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General Physiology > 4 Enzymes (Molecules, Energy, and Biosynthesis) > Flashcards

4 Enzymes (Molecules, Energy, and Biosynthesis) Flashcards

+ 18 Cards on Anki

1
Q

a diverse group of water-insoluble biological molecules. Fats store energy, while phospholipids and sterols are major components of cell membranes.

A

Lipids

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2
Q
  • are polyhydroxy aldehydes and ketones with the general formula (CH₂O)ₙ.
  • a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1
A

Carbohydrates

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3
Q

are complex, abundant organic molecules that contain at least one carboxyl group and one amino group.

A

Proteins

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4
Q

The storage and expression of genomic information. They are composed of nucleotides, which are the monomer components: a 5-carbon sugar, a phosphate group and a nitrogenous base.

A

Nucleic acid

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5
Q

The two main classes of nucleic acids are __ and __.

A

deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

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6
Q

What are the roles of DNA and RNA in cells?

A
  • DNA carries genetic information arranged into genes, passed from cell to cell and generation to generation.
  • RNA translates DNA’s coded message into amino acid sequences during protein synthesis.
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7
Q

The process of increasing the rate of a reaction by using a catalyst, which lowers the activation energy (Ea) of the reaction but does not change the overall energy of the reactants and products. It increases the rates of both forward and reverse reactions without being consumed.

A

Catalysis

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8
Q

There are three major types of catalysts:

A
  • heterogeneous - the catalyst is in a different phase from the reactants.
  • homogeneous - the catalyst is in the same phase as the reactants.
  • enzymes
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9
Q

are biological catalysts that speed up synthetic and metabolic reactions in cells by lowering the activation energy. They are proteins with specific amino acid sequences and structures.

A

Enzymes

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10
Q
  • Are not used up in reactions, nor do they appear in reaction products.
  • They can be denatured and precipitated with salts, solvents, and reagents.
  • Despite increasing reaction rates, they are sensitive to environmental factors and maintain their catalytic properties under optimal conditions.
A

Enzymes

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11
Q

What are enzymes made of?

A

proteins with specific amino acid compositions and sequences.

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12
Q

Are enzymes used up/consumed in reactions?

A

No, enzymes are not consumed in reactions and do not appear in the final products.

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13
Q

How can enzymes be denatured and precipitated? (3)

A
  • salts
  • solvents
  • and other reagents.
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14
Q

Why are enzymes important for cells?

A

Enzymes are crucial for catalyzing all synthetic and metabolic reactions, allowing life-sustaining processes to occur efficiently.

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15
Q

the kinetic energy required to bring reactants into a position where they can interact.

A

Activation energy/free energy of activation

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16
Q

How is activation energy measured?

A

calories - representing the energy required to bring all molecules in a mole of reactant to a reactive state.

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17
Q

What role does activation energy play in a reaction?

A

It is the energy barrier that must be overcome for reactants to convert into products.

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18
Q

Enzymes bind with a substrate to form an activated __, which leads to a lower activation energy for the reaction

A

enzyme-substrate complex

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19
Q

How much faster are enzyme-catalyzed reactions compared to uncatalyzed reactions?

A

10³ to 10¹⁷ times faster

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20
Q
  • Each enzyme is specific for a certain substrate (reactant molecule).
  • The ability of an enzyme to select a specific substrate from a range of chemically similar compounds
A

enzyme specificity

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21
Q

How does enzyme specificity vary? (2)

A
  • stereospecific
  • reaction-specific
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22
Q

act on a single stereoisomer, which are molecules that are chemically identical but have different functional group configurations around a central carbon atom.

A

Stereospecific enzymes

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23
Q

refers to an enzyme producing a single product from its substrate based on reaction

A

Reaction specificity

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24
Q

What is reaction specificity in enzymes?

A

an enzyme producing a single product from its substrate.

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25
Q

a proteolytic enzyme present in the intestine that hydrolyzes peptide bonds where the carbonyl group belongs to a phenylalanine, tyrosine, or tryptophan residue.

A

chymotrypsin

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26
Q

Chymotrypsin __(reaction) the __ in the dipeptide where the carbonyl group is part of phenylalanine, aiding in protein digestion.

A
  • hydrolyzes
  • peptide bond
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27
Q

How does chymotrypsin impact cellular energy and by-products? (2)

A
  • reduces the energy used by the cell
  • decreases the build-up of toxic by-products
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28
Q

This site contributes to enzyme specificity. The highly specific nature of most enzymes arises from the close and complementary fit between the enzyme and substrate at the active site, similar to a lock-and-key mechanism.

A

active site

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29
Q

What is the structure of an enzyme molecule?

A

one or more peptide chains folded into a globular protein with a specific conformation.

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30
Q
  • The __ consists of the side groups of certain amino acid residues brought into proximity by the enzyme’s tertiary structure, even if these residues are widely separated in the amino acid sequence.
  • specific arrangement of amino acid residues that create a unique shape and chemical environment. These residues interact with the substrate through non-covalent forces like hydrogen bonds, ionic interactions, and hydrophobic interactions, allowing the enzyme to catalyze the reaction efficiently.
A

active site

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31
Q

refers to the catalytic potency of an enzyme, indicating how efficiently it catalyzes a reaction.

A

enzyme activity

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32
Q

the number of reactions catalyzed per second by the enzyme.

A

turnover number

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33
Q

What happens when a substrate interacts with the active site of an enzyme?

A

forms an enzyme-substrate (ES) complex.

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34
Q

What happens after the enzyme-substrate complex forms?

A

The product is formed and separates from the enzyme

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35
Q

Can the enzyme be reused after releasing the product?

A

Yes

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36
Q

How do enzymes enhance the probability of a reaction?

A

hold substrates in close proximity to one another, increasing the likelihood of a reaction.

37
Q

What role do proton donors and acceptors in the enzyme’s active site play?

A

They facilitate the reaction by participating in proton transfer.

38
Q

Give two (2) factors that affect enzyme activities

A
  • Temperature
  • pH
39
Q

Factors affecting enzyme activity: How does temperature affect the rate of a chemical reaction? What happens to molecules as their temperature increases?

A
  • Temperature affects the rate of a chemical reaction by influencing the kinetic energy of molecules
  • Higher temperatures increase the average molecular velocity, causing more molecular collisions and increasing the probability of successful interactions between reactants.
  • if the temperature becomes too high, the enzyme can denature, losing its three-dimensional structure and active site, which decreases or stops the reaction.
40
Q

What happens to enzyme activity as temperature continues to rise past a certain point?

A

The reaction rate decreases as the enzyme starts to denature, losing its three-dimensional structure.

41
Q

It is the temperature at which the enzyme operates at maximum efficiency, and the reaction rate is at its highest.

A

Optimal temperature

42
Q

pH and Reaction rate: Increased proton concentration (H⁺) or pH can expose __ charges on the enzyme’s active sites, facilitating interaction with __ charged groups on the substrate. However, if the pH drops too far, it can lead to __ or __ enzyme activity.

A
  • positive
  • negatively
  • denaturation
  • reduced
43
Q

pH and Reaction rate: If the pH increases and becomes more alkaline, the enzyme may gain __ charges, and the substrate may have more __ charges, enhancing interaction between them. However, if the pH rises too far, it can disrupt the enzyme’s structure, leading to reduced activity.

A
  • negative
  • positive
44
Q

the pH at which an enzyme functions most efficiently. Deviations from this optimal range can lead to reduced enzyme activity due to disruption of the enzyme’s structure and active site.

A

Optimal pH

45
Q

What can extreme changes in pH cause in enzymes?

A
  • disrupt the ionic bonds and three-dimensional structure (causing denaturation and loss of function)
46
Q

non-protein chemical compounds necessary for enzyme activity, and they can be coenzymes, prosthetic groups, or metal ions.

A

Cofactors

47
Q

small organic molecules (often derived from vitamins) that bind loosely to enzymes and assist in transferring chemical groups (e.g., NAD⁺, FAD).

A

coenzymes

48
Q

a tightly bound, sometimes permanent, non-protein molecule that is essential for enzyme function (e.g., heme in hemoglobin or catalase).

A

Prosthetic group

49
Q

stabilize negative charges or facilitate substrate binding in enzymatic reactions. (ex. Mg²⁺, Zn²⁺, or Fe²⁺)

A

metal ions

50
Q

the inactive form of an enzyme, consisting only of the protein component, and cannot function without its cofactor.

A

Apoenzyme

51
Q

the active form of an enzyme, consisting of the apoenzyme and its cofactor, capable of catalyzing a biochemical reaction.

A

Holoenzyme

52
Q

often act as covalently attached coenzymes, being part of the enzyme molecule to assist in biochemical reactions.

A

Vitamins

53
Q

Classify the six (6) major categories of enzymes based on the types of reactions they catalyze.

A
  • Oxidoreductase
  • Transferase
  • Hydrolase
  • Lyase
  • Isomerase
  • Ligase
54
Q

Enzymes that catalyze oxidation-reduction reactions, transferring electrons between molecules.

A

oxidoreductase

55
Q

Give an example of an oxidoreductase

A

Dehydrogenases, which remove hydrogen atoms from substrates (e.g., NAD⁺ → NADH).

56
Q

Enzymes that catalyze the transfer of specific groups, such as methyl or phosphate groups, from one molecule (donor) to another (acceptor).

A

Transferase

57
Q

Give an example of a transferase

A

Kinases, which transfer phosphate groups from ATP to other molecules.

58
Q

Enzymes that catalyze the hydrolysis of chemical bonds by adding water, breaking down large molecules into smaller ones.

A

Hydrolase

59
Q

Give an example of a hydrolase

A

Proteases, which break down proteins into amino acids by hydrolyzing peptide bonds.

60
Q

Enzymes that catalyze the breaking of bonds (C-C, C-O, C-N) without water or redox reactions, often forming or adding to double bonds.

A

Lyase

61
Q

Give an example of a lyase

A

Decarboxylases, which remove carbon dioxide from carboxyl groups.

62
Q

Enzymes that catalyze the rearrangement of atoms within a molecule, converting it from one isomer to another.

A

Isomerase

63
Q

Give an example of an isomerase

A

Phosphoglucose isomerase, which converts glucose-6-phosphate to fructose-6-phosphate.

64
Q

Enzymes that catalyze the joining of two molecules, often using ATP, to form new bonds.

A

Ligase

65
Q

Give an example of a ligase

A

DNA ligase, which seals breaks in the DNA backbone by forming phosphodiester bonds.

66
Q
  • Low Substrate Concentration: As substrate concentration ___, more enzyme active sites are occupied, leading to a __ increase in reaction rate.
  • High Substrate Concentration: Reaction rate levels off at a __ because the enzyme’s active sites are saturated, and adding more substrate no longer increases the rate.
A
  • increases
  • linear
  • maximum value (Vmax)
67
Q
  • Higher Enzyme Concentration: __ the reaction rate as more enzymes convert substrates to products.
  • Sufficient Substrate: Rate increases with enzyme concentration as long as there is enough substrate.
  • Substrate Limitation: When __ is low, adding more enzyme doesn’t significantly affect the rate because __ availability becomes the __.
A
  • Increases
    -substrate
  • substrate
  • limiting factor
68
Q

How does product concentration influence enzyme activity?

A

can inhibit enzyme activity, especially in reversible reactions

69
Q

It is a mechanism used to control enzymatic reactions, with enzymes being either irreversibly or reversibly inhibited.

A

Enzyme inhibition

70
Q

What are the two (2) types of enzyme inhibition?

A
  • Competitive inhibition
  • Noncompetitive inhibition
71
Q

It is when an inhibitor permanently binds to an enzyme, often involving toxins.

A

irreversible inhibition

72
Q

The inhibitor competes with the substrate for the active site, and the effect can be overcome by increasing substrate concentration.

A

competitive inhibition

73
Q

The inhibitor binds to a site other than the active site, reducing enzyme activity regardless of substrate concentration.

A

noncompetitive inhibition

74
Q

It is caused by molecules that directly bind to the enzyme’s active site and can be reversed by increasing substrate concentration.

A

Competitive inhibition

75
Q

It is caused by molecules that bind to a region of the enzyme outside the active site and is typically reversed by dilution or removal of the inhibitor.

A

Noncompetitive inhibition

76
Q

Most competitive inhibitors are __.

A

substrate analogs

77
Q

How can noncompetitive inhibition be reversed?

A

by dilution or removal of the inhibitor.

78
Q

How can competitive inhibition be reversed?

A

reversed by increasing substrate concentration.

79
Q

What is the control of enzyme synthesis?

A

It involves regulating the rate of transcription of the gene encoding the enzyme, ensuring that enzymes are only synthesized when needed.

80
Q

How is enzyme activity controlled?

A

By modulator molecules that interact with an allosteric site on the enzyme, distinct from the active site.

81
Q

It is a site on an enzyme where modulator molecules bind, altering the enzyme’s tertiary structure and affecting the active site’s conformation.

A

Allosteric site

82
Q

How does the allosteric site affect enzyme function?

A

It changes the enzyme’s conformation, which can increase or decrease the enzyme’s affinity for its substrate.

83
Q

It is a regulation mechanism where the end product of a metabolic pathway inhibits the activity of the first enzyme in the sequence, slowing down the entire process to limit product accumulation.

A

End-product (feedback) inhibition

84
Q

Which enzyme is typically affected in end-product (feedback) inhibition?

A

first enzyme in the metabolic sequence acts as the regulatory enzyme.

85
Q

How does the end product act in feedback inhibition?

A
  • acts as an allosteric inhibitor.
  • It binds to the allosteric site of the first enzyme in the pathway, altering its shape and decreasing its activity, thus slowing down the entire metabolic sequence.
86
Q

can act as allosteric activators by binding to specific sites on the enzyme, inducing a conformational change that enhances the enzyme’s activity.

A

Cation cofactors

87
Q

the process where food molecules are completely oxidized to carbon dioxide and water using molecular oxygen, resulting in a high energy yield.

A

Aerobic metabolism

88
Q

the process where food molecules are incompletely oxidized to lactic acid (lactate) in the absence of oxygen, resulting in a lower energy yield.

A

Anaerobic metabolism

General Physiology (15 decks)

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