Lecture 4 - Molecules, Energy, and Biosynthesis Flashcards

1
Q

what are the four biomolecules

A
  1. lipids
  2. carbohydrates
  3. proteins
  4. nucleic acid
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2
Q

diverse group of water-insoluble biological molecules

A

lipids

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3
Q

energy stores

A

fats

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4
Q

major components of membrane

A
  • phospholipids
  • sterols
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5
Q
  • sugar molecules
  • polyhydroxy aldehydes and ketones with the general formula of (CH2O)n
A

carbohydrates

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6
Q

most complex and most abundant organic molecules containing at least one carboxyl group and one amino group

A

proteins

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7
Q

store and express genomic information

A

nucleic acids

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8
Q

carries coded information

A

DNA

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9
Q

arranged DNA

A

genes

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10
Q

instrumental in translating the coded message of DNA into sequences of amino acids during synthesis of protein molecules

A

RNA

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11
Q

process of increasing the rate of reaction with the use of a catalyst

A

catalysis

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12
Q

any substance that increases rate of reaction upon addition to a certain reaction

A

catalyst

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13
Q
  • catalyst of biochemical reactions
  • neither used up in the reaction nor do they appear as reaction products
  • proteins of very specific amino acid composition and sequence
A

enzymes

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14
Q

how are enzymes denatured and precipitated

A

salts, solvents, other reagents

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15
Q

effect of enzymes on energy of activation

A

lower

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16
Q
  • kinetic energy required to bring the reactants into position to interact
  • measured as the number of calories required to bring all the molecules in a mole of reactant at a given temperature to a reactive state
A

activation energy / free energy of activation

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17
Q

how do enzymes hasten reactions

A

lower activatiion energy

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18
Q

each enzyme is specific for a certain __

A

substrate

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19
Q

example of enzyme specificity

A
  1. stereospecific
  2. single product
  3. specific bonds
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20
Q
  • reaction in which the stereochemistry of the reactants controls the outcome of the reaction
  • one stereoisomer of certain reactant produces one stereoisomer of a certain product, whereas a different stereoisomer of the same reactant produces a different stereoisomer of the same product
A

stereospecific

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21
Q

molecules that are chemically identical but whose functional groups are attached in different configurations around central carbon atoms

A

stereoisomer

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22
Q

hydrolyses any peptide bond in which the carbonyl group belongs to a phenylalanine, tyrosine, or tryptophan residue

A

chymotrypsin

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23
Q

what does chymotrypsin hydrolyses

A
  • phenylalanine
  • tyrosine
  • tryptophan residue
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24
Q

what does chymotrypsin reduce

A
  • energy used up by cell
  • build-up of toxic by-products
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25
Q
  • highly specific nature of most enzyme
  • arises from the close and complementary fit between enzymes and substrate in a special portion of the enzyme surface
  • substrate can fit like a lock-and-key mechanism
A

active site

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26
Q

Different models of the active site

A
  1. lock-and-key model
  2. induced-fit model
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27
Q
  • early theory for enzyme action
  • enzyme-substrte have specific shape to fit exactly into another
A

lock-and-key model

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28
Q
  • enzymes are flexible structures
  • active site can change the shape to fit the substrate
  • better, widely accepted theory
A

induced-fit model

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29
Q

catalytic potency of an enzyme

A

enzyme activity

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30
Q

number of reactions catalyzed per second by the enzyme

A

turnover number

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31
Q

enzymatic reaction

A
  1. substrate to active site
  2. enzyme-substrate complex (ES) formation
  3. product separates from enzyme
  4. free enzyme can form another ES
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32
Q

how do enzymes accelerate reactions

A
  1. hold substrates in close proximity to enhance probability of a reaction
  2. form unstable intermediate that readily undergoes second reaction
  3. presence of protons donors and acceptors in active site
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33
Q

Factors affecting enzyme activity

A
  1. temperature
  2. pH
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34
Q

increase in temperature

A
  • increase average molecular velocity
  • increase no. of molecular collisions per unit
  • increase probability of successful interaction
35
Q

as velocities increase, the molecules possess __ __ __ and thus are more likely to react upon collision

A

higher kinetic energies

36
Q

as temperature increases, reaction rate __ __

A

initially increases

37
Q

as temperature increases further, reaction rate __

A

decreases

38
Q

why does the reaction rate decrease when the temperature increases further

A

onset of denaturation

39
Q

where is the reaction rate maximal

A

optimal temperature

40
Q

what happens when there is drop in pH

A

exposes more positive sites on an enzyme for interaction with negative groups on a substrate molecule

41
Q

what happens when there is rise in pH

A

binding of positive groups on a substrate to negative sites on the enzymes

42
Q
  • facilitates enzyme reactions but is not required
  • small organic compounds or metals primarily used to support the action of enzymes
A

Cofactors

43
Q

small organic molecules that act as cofactors

A

coenzymes

44
Q
  • enzyme minus its cofactor
  • cannot function without its cofactor/coenzyme
A

apoenzyme

45
Q

ex. of cofactors

A

vitamins

46
Q

cofactor + apoenzyme

A

holoenzyme

47
Q

Six major classes of enzymes

A
  1. oxidoreductases
  2. transferases
  3. hydrolases
  4. lyases
  5. isomerases
  6. ligases
48
Q

type of reaction of oxidoreductases

A

oxidation-reduction

49
Q

type of reaction of transferases

A

group transfer

50
Q

type of reaction of hydrolases

A

hydrolysis reactions (transfer of function groups to water)

51
Q

type of reaction of lyases

A

addition or removal of groups to form double bonds

52
Q

type of reaction of isomerases

A

isomerization (intramolecular group transfer)

53
Q

type of reaction of ligases

A

ligation of two substrates at the expense of ATP hydrolysis

54
Q

example of oxidoreductases

A

lactate dehydrogenase

55
Q

example of transferases

A

nucleoside monophosphate kinase (NMP kinase)

56
Q

example of hydrolases

A

chymotrypsin

57
Q

example of lyases

A

fumarase

58
Q

example of isomerases

A

triose phosphate isomerase

59
Q

example of ligases

A

aminoacyl-tRNA synthetase

60
Q

where does the rate at which an enzymatic reaction proceeds depend on

A

concentrations of
- substrate
- product
- active enzymes

61
Q

molecules that interact with enzymes (temporary or permanent) in some way and reduce the rate of an enzyme-catalyzed reaction or prevent enzymes to work in a normal manner.

A

Enzyme inhibitors

62
Q

irrevirsible enzyme inhibition

A

toxins

63
Q

two types of enzyme inhibition

A
  1. competitive inhibition
  2. noncompetitive inhibition
64
Q
  • caused by molecules that react directly with the active site of the enzyme
  • can be reversed by an increase in substrate concentration
  • most are substrate analogs
A

competitive inhibition

65
Q

how is competitive inhibition reversed

A

increase in substrate concentration

66
Q
  • caused by molecules that bind to a region(s) of the enzyme outside the active site
  • reversed by dilution or removal of inhibitor
  • chemical structure typically differs from that of the substrate
A

noncompetitive inhibition

67
Q

how is noncompetitive inhibition reversed

A

dilution or removal of inhibitor

68
Q

regulation of metabolic reactions

A
  1. control of enzyme synthesis
  2. regulated by modulator molecules
69
Q

how is enzyme synthesis controlled

A

modulation of rate of transcripton

70
Q

when are enzyme synthesized

A

only when needed

71
Q

distinct from the active site

A

allosteric site

72
Q

how is enzyme activity controlled by modulator molecules

A

by binding to the allosteric site affecting affinity of enzyme for its substrate

73
Q

acts as the regulatory enzyme

A

first enzyme

74
Q

inhibit the activity of the first enzyme

A

end product of pathway

75
Q

what is the end product of the pathway

A

allosteric inhibitor

76
Q

several cation cofactors act as __ __ for some enzymes

A

allosteric activators

77
Q

example of where ATP is used for

A
  • biosynthesis
  • mechanical work
  • transport work
78
Q

two kinds of energy-yielding metabolic pathways in animal tissues

A
  1. aerobic metabolism
  2. anaerobic metabolism
79
Q
  • food molecules are completely oxidized to carbon dioxide and water by molecular energy
  • energy yield is far greater
A

aerobic metabolism

80
Q
  • food molecules are oxidized incompletely to lactic acid (lactate)
  • absence of oxygen
A

anaerobic metabolism

81
Q

products of aerobic respiration

A
  • CO2
  • water
  • ATP
82
Q

products of anaerobic respiration

A
  • Mammalian muscle - lactic acid (and ATP)
  • Yeast and some plants - ethanol and CO2 (and ATP)
83
Q

net ATP produced in aerobic respiration

A

32 ATP molecules

84
Q

net ATP produced in anaerobic respiration

A

2 ATP molecules