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Mcat biochem > MCAT BIOCHEM CHP 2 FLASHCARDS > Flashcards

MCAT BIOCHEM CHP 2 FLASHCARDS

(72 cards)

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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
when will many active sites be available and what will form quickly
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
26
what happens when we increase substrate conc? | what becomes less available?
increasing subtrate conc increases the rate of the rxn and less active sites are available
27
after reaction has reached saturation or vmax, will substrate rxn affect rate of rxn
no
28
at saturation how fast is the enzyme going | and how to increase enzyme conc at this point
the enzyme is working at maximum velocity (Vmax) | the only way to increase vmax at this point is to increase the enzyme conc
29
what equation is used to describe enzymes and what abuot it specifically describes it
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
how will conc of enzyme look on the mcat | what equation can we use to relate velocity of the enzyme to substrate conc
conc of enzyme will be constant | take a look and memorize it on page 49
31
study how to manipulate the mm equation on page 50
confirm on page 50
32
relate km to substrate conc | what is it also the affinity of
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
higher km means what for affinity? | lower km means what for affinity?
lower affinity for its subtrate becuz it requires a higher substrate conc to be half saturated
34
can km change by conc of enz or substrate
no
35
what happens when substrate conc is less than km
changes in substrate conc will greatly affect the reaction rate
36
what happens when substrate conc is more than km
the reaction rate increases more slowly as it approaches vmax, where it becomes independent of substrate conc
37
what is vmax relating to enzyme?
it is the maximum enzyme velocity
38
relate vmax to kcat in an equation what does kcat measure? what is the kcat for most enzymes
confirm it on page 50 kcat measures the number of substrate moles or turned over or converted to product 101-103
39
restate the mm equation using kcat
confirm it on page 50
40
what is the mm equation with kcat at low substrate concs, where Km is greater than substrate concs
confirm it on page 50
41
what is the catalytic efficiency of the enzyme
the ratio of kcat/km
42
high turnover= high substrate affinity= and what do these two things cause and what does this indicate
large kcat small km they cause a higher catalytic efficiency, which indicates a more efficient enzyme
43
why do some plots show a s shaped curve on an mm plot?
it is cuz of cooperativity
44
what state is for binding substrate and what does it do
it takes it from t to r state, which makes more want to bind
45
what state is for loss of substrate
it takes it from r to t state which make more want to unbind
46
what coefficient is used to measure cooperativity
hills coefficient
47
what happens when hills constant is more than 1
positive cooperative binding is occurring, and after on ligand is bound the affinity of the enzyme for further ligands increases
48
what happens when hills constant is less than 1
negative cooperative binding is occuring and after one ligand is bound the affiinity of the enzyme for further ligands decreases
49
what happens when hills constant equals 1
the enzyme does not exhibit cooperative binding
50
what is feedback regulation
feedback regulation | enzymes are often subject to regulation by products further down a given metabolic pathway
51
what is feed forward regulation
feed forward regulation is when enzymes are regulated by intermediates that come b4 the enzyme in the pathway
52
how can competitive inhibition be overcome?
adding more substrate so that there is more substrate than inhibitor
53
why does adding competitive inhibitor not change vmax
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
what happens to km with addition of comp inhib and why
km goes up becuz the substrate conc has to be higher to reach half the maximum velocity in the presence of the inhibitor
55
what do noncompetitive inhibs bind to
they bind to an allosteric site instead of the active site which induces a change in enzyme confirmation
56
what are allosteric sites and what do they bind
allosteric sites are non catalytic regions of an enz that bind regulators
57
why can noncomp inhibs be overcome by adding more substrate
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
noncomp inhibs bind equally to what 2 things, unlike what
it binds well to both the enzyme and the enzyme substrate complex, unlike mixed inhibs
59
with noncomp enzymes, what happens once the enzyme's conformation is altered?
no amount of extra substrate will help make an enzyme substrate complex
60
what does a noncomp inhib do to vmax and why | what does it to km and why
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
what is a mixed inhib
it results when an inhib can bind to either the enzyme or the enzyme substrate complex but has a different affinity for each
62
where do mixed inhibs bind
mixed inhibs bind to ALLOSTERIC SITES ONLY
63
how does mixed inhib affect km
it changes the expeirmental value of km dependign n the preference of the inhib for the enzyme vs enzyme substrate complex
64
what happens when the inhib binds preferentially to the enzyme
it makes Km go up(lowers affinity)
65
what happens when the inhib binds preferentially to the enzyme-sub complex
it lowers km(uppers affinity)
66
how do uncomp inhibs bind | how can what they do/bind to be interpreted
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
why do uncomp inhibs bind at an allosteric site
they do this because the enz sub complex has alreddy formed upon binding
68
what creates the conformational change that alllows the inhib to bind
the formation of the enz sub complex
69
what do uncomp inhibs do to km and vmax
they lower them both
70
what 2 things happens during irrevers inhib
the active site is unavailable for a long time or the en is permanently changed
71
characteristic of allosteric enzymes(hint and what sites are available for binding)
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
what forms do an allosteric enz have
it has an active site and an inactive site

Mcat biochem (3 decks)

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