Biology - Review Qns - 4.1 & 4.2 Flashcards Preview

LPC 2018 Biology > Biology - Review Qns - 4.1 & 4.2 > Flashcards

Flashcards in Biology - Review Qns - 4.1 & 4.2 Deck (31):
1

Inhibition

4 characteristics

Depending on bond strength:
Reversible
Irreversible
 
Depending on binding point:
Competitive
Non-competitive

2

Cofactors

Cofactors are additional components required by some enzymes to catalyse a reaction.

3

Can enzymes be reused?

As enzymes do not form part of the product of the reaction they catalyse, they are not used up and can be reused over and over again.

4

Non-competitive inhibition

The inhibitor binds to a site of the enzyme that is not the active site (an allosteric site)
Changes the shape (or conformation) of the enzyme
thereby
It affects the binding of substrate to the active site
or
It blocks the changes in shape needed for the reaction to progress once the substrate is bound.

5

Reversible inhibition

2 Points

The bonds formed between inhibitor and enzyme are weak and easily broken, so the inhibition is reversible.
 
Reversible inhibition can be partially overcome by increasing the concentration of substrate.

6

What major factors affect the rate of enzymatic reactions?

3 factors

Temperature
pH
Concentration
 

7

What is

A biochemical pathway

A biochemical pathway is a sequence of biochemical reactions catalysed by different enzymes, in which the product of each reaction becomes the substrate in the next reaction.

8

How many models are there of enzyme-substrate reaction?

Two

- The lock and key model
- The induced-fit model

9

Coenzymes

3 points

Coenzymes are small, non-protein organic cofactors such as vitamins, ATP, NADH and NADPH.
Coenzymes are needed for reactions in biochemical pathways, including cellular respiration and photosynthesis.
Coenzymes carry chemical groups, protons and electrons between reactions in order to transfer energy between them.

10

What is the active site?

The active site is a three-dimensional pocket-like part of the enzyme that is shaped to interact with its specific substrate.

11

Describe

Catabolic reactions

Catabolic reactions are reactions in which substrates are broken down and energy is released.

12

Affect on enzyme reaction of:

Temperature

High temperatures can alter an enzyme’s three-dimensional structure and change the shape of the active site. This means the enzyme cannot act as a catalyst.
 
This change is called denaturation.

13

What is

Metabolism

Metabolism is the collection of all the biochemical (or metabolic) reactions that occur in living cells.

14

Describe

Enzymes

Most enzymes are globular proteins that have a tertiary or quaternary structure.

15

Describe

Anabolic reactions

Anabolic reactions are reactions in which larger molecules are produced from smaller substrates. They require an input of energy

16

What is Activation Energy?

Activation energy is the amount of energy input required for a reaction to start.

17

Affect on enzyme reaction of:

pH

Enzymes have an optimum pH range and if the enzyme is exposed to a pH outside its tolerances, the enzyme may become denatured.

18

Unloaded coenzymes

Unloaded coenzymes accept a chemical group, proton or electron.

19

competitive inhibition

The inhibitor binds to the active site of the enzyme, blocking the substrate from binding

20

Describe

The induced-fit model

(of enzyme–substrate interaction)

The induced-fit model states that when a substrate binds to the active site of an enzyme, the active site can alter its shape to better ft the shape of the substrate.

21

Affect on enzyme reaction of:

Concentration

The concentrations of enzymes and their substrates will have an effect on the rate of a reaction, as both substrate and enzyme are required for the reaction to occur.

22

Loaded coenzymes

Loaded coenzymes donate a chemical group, proton or electron.

23

Irreversible inhibition

The bonds formed between inhibitor and enzyme are strong, so the binding is irreversible.
 
If the inhibition is irreversible increasing substrate concentration will have no effect.

24

What happens when enzymes and substrates interact?

When enzymes and substrates interact, they form an enzyme–substrate complex.

25

What does an enzyme control

Enzymes control metabolism through the regulation of biochemical reactions at every step of a biochemical (or metabolic) pathway.  
 
Through enzyme regulation, a whole biochemical pathway can be regulated.

26

Phosphorylation and dephosphorylation

Both change the structure (or conformation) of proteins, and therefore both can regulate enzymes.

27

Major factors that determine whether enzymatic reactions can occur

4 factors

Inhibitors
Phosphorylation
Cofactors
Coenzymes.

28

How many types of Metabolic reactions are there?

Two

Catabolic
 Anabolic

29

Describe

'Lock and Key' model

(of enzyme–substrate interaction)

The lock and key model states that the substrate fts into the active site like a key fits into a lock.

30

Enzymes are:

2 Points

 - Often specific to particular substrates, and therefore catalyse specific reactions
 - biological catalysts that increase the rate of reactions by lowering the activation energy needed for reactions to occur.

31

Coenzymes 'loading'

Coenzymes can be
  - unloaded or loaded
  - and cyclically load and unload: