Human Cells: Metabolic Pathways

Question 1

What is metabolism?

Answer 1

All the chemical reactions that take place in cells

Question 2

What is a metabolic pathway?

Answer 2

A series of stepwise chemical reactions that are controlled by enzymes

Question 3

Metabolic pathways are integrated and controlled pathways of what?

Answer 3

Enzyme-catalysed reactions within a cell

Question 4

Metabolic pathways can have what?

Answer 4

Reversible steps, irreversible steps and alternative routes

Question 5

Reactions within metabolic pathways can be what?

Answer 5

Anabolic or catabolic

Question 6

What do anabolic reactions do?

Answer 6

They build up large molecules from small molecules and require energy

Question 7

What do catabolic reactions do?

Answer 7

Break down large molecules into smaller molecules and release energy

Question 8

Metabolic pathways are controlled by what?

Answer 8

The presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes

Question 9

The substrate molecule(s) have a what and the subsequent products have what?

Answer 9

They have a high affinity for the active site.

They have a low affinity, allowing them to leave the active site.

Question 10

When does induced fit occur?

Answer 10

When the active site changes shape to better fit the substrate after the substrate binds

Question 11

What is the activation energy?

Answer 11

The energy required to initiate a chemical reaction

Question 12

What do enzymes do to the activation energy?

Answer 12

Lower it

Question 13

The concentration of substrate and end product affect what?

Answer 13

The direction and rate of an enzyme reaction

Question 14

What happens as the substrate concentration increases?

Answer 14

The rate of the enzyme reaction increases until all of the active sites are occupied by the substrate

Question 15

What are some metabolic reactions?

Answer 15

Reversible and the presence of a substrate or the removal of a product will drive a sequence of reactions in a particular direction

Question 16

What can the concentration of substrate relative to the concentration of product(s) do to the direction of an enzyme-catalysed reaction?

Answer 16

It can change the direction of an enzyme-catalysed reaction

Question 17

What does competitive inhibition involve?

Answer 17

It involves competition for the active site of the enzyme by molecules that resemble the substrate

Question 18

Where do competitive inhibitors bind?

Answer 18

At the active site preventing the substrate from binding

Question 19

Competitive inhibition can be reversed by doing what?

Answer 19

Increasing the substrate concentration

Question 20

Where do non-competitive inhibitors bind?

Answer 20

Away from the active site but change the shape of the active site, preventing the substrate from binding

Question 21

Non-competitive inhibition cannot be reversed by doing what?

Answer 21

Increasing substrate concentration

Question 22

When does feedback inhibition occur?

Answer 22

When the end product in the metabolic pathway reaches a critical concentration

Question 23

The end product inhibits what?

Answer 23

An earlier enzyme, blocking the pathway, and so prevents further synthesis of the end product