Week 3 Energy Systems

Question 1

Define muscles regarding energy

Answer 1

Muscles are the engine that convert chemical energy into mechanical energy

Question 2

What is bioenergetics

Answer 2

Converting foodstuffs into energy

Question 3

Define what 1 calorie is

Answer 3

1 cal is the amount of heat energy needed to raise 1g of water from 14.5 degrees to 15.5 degrees. 1 calorie is 4.2 joules

Question 4

Define carbohydrates as an energy source

Answer 4

Readily available but stores can be limited. Stored as glycogen in the muscle and liver

Question 5

Define fats as an energy source

Answer 5

Less accessible than carbohydrates, broken down to FFA and glycerol. FFA used to form ATP. Limited as an energy source due to rate of release being slow. Stored as triglycerides in muscle and adipose tissue

Question 6

Define protein as an energy source

Answer 6

Gluconeogenesis converts proteins to glucose
Lipogenesis converts proteins to FFAS
Not a primary energy source

Question 7

Define the difference between carbohydrates and fats as energy sources

Answer 7

There is more fats in the body than carbohydrates stored however it is harder to oxidise fats than carbs so carbs is the primary source of energy. Fats are used when glycogen stores r depleted

Question 8

What are enzymes and what do they do?

Answer 8

Catalysts that regulate the speed of a reaction by reducing the activation energy required. Regulated by pH and temp. They interact with specific substrates (lock and key model)

Question 9

Define how the PCr system works

Answer 9

PCr is broken down by creatine kinase which releases phosphate, creatine and energy. This energy is used to make ATP from ADP and P. It is an immediate source of energy and 1 mole of PCr = 1 mole of ATP

Question 10

Define the terms glycolysis, glycogenesis and glycogenolysis

Answer 10

Glycolysis - breakdown of glucose (anaerobic or aerobic)
Glycogenesis - Process where glycogen is synthesised from glucose to be stored in the liver
Glycogenolysis - Process by which glycogen is broken into glucose-1-phosphate to be used by muscles.

Question 11

Briefly describe anaerobic glycolysis and its yield of ATP

Answer 11

Anaerobic glycolysis is the transformation of glucose to lactate to create ATP and precursors for the krebs cycle. .It yields 2 ATP (3 ATP but one is needed to convert glucose to glucose-6-phosphate)

Question 12

Explain the oxidation of carbohydrates

Answer 12

1. Pyruvic acid from glycolysis is converted to acetyl
   coenzyme A (acetyl CoA).
2. Acetyl CoA enters the Krebs cycle and forms 2 ATP,
   carbon dioxide, and hydrogen.
3. Hydrogen in the cell combines with two coenzymes (NAD and FAD) that carry it to the electron transport chain.
4. Electron transport chain recombines hydrogen atoms to produce ATP and water (Oxidative Phosphorylation).
5. One molecule of glycogen can generate up to 39
   molecules of ATP.

Question 13

Explain the oxidation of fats

Answer 13

1. Fatty acids are “activated” before entering the mitochondria
2. They then undergo β-oxidation to acetyl-CoA
3. Acetyl-CoA then enters the TCA cycle for further oxidation
4. NADH/FADH produced to enter ETC to make ATP
   Fat oxidation requires more oxygen and generates more energy than carbohydrate oxidation (129 ATP)

Question 14

Explain the oxidation of proteins

Answer 14

1. Amino acids can be converted into glucose in kidney through gluconeogenesis
2. Glucose is converted to acetyl-CoA to enter krebs
3. The nitrogen in amino acid is converted into Urea and excreted.

Question 15

How much ATP can be produced through oxidation of carbohydrates and fats

Answer 15

Carbohydrates is 37-39
Fats is 129
Fats are harder to oxidise.

Question 16

What are the key enzymes in the following Systems:

1. PCr system
2. Glycolysis
3. Krebs cycle
4. Electron transport chain

Answer 16

1. Creatine kinase
2. Phosphofructokinase and lactate dehydrogenase
3. Citrate synthase and succinate dehydrogenase
4. Cytochrome oxidase

Question 17

What is the common way to measure energy expenditure

Answer 17

Direct and indirect calorimetry

Question 18

How do the 3 energy systems interact?

Answer 18

ATP-PCR system is used in the first 30 seconds of an all out exercise. Anaerobic glycolysis is the first 20 seconds to 2 minutes and The oxidative system starts at 2 minutes and carries on