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biology year 1 > enzymes > Flashcards

enzymes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Suggest what type of protein rennin is and explain how a very small quantity of rennin is able to convert a large quantity of milk.

A 
enzyme ;
plus any 2 of the following
(enzyme) not, changed / used up ; ora
idea of ESC (forms) / substrate and enzyme (bind) ;
products (and enzyme) released at end ;
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2
Q

Explain how the products coded for by the genes interact to give the different pigments.

A

gene products are enzymes ;
multi-enzyme / multi-step, pathway ;
3, steps / enzymes, change tryptophan to red pigment ;
product of one reaction / intermediate compound,
is, substrate / starting point, for next ;
dominant allele gives,
functional / wild-type / AW, enzyme ;
recessive allele gives,
non-functional / different / AW, enzyme ;

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3
Q

Describe how an enzyme, such as pepsin, breaks down a substrate.

A

substrate / protein , shape is (nearly) complementary to
active site ; ora
substrate / protein , enters / fits into , active site (on
enzyme) ;
induced fit / description of induced fit ;
(forms) enzyme-substrate complex / ESC ;
destabilising / straining / AW , of bonds (in substrate) ;
then (forms) enzyme-product complex ;
product(s) / amino acids , leave (active site) ;

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4
Q

Pepstatin acts as a competitive inhibitor of pepsin.What can you conclude about the structure of pepstatin?

A

similar shape to , substrate / (part of) albumin / protein ;

complementary (shape) to (part of) active site ;

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5
Q

Why is the enzyme amylase described as being extracellular?

A

(works) outside cells ;

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6
Q

To calculate the rate of starch breakdown, the student measured the concentration of the breakdown product.
State the other variable the student needed to know in order to calculate the rate of this reaction.

A

time /time taken

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7
Q

plain the shape of the graph of compettive inhibitors

A

linear part of the graph means…
more (successful) collisions with (amylase) active site
(at increasing starch concentration) ; ora
more ESC (at increasing starch concentration) ; ora
so more product formation in a given time (at
increasing starch concentration) ; ora
curve / plateau , means…
all / most , active sites (of amylase) are occupied ;
enzyme / amylase , working , at / near, maximum rate /
Vmax ;
(so) further increase in starch concentration
has no effect (on rate) ;
enzyme concentration , is / becomes , limiting factor ;

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8
Q

The student kept the pH of the solution constant during the experiment.
Explain why it is important that the pH was kept constant.

A

(so) charges in active site do not change ; ora
(so) hydrogen / ionic , bonds unaffected ; ora
(so) tertiary structure / 3D shape / active site ,
unaltered ; ora
(so) enzyme / tertiary structure , does not denature ;
ora
(so) substrate , fits / is complementary shape to , active
site ; ora
so the results are valid / as the rate (of reaction) will
vary if pH varies / so that only one
(independent) variable is changed ;

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9
Q

Suggest two other variables the student should have kept constant during the experiment.

A 
temperature (of the reaction mixture) ;
enzyme / amylase , concentration ;
(total) volume of (reaction) solution ;
concentration of , cofactors / chloride ions / Cl-
;
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10
Q

Name the group of biological molecules to which alcohol dehydrogenase belongs.

A

enzymes

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11
Q

explain why alcohol dehydrogenase is able to break down both ethanol and DEG.

A 
similar, shape / structure ;
example of similarity ;
both , will fit into / complementary (shape) to /
bind to / bond to , active site (of
alcohol dehydrogenase ) ;
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12
Q

Suggest why DEG-contaminated wines with a high ethanol content may result in less DEG poisoning than contaminated wines with a low ethanol content.

A

(ethanol) competes with DEG ; ora
(when at high(er) concentration) ethanol more
likely to , collide with / bind to
/ bond to , active site ; ora
less , DEG breakdown / toxic product ; ora

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13
Q

Many enzymes are associated with non-protein molecules known as cofactors. Some cofactors are small inorganic ions.
Rennin is an enzyme that is involved in the digestion of milk. It converts soluble caseinogen in milk into insoluble casein. The cofactor Ca2+ is associated with this reaction. A student wished to investigate the effect of Ca2+ on the action of rennin.
Describe how the student could carry out this investigation and produce valid results.

A

carry out with and without , Ca2+ / cofactor ;
idea of using at least three concentrations (of Ca2+)
(other than zero) ;
keep , concentration / volume of , enzyme / rennin,
constant ;
keep , concentration / volume of , caseinogen /
substrate / milk, constant ;
keep , temperature / pH , constant ;
measure / AW , appearance of , product / casein
or
measure disappearance of , substrate / caseinogens
or
assess cloudiness (of solution) ;
over time intervals / after fixed time / end point time ;
replicates / repeats ;

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14
Q

Enzyme cofactors are often derived from vitamins and minerals in the diet.Proteins are required in large amounts in the diet whereas vitamins and minerals are required only in small amounts.
Suggest why.

A

idea of cofactors / minerals , being , recycled / used
again ;
idea that in enzyme action total mass of , cofactor /
coenzyme , very small compared to total
mass of protein ;
idea that proteins are used for purposes other than
enzymes ;
proteins are not stored in the body but vitamins and
minerals are ;
some enzymes don’t need cofactors ;

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15
Q

The mechanism of enzyme action was originally explained in terms of the ‘lock-and-key model’. It is now more often explained in terms of the ‘induced-fit’ model.Suggest why the lock-and-key and induced-fit explanations are termed models.

A

idea of simple representation of the , process / structure
or
idea of showing people how it works ;

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16
Q

Suggest why most scientists now accept the induced-fit model rather than the lock-and-key model.

A

supported by , more evidence / new research /
more work ;
idea of fitting evidence more closely (than lock & key) ;

17
Q

Suggest three variables that should be controlled in an investigation of this type

A

enzyme / LDH , concentration / volume ;
substrate / lactate, concentration / volume ;
time ;
idea that fish should be as closely related as
possible ;
pH ;

18
Q

the rate of conversion of lactate to pyruvate at 1 °C was found to be relatively slow when catalysed with LDH from non-Antarctic fish.Suggest reasons for this result.

A

(1°C is) below the optimum temperature / optimum
temperature is higher , for this enzyme ;
(at 1°C) low kinetic energy / KE , of , enzyme /
substrate ;
less chance of substrate entering active site / less
chance of ESC formation / fewer collisions between
substrate and active site ;
idea of activation energy harder to reach ;

19
Q

Suggest how a more flexible structure might help this enzyme work faster at lower temperatures.

A

easier for / increased chance of , substrate, entering active
site ;
more bonds can form / greater surface area for contact
(between active site and substrate) ;
easier for active site to change shape (as part of induced
fit) ;
the induced fit , will be easier / AW ;

20
Q

suggest how the structure of the enzymes may differ in Antarctic and non-Antarctic fish.

A

different, amino acids / amino acid sequence / primary
structure ;
different, (named feature of) secondary / (named feature
of) tertiary / quaternary, structure ;

21
Q

Agarose forms part of a more complex carbohydrate called agar, which is used as a growth medium for bacteria. Bacteria cannot break down the agarose in agar.
Suggest why bacteria cannot break down agarose.

A

(bacteria) do not, make / have, correct enzyme (to digest agarose) ;
agarose, does not fit / not complementary to, active site
(of bacterial enzymes) ;
bacteria unable to transport , substrate / enzyme , across
membrane ;

22
Q

One form of COPD develops because enzymes are released by phagocytes entering the alveoli. This enzyme action can break down elastin in the lining of the bronchioles and alveoli.
Use the example of elastin breakdown to explain the induced-fit hypothesis of enzyme action.

A

elastin is substrate ;
(elastin / substrate) binds to / fits into , active site ;
active site / enzyme / elastase / substrate / elastin,
shape changes ;
idea of closer fit (between active site and substrate) ;
more bonds form (between substrate and active site) ;
forms enzyme-substrate-complex / ESC ;
idea that (change in shape of active site) destabilises /
weakens , bonds (in substrate) / substrate ;
activation energy reduced ;
idea of further shape change of, active site / enzyme,
after products form ;

23
Q

Explain the term biological catalyst.

A

(enzymes are) proteins / used in metabolism / used in
named metabolic pathway ;
alter rate of (chemical) reaction / lowers activation energy /
provides alternative route for reaction /
is not changed / is not used up ;

24
Q

The student measured the volume of oxygen produced at five different temperatures using samples of the liquidised celery.
State the other variable that needs to be measured in order to calculate the rate of reaction.

A

time

25
Q

Identify one potential problem with using samples of liquidised celery as a source of catalase in this investigation and suggest a way to minimise this problem.

A

idea of different samples have different
concentrations of, catalase / enzyme ;
One of
source the extract for the whole experiment from a
single source ;
thorough , mixing , required before use ;
filter / purify , extract ;
idea of using , known / standard , concentration of
enzyme ;
commercial source of catalase ;

26
Q

Neuraminidase is an enzyme which is present on the protein coat of the influenza virus.
This enzyme is used to break down the host cell membrane and allow the influenza viruses to leave the infected cell. Tamiflu® is a neuraminidase inhibitor.
Suggest how Tamiflu® could inhibit neuraminidase.

A

Tamiflu® is , competitive / non-competitive inhibitor ;
correct detail of inhibition method that does not
contradict stated type of inhibition ;
prevents , substrate binding to active site /
formation of enzyme-substrate complex /
formation of ESC ;

27
Q

mylase is an enzyme that hydrolyses amylose to maltose. Maltose, like glucose, is a reducing sugar. A student investigated the action of amylase on amylose. She mixed amylase with amylose and placed the mixture in a water bath.
Describe how she could measure the change in concentration of maltose (reducing sugar) as the reaction proceeds.

A

take samples at a range of times / AW ;
same volumes (of solutions) added / removed (each time) ;
heat with, Benedict’s (solution) / CuSO4 and NaOH ;
(use of ) excess Benedict’s ;
changes to, green / yellow / orange / brown / (brick) red ;
remove precipitate / obtain filtrate ;
colorimeter ;
calibrate / zero, using, a blank / water / (unreacted)
Benedict’s ;
use (red / orange) filter ;
reading of, transmission / absorbance
OR
mass of precipitate ;
more transmission / less absorbance, of filtrate,
OR
greater mass ppt, = more maltose present ; ora
using, standard / known, concentrations (of maltose) ;
(obtain) calibration curve ;
plot, transmission / absorbance / mass of ppt, against
(reducing sugar) concentration ;
use graph to read off concentration of maltose / AW ;

28
Q

Suggest how chloride ions have this effect on the rate of reaction.

A

(acts as a) cofactor ;
(Cl-) binds to, enzyme / amylase / amylose / substrate ;
enzyme substrate complex / ESC, forms more, easily /
quickly ;

biology year 1 (15 decks)

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