Bioenergetics and ATP synthesis

Question 1

What is Gibb’s free energy?

Answer 1

Amount of energy in a system available to do work

G=H-T.S

Question 2

What does it tell us if delta G is negative?

Answer 2

Energy is liberated and the reaction is exergonic

A reaction can occur spontaneously

Question 3

What does it tell us if delta G is positive?

Answer 3

Reaction is endergonic

Reaction will need an energy input

Question 4

What does it tell us if delta G is 0?

Answer 4

System is at equilibrium

No net change can take place

Question 5

What does it mean if an organism is a chemoorganotroph?

Answer 5

Extracts energy from organic compounds by oxidation

Question 6

What should extraction of energy from food by controlled?

Answer 6

Don’t want to release all the energy at once because would increase body temp too much
Coupled reactions more efficient
Small carrier molecules are more mobile to travel around body

Question 7

What do dehydrogenase do?

Answer 7

Oxidise organic compounds by abstracting protons and electrons and passing them to a mobile carrier in biodegradation and energy abstraction
Can reduce organic compounds by adding protons and electron from mobile electron carrier

Question 8

Name 3 electron carriers.

Answer 8

NADH
NADPH
FADH2

Question 9

What is ATP?

Answer 9

Energy rich molecule with high phosphoryl transfer potential

Question 10

What does a catabolic reaction do?

Answer 10

Transforms fuels into usable cellular energy

Question 11

What does an anabolic reaction do?

Answer 11

Utilise the useful energy formed by catabolism to generate complex structures from simple ones

Question 12

What are the 3 principal ways that metabolic pathways are regulated?

Answer 12

Levels and accessibility of substrates
Amounts of metabolic enzymes
Modulation of catalytic activities of enzymes

Question 13

What does an allosteric enzyme do?

Answer 13

Has a site distinct from the substrate-binding site. Ligands bind to this causing conformational changes so affinity for substrate and ligands changes

Question 14

What is glycolysis?

Answer 14

Conversion of glucose to pyruvate
Anaerobic
Happens in cytosol

Question 15

What are the 2 steps of glycolysis?

Answer 15

Trapping and destabilising glucose to produce 2 X 3C molecules
Oxidation of the 3C molecules to pyruvate

Question 16

What is gluconeogenesis?

Answer 16

Glucose formation from non-carbohydrate precursors

Question 17

What is the major site of gluconeogenesis?

Answer 17

Liver

Question 18

Why do animals store energy as glycogen?

Answer 18

Controlled breakdown and synthesis helps maintain blood-glucose levels
Important: glucose only fuel for brain under non-starvation conditions

Question 19

Where is glycogen mainly stored?

Answer 19

Liver and muscle

Question 20

What is glycogenesis?

Answer 20

Glycogenesis 
Convert glucose to glucose 6-P
Glucose 6-P converted to glucose 1-P 
Activated to produce UDP-glucose 
Glycosyl units added to non-reducing end of glycogen molecule

Question 21

What does ubiquitin do?

Answer 21

Attaches to proteins and marks them for degradation