3.1.4.2 Proteins - Enzyme Action Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 1) > 3.1.4.2 Proteins - Enzyme Action > Flashcards

Flashcards in 3.1.4.2 Proteins - Enzyme Action Deck (25)
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1
Q

Define an enzyme

A

Enzymes are biological catalysts that speed up chemical reactions without being used up or changed.

1
Q

How did scientists discover the induced fit model of enzyme action?

A

They noticed that other molecules could bind to enzymes, which then affected the enzyme’s activity. This led to the conclusion that the enzyme shape must be changing.

2
Q

What is a substrate?

A

The substance on which an enzyme acts

3
Q

Why are enzymes essential to organisms?

A

They allow essential chemical reactions to occur rapidly at low temperatures e.g. 37 °C.

4
Q

Enzymes that catalyse chemical reactions outside of cells are called…

A

extracellular enzymes

5
Q

Which 3 conditions must be satisfied for a chemical reaction to take place?

A
  • The substrates must collide with sufficient energy to alter the arrangement of their atoms
  • The energy of the products must be lower than the substrates.
  • The activation energy needs must be met.
5
Q

The functional part of an enzyme is called the…

A

active site

6
Q

Describe the lock and key model of enzyme action

A
  • A substrate is specific to an enzyme.
  • A substrate binds to the active site of an enzyme.
  • This lowers the activation energy.
  • Product is released from enzyme.
8
Q

Which have a higher energy level: substrates or products?

A

substrates

9
Q

The specific 3D shaped active site of an enzyme is determined by..

A

its sequence of amino acids (primary structure)

10
Q

Enzymes that catalyse reactions inside of cells are called…

A

intracellular enzymes

11
Q

When a substrate binds to the active site we call the resulting structure an…

A

enzyme-substrate complex

12
Q

A substrate does not have the same shape as the active site it has a _____________ shape.

A

complementary

13
Q

What does the following describe:

  • A substrate is specific to an enzyme.
  • A substrate binds to the active site of an enzyme.
  • This lowers the activation energy.
  • Product is released from enzyme.
A

The lock and key model of enzyme action

14
Q

Hormones are proteins that have a binding site so that they can switch on or off bodily processes. Are they enzymes?

A

No - many proteins have binding sites or receptor sites. These are not active sites.

15
Q

Which type of biological molecule are enzymes?

A

Proteins

16
Q

Which structural type of protein are enzymes?

A

Globular proteins

17
Q

What do we call the initial energy required for a chemical reaction to take place?

A

Activation energy

19
Q

How does a substrate temporarily bind to an enzyme active site?

A

The substrate temporarily forms bonds with certain amino acids in the active site.

20
Q

What does the following describe:

  • Substrate approaches active site
  • Enzyme changes shape and forms functional active site.
  • Enzyme moulds to substrate
  • Change in shape puts a strain on bonds of substrate, lowering activation energy.
  • Product is released from enzyme.
A

The induced fit model of enzyme action

21
Q

What is the name of the currently accepted model of enzyme action?

A

The induced fit model of enzyme action

22
Q

Describe the lock and key model of enzyme action.

A
  • A substrate is specific to an enzyme.
  • A substrate binds to the active site of an enzyme.
  • This lowers the activation energy.
  • Product is released from enzyme.
23
Q

Why are enzymes still effective even in small amounts?

A

Because they are not used up or changed so can be used again and again.

24
Q

Describe the induced fit model of enzyme action

A
  • Substrate approaches active site
  • active site not complementary/will fit substrate
  • active site changes shape and forms functional active site - as substrate binds
  • Enzyme moulds to substrate
  • Change in shape puts a strain on bonds of substrate, lowering activation energy.
25
Q

Why does formation of enzyme substrate complex increase rate of reaction?

A

Reduces activation energy

due to the bending/weakening of bonds

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