1
Q
What is the definition of biochemistry?
A
A blend of biology and chemistry that helps understand complex biological processes
Principles in biochemistry are essential for understanding life.
2
Q
What are the three main components of an atom?
A
- Protons
- Neutrons
- Electrons
Protons and neutrons make up the nucleus, while electrons reside in the electron cloud.
3
Q
What is the charge of protons, neutrons, and electrons?
A
- Protons: Positive
- Neutrons: Neutral
- Electrons: Negative
These charges determine the interactions between atoms.
4
Q
What is an electron shell?
A
A region around an atom’s nucleus where electrons reside
Each shell can hold a specific number of electrons, affecting atomic reactivity.
5
Q
Define electronegativity.
A
A measure of an atom’s ability to pull electrons towards itself
Atoms with high electronegativity are more reactive.
6
Q
What type of bonding occurs when an atom gives up an electron to another atom?
A
Ionic bonding
This type of bond forms when one atom becomes positively charged and the other negatively charged.
7
Q
What is covalent bonding?
A
A type of bonding where atoms share electrons
This occurs between atoms with similar electronegativity values.
8
Q
In a water molecule (H2O), which atom has a higher electronegativity?
A
Oxygen
This leads to polar covalent bonding and the formation of a polar molecule.
9
Q
What is a polar molecule?
A
A molecule with both positive and negative charges
Water is an example, with partial charges due to unequal electron sharing.
10
Q
What are hydrogen bonds?
A
Weak bonds formed between the positive end of one water molecule and the negative end of another
These bonds are crucial for water’s unique properties.
11
Q
Define cohesion in the context of water.
A
The tendency of water molecules to stick together
This property is due to hydrogen bonding.
12
Q
What is adhesion?
A
The ability of water to stick to other substances
This property helps in processes like water movement in plants.
13
Q
What does surface tension refer to?
A
The difficulty of breaking the surface of water due to hydrogen bonding
This allows certain insects to walk on water.
14
Q
What is specific heat?
A
The amount of thermal energy required to change a substance’s temperature
Water has a high specific heat due to strong hydrogen bonds.
15
Q
What is evaporative cooling?
A
The process where water absorbs thermal energy to evaporate, cooling the remaining liquid
This is important for temperature regulation in organisms.
16
Q
What is the role of hydrogen bonds in water’s high specific heat?
A
They require a large amount of thermal energy to break before temperature increases
This property helps maintain stable temperatures in environments.
17
Q
What is the process called where water requires a large amount of thermal energy to evaporate?
A
Evaporative Cooling
This occurs due to hydrogen bonds needing to break before water molecules can separate and evaporate.
18
Q
Water’s solid form, ice, is less dense than its liquid form due to what type of bonding?
A
Hydrogen bonding
This unique property allows ice to float on water, which is crucial for polar environments.
19
Q
In the equation 2H2O → H3O+ + OH−, what does the process represent?
A
Ionization of water
This process forms hydronium and hydroxide ions, changing the properties of the solution.
20
Q
An acid is defined as a molecule that, when added to water, does what?
A
Adds H+ to the solution
This results in a greater concentration of H+ compared to OH−.
21
Q
What is the pH of a neutral solution of water?
A
7
This is determined by the equal concentration of H+ and OH− ions.
22
Q
True or false: A base is a molecule that, when added to water, increases the concentration of H+ ions.
A
FALSE
A base increases the concentration of OH− ions instead.
23
Q
What is the relationship between pH and H+ concentration expressed in the equation?
A
pH = − log[H+]
This equation allows for quantifying acidity in solutions.
24
Q
What is the term for the conjugate base of acetic acid?
A
Acetate
Acetic acid can donate H+ ions, turning into acetate.
25
According to **Le Chatelier’s principle**, what happens when a system at equilibrium is subjected to a change?
The system adjusts to counteract the change
## Footnote
This helps restore equilibrium.
26
What does the **Henderson-Hasselbalch equation** relate?
pH, pKa, and the ratio of base to acid concentration
## Footnote
It is useful for determining buffer systems.
27
What is the **pI** of an amino acid?
The pH at which it is electrically neutral
## Footnote
At this point, the amino acid exists as a zwitterion.
28
What type of acids completely dissociate in solution, such as hydrochloric acid?
Strong acids
## Footnote
They release H+ ions completely when dissolved.
29
Amino acids are considered **diprotic** because they can do what?
Give and take up to two H+ ions
## Footnote
This allows them to act as buffers in two pH ranges.
30
What is the significance of the **half-equivalence point** on a titration curve?
pH = pKa
## Footnote
This indicates the buffer solution contains equal concentrations of acid and conjugate base.
31
What is the **K a** value in relation to acids?
Acid dissociation constant
## Footnote
It measures how well an acid can release H+ ions.
32
In a titration curve, what does a **buffer region** indicate?
Flat region where pH changes minimally with added strong base
## Footnote
This shows the effectiveness of the buffer.
33
What is the **zwitterion form** of an amino acid?
The form where the amino acid has both a positive and a negative charge
## Footnote
This occurs at the **isoelectric point (pI)** of the amino acid.
34
How can the **pI** of an amino acid be calculated?
By finding the average of both **pK a values**
## Footnote
Understanding pI is crucial for predicting an amino acid’s behavior in different pH environments.
35
True or false: Amino acids can only act as effective acid-base buffers when combined with other diprotic bases.
FALSE
## Footnote
Amino acids can act as buffers at pH values around their **pK a values**.
36
What are the **three types** of amino acids based on their pK a values?
* Diprotic
* Triprotic
* Polyprotic
## Footnote
The classification depends on the number of **disassociation constants (K a)** they possess.
37
What are the **four main classes** of biological macromolecules?
* Carbohydrates
* Lipids
* Proteins
* Nucleic Acids
## Footnote
These macromolecules are essential for various biological processes.
38
What are the **monomers** of carbohydrates called?
Monosaccharides
## Footnote
Examples include glucose, fructose, and galactose.
39
What are the **polymers** of carbohydrates known as?
Polysaccharides
## Footnote
Common examples include starch, cellulose, and glycogen.
40
What is the process called when monomers are bonded together to form larger molecules?
Dehydration synthesis
## Footnote
This process requires energy to remove water and form covalent bonds.
41
What is the opposite process of dehydration synthesis?
Hydrolysis
## Footnote
Hydrolysis involves adding water to split molecules and release energy.
42
What are the **three important types** of lipids?
* Fats
* Phospholipids
* Steroids
## Footnote
Each type plays a crucial role in biological functions.
43
What is a **triglyceride** composed of?
One glycerol molecule and three fatty acids
## Footnote
Triglycerides are a major form of fat storage in organisms.
44
What distinguishes **saturated fats** from **unsaturated fats**?
Saturated fats have no double bonds between carbon atoms
## Footnote
Unsaturated fats contain one or more double bonds, causing kinks in their structure.
45
What is the structure of a **phospholipid**?
A glycerol backbone, two fatty acids, and a phosphate group
## Footnote
Phospholipids are amphipathic, having both hydrophobic and hydrophilic regions.
46
What is the primary function of **phospholipid bilayers**?
To form cell membranes
## Footnote
This structure is essential for cellular compartmentalization.
47
What are **steroids** characterized by?
Four interconnected carbon rings
## Footnote
Cholesterol and hormones like testosterone and estrogen are examples of steroids.
48
What are the **monomers** of proteins?
Amino acids
## Footnote
There are twenty unique amino acids, each with distinct properties.
49
What is the process of forming proteins from amino acids called?
Protein folding
## Footnote
The structure and function of proteins depend on the sequence of amino acids.
50
What are the **monomers** of nucleic acids?
Nucleotides
## Footnote
Nucleotides consist of a pentose sugar, a nitrogenous base, and a phosphate group.
51
What are **nucleic acids** the basis of?
Genetic code
## Footnote
Nucleic acids allow the phenomena of evolution and heredity to occur.
52
What are the **monomers** of nucleic acids called?
Nucleotides
## Footnote
Nucleotides consist of a pentose sugar, a nitrogenous base, and a phosphate group.
53
Name the two types of **nitrogenous bases**.
* Pyrimidines
* Purines
## Footnote
Pyrimidines include cytosine (C), thymine (T), and uracil (U); purines include adenine (A) and guanine (G).
54
What are **polymers** made from nucleic acid monomers called?
Polynucleotides
## Footnote
Notable examples include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
55
What type of bond joins **nucleotides** together?
Phosphodiester bonds
## Footnote
These bonds are formed through dehydration synthesis and create the sugar phosphate backbone.
56
In DNA, the pentose sugar is known as _______.
Deoxyribose
## Footnote
DNA has a double helix structure formed by two polynucleotide strands.
57
What is the process called where two strands of DNA are connected by their **nitrogenous bases**?
Base pairing
## Footnote
In DNA, adenine pairs with thymine, and cytosine pairs with guanine.
58
In RNA, which nitrogenous base replaces **thymine**?
Uracil
## Footnote
The pentose sugar in RNA is ribose instead of deoxyribose.
59
True or false: The order of **nitrogenous bases** in DNA is the basis of our genetic code.
TRUE
## Footnote
This order is transcribed into RNA, which acts as instructions for amino acid and protein synthesis.
60
What is the combined guanine and cytosine content if 18% of the bases in DNA are **adenine**?
64 percent
## Footnote
Since adenine pairs with thymine, 18% adenine means 18% thymine, totaling 36%, leaving 64% for guanine and cytosine.
61
What is the study of **energy flow** and energy transformations within living organisms called?
Bioenergetics
## Footnote
Understanding bioenergetics is essential for comprehending complex life processes.
62
What is the simplest definition of **energy**?
The ability or capacity to do work
## Footnote
Energy can exist in various forms, each with specific functions.
63
What type of energy is associated with **motion**?
Kinetic energy
## Footnote
Kinetic energy can do work through motion, such as a motor protein transporting molecules.
64
What is **potential energy**?
Stored form of energy
## Footnote
It is associated with the position, shape, or configuration of an object or system.
65
What type of energy is stored within the **chemical bonds** of molecules?
Chemical energy
## Footnote
Chemical energy is a type of potential energy.
66
In order to form a bond, energy must be _______.
Released
## Footnote
Conversely, breaking chemical bonds requires energy to be added.
67
To break **chemical bonds**, what must be added?
Energy
## Footnote
Adding kinetic or thermal energy results in movement, causing the bond to break.
68
What happens to the energy of a molecule with **stronger bonds**?
Contains less energy
## Footnote
Stronger bonds require a larger energy input to break apart.
69
What is the **chemical potential energy** stored in glucose released as?
Carbon dioxide (CO2) and water (H2O)
## Footnote
The breakdown of glucose forms low-energy products.
70
What does the **first law of thermodynamics** state?
Energy cannot be created nor destroyed
## Footnote
Energy is conserved and can only be converted into different forms.
71
In the context of energy, what is **entropy**?
A measure of randomness
## Footnote
Entropy tends to increase over time in a system.
72
What does the **second law of thermodynamics** state?
The entropy of a system tends to increase over time
## Footnote
This leads to greater disorder in systems.
73
What is **Gibbs free energy**?
Energy that can be used to perform meaningful work
## Footnote
It does not include thermal energy formed from entropy.
74
The equation for change in **Gibbs free energy** is ∆G = ∆H − T∆S. What does ∆G represent?
Change in Gibbs free energy
## Footnote
This value helps determine the spontaneity of a chemical reaction.
75
A chemical reaction with a **positive ∆G** value is known as what?
Non-spontaneous
## Footnote
These reactions require energy input and are called endergonic.
76
A chemical reaction with a **negative ∆G** value is known as what?
Spontaneous
## Footnote
These reactions release energy and are called exergonic.
77
What is the **equilibrium** of a chemical reaction?
When forward and reverse reactions occur at the same rate
## Footnote
This results in no net change in the concentration of products and reactants.
78
What are the **four levels of protein structure**?
* Primary
* Secondary
* Tertiary
* Quaternary
## Footnote
Each level focuses on different biochemical properties.
79
What is the **primary structure** of a protein?
The sequence of amino acids
## Footnote
This sequence determines the protein's higher-level structures.
80
What are **amino acids**?
The monomers of proteins
## Footnote
They are the smallest subunits of a polypeptide chain.
81
What are the two chemical groups that make up an **amino acid**?
* Carboxyl group
* Amine group
## Footnote
Both groups are attached to a carbon atom.
82
What are **helix breakers** in protein structure?
* Proline
* Glycine
## Footnote
These amino acids disrupt the formation of α helices.
83
What are **β pleated sheets** formed by?
Hydrogen bonds between parallel parts of a polypeptide chain
## Footnote
These structures are strong and can be found in silk proteins.
84
What is the **tertiary structure** of a protein?
The overall 3D shape formed by interactions between R groups
## Footnote
This structure is crucial for the protein's function.
85
What are **β strands** in protein structure?
Parts of a single polypeptide that line up to form β pleated sheets
## Footnote
These sheets can be strong, as seen in silk fibers made of proteins primarily composed of β pleated sheets.
86
The **tertiary structure** of a protein arises from interactions between what?
R groups of amino acids in a polypeptide
## Footnote
Tertiary structure and secondary structure can affect the protein simultaneously.
87
What type of interactions are caused by **hydrophobic interactions**?
Nonpolar and polar R groups interacting with the environment
## Footnote
Nonpolar amino acids tend to aggregate beneath polar amino acids in a polypeptide chain.
88
What are the two types of bonding that can occur in tertiary protein structure?
* Ionic bonding
* Covalent bonding
## Footnote
Ionic bonding is affected by pH, while covalent bonding can form disulfide bridges between cysteine amino acids.
89
Which amino acids can be modified through **phosphorylation**?
* Serine
* Threonine
* Tyrosine
## Footnote
Phosphate groups are hydrophilic and can influence the tertiary structure of proteins.
90
What is the **quaternary structure** of a protein?
When multiple polypeptides interact to form one aggregate protein
## Footnote
Examples include collagen and hemoglobin.
91
What is the role of **enzymes** in chemical reactions?
Catalyze reactions, speeding them up
## Footnote
Enzymes are essential for many cellular processes.
92
What are the molecules that enzymes act upon called?
Substrates
## Footnote
Each enzyme typically binds to a specific substrate.
93
What is the **active site** of an enzyme?
The specific region that binds to the substrate
## Footnote
The shape of the active site must match the substrate for proper function.
94
What are the two popular models for enzyme-substrate binding?
* Lock-and-Key hypothesis
* Induced Fit hypothesis
## Footnote
Both models describe how enzymes interact with substrates.
95
What is **Levinthal’s paradox**?
The thought experiment illustrating the complexity of protein folding
## Footnote
It suggests that polypeptides can fold into their correct conformations much faster than theoretically possible.
96
What is **catalysis**?
The acceleration of a chemical reaction by a catalyst
## Footnote
Enzymes are the primary biological catalysts in cells.
97
What does **activation energy (Ea)** refer to?
The energy required to start a chemical reaction
## Footnote
Even spontaneous reactions require an input of energy to proceed.
98
What is the effect of enzymes on **activation energy**?
They lower the amount of energy necessary to start a reaction
## Footnote
This allows reactions to occur more readily in cellular environments.
99
What are the two main types of **enzyme inhibition**?
* Noncompetitive inhibition
* Competitive inhibition
## Footnote
These types can be reversible or irreversible.
100
What is **allosteric regulation**?
Control of enzymatic activity through binding at a site other than the active site
## Footnote
This includes both stimulation and inhibition of enzymatic activity.
101
What is **cooperativity** in enzymatic regulation?
When a substrate acts as an allosteric regulator affecting other active sites
## Footnote
It can increase or decrease activity throughout an enzyme.
102
What is the phenomenon called when a substrate acts as an **allosteric regulator**?
Cooperativity
## Footnote
Cooperativity can increase or decrease activity throughout an enzyme.
103
What are the two types of **cooperativity**?
* Positive cooperativity
* Negative cooperativity
## Footnote
Positive cooperativity increases substrate binding likelihood, while negative cooperativity decreases it.
104
An example of **positive cooperativity** can be found in which enzyme?
ATP synthase
## Footnote
Binding of H+ ions leads to increased affinity for other H+ ions.
105
An example of **negative cooperativity** can be found in which protein?
Hemoglobin
## Footnote
Binding of O2 decreases the affinity for CO2 in the rest of the protein.
106
What is the **Hill coefficient** used to quantify?
Levels of cooperativity
## Footnote
nHill values indicate positive (>1), negative (<1), or no cooperativity (=1).
107
What does a **Hill coefficient** of nHill > 1 indicate?
Positive cooperativity
## Footnote
Indicates increased likelihood of substrate binding.
108
What does a **Hill coefficient** of nHill < 1 indicate?
Negative cooperativity
## Footnote
Indicates decreased likelihood of substrate binding.
109
What is **feedback inhibition**?
Products of an enzyme-controlled reaction inhibit its creation
## Footnote
Helps regulate levels of specific molecules in a cell.
110
An example of **feedback inhibition** is found in which enzyme?
Pyruvate dehydrogenase
## Footnote
Acetyl-CoA inhibits its own production.
111
What is the **Michaelis-Menten equation** used for?
To determine the rate of enzyme-catalyzed reactions
## Footnote
It relates reaction velocity to substrate concentration.
112
In the **Michaelis-Menten equation**, what does Vmax represent?
Maximum rate of the reaction
## Footnote
Indicates the highest velocity an enzyme can achieve.
113
What does KM represent in the **Michaelis-Menten equation**?
Michaelis constant
## Footnote
Measures the affinity between the enzyme and its substrate.
114
What happens to reaction rate when substrate concentration is increased beyond a certain point?
It reaches Vmax
## Footnote
The enzyme becomes saturated and cannot catalyze faster.
115
What is a **Lineweaver-Burk plot**?
A double reciprocal plot of the Michaelis-Menten equation
## Footnote
Used to visualize enzyme kinetics and inhibition effects.
116
In **competitive inhibition**, what happens to KM and Vmax?
* Increased KM
* Unaffected Vmax
## Footnote
Inhibitor binds to the active site, requiring more substrate to reach half-max rate.
117
In **noncompetitive inhibition**, what happens to KM and Vmax?
* Unaffected KM
* Decreased Vmax
## Footnote
Inhibitor binds to allosteric site, reducing catalytic efficiency.
118
What is the effect of **uncompetitive inhibition** on KM and Vmax?
* Decreased KM
* Decreased Vmax
## Footnote
Inhibitor binds to enzyme-substrate complexes, trapping the substrate.
USABO
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