Answer: Excess ethanol metabolism leads to an accumulation of NADH that inhibits fatty acid metabolism.
Explanation:
Fatty acid metabolism is often activated by limited or absence of NADH, however ethanol (the main constituent of most alcoholic drinks) on metabolism yields several molecules of NADH which rather stimulates belly/abdominal fat production often referred to as "beer gut".
Answer: Mitochondria are shaped to maximize their productivity. They are made of two membranes. The outer membrane covers the organelle and contains it like a skin. The inner membrane folds over many times and creates layered structures called cristae.
Answer:
A. He has a large buildup of lactate in his muscles.
Explanation:
Ideally, our body cells, via the process of aerobic cellular respiration, need oxygen to break down glucose. However, during rigorous activities or exercises, oxygen can become unavailable for use. In this case, the body cells switch to use another way of cellular respiration, which is FERMENTATION.
This fermentation causes a build up of lactic acid/lactate (its byproduct) in the cells of the muscles being used, which physically causes a burning and aching sensation just as the case of this hiker. The climbing of the steep path is causing causing the fast usage of oxygen in his cells.
Answer:
D. Enzymes open the DNA strand, remove a segment of DNA from the strand that contains the damage, and resynthesize the correct DNA sequence.
Explanation:
From time to time, the DNA gets exposed to certain chemicals or radiation that damages it. However, the cell has a DNA repair mechanism in place called NUCLEOTIDE EXCISION REPAIR (NER).
NUCLEOTIDE EXCISION REPAIR (NER) is one of the DNA repair mechanisms in which certain enzymes open the DNA strand, remove a segment of DNA that contains the damaged gene or nucleotide bases, and resynthesize the correct DNA sequence using the pair of the damaged one.
The correct answer is: D) Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate (junctional folds of the sarcolemma) and sodium enters the cell.
The motor neuron cell is connected to muscle cell via synaptic cleft, where neurotransmitter is released. The muscle side of this synapse is called motor end plate. Released neurotransmitter is acetylcholine and it binds to its receptor (ACh receptor) on the motor end plate. As it binds, ion channels open, and Na+ gets into the muscle cell. This event reduces the voltage difference between the inside and outside of the cell and causes depolarization which creates a wave through the entire muscle cell (its membrane-sarcolema). As a consequence, Ca2+ is released from the sarcoplasmic reticulum which will cause the contraction of the muscle cell.
