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biochem > enzymes > Flashcards

enzymes Flashcards

1
Q

oxidoreductases

A

REDOX rxns that involve the transfer of electrons

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2
Q

transferases move a

A

function group from one molecule to another

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3
Q

hydrolases catalyze

A

cleavage w/ the addition of water

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4
Q

lyases catalyze cleavage without

A

the addition of water and transfer of electrons

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5
Q

isomerases catalyze the interconversion of

A

isomers

including constitutional isomers + stereoisomers

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6
Q

ligases join two large

A

biomolecules often of the same type

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7
Q

lipases catalyze the

A

hydrolysis of fats

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8
Q

dietary fats are broken down into

A

fatty acids and glycerol/other alcohols

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9
Q

kinases add a

A

phosphate group

type of transferase

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10
Q

phosphatases remove a

A

phosphate group

type of transferase

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11
Q

phosphorylases introduce a

A

phosphate group into an organic molecule (notably glucose)

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12
Q

exergonic rxn

A

RELEASE energy

gibbs free E = negative

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13
Q

endergonic rxns

A

require energy

gibbs free E = positive

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14
Q

enzymes do not alter the

A

gibbs free E or enthalpy or the final equilibrium position

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15
Q

enzymes only alter the

A

changing the rate of the reaction

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16
Q

as substrate increases, so does the

A

rxn rate until a max value is reached

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17
Q

K is the [S] at which an enzyme…

A

runs at half its Vmax

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18
Q

Vmax is the max rate at which an enzymes can….

A

catalyze a rxn

all enzyme active sites are saturated w/ substrate

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19
Q

cooperative enzymes display what kind of curve

A

sigmoidal curve b/c of activity change with substrate binding

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20
Q

enzymes stabilize the

A

transition state

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21
Q

enzymes provide a favorable microenvironment and/or…

A

bonding w/ the substrate molecules

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22
Q

site of catalysis is called

A

the active site

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23
Q

lock and key theory

A

enzyme and substrate are complementary and fit together like a key into a lock

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24
Q

induced fit theory is where the enzyme and substrate…

A

undergo conformational changes to interact fully

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25
Q

metal cation that is required by some enzymes

A

cofactor

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26
Q

what molecule is required by some enzymes

A

organic molecules

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27
Q

how does temp and pH affect enzymes

A

denaturation and loss of activity due to loss of 2/3/4 structure of proteins

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28
Q

salinity can impact the actions of

A

enzymes

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29
Q

feedback inhibition is when an enzyme is inhibited by

A

high levels of a product from later in the same pathway

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30
Q

reversible inhibition is the ability to replace the inhibitor with a….

A

compound of greater affinity or to remove i.t. using mild lab treatment

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31
Q

competitve inhibition

A

when inhibitior is similar to the substrate

binds at the active site

blocks substrate from binding

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32
Q

competitive inhibition can be overcome by

A

adding more substrate

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33
Q

vmax and km in competitive inhibtion

A

vmax unchanged

km increases

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34
Q

uncompetitive inhibition is when the inhibitors binds…

A

only w/ the ES complex

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35
Q

vmax and km in uncompetitive inhibtion

A

vmax and km decrease

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36
Q

noncompetitive inhibition is when the inhibitors binds with…

A

equal affinity to the enzyme and ES complex

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37
Q

vmax and km for noncompetitive inhibition

A

vmax decreases and km unchanged

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38
Q

mixed inhibition is when the inhibitor binds with unequal…

A

affinity to the enzyme and ES complex

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39
Q

vmax and km in mixed inhibition

A

vmax decreases

km increases/decreases depending on if the inhibitor has a higher affinity for the enzyme or ES complex

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40
Q

irreversible inhibition alters the enzyme in such a way that the

A

active site is unavailable for a prolonged duration / permanently

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41
Q

suicide inhibitor is a substrate analogue that binds…

A

IRREVERSIBLY to the active site via a covalent bond

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42
Q

allosteric effector binds at the allosteric site and induces a…

A

change in the conformation of the enzyme

the substrate can no longer bind to the active site

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43
Q

allosteric effector displays

A

cooperativity

does not obey MM-kinetics

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44
Q

positive allosteric effectors exert a

A

positive effect

increase activity

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45
Q

negative allosteric effector exert a

A

negative effect

decrease activity

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46
Q

homotropic effector is an allosteric regulator that is also the…

A

substrate

e.g. O2 is a homotropic allosteric regulator of hemoglobin

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47
Q

heterotropic effector is an allosteric regulator molecule that is

A

different from the substrate

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48
Q

what is phosphorylation

A

covalent modification with phosphate

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49
Q

catabolism

A

phosphorylated = active

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50
Q

anabolism

A

phosphorylated = inactive

51
Q

glycolsylation is the covalent modification with

A

carbohydrates

52
Q

zymogens is the

A

precursor to an enzyme

53
Q

zymogens are secreted in an inactive form and are…

A

activated by cleavage

54
Q

which proteins made up the cytoskeleton/anchoring proteins/EC matrix

A

structural proteins

55
Q

common structural proteins

A

collagen

elastin

keratin

actin

tubulin

56
Q

motor proteins have 1+ heads capable of

A

force generation through a conformation change

57
Q

motor proteins have catalyic activity, acting as

A

ATPases to power movement

58
Q

common applications w/ motor proteins

A

muscle contraction

vesicle mvmt within cells

cell motility

e.g. myosin, kinesin, dynein

59
Q

binding proteins bind a

A

specific substrate

either to sequester it in body or hold concentration at steady state

60
Q

what does cell adhesion molecules allows cells to do

A

allows cells to bind to other cells/surfaces

61
Q

cadherins are

A

calcium-dependent glycoproteins holding similar cells together

62
Q

intergrins have two membrane-spanning chains and allow cells to…

A

adhere to proteins in EC matrix

63
Q

selectins allows cells to adhere to

A

carbs on surfaces of other cells

commonly used in immune system

64
Q

antibodies are aka

A

immunoglobulins (Ig)

used by immune system to target a specific antigen

65
Q

ion channels can be used for

A

regulating ion flow in/out of cell

66
Q

ungated channels are

A

ALWAYS OPEN

67
Q

voltage-gated channels are

A

OPEN within a range of membrane potentials

68
Q

ligand-gated channels open in the

A

presence of specific binding substance (usually a hormone or neurotransmitter)

69
Q

enzyme-linked receptors participate in cell signalling through

A

EC ligand binding and initiation of 2nd messenger cascades

70
Q

GCPR has a membrane-bound protein called the

A

G-protein (has three subunits)

71
Q

1st messenger ligand initiates the

A

2nd messenger and the cascade response

72
Q

epinephrine is a ligand

A

2st messenger

73
Q

at the end of the GCPR process,

A

phosphodiesterase deactivated cAMP

GTP hydrolyzed back to GDP

74
Q

electrophoresis uses a

A

gel matrix to observe migration of proteins in response to an electric field

75
Q

native PAGE maintains the protein’s shape but results are

A

difficult to compare b/c mass/charge ratio differs by protein

76
Q

SDS-PAGE denatures proteins and masks the

A

native charge so size comparison is more accurate

func protein cannot be recaptured from gel

77
Q

isoelectric focusing separates proteins by the

A

pI

protein migrates towards electrode until i.t. reaches region where pH = pI of protein

78
Q

chromatography separates protein mixtures on the basis of

A

their affinity for a stationary phase or mobile phase

79
Q

column chromatography uses beads of a

A

polar compound (stationary phase) with a non-polar solvent (mobile phase)

80
Q

ion-exchange chromotography uses a

A

charged column and a variably salin eluent

81
Q

size exclusion chromotography relies on

A

poroous beads

larger molecules elute first - not trapped in small pores

82
Q

affinity chromotography uses a bound receptor or ligand and an eluding with a….

A

free ligand or receptor for the protein of interest

83
Q

how is protein structure primarily determined

A

XRAY crystallography after protein isolated then NMR can be used

84
Q

edmand degradation determines

A

AA sequence

85
Q

bradford protein assay is most

A

common

uses color change from brown-green to blue

86
Q

what does topoisomerase do

A

unwind the DNA double helix

87
Q

helicase function

A

breaks H-bonds b/w the nitrogenous bases in order to separate DNA strands

88
Q

single strand binding protein (SSB) binds to

A

single-stranded DNA and prevents annealing of ssDNA into double-stranded DNA

89
Q

what does DNA primase do

A

catalyzes synthesis of RNA primer

90
Q

RNA primers allows for

A

DNA replication to start

short RNA nucleotide sequences that are complementary to the ssDNA

91
Q

DNA polymerase adds

A

nucleotides to the growing strand

92
Q

how to read DNA template

A

3’ to 5’

93
Q

how is the new strand of DNA synthesized

A

5’ to 3’

94
Q

DNA polymerase removes the

A

RNA primer at the end of the strand

95
Q

okazaki fragments are short, newly synthesized DNA fragments formed

A

on the lagging template strand during DNA replication

96
Q

DNA ligase join the

A

DNA strands together by catalyzing formation of phosphodiester bonds

97
Q

proofreading DNA/RNA

A

DNA has proofreading, RNA does NOT

98
Q

DNA replication is more (what) than RNA replication

A

accurate

99
Q

stability of DNA/RNA

A

RNA is less stable b/c it contains sugar ribose instead of DNA’s deoxyribose

100
Q

because RNA is less stable, it…

A

degrades rapidly in cytoplasm

101
Q

strands of DNA wrap around a

A

histone protein forming nucleosomes

102
Q

nucleosomes coil together and form

A

chromatin

103
Q

chromatin loops and coils together to form

A

supercoils

104
Q

supercoils bunch together to form

A

chromosomes

105
Q

charge of DNA

A

negative due to phosphate backbone

106
Q

3 parts of a nucleotide

A

5 carbon sugar

nitrogen-rich base

phosphate group

107
Q

nucleoside lacks

A

phosphate group

108
Q

nucleotide pairs

A

adenine - thymine
guanine - cytosine

109
Q

adenine-thymind has how many H-bonds

A

2 H-bonds

110
Q

guanine-cytosine has how many H bonds

A

3 H bonds

stronger than A-T

111
Q

what holds DNA backbone together

A

phosphodiester bonds between sugar and phosphate groups

112
Q

hydrogen bonds hold what together in DNA

A

nucleotide bases together inside the double helix

113
Q

how many rings in pyrimidine

A

1 ring

114
Q

how many rings in purines

A

2 rings

pyrimidine ring fused to an imidazole ring

115
Q

pyrimidines

A

cytosine

thymine

uracil (RNA only)

116
Q

purines

A

adenine

guanine

117
Q

purines and pyrimidines have a 1:1 ratio as per

A

Chargaff’s rule

118
Q

purine and pyrimidine have what kind of width

A

UNIFORM

119
Q

purine + purine is too

A

wide

120
Q

pyrimidine + pyrimidine is too

A

narrow

121
Q

diameter of DNA double helix =

A

20 angstroms

122
Q

RNA is a polymer of

A

nucleotides

123
Q

how does RNA differ from DNA

A

1) RNA is single stranded

2) sugar is ribose + more reactive

3) nitrogenous base is uracil (U) not thymine (T)

124
Q
A

biochem (11 decks)

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