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Biology > Enzymes > Flashcards

Enzymes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the turnover number?

A

the number of reactions an enzyme can catalyse per second

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2
Q

what is the role of an enzyme?

A

an enzyme speeds up metabolic reactions, and their actions affect structure and function within the cell and organism.

enzymes reduce the amount of energy needed for a reaction to happen and so that cells can carry out their functions

so enzymes help keep cellular functions running smoothly.

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3
Q

what is an intracellular enzyme + example?

A

this is an enzyme working inside the cell
catalase is found in nealy all living organisms that are exposed to O2. it protects cells by breaking hydrogen peroxide into H2O and O2
in eukaryotic cells catalase is found in vesciles called peroxisomes

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3
Q

what happens in a catabolic pathway?

A

metabolites are brocken down to smaller molecules and release energy

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4
Q

what is a metabolic pathway?

A

it is a series of consecutive reactions, where every step is catalysed by a specific enzyme.

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5
Q

describe 2 ways how metallic ion cofactors enable enzymes to work efficiently

A

they may bind to the active site together with the substrate to act as a co substrate to make the substrate complementery.
or they may change the charge distrubution on surface of active site which enables ESC to form more easily

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5
Q

what is a coenzyme?

A

small organic non-protein molecules that temporarily bind to the active site

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6
Q

what happens in an anabolic pathway ?

A

energy is used to synthisise larger molecules from smaller ones

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6
Q

what is an extracellular enzyme and give an example?

A

enzymes can be secreted from cells and act on their substrate from outside the cell.
amylase - produced in the salivery glands to digest starch into maltose. also made in pancreas to catalyse same reaction in lumen of small intestine

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6
Q

what is a cofactor?

A

a substance that has to be present to ensure that an enzyme catalysed reaction takes place at appropriate rate

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6
Q

what is a prosthetic group?

A

it is a cofactor that is perminantly bound by covalent bonds to an enzyme molecule

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7
Q

what is an enzyme-substrate complex?

A

it is a complex formed by temporary binding of the substrate and the enzyme

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7
Q

what is a co- substrate?

A

when they and the substate form the correct shape of the enzyme together

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8
Q

how are metallic ion cofactors different from prosthetic groups?

A

metallic ions bond temporalrily and prosthetic groups bond perminently as a pert of the structure

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9
Q

what bonds form between metallic ion cofactors and the enzyme?

A

ionic bonds

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10
Q

why are enzymes biological catalysts?

A

they speed up the rate of chemical reactions in living organisms without beings used up or a perminant change.

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10
Q

what bonds form between a prosthetic group and the enzyme?

A

covalent bonds

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11
Q

what bonds form between coenzymes and the enzyme or substrate molecules?

A

ionic or hydrogen

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11
Q

what is the induced fit hypothesis?

A

when the substrate and active site interact with each other, as substrate enters the R-groups on amino acids that make up the active site with change slightly. This is a conformational change to ensure ideal binding arrangment which maximised ability of enzyme to catalyse the reaction

11
Q

how do the product molecules know when to exit the active site?

A

the products have slightly different shape to the subsrate so they detatch

12
Q

what bonds bind the substrate to the active site?

A

hydrogen, ionic attractions, van der waals forces, hydrophobic interactions.

12
Q

how do enzymes lower the activation energy of a reaction?

A

they bring the substrate close enough together to react without the need for excessive energy

13
Q

why can a large amount of substrate be catalysed by a small amount of enzyme?

A

Because once the enzyme is done with the reaction it is free of product and is able to accept another substrate

13
Q

what happens in terms of energy if a substance is heated?

A

this extra energy (heat) causes them to gain kinetic energy which makes them move faster, this increases the rate and force of collisions between molecules

13
Q

what happens if both the enzyme and substrate are heated?

A

both will gain kinetic energy and move faster, this will increase rate of succesful collisions which increases the rate of formation of ESCs and therefore produces the rate of formation of EPCs

14
Q

what happens if enzyme molecules vibrate too much?

A

may break weak ionic and hydrogen bonds that hold the enzymes active site in its tertiary structure. so the AC shape begins to change so substrate molecule wont fit so rate of reactions will decrease

15
Q

how does the enzyme become denatured?

A

more enerygy is applied so AS shape irreversibly changes and substrate molecules now arn’t complementory, so reaction cant happen and the enzyme denatures

15
Q

what are the units for trate of reaction?

A

s-1

16
Q

what is the definition of a temperature coefficient?

A

the increase in rate of a process when the temp is increased by 10oc.

17
Q

what is the temperature coefficient equation?

A

Q10 =(rate of reaction at (x + 10) °C) ÷ (rate of reaction at x °C)

18
Q

what is the temperature coefficient for an average reaction in a test tube? and what it mean?

A

approx 2. this means for every 10 o c rise the rate of reaction is doubled.

18
Q

what is a biological buffer?

A

a chemical that resists changes in pH. these chemicals will accepts or donate H+ ions to either make the solution more or less acidic

19
Q

what happens to an active site if it is too acidic?

A

H+ ions will interfere with charges on the active site because positive H s will cluster around negative parts (AA R-groups). which will interfere with the binding of the substrate molecule.

19
Q

what will happen to an enzyme is it is too acidic?

A

excess H+ ions are attracted to negativly charged parts of the molecule and interfere with the hydrogen and ionic bonds. and change the tertiary structure of the protein so the shape of the actiev site will change.

19
Q

what is a competative inhibitor?

A

substances that have a similar shape to the substrates. so it competes with the substrate for the active site. it will fit into the AC so the substrate cant.

19
Q

how does increasing inhibitor conc effect rate of reaction?

A

more inhibitor molecules collide with AS so effect of inhibition is greater

20
Q

how does increasing substrate concentration effect rate of reaction?

A

effectively dillutes the effect of inhibitor

20
Q

what is a perminent competitive inhibitor called ?

A

inactivator

21
Q

what is a non competitive inhibitor?

A

if the inhibitor binds to the enzyme somewhere other than the active site, they don’t compete with the substrate for a place on the AS.

22
Q

what is the site called that a non competitive inhibitor binds too?

A

allosteric site

23
Q

what effect does a non competitive inhibitor have on the enzyme?

A

they disrupt the enzymes tertiary structure and change its AS shape so it is no longer complementory. ES complexes cant form.

24
Q

what is end product inhibition?

A

when the end product of a metabolic pathway acts as the inhibitor to the 1st enzyme. it ultimatly inhibits the production of itself. it is example of negative feedback

25
Q

how will having too much end product affect inhibition?

A

if conc of end product is too high then more inhibition will occur because there will be more end product to bind to the 1st enzyme and inhibit itself.

26
Q

what happens if there is greater end product inhibition?

A

decrease in concentration of end product

27
Q

what happens as concentration of end product decreases? why?

A

inhibition decreases, because there is not enough end product to sustain the inhibition and the 1st enzyme will become reactivated again

Biology (14 decks)

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