Cell Metabolism (MBC)

Question 1

What is the Gibbs Free Energy value for ATP hydrolysis?

Answer 1

~ -31 KJ/mol

Question 2

What are catabolic processes?

Answer 2

Break down of complex (i.e. food) molecules into smaller biosynthetic components and the release of energy as a result

Question 3

What is energy released as in catabolic reactions? [2]

Answer 3

1. Useful energy forms

2. Lost heat

Question 4

What are anabolic processes?

Answer 4

Generation of larger, more complex molecules from simpler molecules

Question 5

How are catabolism and anabolism related?

Answer 5

Anabolism is, in essence, the opposite of catabolism.

Catabolism involves breaking down large molecules whereas anabolism is building larger molecules.

Question 6

What is the key process of anabolic pathways?

Answer 6

Biosynthesis

Question 7

What are the three main stages of carbohydrate metabolism?

Answer 7

1. Glycolysis
2. TCA or Krebs Cycle
3. Oxidative Phosphorylation

Question 8

What is glycolysis? (aerobic)

Answer 8

Oxidation of glucose within the cytoplasm of individual cells, generating ATP and NADH

Question 9

What are the overall (net) products of glycolysis?

Answer 9

• 2 Pyruvate molecules
• 2 ATP
• 2 NADH

Question 10

Where does glycolysis occur in the cell?

Answer 10

In the cytoplasm

Question 11

What happens in the TCA cycle?

Answer 11

Further oxidation of small molecules within the mitochondria to generate reduced co-factors (NADH & FADH2), an ATP equivalent (GTP), and waste products (CO2)

Question 12

What happens in oxidative phosphorylation?

Answer 12

The generation of the majority of cellular ATP by the reduction of oxygen to water. This process involves the use of an electron transfer chains and reduced co-factors

Question 13

Where does the TCA cycle occur?

Answer 13

Mitochondrial matrix

Question 14

Where does oxidative phosphorylation occur?

Answer 14

Inner mitochondrial membrane

Question 15

What is the main waste product from amino acid breakdown?

Answer 15

Urea (from the conversion of ammonium ions)

Question 16

What are the two main waste products of cellular metabolism?

Answer 16

• Carbon Dioxide

- Water

Question 17

Compare glucose combustion and glucose metabolism in terms of:

• Gibbs Free Energy
• Activation energies + how they’re overcome
• Free energy release

Answer 17

Combustion:

• Gibbs = -2872 KJ/mol
• Large activation energy overcome by heat in one big step
• Free energy released as heat

Metabolism:

• Gibbs = -2782 KJ/mol
• Small activation energies overcome in several discrete (and smaller) steps by enzymes and body temp
• Released free energy is stored in carrier molecules, e.g. ATP

Question 18

Approximately how many ATP molecules are generated in cellular (carbohydrate) metabolism from the complete oxidation of glucose?

Answer 18

~ 38 ATP molecules/glucose

Question 19

Gibbs Free Energy value for ATP hydrolysis is -38 KJ/mol while carbohydrate metabolism (which generates ~38 ATP molecules per glucose) has a free energy value of -1178 KJ/mol.

What is the percentage efficiency of cellular (carbohydrate) metabolism?

Answer 19

~ 20%

Question 20

Name the 6 reactions which define metabolism

Answer 20

1. Redox
2. Ligation requiring ATP cleavage
3. Isomerisation
4. Group transfer
5. Hydrolysis
6. (+) or (-) of functional groups

Question 21

Describe the metabolic reaction:

Redox

Answer 21

Electron transfer

Question 22

Describe the metabolic reaction:

Ligation requiring ATP cleavage

Answer 22

Formation of covalent bonds

Question 23

Describe the metabolic reaction:

Isomeration

Answer 23

Rearrangement of atoms to form isomers

Question 24

Describe the metabolic reaction:

Group transfer

Answer 24

Transfer of a functional group from one molecule to another

Question 25

Describe the metabolic reaction:

Hydrolysis

Answer 25

Cleavage of bonds by the (+) of water

Question 26

Describe the metabolic reaction:

(+) or (-) of functional groups

Answer 26

(+) of functional groups to a double bond or (-) of functional groups to form a double bond

Question 27

Which of the six key metabolic reactions does this describe?

Cleavage of bonds by the (+) of water

Answer 27

Hydrolysis

Question 28

Which of the six key metabolic reactions does this describe?

Transfer of a functional group from one molecule to another

Answer 28

Group transfer

Question 29

Which of the six key metabolic reactions does this describe?

Electron transfer

Answer 29

Redox

Question 30

Which of the six key metabolic reactions does this describe?

(+) of functional groups to a double bond or (-) of functional groups to form a double bond

Answer 30

Addition or removal of functional groups

Question 31

Which of the six key metabolic reactions does this describe?

Rearrangement of atoms to form isomers

Answer 31

Isomerisation

Question 32

Which of the six key metabolic reactions does this describe?

Formation of covalent bonds

Answer 32

Ligation requiring ATP cleavage

Question 33

Glycolysis is essentially an anaerobic process.

True or False?

Answer 33

True

Question 34

Which stage of carbohydrate metabolism might link back to anaerobic pathways in prehistoric bacteria?

Answer 34

Glycolysis

Question 35

How many reaction steps make up glycolysis?

Answer 35

10

Question 36

Glycolysis can be split into two halves.

What is the main concept of each half?

Answer 36

1. Formation of a high energy compound - consumption of ATP

2. Splitting of a high energy compound - generation of ATP

Question 37

Name the 10 enzymes involved in glycolysis.

Answer 37

1. 
2.
3.
4.
5.
6.
7.
8.
9.
10.

Question 38

Name the product(s) produced from each step of glycolysis

Answer 38

Step:

1. 
2.
3.
4.
5.
6.
7.
8.
9.
10.