1.4 - Biological reactions are regulated by enzymes Flashcards

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1
Q

What is metabolism?

A

a series of enzyme-controlled reactions in the body

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2
Q

What are the two main types of reaction?

A

Anabolic reaction
Catabolic reaction

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3
Q

What does an anabolic reaction do? What does a catabolic reaction do?

A

Anabolic: protein synthesis where amino acids are built up into more complex polypeptides
Catabolic: digestion of proteins, where complex polypeptides are broken down into simple amino acids

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4
Q

what are enzymes?

A

all enzymes are tertiary globular proteins where the protein chain is folded back on itself into a spherical or globular shape

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5
Q

what can enzymes be described by and what does this mean?

A

can be described as biological catalysts as they speed up the rate of metabolic reaction, but they are not changed by the reaction and do not get used up.

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6
Q

where are all enzymes made?

A

inside the cell

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7
Q

what are the sites of enzyme action?

A

extracellular
intracellular

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8
Q

What are the two different models for enzyme reaction?

A
  1. lock and key theory
  2. induced fit hypothesis
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9
Q

What does the lock and key model suggest?

A

that the substrate has a complementary shape to the enzymes active site and therefore that many enzymes only catalyse one substrate

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10
Q

What does the induced fit hypothesis suggest?

A

active site of enzyme changes shape slightly to accommodate the substrate to form an enzyme substrate complex, the reverts to it’s original active site shape

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11
Q

what is the example for the induced fit hypothesis? And how does it work?

A

the enzyme lysozyme
it is an antibacterial enzyme in human saliva, tears and mucus
it attaches to the wall of bacteria and breaks glycosidic bonds

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12
Q

what does itt mean if an enzyme has disulphide bonds present?

A

it is likely to withstand quite high temperatures

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13
Q

Enzymes are biological catalysts. How do they bring about the effect of speeding up a reaction?

A

The substrates fit into the active site of the enzyme and therefore lowers the activation energy

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14
Q

What are the four factors affecting enzyme rate of reaction?

A
  1. substrate concentration
  2. temperature
  3. pH
  4. enzyme concentration
  5. presence of inhibitors
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15
Q

how does substrate concentration effect the enzyme rate of reaction?

A

when the substrate increases in an enzyme-controlled reaction, there is a greater chance of a successful collision between the substrate and the enzyme, resulting in more enzyme-substrate complexes forming.

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16
Q

what is a plateau?

A

the maximum rate of reaction for the conditions reached

17
Q

how does temperature effect the enzyme rate of reaction?

A

temp increases, enzyme and substrate molecules gain mroe kinetic energy, increasing chance of more successful collisions, therefore increasing chance of more substrate complexes formed.

18
Q

what happens above the optimum rate of reaction for enzymes?

A

rate of reaction decreases rapidly as hydrogen bonds in the tertiary structure break due to increased vibrations resulting in a change to the shape of the active site (denaturing)

19
Q
A