Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOLOGY (OCR A-LEVEL) > CHAPTER 4 - ENZYMES > Flashcards

CHAPTER 4 - ENZYMES Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is an enzyme?

A

A biological catalyst ( speeds up metabolic reactions and doesn’t get used up)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an anabolic enzyme reaction?

A

Building up molecules - requires energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a catabolic enzyme reaction?

A

Breaking down large molecules - releases energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the lock and key model?

A

The substrate is already complimentary to the active site of the enzyme.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the induced-fit hypothesis?

A

The active site of enzyme changes shape slightly as substrate enters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name 1 intracellular (works inside the cell) enzyme

A

Catalase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name 3 extracellular (works outside the cell) enzymes

A

Amylase
Maltase
Trypsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

State 2 features of catalase

A
  • found in all organisms exposed to oxygen

- catalyses decomposition of hydrogen peroxide (by product of many metabolic reactions/harmful) to water and oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does amylase do?

A

Works in saliva to catalyse hydrolysis of starch into maltose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does maltase do?

A

Works in small intestine to catalyse hydrolysis of maltose into glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does trypsin do?

A

Catalyses hydrolysis of peptide bonds of large polypeptides into smaller ones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the 2 steps of starch digestion?

A
  1. Amylase partially breaks down starch polymers into maltose
  2. Maltase breaks down maltose into glucose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is trypsin also known as?

A

Protease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where is trypsin produced and released?

A

Produced in pancreas/ released into small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the digestion of protein?

A

Polypeptides broken down into amino acids by protease. Absorbed by cell lining in the digestive system and then absorbed into bloodstream.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to enzyme reactions when temp increased?

A
  • more kinetic energy
  • more collisions
  • more successful collisions between enzyme and substrate
  • increase rate of reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define temperature coefficient (Q10)

A

measure of how much rate of reaction increase with 10 degree rise in temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do you calculate Q10

A

rate at higher temp
—————————
rate at lower temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens to the enzyme when temp is increased too much?

A
  • vibrations increase and bonds strain till broken
  • tertiary structure changes (denatured)
  • active site shape no longer complimentary to substrate
  • enzyme no longer functions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is optimum temperature?

A

Temp at which enzyme has highest rate of activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Optimum temp of human body?

A

40

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Optimum temp of thermophilic bacteria (hot)

A

70

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Optimum temp of psychrophilic organisms (cold)

A

5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens to rate of reaction above optimum temp?

A

Decreases rapidly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What happens to rate of reaction below optimum temp?

A

Still present but less rapid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Features of enzymes in cold environments.

A
  • more flexible structure (particularly at active site)
  • less stable than enzymes working at high temps
  • small temp change will denature them
27
Q

Features of enzymes in hot environments.

A
  • more stable (increased h bonds and disulphide bonds in tertiary)
  • shape and active site of enzyme more resistant to temp change
28
Q

What is optimum pH?

A

A narrow range where the enzyme will function.

29
Q

What happens when pH is altered slightly?

A

Structure of enzyme and active site is altered slightly

30
Q

What happens when pH returns to optimum?

A

Renaturation: enzyme resumes its normal shapes and catalyses reactions

31
Q

What happens when pH significantly changed?

A

Structure of enzyme irreversibly altered/ active site no longer complimentary to substrate.

32
Q

What does amylase catalyse?

A

Starch ——> maltose

33
Q

What does pepsin and trypsin catalyse?

A

Proteins ——> polypeptides

34
Q

What does lipase catalyse?

A

Triglycerides——> glycerol + fatty acids

35
Q

What does Maltase catalyse?

A

Maltose ——> glucose

36
Q

What happens when substrate conc increases?

A
  • higher collision rate with enzyme active sites
  • more enzyme-substrate complexes formed
  • rate of reaction increases
37
Q

What happens when conc of enzyme increases?

A
  • more active sites available

- enzyme-substrate complexes formed at a faster rate

38
Q

Define concentration

A

Number of molecules per unit volume

39
Q

Define Vmax

A

Maximum rate enzyme is working at

40
Q

How do you calculate the rate of reaction? (cm3s-1)

A
  1. Draw tangent from 0
  2. Calculate gradient: change in y
    ——————
    change in x
41
Q

What is competitive inhibition?

A

A competitive inhibitor binds to active site of enzyme and blocks the substrate from binding.

42
Q

How does competitive inhibition effect the rate of reaction?

A
  • reduces rate for given conc of substrate , Vmax doesn’t change for enzyme it inhibits
  • substrate conc increased, more substrate then inhibitor, Vmax can still be reached
43
Q

State 2 examples of competitive inhibition.

A
  • statins inhibit enzyme for synthesis of cholesterol to help reduce blood cholesterol conc
  • aspirin irreversibly inhibits cox enzyme - prevents synthesis of prostaglandins and thromboxanxe (chemicals causing pain and fever)
44
Q

What is non-competitive inhibition?

A

A non-competitive inhibitor binds to the allosteric site of an enzyme which cause tertiary structure and active site to change shape so substrate is no longer complimentary and cannot bind.

45
Q

How does non-competitive inhibition effect the rate of reaction?

A
  • increase conc of enzyme or substrate does not overcome effect on NC inhibitor
  • increasing conc of NC inhibitor further decreases rate, less active sites available
46
Q

What are 2 examples of irreversible non-competitive inhibitors?

A
  • organophosphate (insecticides and herbicides) inhibit enzyme acetyl cholinesterase (nerve impulse transmission) — leads to muscle cramps, paralysis, death if ingested
  • proton-pump inhibitor treats long term indigestion. Blocks enzyme system from secreting H ions into stomach - can lead to formation of stomach ulcers
47
Q

When does end-product inhibition occur?

A

When product of enzyme controlled reaction acts as inhibitor to enzyme that produces it ( negative feedback control mechanism for a reaction)

48
Q

How does ATP regulate its own production?

A

PFK competitively inhibits ATP

49
Q

What happens at high ATP levels?

A
  • ATP bond to allosteric site of PFK
  • prevents addition of second phosphate to glucose
  • glucose not broken down
  • ATP not produced at same rate
50
Q

What happens at low levels of ATP?

A
  • less ATP binds to PFK
  • enzyme can catalyse addition of second phosphate to glucose
  • respiration resumes
  • more ATP produced
51
Q

What is a cofactor?

A

Non-protein substance that helps the enzyme to work (makes up part of active site or binds to allosteric site to alter tertiary and active site so substrate can bind)

52
Q

What do inorganic cofactors do?

A
  • help enzyme and substrate bind

- does not participate in reaction

53
Q

Examples of inorganic cofactors.

A
  • minerals in diet

- chloride ions cofactors for amylase enzyme

54
Q

What do coenzymes (organic cofactors) do?

A

Act as carriers moving chemical groups between enzymes.

  • participate in reaction and changed slightly
  • continually recycled during process
55
Q

Example of coenzyme

A

Vitamins

56
Q

Example of coenzyme

A

Vitamins

57
Q

What is a prosthetic group?

A

A cofactors that is tightly bound to an enzyme

58
Q

Example of prosthetic group.

A
  • zinc ions are prosthetic group for carbonic anhydrase
  • zinc ion becomes permanent part of enzymes active site
  • carbonic anhydrase important for metabolism of carbon dioxide
59
Q

What is precursor activation?

A

Enzymes produced in inactive form (so doesn’t damage cell where it’s synthesised and to control enzyme activity) and needs a cofactor to bind to activate it

60
Q

What is an apoenzyme?

A

Precursor inactive protein ( no factor added)

61
Q

What is a holoenzyme?

A

Active form of enzyme (cofactor added)

62
Q

What is a zymogen?

A

An inactive precursor enzyme that requires covalent modification usually by another enzyme.

63
Q

What are 2 examples of zymogens?

A
  1. Trypsinogen (inactive) : another enzyme changes covalent bonding to make it trypsin
  2. Pepsinogen (inactive): extreme stomach pH changes covalent bonding to make it active pepsin

BIOLOGY (OCR A-LEVEL) (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions