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Mcat biochem > MCAT BIOCHEM CHP 2 FLASHCARDS > Flashcards

MCAT BIOCHEM CHP 2 FLASHCARDS

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MCAT flashcards
1
Q

what do redox rxns consist of?

A

transfer of electrons between moles

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2
Q

what role so cofactors play in use with oxidoreductases?

A

they acts as electron carriers, like NAD+ and NADP+

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3
Q

electron donor=

electron acceptor=

A

reductant

oxidant

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4
Q

what to oxidos tend to end in?

A

dehydrogenase and reductase

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5
Q

what ending does a final electron acceptor have?

A

oxidase

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6
Q

what do transferases do?

A

transferases catalyze the transfer of a functional group from one mole to another

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7
Q

what type of enzyme is a kinase

A

kinases are transferases

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8
Q

what do kinases do?

A

kinases catalyze the transfer of a phosphate group usually from ATP to another molecule

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9
Q

what do hydrolases do?

A

hydrolases catalyze the breaking of a compound into two moles using the addition of water

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10
Q

name a popular example of a hydrolase and what does it do

A

phosphatase is a popular hydrolase and it cleaves a phosphate group from another mole

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11
Q

what are some other hydrolases and what do they do

A

nucleases lipases and peptidases

they break down nucleic acids lipids and peptides namely

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12
Q

what do lyases do

do they req water and do they act as oxido reductases

A

lyases catalyze the cleavage of a single molecule into two products
no water needed!
no they dont act like oxidos

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13
Q

what type of rxns do lyases also catalyze (2 types) and what is the specific name for the second type

A

they catalyze the reverse of their specific reactions
they also catalyze the synthesis of two molecules into a single molecule may also be catalzyed by a lyase, these are called synthases

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14
Q

what do isomerases do

A

isomerases catalyze the rearrangement of bonds within a mole

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15
Q

what do ligases do and btween what types of moles

A

ligases catalyze addition or synthesis reactions usually btween large similar moles and often require ATP(synthesis reactions with smaller moles generally accomplished lyases

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16
Q

whats the mnemonic for types of enzymes

A

LIL HOT

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17
Q

are cofactors and coenzymes proteins

A

nope

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18
Q

why are cofactors and coenzymes small

A

they are small because they need bind to the active site of the enzyme and participate in the catalysis of the reaction, by carrying charge thru protonation deprotonation and ionization

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19
Q

enzymes w/o cofactors=

enzymes with cofactors=

A

apoenzymes

holoenzymes

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20
Q

what are tightly bound cofactors or coenzymes that are necessary for enzyme function

A

prosthetic groups

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21
Q

whats are generally inorganic molecules or metal ions and are often ingested as dietary minerals

A

cofactors

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22
Q

whats are small organic groups, the majority of which are vitamins or derivatives of vitamins such as NAD+ FAD and coenzyme A

A

coenzymes

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23
Q

water soluble vitamins include two types?

and why must they be replenished?

A

B complex vitamins
Vitamin C (ascorbic acid)
must be replenished becus they are excreted easily

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24
Q

fat soluble vitamins? how are they regulated and what does that quantify

A

ADEK, regulated by partition coefficients which quantify the ability of a molecule to dissolve in a polar vs nonpolar environment

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25
Q

when will many active sites be available and what will form quickly

A

many active sites will be available and we will quickly form products and quickly reach equilibrium when there is a high enzyme concentration relative to substrate

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26
Q

what happens when we increase substrate conc?

what becomes less available?

A

increasing subtrate conc increases the rate of the rxn and less active sites are available

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27
Q

after reaction has reached saturation or vmax, will substrate rxn affect rate of rxn

A

no

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28
Q

at saturation how fast is the enzyme going

and how to increase enzyme conc at this point

A

the enzyme is working at maximum velocity (Vmax)

the only way to increase vmax at this point is to increase the enzyme conc

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29
Q

what equation is used to describe enzymes and what abuot it specifically describes it

A

michaelis menton equation

describes how the rate of the rxn v depends on the conc of both the enzyme and the subtrate, which forms the product

30
Q

how will conc of enzyme look on the mcat

what equation can we use to relate velocity of the enzyme to substrate conc

A

conc of enzyme will be constant

take a look and memorize it on page 49

31
Q

study how to manipulate the mm equation on page 50

A

confirm on page 50

32
Q

relate km to substrate conc

what is it also the affinity of

A

km is the substrate conc at which the enzyme’s active sites are full
km can measure the affinity of the enzyme for its substrate

33
Q

higher km means what for affinity?

lower km means what for affinity?

A

lower affinity for its subtrate becuz it requires a higher substrate conc to be half saturated

34
Q

can km change by conc of enz or substrate

A

no

35
Q

what happens when substrate conc is less than km

A

changes in substrate conc will greatly affect the reaction rate

36
Q

what happens when substrate conc is more than km

A

the reaction rate increases more slowly as it approaches vmax, where it becomes independent of substrate conc

37
Q

what is vmax relating to enzyme?

A

it is the maximum enzyme velocity

38
Q

relate vmax to kcat in an equation
what does kcat measure?
what is the kcat for most enzymes

A

confirm it on page 50
kcat measures the number of substrate moles or turned over or converted to product
101-103

39
Q

restate the mm equation using kcat

A

confirm it on page 50

40
Q

what is the mm equation with kcat at low substrate concs, where Km is greater than substrate concs

A

confirm it on page 50

41
Q

what is the catalytic efficiency of the enzyme

A

the ratio of kcat/km

42
Q

high turnover=
high substrate affinity=
and what do these two things cause and what does this indicate

A

large kcat
small km
they cause a higher catalytic efficiency, which indicates a more efficient enzyme

43
Q

why do some plots show a s shaped curve on an mm plot?

A

it is cuz of cooperativity

44
Q

what state is for binding substrate and what does it do

A

it takes it from t to r state, which makes more want to bind

45
Q

what state is for loss of substrate

A

it takes it from r to t state which make more want to unbind

46
Q

what coefficient is used to measure cooperativity

A

hills coefficient

47
Q

what happens when hills constant is more than 1

A

positive cooperative binding is occurring, and after on ligand is bound the affinity of the enzyme for further ligands increases

48
Q

what happens when hills constant is less than 1

A

negative cooperative binding is occuring and after one ligand is bound the affiinity of the enzyme for further ligands decreases

49
Q

what happens when hills constant equals 1

A

the enzyme does not exhibit cooperative binding

50
Q

what is feedback regulation

A

feedback regulation

enzymes are often subject to regulation by products further down a given metabolic pathway

51
Q

what is feed forward regulation

A

feed forward regulation is when enzymes are regulated by intermediates that come b4 the enzyme in the pathway

52
Q

how can competitive inhibition be overcome?

A

adding more substrate so that there is more substrate than inhibitor

53
Q

why does adding competitive inhibitor not change vmax

A

it doesnt change vmax because if enough substrate was added it will outcompete the inhibitor and be able to run the reaction at maximum velocity

54
Q

what happens to km with addition of comp inhib and why

A

km goes up becuz the substrate conc has to be higher to reach half the maximum velocity in the presence of the inhibitor

55
Q

what do noncompetitive inhibs bind to

A

they bind to an allosteric site instead of the active site which induces a change in enzyme confirmation

56
Q

what are allosteric sites and what do they bind

A

allosteric sites are non catalytic regions of an enz that bind regulators

57
Q

why can noncomp inhibs be overcome by adding more substrate

A

they cant be overcome by adding more substrate becuz the two molecules are not competing for the same site and becuz this inhib is noncomp

58
Q

noncomp inhibs bind equally to what 2 things, unlike what

A

it binds well to both the enzyme and the enzyme substrate complex, unlike mixed inhibs

59
Q

with noncomp enzymes, what happens once the enzyme’s conformation is altered?

A

no amount of extra substrate will help make an enzyme substrate complex

60
Q

what does a noncomp inhib do to vmax and why

what does it to km and why

A

it decreases vmax becuz there is less enzyme available to react
it doesnt change km becuz copies of the enzyme that are still active maintain the same affinity for their substrate

61
Q

what is a mixed inhib

A

it results when an inhib can bind to either the enzyme or the enzyme substrate complex but has a different affinity for each

62
Q

where do mixed inhibs bind

A

mixed inhibs bind to ALLOSTERIC SITES ONLY

63
Q

how does mixed inhib affect km

A

it changes the expeirmental value of km dependign n the preference of the inhib for the enzyme vs enzyme substrate complex

64
Q

what happens when the inhib binds preferentially to the enzyme

A

it makes Km go up(lowers affinity)

65
Q

what happens when the inhib binds preferentially to the enzyme-sub complex

A

it lowers km(uppers affinity)

66
Q

how do uncomp inhibs bind

how can what they do/bind to be interpreted

A

they bind ONLY TO THE ENZ-SUBSTRATE COMPLEX and lock the substrate in the enzyme stopping its release
this can be interpreted as increasing affinity btween the enzyme and the substrate

67
Q

why do uncomp inhibs bind at an allosteric site

A

they do this because the enz sub complex has alreddy formed upon binding

68
Q

what creates the conformational change that alllows the inhib to bind

A

the formation of the enz sub complex

69
Q

what do uncomp inhibs do to km and vmax

A

they lower them both

70
Q

what 2 things happens during irrevers inhib

A

the active site is unavailable for a long time or the en is permanently changed

71
Q

characteristic of allosteric enzymes(hint and what sites are available for binding)

A

they have multiple binding sites
they have an active site as well as at least one other site than can regulate the availability of the active site, and this is called an allosteric site

72
Q

what forms do an allosteric enz have

A

it has an active site and an inactive site

Mcat biochem (3 decks)

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