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module 2: foundations to biology > 2.4 enzymes > Flashcards

2.4 enzymes Flashcards

1
Q

what are enzymes

A

biological catalysts that speed up the rate of reactions without being used up

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2
Q

what is the active site of an enzyme

A

area on the surface which is complementary to the shape of the substrate molecules

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3
Q

what is a catalyst

A

chemical/ substance that speed up the rate of reaction without being used up/changed

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4
Q

what is the turnover number

A

the number of reactions that an enzyme molecule can catalyse per second

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5
Q

what is an extracellular enzyme and exapmles

A

works outside of cells
amylase, trypsin

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6
Q

what is an intracellular enzyme and examples

A

made and retained in the cell
catalase

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7
Q

what are metabolites

A

the reactants, intermediates and products

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8
Q

what is a catabolic reaction

A

metabolites are broken down into smaller molecules and release energy

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9
Q

what is an anabolic reaction

A

energy used to synthesise larger molecules

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10
Q

what is metabolic/metabolism

A

the chemical reactions that that place inside cells

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11
Q

what is a product and substrate

A

molecule produced from substrate molecules
molecule altered by an enzyme

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12
Q

what does catalase do, consist of and where is it found

A

protects the cell from damage from reactive oxygen by breaking down hydrogen peroxide
4 polypetide chains and a haem group (iron)
vesicles

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13
Q

what does amylase digest, where is it produced and acts

A

starch into maltose
pancreas/salivary glands
acts in the mouth

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14
Q

what does trypsin do, where is it produced and acts

A

digests proteins into smaller peptides by hydrolysing peptide bonds
pancreas
acts in the lumen of small intestines

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15
Q

describe the induced fit model and how it releases products

A

the active site and substrate still have a complementary shape
when binded the active site changes shape so it fits around the substrate more closely forming an enzyme substrate complex
products have been converted it forms an enzyme product complex which detaches due to difference in shape from the active site released

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16
Q

what is an enzyme substrate complex

A

enzyme with substrate molecule in its active site bound by non covalent bonds

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17
Q

what is a enzyme product complex

A

substrate is built up or broken down into a product in its active site bound by non covalent bonds

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18
Q

describe the lock and key model forming smaller products

A

active site is a fixed shape and complementary to substrate
temporary hydrogen bonds hold substrate and enzyme together forming enzyme substrate complex
substrate broken down into smaller products

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19
Q

describe the lock and key model forming larger products

A

two smaller substrates fit into active site, forms an enzyme substrate complex
bonds form between substrate molecules forming an enzyme product complex
larger product leaves the site

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20
Q

describe the induced fit hypothesis

A

substrate and active site are complementary
active site changes shape of the side chains (R groups) slightly to have a closer fit

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21
Q

how do enzymes lower the activation energy

A

specific active site to substrate
brings the molecules close without excessive heat
so activation lowers and rate of reaction speeds up

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22
Q

identify the factors impacting rate of enzyme activity

A

temperature
pH
enzyme concentration
substrate conc.

23
Q

how does temperature speed up metabolic reactions

A

gains kinetic energy so molecules move faster
increases rate of successful collisions
rate of ES complexes increases so the ROR increases
up to the maximum point/ optimum temperature

24
Q

how are enzymes denatured by temperature

A

heat makes molecules vibrate which breaks weak bonds holding the tertiary structure of enzymes active site
ROR decreases as substrates no longer fit
as more heat applied the active site irreversibly changes and is no longer complementary
reaction no longer takes place = denatured

25
Q

what is temperature coefficient Q10

A

increase in rate of reaction when temperature increases by 10 degrees

26
Q

what does Q10=2 mean

A

ROR doubles as increased by 10 degrees

27
Q

what is pH

A

indicates whether a subtance is acidic, alkaline, or neutral

28
Q

what is a buffer

A

something that resists changes in pH

29
Q

how does change in pH impact enzymes

A

increases concentration of hydrogen ions (positive)
attracted to negative ions on active site
H+ interfers with hydrogen bonds and ionic forces holding tertiary structure
causes it to change shape
ROR decreases as substrate no longer fits

30
Q

what happens when enzymes optimum pH is restored

A

bonds reform and active site shape restored

31
Q

what is a competitive inhibitor

A

inhibition of an enzyme where the inhibitor has a similar shape to the substrate
competes for the enzymes active site
blocks it and prevents formation of enzyme substrate complexes

32
Q

what is a non competitive inhibitor

A

inhibition of an enzyme where the competitor molecule attaches to the allosteric part of the enzyme/ not the active site
changes the shape of the active site so substrate is no longer complementary and no more ES complexes forming

33
Q

what is a reversible inhibitor

A

inhibitor can be released to resume enzymes function

34
Q

what happens to the rate of reaction with a competitive inhibitor

A

competes directly with substrate molecule
reduces the rate of ES complexes forming and products being formed
slower ROR

35
Q

how can you reverse the effects of competitive inhibitors

A

increase the concentration of substrates
more chance of enzyme colliding with substrate

36
Q

what happens to ROR with a non competitive inhibitor

A

the maximum rate reduces

37
Q

what is end product inhibition

A

enzyme catalased reactions are regulated by product molecules staying tightly bound to the enzyme so no more can be formed

38
Q

how do presence of organelles increase efficiency of metabolic reactions

A

enzymes are bound to organelle membranes

39
Q

name two metabolic poisons that act as enzyme inhibitors

A

cyanide
snake venom

40
Q

what is cyanide made of, what does it do and how

A

inhibits aerobic respiration and catalase
when ingested KCN is hydrolysed to produce hydrogen cyanide a toxic gas that dissolves into H+ and CN- ions
binds irreversibly to enzyme in mitochondria
inhibits final stage of respiration

41
Q

what does snake venom do

A

inhibits enzyme acetylcholinesterase (AChE)
which brekas down neurotransmitter ACh
if inhibited it causes muscle contraction/ paralysis as ACh stays bound to receptors on muscle membrane

42
Q

name medicinal drugs that act as medicinal inhibitors

A

aspirin
ATPase inhibitors
ACE inhibitors
Protease inhibitors
nucleoside reverse transcriptase inhibitors

43
Q

what are cofactors

A

non protein component that binds to enzymes to ensure an enzyme catalased reaction takes place

44
Q

what are coenzymes

A

organic cofactors that bind temporarily to active siteof enzyme
contain carbon

45
Q

what are inorganic cofactors

A

inorganic molecules that help substrate and enzyme bind together but dont get directly used in reaction

46
Q

name the cofactor that is permanently bound to enzyme

A

prosthetic groups

47
Q

name the prosthetic group in carbonic anahydrase

A

zinc ion

48
Q

name the cofactor in amylase

A

chloride ion

49
Q

what happens to coenzymes during reactions

A

bind to enzyme
continually recycled to original state
act as a carrier between enzymes

50
Q

name a source of coenzymes

A

vitamins
NAD is derived from vitamin B3

51
Q

name a source of cofactors

A

minerals

52
Q

State the difference between cofactors and coenzyme

A

cofactors = a non-protein component to help enzymes carry out their functions
Coenzymes = organic cofactors

53
Q

explain what happens when substrate concentration increases

A

more ESC can form
more product form
ROR increases

54
Q

explain what enzyme concentration does

A

more active sites available
more successful collisions
more ESC can form

module 2: foundations to biology (6 decks)

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