Metabolism - Handout 2

Question 1

Catabolic reactions

Answer 1

Breakdown reactions that release energy.

Question 2

Anabolic reactions

Answer 2

Building reactions that require energy.

Question 3

What is oxidation? Is energy produced or required for these type of recations?

Answer 3

• The loss/removal of electrons (becomes lower in energy)
• Produces energy.

Mnemonic: OIL RIG (Oxidation Is Loss, Reduction Is Gain)

Question 4

What is reduction? Is energy produced or required?

Answer 4

• Gain of electrons (becomes higher in energy)
• Requires energy

Question 5

What is phosphorylation?

Answer 5

Gain of a phosphate group.

Ex. ADP → ATP

Question 6

List the 3 types of phosphorylation that generate ATP, give an example of each.

Answer 6

1. Substrate level phosphorylation - ex. glycolysis
2. Oxidative phosphorylation - ex. electron transport chain
3. Photophosphorylation - ex. use of light trapping pigments such as chlorophyll (don’t focus on this type of phosphosphorylation)

Question 7

Explain the overall function of glycolysis (aka Embden Meyerhof Parnas - EMP pathway).

Answer 7

• Substrate level phosphorylation.
• Produces ATP.
• Reduces NAD+ to NADH.
• Oxidizes glucose to pyruvic acid.
• In respiration, pyruvic acid is converted to the first reactant in Kreb’s cycle.

Question 8

Explain the overall function of Kreb’s cycle.

Answer 8

• Produces ATP.
• Reduces NAD+ to NADH.
• Reduces FADH to FADH2.
• NADH and FADH2 carry electrons to the ETC

Question 9

Explain the overall function of the electron transport chain (ETC).

Answer 9

• Use the energy from electrons to produce lots of ATP
• This occurs via oxidative phosphorylation

Question 10

Explain the overall function of fermentation.

Answer 10

• Incorporate the pyruvic acid and elcetrons carried by NADH from glycolysis into fermentation end products (i.e. acids and alcohol)
• Ineffeciently produces ATP and NAD+

Question 11

What anerobic oxidation reaction occurs in glycolysis?

Answer 11

Glucose is oxidized to pyruvic acid.

Question 12

What is the reduction reaction in glycolysis?

Answer 12

2 NAD+ are reduced to NADH

Question 13

How many net ATP are produced by glycolysis.

Answer 13

2 ATP are produced by substrate-level phosphorylation.

Question 14

What are the functions of the pentose phosphate pathway?

Answer 14

• It allows the breakdown of of pentoses.
• It produces important intermediate pentoses used in synthesis of nucleic acids, glucose from carbon dioxide in photosynthesis, and some amino acids
• Examples: Bacillus subtilis, E. coli, and Enterococcus faecalis

Question 15

What is the most common glycolysis alternative?

Answer 15

The pentose phosphate pathway.

Question 16

What is another name for the pentose phosphate pathway?

Answer 16

The hexose monophosphate shunt.

Question 17

How many ATP per cycle are produced in the pentose phosphate pathway?

Answer 17

1 ATP/cycle

Question 18

What pathway can run without glycolysis?

Answer 18

The Entner-Doudoroff pathway.

Question 19

Give a clinically relevant example of a microbial genus that uses the Entner-Doudoroff pathway.

Answer 19

Pseudomonas

Question 20

What are the products of the Entner-Doudoroff pathway per molecule of glucose?

Answer 20

2 NADPH and 1 ATP

Question 21

What are the two other common names for Krebs cycle?

Answer 21

• Tricarboxylic acid (TCA) cycle
• Citric acid cycle

Question 22

What are the net products of Krebs cycle, per 2 acetyl CoA?

Answer 22

• 4 CO₂
• 6 NADH
• 2 FADH₂
• 2 ATP