Describe the structure of a muscle fibre and explain differences between fast and slow twitch.
- Muscles are made form muscle fibres arranges in bundles.
- Each fibre is made of a bundle of myofibrils.
- The unit of contraction is the sarcomere, and many are arranged in parallel giving the muscle a striated appearance.
- Sarcomere contains overlapping actin (thin filament) and myosin (thick filament).
- Slow twitch muscles:
- Dark red
- lots of myoglobin, mitochondria and stored glycogen
- lactate intolerant
- dense capillary network
- weaker force of contraction
- Aerobic respiration
- Fast twitch muscles:
- Anaerobic respiration
- little myoglobin
- more powerful
- lactate tolerant
- poor capillary network, no glycogen and mitochondria
Explain contraction of skeletal muscle
Describe how muscles, skeleton and ligaments produce locomotion (antagonistic pairs)
Describe overall reaction of aerobic respiration
Describe how to investigate rate of respiration practically
Phosphorylation of ADP and hydrolysis of ATP
Describe the role of glycolysis in aerobic and anaerobic respiration
- 1. ATP is used to phosphorylate glucose, creating two molecules of triose phosphate.
- 2. Triose phosphate is oxidised forming 2 molecules of pyruvate. For each molecule of pyruvate, 2 NADH and 2 ATP are formed.
- 3. The net gain is 2 NADH and 2 ATP.
- 4. In aerobic: pyruvate moves into matrix of mitochondria.
- In anaerobic: Pyruvate is converted to lactate.
Describe oxidative phosphorylation
Explain the fate of lactate after anaerobic respiration
- Anaerobic respiration doesn't involve the link reaction, krebs cycle or oxidative phosphorylation.
- Glucose is converted to pyruvate in glycolysis.
- Reduced NAD transfers hydrogen to pyruvate to form lactate and NAD.
- NAD can then be reused in glycolysis.
- Lactate can be broken down back to pyruvate and sent to the Krebs cycle or liver cells convert the lactic acid back into glucose.