Enzymes Flashcards

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1
Q

lock and key hypothesis means

A

The substrate fits perfects into the enzyme active site

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2
Q

theory of induced fit means

A

The shape of the active site changes to fit more perfectly around the substrate, putting pressure on the bonds in the substrate to lower the activation energy

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3
Q

Enzymes working inside the cell are called… and outside the cell are called …

A

Enzymes working inside the cell are called intracellular and outside the cell are called extracellular

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4
Q

The active site and substrate are not the same shape, they are:

A

Complementary

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5
Q

Enzymes only catalyse one substrate, so they are described as

A

Specific

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6
Q

The rate of an enzyme catalysed reaction increases with increasing temperature due to…

A

Increased kinetic energy causing increased frequency of successful collisions

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7
Q

When the temperature is too high enzymes will…

A

Denature, meaning the hydrogen bonds break and the shape of the active site is lost

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8
Q

Enzyme controlled reactions will be fastest at a temperature and pH described as the

A

Optimum

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9
Q

The four factors that can limit the rate of an enzyme controlled reaction are

A

Temperature, pH, enzyme concentration, substrate concentration

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10
Q

What does a buffer do?

A

Maintain a constant pH

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11
Q

What happens when pH is only slightly above or below the optimum

A

Small changes in pH cause small reversible changes in enzyme structure, causing inactivation.

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12
Q

What is inhibition?

A

Inhibition is when enzyme action is slowed down or stopped by another substance

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13
Q

What is a competitive inhibitor?

A

A competitive inhibitor is structurally similar to the substrate and binds to the enzyme active site, blocking it.

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14
Q

What is a non competitive inhibitor

A

Non-competitive inhibition involves an inhibitor binding away from the active site, altering the active site’s shape

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15
Q

What effect will increasing substrate concentration have when either a competitive or non competitive inhibitor is present?

A

Competitive if the substrate concentration is increased so will the rate of reaction. Non competitive the rate of reaction is unaffected by substrate concentration.

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16
Q

What do you call a site that is not the active site?

A

allosteric site

17
Q

Give an example of a non competitive inhibitor

A

Cyanide

18
Q

Give three advantages of immobilising enzymes

A

They can be re-used, they are more stable at extremes of temperature and pH, they do not contaminate the product, enzymes can be combined or used in continuous processes

19
Q

What is the function of the nucleus?

A

Contains the DNA which codes for protein synthesis