important for test

Question 1

nueromuscular junction

how skeletal muscle contracts by the sliding filament theory.

Answer 1

1. Action potential in a motor neuron triggers the release of Ca2+ ions from the sarcoplasmic reticulum
2. Calcium ions bind to troponin (on actin) and cause tropomyosin to move, exposing binding sites for the myosin heads
3. ATP binds to myosin head
4. ATP hydrolysis (ATP → ADP + P) causes the myosin heads to change orientation
5. Myosin heads binds to the actin filament creating a cross-bridge
6. ADP and P release resulting in ENERGY released causing the myosin head to move the actin filaments towards the centre of the sarcomere (power stroke)
7. ATP is able to re-attach to myosin head breaking the cross bridge
8. Cycle is able to restart

end result:
The sliding of actin along myosin therefore shortens the sarcomere, causing muscle contraction, This decreases the length of the H Zone and I band of the sarcomere
A band remains the same length
Actin and myosin do not change in length. They simply overlap each other more causing shortening

Question 2

nueromuscular junction

structure involved in sliding fillament theory

Answer 2

Question 3

aerobic glycolysis

Answer 3

In the presence of oxygen, pyruvate is processed by the Krebs cycle, which liberates electrons that are passed through the electron transport chain producing energy (ATP).
Glucose + Oxygen → CO2 + H2O + ATP
Steps
1. Glycolysis
1. Link Reaction
1. Krebs Cycle
1. Electron Transport Chain