption of energy
C. Anabolism forms macromolecules needed for cell functions
D. Catabolism produces chemical energy
E. Catabolism is convergent
A. Catabolism generates highly reduced species with long hydrocarbon chains
202
Which of the following statements is false:
A. Metabolic pathways are used to obtain chemical energy
B. Metabolic pathways are used to polymerize monomeric precursors into
macromolecules
C. Catabolism is exergonic
D. Anabolism is oxidative
D. Anabolism is oxidative
203
Km
The substrate concentration at which the reaction velocity is half of its maximum value (Vmax).
204
kcat/Km
A measure of an enzyme's catalytic efficiency and specificity for a particular substrate under conditions where the substrate concentration is much lower than km
204
Vmax
The maximum reaction rate of an enzyme-catalyzed reaction when the enzyme active sites are fully saturated with substrate.
205
Phosphorylation and dephosphorylation are examples of _____________________ covalent modifications.
reversible
206
Proteolytic cleavage (e.g., activation of trypsin from trypsinogen) is an ____________________ modification
irreversible
207
So if enzyme A has Km = 0.1 mM and enzyme B has Km = 10 mM,
which will reach 1/2 vmax faster
enzyme A binds substrate tighter and reaches ½ Vmax faster.
208
Low Km →
High affinity (enzyme binds substrate easily)
209
High Km →
Low affinity (enzyme needs more substrate to reach ½ Vmax)
210
Vmax happens when
every enzyme molecule is bound to substrate (enzyme is “saturated”).
Adding more substrate won’t make the reaction faster beyond this point.
211
Enzyme Efficiency:
kcat
(turnover number) = how many substrate molecules one enzyme converts to product per second.
212
kcat/Km =
combines speed and affinity — the higher, the better the enzyme.
213
At low [S], v
increases almost linearly.
214
At high [S], the enzyme saturates
→ v plateaus at Vmax.
215
types of enzyme regulators
noncovalent modification (allosteric)
covalent modification
irreversible
reversible
216
Reversible inhibitors can be classified into:
Competitive
Uncompetitive
Mixed
217
react with the enzyme.
One inhibitor molecule can permanently shut off one enzyme molecule (suicide inhibitors)
Irreversible inhibitors (inactivators)
218
straight-line version used to calculate Km and Vmax.
Lineweaver–Burk
219
noncompetitive vs uncompetitive inhibitors
noncompetitive(mixed) inhibitors can bind to either the free enzyme ((E)) or the enzyme-substrate complex ((ES)), while uncompetitive inhibitors can only bind to the enzyme-substrate complex ((ES))
220
two sugars (sucrose, lactose)
Disaccharides
221
single chain with aldehyde or ketone group
Monosaccharides
222
two monosaccharides linked by glycosidic bond
Disaccharides
223
long chains (branched or unbranched) of monosaccharides
Polysaccharides
224
Structural isomers
(different arrangement of atoms)
225
Stereoisomers
(same formula, different 3D arrangement)
226
Enantiomers:
mirror images (D- and L- forms)
227
Epimers:
differ at one chiral carbon
228
Configuration
fixed spatial arrangement (D or L form)
229
Configuration
rotation around bonds in cyclic form (α or β anomers)
230
How do monosaccharides form cyclic structures?
A hydroxyl group reacts with the carbonyl group (aldehyde or ketone) forming a hemiacetal (aldose) or hemiketal (ketose) ring.
231
What are anomers
Anomers are cyclic isomers that differ at the anomeric carbon:
232
–OH group points up (same side as CH₂OH)
β-anomer:
233
–OH group points down (opposite side from CH₂OH)
α-anomer:
234
What is mutarotation?
The spontaneous interconversion between α and β anomers in aqueous solution through the open-chain form.
235
Which sugar derivatives can be produced from hexoses?
Which sugar derivatives can be produced from hexoses?
Sugar alcohols (e.g., sorbitol)
Sugar acids (e.g., gluconic acid)
Amino sugars (e.g., glucosamine)
Deoxy sugars (e.g., deoxyribose)
236
Sugar alcohols
(e.g., sorbitol)
237
Sugar acids
(e.g., gluconic acid)
238
Amino sugars
(e.g., glucosamine)
239
Deoxy sugars
(e.g., deoxyribose)
240
What are the structural and functional roles of these sugar derivatives?
They participate in energy metabolism, structural components of cell walls, glycoproteins, and signaling molecules.
241
What are the reduction properties of monosaccharides?
Reducing sugars can donate electrons (reducing agents).
242
What are the oxidation properties of monosaccharides?
Aldoses can be oxidized to acids; reduction forms sugar alcohols.
243
How are these redox properties used for glucose monitoring?
Tests like Benedict’s test or Clinitest detect reducing sugars by color change due to Cu²⁺ → Cu⁺ reduction. Glucose oxidase-based strips use oxidation to measure glucose levels.
244
How are carbohydrates classified?
By number of sugar units: monosaccharides (1), disaccharides (2), oligosaccharides (3–10), and polysaccharides (many).
245
What are the main structural features distinguishing each class of carbohydrates?
Monosaccharides: single chain; Disaccharides: two sugars with glycosidic bond; Polysaccharides: long chains, branched or unbranched.
246
What types of isomerism exist in monosaccharides?
Structural isomers, stereoisomers (enantiomers, epimers).
247
What are configuration isomers vs. conformation isomers in monosaccharides?
Configuration: D or L forms (fixed); Conformation: α or β anomers (ring orientation).
248
What is mutarotation?
Interconversion between α and β anomers in aqueous solution via open-chain form.
249
Which sugar derivatives can be produced from hexoses?
Sugar alcohols, sugar acids, amino sugars, deoxy sugars.
250
What are the structural and functional roles of these sugar derivatives?
Energy metabolism, structural roles, signaling, and as components of glycoproteins and cell walls.
251
What are the oxidation and reduction properties of monosaccharides?
Reducing sugars can donate electrons; aldoses oxidize to acids and reduce to sugar alcohols.
252
How are redox properties used for glucose monitoring?
Tests like Benedict’s or glucose oxidase-based strips detect glucose via oxidation–reduction reactions causing color change.
253
What defines disaccharides and how are they linked?
Two monosaccharides joined by O-glycosidic bonds (e.g., maltose α1→4, lactose β1→4, sucrose α1→2).
254
How do polysaccharides differ in structure and function?
Starch and glycogen are branched energy storage forms; cellulose is linear and structural.
255
What are physiological roles of structural vs. storage polysaccharides?
Structural (cellulose, chitin) provide support; storage (starch, glycogen) store energy.
256
What are glycoconjugates and their major classes?
Carbohydrates covalently linked to biomolecules: glycoproteins, glycolipids, proteoglycans.
257
What are the roles of glycoconjugates in cells and tissues?
Involved in cell recognition, signaling, immune defense, and structural integrity.
258
How are carbohydrate-related diseases connected to metabolism?
Diabetes: impaired glucose metabolism; bacterial infection: adhesion via sugars; heart disease: altered glycosylation.
259
Which carbohydrate-related or glycosylated drugs are important?
Penicillins, Digoxin, Heparin, Low Molecular Weight Heparins, and Eptifibatide.
260
What are β-lactamase inhibitors and how do they help antibiotics?
They block β-lactamase enzymes that degrade penicillins, protecting the antibiotic (e.g., Amoxicillin + Clavulanic acid = Augmentin).
261
How does Digoxin work in treating heart failure and atrial fibrillation?
It inhibits Na⁺/K⁺ ATPase, increasing intracellular Ca²⁺ and strengthening cardiac contractions.
262
What is the mechanism and use of heparin and LMWH?
They enhance antithrombin III activity to prevent clot formation; used as anticoagulants.
263
Which diagnostic tests use carbohydrate chemistry for glucose measurement?
Clinitab, Dextrostix, Clinistix, Tes-Tape, OneTouch glucose meters.
264
How do these glucose tests work chemically?
They detect glucose through oxidation by glucose oxidase or reduction of Cu²⁺ to Cu⁺ in older tests.
265
How do carbohydrates play a role in thrombosis, viral infections, or gastric diseases?
Carbohydrate molecules on cell surfaces mediate pathogen binding; bacterial peptidoglycan contributes to infection; abnormal glycosylation can promote cancer.
266
How are carbohydrate-related diseases connected to metabolism?
Diabetes: impaired glucose metabolism
Bacterial infections: pathogens use surface carbohydrates to adhere
Heart disease: altered glycosylation affects signaling and inflammation
267
(proteins + carbs)
Glycoproteins
268
(lipids + carbs)
Glycolipids
269
(core protein + long polysaccharide chains)
Proteoglycans (core protein + long polysaccharide chains)
270
What are carbohydrates, and what major biological roles do they play in living organisms?
Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen (CH₂O)n. They serve as energy sources (e.g., glucose), energy storage (e.g., glycogen, starch), structural materials (e.g., cellulose), and components of nucleic acids and cell membranes.
271
what are the physiological roles of structural vs. storage polysaccharides?
Structural: provide support (cellulose, chitin)
Storage: reserve energy (starch in plants, glycogen in animals)
272
Natural sugars are
D
273
Relative configuration that determines L or D
Distant chiral carbon oh
274
T or false alpha and beta are different configurations (not conformations)
they are diastereomers and can only be inter-converted by bond cleavage.
True
275
"up" or "down”
Axial
276
is "sideways
equatorial
277
basis of Clinitab® test for measuring urine glucose levels
Fehling’s reaction - copper is reduced from +2 to +1 thus glucose is a reducing sugar
278
When are reducing properties of a sugar displayed?
Reducing properties are displayed only if the sugar can adopt an acyclic form.
For cyclic forms, the glycosidic OH must be free (not involved in a glycosidic bond
279
Starch (amylose + amylopectin) and glycogen are
storage polysaccharides in plant and animal cells:
280
Amylopectin
highly branched, complex carbohydrate that makes up a major part of plant starch
281
a versatile polysaccharide derived from chitin, primarily used in biomedical applications, agriculture, and water treatment due to its biocompatibility, biodegradability, and antimicrobial properties
chitusan
282
How does pencilin work
polysaccharide chain cross-linking (step 8) inhibited by penicillins thus weakening the bacterial cell wall
283
Suicide inhibitor (penicillins ) Overcoming bacterial resistance:
use a suicide inhibitor of b-lactamase (clavulanic acid) to preserve the potency of an antibiotic:
284
has utility in preventing platelet aggregation
and blood clots in order to reduce the risk of acute cardiac ischemic events (together with aspirin, heparin). It is approved for use during surgical installation of coronary stents among other uses.
an integrin blocker Eptifibatide (Integrilin®)
285
How does helicobacter.p cause inflammation
- the bacterium adheres to the gastric surface through the interaction of a surface lectin and a blood group antigen (glycoconjugated) of the gastric epithelium
286
Lack of Vitamin D demineralization of bone tissue: skeletal deformities, delayed growth, high risk of bone fracture, dental problems, muscle weakness
- this vitamin is added to foods routinely
Ricketts
287
Essential for vision, especially in low light
Supports immune function
Promotes healthy skin and mucous membranes
Plays a role in cell growth and differentiation
Vitamin A
288
Lipids are best defined as:
Hydrophobic or amphipathic molecules composed mostly of hydrocarbons
289
One main physiologic role of lipids is:
Long-term energy storage
290
Fatty acids are composed of:
A hydrocarbon chain with a terminal carboxyl group
291
An essential fatty acid is one that:
Must be obtained from the diet
292
Omega-3 and Omega-6 fatty acids differ in:
The position of the first double bond from the methyl end
293
Fatty acids self-assemble into micelles because:
They have both hydrophobic and hydrophilic regions (amphipathic)
294
A triglyceride consists of:
Three fatty acids linked to glycerol
295
Main role of triglycerides:
Long-term energy storage and insulation
296
Waxes are:
Fatty acids esterified to long-chain alcohols
297
Key structural feature of glycerophospholipids:
Two fatty acids and a phosphate-containing head group
298
Main biological role of glycerophospholipids:
Forming cell membranes
299
Sphingolipids contain:
A sphingosine backbone
300
Phospholipase specificity refers to:
Selective digestion of specific bonds in phospholipids
301
Glycosphingolipids play a role in:
Cell recognition and signaling (e.g.
302
Sterols are characterized by:
Four fused hydrocarbon rings
303
A major physiological role of cholesterol is:
Maintaining membrane fluidity
304
Steroid hormones are derived from:
Cholesterol
305
Respiratory Distress Syndrome in infants is caused by deficiency of:
DPPC (Dipalmitoylphosphatidylcholine)
306
Lack of DPPC leads to:
Increased alveolar surface tension and alveolar collapse
307
Thrombosis is influenced by lipid metabolism because:
Eicosanoids regulate platelet aggregation
308
Leukotrienes involved in asthma are derived from:
Arachidonic acid
309
Rickets is caused by deficiency of:
Vitamin D
310
Synthetic DPPC is used to treat:
Neonatal Respiratory Distress Syndrome
311
Linoleic and linolenic acids are:
Essential fatty acids
312
Prednisone and prednisolone are:
Corticosteroid drugs derived from cholesterol
313
Calcitriol (Rocaltrol) is the active form of:
Vitamin D
314
Primary role of Vitamin E is:
Antioxidant protection of cell membranes
315
Vitamin K1 is directly involved in:
Blood clotting factor activation
316
Warfarin functions as:
An inhibitor of Vitamin K–dependent clotting factor activation
317
Coenzyme Q (Ubiquinone) is essential for:
Electron transport chain and ATP production
318
A gene is best defined as:
A sequence of DNA that encodes a functional product
319
A genome refers to:
The complete set of DNA in an organism
320
A chromosome is:
A DNA molecule packaged with proteins (histones)
321
The flow of genetic information in vivo normally follows:
DNA → RNA → Protein
322
DNA cloning involves:
Producing multiple identical copies of a DNA fragment
323
A plasmid used for cloning must contain:
An origin of replication and selectable marker
324
A key implication of DNA cloning in biotechnology is:
It allows production of recombinant proteins (e.g., insulin)
325
Restriction endonucleases recognize:
Specific short DNA palindromic sequences
326
When restriction enzymes cut DNA, they often create:
Sticky or blunt ends
327
One consequence of restriction enzyme cleavage is:
DNA fragments can be ligated into vectors
328
RFLP is used primarily for:
DNA sequence variation and genetic fingerprinting
329
RFLP significance lies in:
Identifying individual genetic differences
330
A DNA library is:
A collection of DNA sequences cloned into vectors
331
A cDNA library represents:
Only genes expressed as mRNA
332
A genomic library differs from a cDNA library because it contains:
Introns and regulatory sequences as well
333
PCR is used to:
Amplify specific DNA sequences
334
A key enzyme required for PCR is:
DNA polymerase resistant to high temperature
335
The correct order of PCR steps is:
Denaturation → Annealing → Extension
336
Recombinant DNA technology allows production of:
Insulin, growth hormone, monoclonal antibodies
337
Proteomics refers to the study of:
All proteins expressed in a cell
338
Metabolomics focuses on:
Small molecules and metabolic intermediates
339
A gene is best defined as:
A sequence of DNA that encodes a functional product
340
A genome refers to:
The complete set of DNA in an organism
341
A chromosome is:
A DNA molecule packaged with proteins (histones)
342
The flow of genetic information in vivo normally follows:
DNA → RNA → Protein
343
DNA cloning involves:
Producing multiple identical copies of a DNA fragment
344
A plasmid used for cloning must contain:
An origin of replication and selectable marker
345
A key implication of DNA cloning in biotechnology is:
It allows production of recombinant proteins (e.g., insulin)
346
Restriction endonucleases recognize:
Specific short DNA palindromic sequences
347
When restriction enzymes cut DNA, they often create:
Sticky or blunt ends
348
One consequence of restriction enzyme cleavage is:
DNA fragments can be ligated into vectors
349
RFLP is used primarily for:
DNA sequence variation and genetic fingerprinting
350
RFLP significance lies in:
Identifying individual genetic differences
351
A DNA library is:
A collection of DNA sequences cloned into vectors
352
A cDNA library represents:
Only genes expressed as mRNA
353
A genomic library differs from a cDNA library because it contains:
Introns and regulatory sequences as well
354
PCR is used to:
Amplify specific DNA sequences
355
A key enzyme required for PCR is:
DNA polymerase resistant to high temperature
356
The correct order of PCR steps is:
Denaturation → Annealing → Extension
357
Recombinant DNA technology allows production of:
Insulin, growth hormone, monoclonal antibodies
358
Proteomics refers to the study of:
All proteins expressed in a cell
359
Metabolomics focuses on:
Small molecules and metabolic intermediates
360
What are the three components of a nucleotide?
Nitrogenous base + Pentose sugar + Phosphate group(s)
361
What is the difference between a nucleoside and a nucleotide?
Nucleoside = base + sugar; Nucleotide = base + sugar + phosphate
362
Which bases are purines?
Adenine and Guanine (two-ring structures)
363
Which bases are pyrimidines?
Cytosine, Thymine, and Uracil (one-ring structures)
364
Which base is found in DNA but NOT RNA?
Thymine
365
Which base is found in RNA but NOT DNA?
Uracil
366
What sugar is found in DNA?
Deoxyribose (lacks OH on 2' carbon)
367
What sugar is found in RNA?
Ribose (contains OH on 2' carbon)
368
List the nucleotides in DNA.
A, G, C, T
369
List the nucleotides in RNA.
A, G, C, U
370
What is the role of 5-methylcytosine in DNA?
Epigenetic regulation of gene expression
371
What is the role of modified bases such as pseudouridine and inosine in RNA?
Help stabilize folding and improve translation accuracy, especially in tRNA
372
What are the major roles of nucleotides besides being DNA/RNA building blocks?
Energy carriers (ATP), second messengers (cAMP), coenzyme components (NAD+, FAD)
373
What structural difference makes RNA less stable than DNA?
RNA has a 2' OH group which increases reactivity
374
Is DNA double-stranded or single-stranded?
Double-stranded
375
Is RNA double-stranded or single-stranded?
Usually single-stranded
376
Describe B-DNA.
Most common form, right-handed helix
377
Describe A-DNA.
Right-handed, more compact, seen in dehydrated conditions
378
Describe Z-DNA.
Left-handed helix, forms under high GC content or supercoiling stress
379
What unusual DNA structures occur at palindromic sequences?
Hairpins and cruciforms
380
What structure can form in G-rich telomeres?
G-quadruplexes
381
List common RNA secondary structures.
Hairpins, stem-loops, bulges, pseudoknots
382
What are the three main structural regions of mRNA?
5' cap, coding region, 3' poly-A tail
383
What is DNA melting (denaturation)?
Separation of strands due to heat
384
What does melting temperature (Tm) indicate?
GC content (higher GC = higher Tm)
385
What is DNA renaturation (annealing)?
Rejoining of complementary strands when cooled
386
What is deamination?
Loss of an amino group, e.g., cytosine → uracil
387
What is depurination?
Loss of a purine base from DNA (A or G)
388
What causes oxidative DNA damage?
Reactive oxygen species (ROS)
389
How does UV radiation damage DNA?
Causes thymine dimers that block replication
390
What disease results from failure to repair UV damage?
Xeroderma pigmentosum
391
How do alkylating agents like mechlorethamine damage DNA?
They crosslink DNA strands, preventing replication
392
How do intercalators like doxorubicin work?
They insert between DNA bases and block replication
393
What does 5-fluorouracil inhibit?
Thymine synthesis (pyrimidine analog)
394
What does 6-mercaptopurine inhibit?
Purine synthesis
395
Which disease is commonly linked to DNA damage and mutations?
Cancer
Med Chem
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