Botany🦋 > Biomolecules > Flashcards

Biomolecules Flashcards

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1
Q

Q: How does the elemental composition of living tissue compare to the earth’s crust?

A

A: All elements in the earth’s crust are present in living tissue but the relative abundance of carbon and hydrogen is higher in living organisms.

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2
Q

Q: What is the first step in performing a chemical analysis of living tissue?

A

A: Grind a living tissue (like a vegetable or piece of liver) in trichloroacetic acid (Cl3CCOOH) using a mortar and pestle to obtain a thick slurry.

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3
Q

Q: What two fractions are obtained after straining the slurry through cheesecloth?

A

A: The filtrate (acid-soluble pool) and the retentate (acid-insoluble fraction).

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4
Q

Q: What has been found in the acid-soluble pool?

A

A: Scientists have found thousands of organic compounds in the acid-soluble pool.

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5
Q

Q: How is a specific organic compound identified after extraction?

A

A: The extract is subjected to various separation techniques to isolate and purify the compound followed by analytical techniques to determine its molecular formula and structure.

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6
Q

Q: What is the definition of ‘biomolecules’?

A

A: All the carbon compounds that we get from living tissues can be called ‘biomolecules’.

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7
Q

Q: How do we analyze the inorganic elements and compounds in living organisms?

A

A: Through a destructive experiment where tissue is dried to find the “dry weight” and then fully burnt to create “ash.”

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8
Q

Q: What happens to carbon compounds during the burning of tissue?

A

A: They are oxidised to gaseous form (CO2, water vapour) and are removed.

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9
Q

Q: What does the “ash” contain?

A

A: It contains inorganic elements like calcium and magnesium etc.

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10
Q

Q: Where are inorganic compounds like sulphate and phosphate found during acid analysis?

A

A: They are seen in the acid-soluble fraction.

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11
Q

Q: What is the difference between elemental analysis and compound analysis?

A

Elemental analysis gives the composition of elements (H, O, C, etc.), while compound analysis identifies the organic and inorganic constituents.

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12
Q

Q: How does the classification of these compounds differ between chemistry and biology?

A

A: Chemistry identifies functional groups (aldehydes, ketones, etc.), while biology classifies them into amino acids, nucleotide bases, fatty acids, etc.

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13
Q

Many amino acids are present based on what?

A

Nature of R group

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14
Q

How many amino acids occur in proteins?

A

20 types.

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15
Q

The chemical and physical properties of amino acids are essentially of

A

the amino, carboxyl and the R functional groups.

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16
Q

Lipids are generally

A

water insoluble

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17
Q

Lipids could be

A

simple fatty acids (or) glycerol + fatty acids

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18
Q

Glycerides are also called as fats or oils based on

A

melting point

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19
Q

Some tissues especially the neural tissues have

A

lipids with more complex structures.

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20
Q

Living organisms have a number of carbon compounds in which

A

heterocyclic rings can be found.

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21
Q

Q: What are the primary substituent groups on an alpha-amino acid?

A

A: An amino group and an acidic group as substituents on the same carbon (the alpha-carbon).

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22
Q

Q: Why are amino acids considered “substituted methanes”?

A

A: Because they have four substituent groups (Hydrogen, Carboxyl, Amino, and a variable R group) occupying the four valency positions of a central carbon.

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23
Q

Q: Which specific R-groups define Glycine, Alanine and Serine?

A

A: Glycine has hydrogen (H), Alanine has a methyl group (-CH3) and Serine has a hydroxy methyl group (-CH2OH).

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24
Q

Q: How are amino acids classified based on the number of amino and carboxyl groups?

A

A: Acidic (e.g. Glutamic acid), , Basic (e.g., Lysine), and Neutral (e.g., Valine).

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25
Q: Name three examples of aromatic amino acids.
A: Tyrosine, Phenylalanine and Tryptophan.
26
Q: Why does the structure of an amino acid change in solutions of different pH?
A: Because of the ionizable nature of the $-NH_2$ and $-COOH$ groups which can form a Zwitterionic state.
27
Q: What is the basic structure of a fatty acid?
A: A carboxyl group attached to an R group (ranging from 1 to 19 carbons).
28
Q: How many carbons are in Palmitic acid and Arachidonic acid?
A: Palmitic acid has 16 carbons and Arachidonic acid has 20 carbons (both including the carboxyl carbon).
29
Q: What is the difference between saturated and unsaturated fatty acids?
A: Saturated fatty acids lack double bonds while unsaturated fatty acids have one or more C=C double bonds.
30
Q: What is the chemical name for Glycerol?
A: Trihydroxy propane.
31
Q: What are glycerides and how are they formed?
A: They are fatty acids esterified with glycerol; they can be monoglycerides diglycerides, or triglycerides.
32
Q: What distinguishes "oils" from "fats" in terms of physical properties?
A: Oils have a lower melting point (e.g. gingelly oil) and remain liquid in winter.
33
Q: What are phospholipids and where are they found?
A: They are lipids containing phosphorus and a phosphorylated organic compound; they are found in cell membranes (e.g. Lecithin).
34
Q: Name the five nitrogenous bases found in living organisms.
A: Adenine, Guanine, Cytosine, Uracil, and Thymine.
35
Q: What is the difference between a Nucleoside and a Nucleotide?
A: A nucleoside is a nitrogen base attached to a sugar; a nucleotide is a nucleoside with a phosphate group esterified to the sugar.
36
Q: Give examples of nucleosides and their corresponding nucleotides.
Adenosine - Adenylic acid Guanosine - Guanylic acid Thymidine - Thymidylic acid Uridine - Uridylic acid Cytidine - Cytidylic acid
37
Q: What constitutes nucleic acids like DNA and RNA?
A: DNA and RNA consist of nucleotides only and function as genetic material.
38
However, when one analyses plant, fungal and microbial cells, one would see thousands of compounds other than these primary metabolites,
e.g. alkaloids, flavonoids, rubber, essential oils, antibiotics, coloured pigments, scents, gums, spices. These are called secondary metabolites
39
While primary metabolites have identifiable functions and play known roles in normal physiologial processes, we do not at the moment
understand the role or functions of all the ‘secondary metabolites’ in host organisms
40
However, many of secondary metabolites are useful to
‘human welfare’ (e.g., rubber, drugs, spices, scents and pigments). Some secondary metabolites have ecological importance.
41
Q: What is the one feature common to all compounds found in the acid soluble pool?
A: They all have molecular weights ranging from approximately 18 to around 800 daltons (Da).
42
Q: Which four types of organic compounds are found in the acid insoluble fraction?
A: Proteins, nucleic acids, polysaccharides, and lipids.
43
Q: What is the molecular weight of most classes in the acid insoluble fraction (with the exception of lipids)?
A: Ten thousand daltons and above.
44
Q: Into which two types are biomolecules (chemical compounds in living organisms) divided based on weight?
A: Micromolecules (or biomolecules) and macromolecules (or biomacromolecules).
45
Q: How are micromolecules (or simple biomolecules) defined by their molecular weight?
A: They have molecular weights less than one thousand daltons.
46
Q: Which molecules are referred to as macromolecules or biomacromolecules?
A: Those which are found in the acid insoluble fraction (usually with weights above 10000 Da, excluding lipids)
47
Q: What is the structural nature of the molecules in the insoluble fraction excluding lipids?
A: They are polymeric substances.
48
Q: Why is there a question about lipids being in the acid insoluble fraction?
A: Because their molecular weights do not exceed 800 Da yet they appear in the macromolecular (insoluble) fraction.
49
Q: How are lipids present in the cell besides existing as small molecular weight compounds?
A: They are arranged into structures like the cell membrane and other membranes.
50
Q: What happens to the cell structure when a tissue is ground?
A: The cell structure is disrupted.
51
Q: What happens to cell membranes and other membranes during the grinding process?
A: they are broken into pieces and form vesicles.
52
Q: Why do membrane fragments in the form of vesicles separate into the acid insoluble pool?
A: Because these vesicles are not water-soluble.
53
Q: Are lipids strictly considered macromolecules?
A: No, lipids are not strictly macromolecules.
54
Q: What does the acid soluble pool roughly represent in terms of cellular composition?
A: The cytoplasmic composition.
55
Q: What makes up the acid insoluble fraction of a cell?
A: The macromolecules from the cytoplasm and the organelles.
56
Q: What do the acid soluble and insoluble fractions represent when combined?
A: They represent the entire chemical composition of living tissues or organisms.
57
Q: When arranging the chemical composition of living tissue by abundance what is the most abundant chemical?
A: Water.
58
Q: What are proteins structurally defined as?
Proteins are polypeptides.
59
Q: How are amino acids arranged in a protein?They are linear chains of amino acids linked by peptide bonds.
They are linear chains of amino acids linked by peptide bonds.
60
Q: What is each protein a polymer of?
Each protein is a polymer of amino acids.
61
Q: Why is a protein considered a heteropolymer rather than a homopolymer?
Because there are 20 types of amino acids (e.g. alanine, cysteine, proline, tryptophan, lysine, etc.), making the chain varied.
62
Q: What is the definition of a homopolymer?
A homopolymer has only one type of monomer repeating ‘n’ number of times.
63
Q: Why is information about amino acid content important for nutrition?
Because certain amino acids are essential for our health and must be supplied through our diet.
64
Q: What is the primary source of essential amino acids for humans?
A: Dietary proteins.
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66
Q: Into what two categories can amino acids be classified based on dietary needs?
Essential or non-essential.
67
Q: What are non-essential amino acids?
They are the amino acids that our body can make on its own.
68
Q: How do we obtain essential amino acids?
We get essential amino acids through our diet/food.
69
Q: What is the general role of proteins in living organisms?
Proteins carry out many different functions. Some transport nutrients across the cell membrane. Some fight infectious organisms. Some are hormones and some are enzymes.
70
Q: Collagen is the
most abundant protein in the animal world
71
Q: Ribulose bisphosphate Carboxylase-Oxygenase (RuBisCO) is the
most abundant protein in the entire biosphere
72
73
Q: Besides proteins and nucleic acids, what other class of macromolecules is found in the acid insoluble pellet?
Polysaccharides (carbohydrates).
74
Q: What are polysaccharides structurally?
They are long chains of sugars.
75
Q: How can the physical structure of a polysaccharide be described?
They are threads (like a cotton thread) containing different monosaccharides as building blocks.
76
Q: What type of polysaccharide is cellulose?
It is a polymeric polysaccharide consisting of only one type of monosaccharide which is glucose.
77
Q: Is cellulose a homopolymer or a heteropolymer?
Cellulose is a homopolymer.
78
Q: What is the function of starch in plant tissues?
It is a variant of cellulose that serves as a storehouse of energy.
79
Q: What is the animal variant of starch called?
Glycogen.
80
Q: What is the building block of the polymer Inulin?
Fructose.
81
Q: In a polysaccharide chain like glycogen what are the two ends called?
The right end is the reducing end and the left end is the non-reducing end.
82
Q: Do polysaccharides like glycogen have branches?
Yes, they have branches
83
Q: What kind of secondary structure does starch form?
Starch forms helical secondary structures.
84
Q: How does starch react with Iodine (I2)?
Starch can hold I2 molecules in its helical portion creating a blue-colored complex.
85
Q: Why can't cellulose hold Iodine (I2)?
A: Cellulose does not contain complex helices and therefore cannot hold the I2 molecules.
86
Q: What is a primary structural component of plant cell walls?
Cellulose.
87
Q: What are paper made from plant pulp and cotton fiber composed of?
They are cellulosic.
88
Q: What are some examples of building blocks in more complex polysaccharides?
Amino-sugars and chemically modified sugars (e.g. glucosamine, N-acetyl galactosamine)
89
Q: What complex polysaccharide is found in the exoskeletons of arthropods?.
Chitin
90
Q: Are complex polysaccharides like chitin mostly homopolymers or heteropolymers?
They are mostly homopolymers.Nucleic Acids
91
Q: What is the other type of macromolecule found in the acid insoluble fraction of living tissue?
Nucleic acids.
92
Q: What are nucleic acids structurally?
They are polynucleotides.
93
Q: Which three classes of molecules comprise the "true macromolecular fraction" of a cell?
Polysaccharides, polypeptides (proteins), polynucleotides
94
Q: What is the building block of a nucleic acid?
A nucleotide.
95
Q: What are the three chemically distinct components of a nucleotide?
A heterocyclic compound, a monosaccharide (sugar), phosphoric acid or phosphate
96
Q: Which nitrogenous bases are classified as substituted purines?
Adenine and Guanine.
97
Q: Which nitrogenous bases are classified as substituted pyramidines?
cytosine & thymine
98
Q: What are the names of the two types of skeletal heterocyclic rings in nucleic acids?
Purine and pyrimidine.
99
Q: What types of sugars are found in polynucleotides?
Either ribose (a monosaccharide pentose) or 2’ deoxyribose.
100
Q: What is a nucleic acid containing deoxyribose called?
Deoxyribonucleic acid (DNA).
101
Q: What is a nucleic acid containing ribose called?
A: Ribonucleic acid (RNA).
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