Topic 5 - Energy In The Body

Question 1

What are catabolic and anabolic reactions?

Answer 1

Catabolic = the breaking down of larger molecules into smaller ones/energy releasing/oxidative - release H atoms/exogonic
Anabolic = the synthesis of larger cellular molecules from intermediary metabolites/ energy requiring/ Reducing - H atoms released

Question 2

What is the basal metabolic rate?

Answer 2

• Energy required by an individual physical, digestive and emotional rest at 18 degrees C.

Question 3

What does exergonic and endergonic mean?

Answer 3

Exergonic - release energy

Endergonic - requires energy

Question 4

What sign would the Gibbs free energy value be for exergonic and endergonic reactions?

Answer 4

Exergonic - negative

Endergonic - positive

Question 5

What are the reduced forms of these fuels?

• FAD
• NAD+
• NADP+

Answer 5

• FAD2H
• NADH + H+
• NADPH + H+

Question 6

What happens in reduction of a fuel?

Answer 6

• 2 hydrogen atoms are are added to fuel (they are hydrogen carriers)

Question 7

How is ATP energy currency?

Answer 7

• the energy is in the phosphate group bonds and when its released it can be used
• constantly cycled, NOT A STORE!

Question 8

When [ATP] is high, what happens?

When [ATP] is low and [ADP], [AMP] is high, what happens?

Answer 8

1. Anabolic pathways activated

2. Catabolic pathways are activated

Question 9

Which molecule is used as a temporary store of energy?

Answer 9

• creatine phosphate, creatine is phosphorylated by creatine kinase enzyme, taking a phosphate group from ATP, so the energy is caught up in that phosphate group bond.

Question 10

Creatine + ATP Creatine Phosphate + ADP

What happen when ATP conc is high and low?

Answer 10

High = creatine phosphate formed 
Low = reaction reversed for ATP increase

Question 11

Why is Creatine kinase a marker for MI?

Answer 11

• Creatine kinase is released into the blood from damaged muscle tissue
• it occurs in heart muscle at a specific isoform ratio so we can know it has come from damaged cardiac myocytes

Question 12

What happens when creatine and creatine phosphate spontaneously break down?

Answer 12

• creatinine forms

Question 13

What is creatinine a marker of and why?

Answer 13

muscle mass - creatine excretion is directly proportional to muscle mass
Urine dilution - more C means less water and less C means more water, its a standard to measure water content against