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A-level Biology > 2.4 Enzymes (spec) > Flashcards

2.4 Enzymes (spec) Flashcards

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1
Q

What is an enzyme?

A

Biological catalysts that speed up metabolic reactions in living organisms

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2
Q

How does structure of an enzyme determine its function?

A
  • Needs cofactors to help catalyse some reactions
  • Instructions for making enzymes is encoded in its genes (if there is a mutation then the tertiary structure might be different and it won’t be complementary)
  • If enzyme is deficient a metabolic disorder may occur
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3
Q

What are intracellular enzymes?

A

Metabolic reactions inside the cell

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4
Q

What does catabolic mean?

A

Breaks down

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5
Q

What does anabolic mean?

A

Builds up

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6
Q

What are examples of intracellular reactions?

A

Respiration and photosynthesis

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7
Q

Describe action of catalase

A

Protects cell from reactive oxygen by breaking down hydrogen peroxide

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8
Q

What is the turnover rate of catalase?

A

6 million per second (highest)

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9
Q

What are extracellular enzymes?

A
  • Secreted by cells and made to act outside (many in digestive system - digest food molecules)
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10
Q

Describe the action of amylase

A
  • Produced in salivary glands and pancreas

- Digest starch and makes maltose

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11
Q

Describe the action of trypsin

A
  • Produced in the pancreas

- Acts in lumen to digest proteins into peptide by hydrolysing peptide bonds

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12
Q

Describe the lock and key hypothesis

A
  • Active site is complementary to substrate
  • Have kinetic energy meaning randomly collide
  • When collide create enzyme-substrate complex
  • Leaves as a product
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13
Q

Describe the induced fit hypothesis

A
  • Enzyme is not a rigid/fixed structure
  • Presence of a substrate causes shape change
  • Moulding creates more effective binding
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14
Q

What is the effect of temperature of enzyme action?

A
  • Extra energy causes to move faster
  • Increases rate of collision/reaction
  • When too hot vibrates breaking bonds and tertiary structure
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15
Q

What is the optimum temperature?

A

Temperature where the rate of reaction is at its maximum

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16
Q

What is the temperature coefficient?

A

rate of reaction at T

17
Q

What does the temperature coefficient show?

A

There is an increase in rate when temperature is increased by 10 degrees

18
Q

What are the effects of pH?

A
  • Negative ions are attracted to positive ions

- Causes bonds to make and break losing tertiary structure of enzyme and meaning that the active site is complimentary

19
Q

What is a buffer?

A

Chemicals that resist changes in pH

20
Q

What is the effect of substrate concentration?

A
  • No substrate = no reaction

- If all substrate is used up it becomes the limiting factor

21
Q

What are prosthetic groups?

A

Cofactors that permanently bind by covalently

22
Q

What is an example of prosthetic groups?

A

CO2 + H2O ——-> H2CO3 + H2 + HCO3-

Carbonic anhydrase catalyses and has zinc permanently bound

23
Q

What are coenzymes?

A
  • Small, organic protein molecules
  • Temporarily bind to active site
  • Just before/when substrate binds
  • Chemically changes reaction
  • Recycled to original state
24
Q

What are examples of coenzymes?

A

Vitamins are a source of coenzymes

B12 contains Cobalamin Coenzymes

25
Q

What are cofactors?

A
  • Ions that are not permanently bound

- Ease formation of enzyme - substrate complex

26
Q

What are co-substrates?

A
  • Make substrate complementary to the active site

- Change charge distribution on the surface of the molecule

27
Q

What is an example of a coenzyme?

A

Amylase digests starch to maltose

Chloride ions have to be present

28
Q

What is competitive inhibition?

A
  • Fits into the active-site so substrate cannot enter
29
Q

What does relative concentration depend on?

A

Amount of inhibition

30
Q

What is non-competitive inhibition?

A
  • Binds to allosteric site
  • Disrupts enzymes tertiary structure and is no longer complementary
  • Maximum rate of reaction is reduced
31
Q

What are two examples of metabolic poisons?

A

Cyanide

Snake venom

32
Q

What is the action of cyanide?

A

Inhibits aerobic respiration

KCN hydrolysed to produce hydrogen cyanide (posion)

33
Q

What is the action of snake venom?

A

Inhibits muscular synapses

Causes paralysis

34
Q

What are two examples of medicinal drugs?

A

Aspirin

ATPase

35
Q

What is the action of aspirin?

A

Prevents formation of prostaglandins

Stops inflammation

36
Q

What is the action of ATPase?

A

Inhibits sodium potassium pump and allows more calcium ions to enter cells
Increases muscular contraction and strengthens heartbeat

37
Q

What is product inhibition?

A

Products stay tightly bound to enzyme and aren’t released

38
Q

What is a metabolic pathway?

A

Product of one reaction becomes the substrate of another

A-level Biology (23 decks)

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