M2- Chapter 4 - Enzymes

Question 1

What is metabolism

Answer 1

The sum of all the different reactions and reaction pathways happening in a cell or an organism

Question 2

What is Vmax

Answer 2

Enzymes can only increase the rates of reaction up to a point. This is called Vmax.

Question 3

What is the specificity of an enzyme

Answer 3

Enzymes can only catalyse 1 reaction, and hence they only accept that one substrate.

Question 4

What are enzymes

Answer 4

Biological catalysts

Question 5

How do enzymes help molecules?

Answer 5

They lower the activation energy needed.
by:
- Lock and key hypothesis
- Induced Fit hypothesis

Question 6

Lock and Key hypothesis

Answer 6

The active site is an area within the tertiary structure that has a shape that is complementary to the shape of the substrate. It creates an enzyme-substrate complex.

Question 7

How does the lock and key hypothesis lower the activation energy

Answer 7

The substrate is held in such a way that atoms are close enough to react. The R-Groups create a temporary bonds between the substrate by the active site.

Question 8

Induced Fit hypothesis

Answer 8

The idea that the active site actually changes shape slightly to fit the substrate.
The weak interactions between the substrate and the enzyme rapidly induces changes in the enzyme’s tertiary structure that strengthens the bonding and puts strain on the substrate molecule.
Hence, it weakens a particular bond in the substrate, lowering the activation energy.

Question 9

What is an extracellular enzyme

Answer 9

They work outside the cells that make them.

Question 10

How are nutrients usually found?

Answer 10

In the form of polymers (polymers and polysaccharides)

Question 11

Examples of intracellular enzymes:

Answer 11

Catalase

Question 12

Examples of intracellular enzymes:

Answer 12

Amylase and Trypsin

Question 13

How does temperature affect enzymes

Answer 13

increase KE
increase particles moving faster
increase successful collisions
increase the rate of the reaction

Question 14

What is the temperature coefficient (Q10)

Answer 14

How much the rate of a reaction increase with a 10 degrees rise in temperature. (Usually 2 for an enzyme-controlled reactions)

Question 15

What happens when an enzyme denatures due to temperature

Answer 15

increase temperature 
increase vibration 
increase the bond strain and they break 
increase changing of tertiary structure
active site changes

Question 16

Enzymes in cold temperatures

Answer 16

they are more flexible structures, meaning they are less stable. This means small temperatures changes will denature them.

Question 17

Enzymes in hot temperatures

Answer 17

They have more bonds (especially hydrogen and disulfide bonds). Hence, they are a lot more stable and resistant to changes in temperature.

Question 18

A change in pH means

Answer 18

Change in H+ ion concentration

Question 19

Increase H+ conc means

Answer 19

Low pH (acidic)

Question 20

Decrease H+ conc means

Answer 20

High pH (alkaline)

Question 21

Renaturation

Answer 21

Small changes with pH concentration can cause the active site to change, but if the pH is returned, the active site can go back to its original shape.
However, if the pH is significantly beyond the optimum temperature, the enzyme might denature permanently.

Question 22

How does a change in pH affect the active site?

Answer 22

Hydrogen ions can interact with the polar and charged R-Groups, and hence change the tertiary structure of the enzymes.
Increasing Hydrogen ions means increase bonds breaking.

Question 23

Increasing the substrate or enzyme concentration means what

Answer 23

The rate of the reaction will continue to increase till Vmax, and when one of the factors becomes a limiting factor.

Question 24

What is an enzyme

Answer 24

A biological catalyst

They are proteins that speed up metabolic reactions

Question 25

How to check the reliability of data

Answer 25

Repeat experiments Find the mean or standard deviation Identify any anomalous results Compare results

Question 26

How to measure the change in concentration as a reaction proceeds?

Answer 26

``` Take samples at a range of temperatures Remove samples Heat with Benedict’s solution Change to colour to brick red Remove precipitate and filter Calibrate using plain water Use a red filter Read the transmission Using a known concentration to transmission calibration curve Read off the concentration ```

Question 27

Describe how an antibiotic- resistant population could develop

Answer 27

Mutation Resistant ones survive Alleles passed down to offspring Carries over generations

Question 28

Explain the induced-fit hypothesis of breaking molecules

Answer 28

``` What is the substrate? Substrate fits into active site Active site changes shape To fit the substrate better Gets more bonds Forms an ESC Puts strain on the molecule to break The activation energy is reduced Shape of active site changes again once the products have left ```

Question 29

Explain how the an enzyme breaks down a substrate

Answer 29

The substrate is complimentary to the active site Substrate enters the active site The enzyme changes shape to fit the substrate An ESC is formed Straining of bonds Substrate leaves the enzyme’s active site

Question 30

cofactor

Answer 30

a non-protein substance that allows some enzymes to work

Question 31

inorganic cofactors

Answer 31

they held the substrate bind to the enzymes, but they don't directly participate They aren's used up at all.

Question 32

Example of inorganic cofactors

Answer 32

Chlorine for amylase.

Question 33

Coenzymes

Answer 33

Organic cofactors They do participate in the reactions They are constantly being changed and they act as carriers moving chemical groups that are continuously recycled.

Question 34

What is a prosthetic group

Answer 34

A cofactor that is tightly bound to an enzyme

Question 35

example of coenzymes

Answer 35

Vitamins

Question 36

Example of a prosthetic group

Answer 36

Zn ions for carbonic anhydrous. | They are a permanent group of the enzyme's active site.

Question 37

Competitive inhibitors

Answer 37

They are very close and similar to the shape of the substrate but not identical. No reaction occurs, the active site is only blocked. Generally reversible

Question 38

Non-competitive inhibitors

Answer 38

Completely different shape to the active site But it joins the enzyme somewhere else (at an allosteric) and causes the active site to change. So the reaction cannot go on.

Question 39

Explain the graph for the types of inhibitors

Answer 39

Competitive ones reach the top of the plateau but they take more time. Non-competitive ones don't even reach the plateau, but they do reach their own plateau at the same rate.

Question 40

Reversible reaction- inhibitors

Answer 40

Competitive inhibitors | There are weaker ions/ hydrogen bonds

Question 41

Non-reversible reaction- inhibitors

Answer 41

Non-competitive inhibitors. | They have covalent bonding

Question 42

Drugs

Answer 42

An antiviral drugs- reverse transcriptase inhibitor prevents viral DNA from replicating. Penicillin inhibits transpeptidase, which forms the protein to synthesise bacterial cell walls.

Question 43

Metabollic poisons

Answer 43

Cyanide- non-competitive inhibitors of cytochromec oxidase. Arsenic- Non-competitive inhibitors of pyruvate dehydrogenase. Malonate- competitve inhibitor of succinate dehydrogenase.