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Module 2: Foundations in Biology > Enzymes > Flashcards

Enzymes Flashcards

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1
Q

what are enzymes?

A
  • biological catalysts with specific tertiary structures, allowing their active site to bind to specific substrates
  • not used up and lower activation energy of reactions
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2
Q

what does the lock and key model describe

A

describes the substrate being perfectly complementary to the active site.

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3
Q

what does the lock and key model not explain

A

how the ES complex is stabilised

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4
Q

what does the induced fit model describe

A

it describes hoe the active site changes shape to add a strain to the substrate, reducing the activation energy of the reaction

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5
Q

what are extracellular enzymes

A

enzymes produced inside cells but secreted out of cell and act outside of cell

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6
Q

examples of extracellular enzymes

A

trypsin and amylase

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7
Q

what are intracellular enzymes

A

enzymes produced in cells that act in cells

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8
Q

what are catabolic reactions

A

large molecules broken down into smaller ones releasing energy

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9
Q

what are anabolic reactions

A

large molecules made from smaller ones using energy

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10
Q

what’s hydrogen peroxide

A
  • harmful by-product of many metabolic processes
  • rapidly broken down to oxygen and water by intracellular enzyme catalase
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11
Q

action of amylase

A
  • catalyses hydrolysis of starch into maltose
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12
Q

action of trypsin

A
  • catalyses the breakdown of peptide bonds, breaking down polypeptides into smaller ones
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13
Q

where is trypsin made and where does it act

A
  • produced in pancreas
  • acts in small intestine
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14
Q

where is amylase made and where does it act

A
  • made in the salivary glands
  • acts in the mouth
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15
Q

what’s enzyme activity limited by

A

rate of successful collisions with substrates and by shape of active site

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16
Q

what effect does increasing temp have on enzyme activity

A
  • kinetic energy of the molecules increases, increasing successful collisions
  • above the optimum temperature, bonds break and tertiary structure is denatured
  • shape of active site changes so substrate no longer fits
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17
Q

what effects does change in pH away from optimum have on enzyme activity

A
  • alters the charges of amino acids as well as the ionic and hydrogen bonds, altering the tertiary structure and denaturing the enzyme
  • shape of active site changes so substrate no longer fits
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18
Q

what does the temp coefficient show

A

the increase in ror when temp increases by 10C

19
Q

equation for temp coefficient

A

Q10 = ror at (T+10C) / ror at TC

20
Q

effect of enzyme concentration of enzyme activity

A
  • as conc of enzyme increases so does the rate as its more likely that a substrate molecule collides successfully with with active site and form ESC
  • ror increases until substrate conc becomes the limiting factor so adding more enzyme has no effect
21
Q

effect of substrate concentration of enzyme activity

A
  • as substrate conc rises form 0, ESC form faster and rate increases as more substrate means that successful collision between enzyme and substrate is more likely
  • eventually, all active sites will be saturated and rate plateaus as all active sites are are full
  • rate will decrease over time if no more substrate is added
22
Q

what are enzyme inhibitors

A

molecules that affect the way substrate and enzymes interact and affect product turnover

23
Q

what are competitive inhibitors

A
  • have similar shape to substrate and compete with it for the active site. Higher substrate conc will overcome this
24
Q

what are non-competitive inhibitors

A
  • bind to the allosteric site on enzymes and alter the shape of the active site, reducing maximum ror
25
Q

what bonds so reversible inhibitors form with enzyme

A
  • weak ionic or H bonds
26
Q

what bonds so reversible inhibitors form with enzyme

A
  • strong covalent bonds
27
Q

what are cofactors

A
  • non-protein substance that binds to enzyme that allows it to function
  • aren’t used up in reactions and don’t change
28
Q

what are coenzymes

A

organic cofactors

29
Q

what’s a prosthetic group

A

cofactor that is tightly and permanently bound to enzyme

30
Q

cofactor for amylase

A

Cl-

31
Q

what are sources of coenzymes

A

vitamins

32
Q

cofactor/prosthetic group for carbonic anhydrase

A

Zn2+

33
Q

role of carbonic anhydrase

A

catalyses the production of carbonic acid from H2O and CO2 in RBCs

34
Q

medicinal drugs that act as enzyme inhibitors

A
  • penicllin
  • antibiotics
35
Q

how do antiviral drugs act as enzyme inhibitors

A
  • reverse transcriptase inhibit the enzyme reverse transcriptase, which catalyses the replication of viral DNA. This prevents the virus from replicating
36
Q

how do antibiotics act as enzyme inhibitors

A
  • penicillin inhibits the enzyme transpeptidase, which catalyses the the formation of proteins in bacterial cell walls. This weakens it a prevents regulation of osmotic pressure so cell bursts and dies
37
Q

metabolic poisons that act as enzyme inhibitors

A
  • cyanide
  • malonate
  • arsenic
38
Q

how does arsenic act as an enzyme inhibitor

A

inhibits pyruvate dehydrogenase, another enzyme that catalyses respiration reactions

39
Q

how does malonate act as an enzyme inhibitor

A

inhibits succinate dehydrogenase which catalyses respiration reactions

40
Q

how does cyanide act as an enzyme inhibitor

A

irreversible inhibitor of cytochrome c oxidase, an enzyme that catalyses respiration reactions. cells that can’t respire die.

41
Q

what’s a metabolic pathway

A

series of connected metabolic reactions. Product of first reaction takes part in second reaction and so on. Each reaction is catalysed by a different enzyme

42
Q

what’s end-product inhibition

A
  • where final product can provide negative feedback on the reactions that form them by inhibiting enzymes earlier on in the metabolic pathway
  • when level of product starts to drop, there will be less inhibition so more product is formed and vice versa
43
Q

why are some enzymes produced as inactive precursor molecules in metabolic pathways

A
  • to prevent damage being caused to cell (like protease that may break down proteins in the cell)
  • once part of precursor molecule that inhibits enzyme is removed, enzyme becomes active
44
Q

what does enzyme availability depend on

A

balance of synthesis and degredation

Module 2: Foundations in Biology (6 decks)

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