I don’t know the first two but the last one the thousands of subunits are called nucleotides
Answer:
It enters the citric acid cycle and associates with a 4-carbon molecule, forming citric acid, and then through redox reactions regenerates the 4-carbon molecule.
Explanation:
Acetyl-CoA(2C) associates with oxalacetate(4C) to form citric acid(6C). Then through redox reactions, CO2 molecules result from decarboxylation (COOH becomes R-(R1)CH-R2). And through dehydrogenation H2 molecules are incorporated in NADH+ in FADH2, resulting in the 4-carbon molecule at the beginning (oxalacetate). That's why it's called a cycle(Kreb's cycle or citric acid cycle)
Answer:
A- Acetylcholine is released by axon terminals of the motor neuron.
Explanation:
The general mechanism of muscle contraction can be explained as follows:
a) The action potential which is generated, travels along the motor nerve to its ends on muscle fiber (or motor end plate) at the neuro-muscular junction.
b) The nerve endings then secrete small amounts of neurotransmitter called acetylcholine.
c) The actylecholine binds to the receptors on the membrane of muscle fiber and opens the voltage gated sodium channels.
d) Opening of these channels leads to flow of large quantities of sodium ions into the muscle fiber which ultimately results in initiation of action potential in muscle fiber.
e) This action potential depolarizes the fiber including the T-tubules, triggering the release of calcium ions from sarcoplasmic reticulum.
f) The calcium ions thus released initiated the process of muscle contraction.
