2.1.4 Enzymes Flashcards

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1
Q

What are intracellular enzymes? Give an example

A

Enzymes that act within cells
E.g. catalase

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2
Q

What are extracellular enzymes? Give an example

A

Enzymes that act outside of the cell
E.g. digestive enzymes amylase and trypsin

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3
Q

What enzyme is needed to break down starch to maltose and where is it produced?

A

Amylase
Salivary glands and pancreas

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4
Q

What enzyme is needed to break down maltose to glucose and where is it produced?

A

Maltase
Small intestine

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5
Q

What is the normal temperature coefficient for enzyme controlled reactions?

A

Two

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6
Q

What is temperature coefficient?

A

Measure of how much rate of reaction increases with a 10ยบC change in temperature

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7
Q

Explain the effects of increasing temperature on enzyme activity?

A
  • Increased kinetic energy so more frequent successful collisions. Rate increases
  • Optimum temperature reached. Highest rate of activity
  • Bonds vibrate and break. Active site denatures as the tertiary shape changes
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8
Q

What are the adaptations of enzymes in cold environments?

A
  • More flexible structures
  • Less stable
  • Smaller temperature changes will denature it
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9
Q

What are the adaptations of enzymes in hot environments?

A
  • More stable
  • More resistant to change as temperature rises
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10
Q

What is the optimum pH for pepsin and where does it act?

A

pH 1-2
Stomach

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11
Q

What is the optimum pH for trypsin, lipase and maltase and where does it act?

A

pH 8
Small intestine

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12
Q

What happens when substrate concentration increases?

A
  • Higher collision rate
  • More enzyme-substrate complexes
  • Reaches Vmax
  • Enzyme concentration becomes limiting factor

Same for increasing enzyme concentration, just substrate concentration becomes limiting factor

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13
Q

What is Vmax?

A

All of the active sites are occupied by substrates

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14
Q

How to get a higher Vmax on substrate concentration graph?

A

Increase concentration of enzyme to make more active sites available

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15
Q

How does a competitive inhibitor work?

A
  • Has similar shape to substrate
  • Binds to active site temporarily
  • Reduced substrates binding so rate of reaction decreases
  • Vmax remains same as increasing substrate concentration can overcome effects
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16
Q

How does a non-competitive inhibitor work?

A
  • Binds to allosteric site
  • Tertiary structure changes
  • Active site no longer complementary to substrate
  • Lower Vmax as increasing substrate concentration cannot overcome effects
17
Q

What is end product inhibition?

A
  • Product of reaction inhibits the enzyme
  • Negative feedback
  • Ensures resource are not wasted
  • Non-competitive inhibition
18
Q

What is a cofactor?

A

Non-protein molecule which helps enzymes carry out their function

19
Q

What is a coenzyme?

A

A cofactor that is an organic molecule

20
Q

Where are inorganic cofactors derived from? Give example

A

Minerals
E.g. Chloride on amylase

21
Q

Where are coenzymes derived from? Give example

A

Vitamins
E.g. Vitamin B3 to synthesise NAD

22
Q

What are prosthetic groups? Give example

A

Cofactors which are permanently bound to a protein
E.g. Zinc ions in carbonic anhydrase

23
Q

What is precursor activation?

A

Inactive enzymes undergo a change in tertiary structure to be activated. Normally by:
- Addition of a cofactor
- Action of another enzyme
- Changes in conditions