Enzymes

Question 1

What are enzymes?

Answer 1

They are globular proteins that are catalysts

Question 2

Why are enzymes advantageous?

4

Answer 2

• They speed up reactions (by lower the activation energy of reactions)
• They are not used up
• They are not changed
• They catalyse many reactions per second

Question 3

How do extracellular enzymes work?

Answer 3

The enzymes are secreted from cells through exocytosis and to catalyse extracellular reactions.

Question 4

Give one main example of extracellular in mammals?

Answer 4

The secretion of amylase in the salvary glands.

Question 5

Give one main example of extracellular in Bacteria/Saprotrophic fungi?

Answer 5

They secrete amylase,lipases and proteases onto their food.

Question 6

How does intracellular enzymes (in solution) work?

Answer 6

Intracellular enzymes act in solution, inside cells

Question 7

Give and example of intracellular (in solution) in mammals?

Answer 7

Enzymes that catalyse glucose in glycolysis

Question 8

Give and example of intracellular (in solution) in plants?

Answer 8

enzymes in solution in the stroma of the chloroplasts catalyse the synthesis of glucose

Question 9

How does intracellular enzymes (membrane-bound) work?

Answer 9

intracellular enzymes (membrane-bound) may be attached to membranes.

Question 10

Give the main example of intracellular enzymes (membrane-bound)?

Answer 10

On the cristae of mitochondria and the grana of chloroplasts, where they transfer electrons and hydrogen ions in ATP formation

Question 11

What is the complex known as when a substrate binds to an active site?

Answer 11

An enzyme-substrate complex

Question 12

what happens after a enzyme-substrate complex occurs?

Answer 12

Products are release, leaving the enzyme unchanged with the active site ready to receive another substrate molecule

Question 13

What is activation energy?

Answer 13

The minimum amount of energy required for molecules to react, breaking existing bonds and making new ones

Question 14

What can temperature, P.H do to enzymes?

Answer 14

They can change the three dimensional structure of the enzyme and can break and alter the configuration of active sites

Question 15

What positive effect does temperature do to enzymes?

Answer 15

Increases kinetic energy of enzymes and substrates resulting in more successful collisions thus increasing the rate of reaction

Question 16

What negative effect can temperature (if too high) do to enzymes?

(2)

Answer 16

• The vibrations breaks hydrogen bonds also changing the tertiary structure
• Can denature the enzyme so the substrate wont fit

Question 17

What negative effect can temperature (if too low) do to enzymes?

Answer 17

The enzyme will be inactive as there is very low kinetic energy.

Question 18

What happens to enzymes if the P.H is extreme?

Answer 18

In can denature the enzyme

Question 19

What happens to enzymes if the P.H is small?

Answer 19

it can cause (reversible) changes in the enzyme structure and reduce activity

Question 20

How are amino acid side chains on enzymes active sites affected by hydrogen and hydroxyl ions?

Answer 20

• At low PH, excess H+ ions are attracted to negative charges and neutralises them
• At high PH, excess OH- ions are attracted to positive charges and neutralises them.

Question 21

What bonds are affected by hydrogen and hydroxyl ions?

Answer 21

They disrupt the ionic and hydrogen bonds maintaining the the shape of the active site

Question 22

What effect occurs if the substrate concentration is at a constant?

Answer 22

The rate of reaction increases as the substrate concentration increases.

Question 23

What effect occurs if the substrate concentration is low?

Answer 23

The enzyme molecules have only a few substrate molecules to collide with so don’t work to their full capacity

Question 24

What effect occurs if the substrate concentration is high?

Answer 24

.