An athlete trains for a weight-lifting event in the Olympics. What type of muscle fiber would be the most important for this ath
lete to develop? Select one:
a. Slow twitch, because they contain more mitochondria than fast twitch fibers
b. Fast twitch, because they primarily use aerobic respiration
c. Fast twitch, because they primarily use lactic acid fermentation
d. Slow twitch, because they can contract for long periods of time without fatiguing
Two types of skeletal muscles are used in exercise: fast twitch and slow twitch.
Slow-twitch muscles help in long-endurance exercises like marathon running as they have more mitochondria and use aerobic respiration to produce energy.
But fast-twitch especially types IIb muscle is used in the exercise which requires powerful bursts like weight-lifting and sprinting as fibres do not have the capability to store oxygen so begin producing energy by lactic acid fermentation.
This is because the GP120 protein
of the HIV virus that forms the ‘knob’ is
essential for the infection of CD4 cells
of the immune system by the virus. The glycoprotein is, therefore, a good
target for vaccines especially since the
molecule is highly conserved because most mutations in the region could be highly deleterious to the virus.
Mitosis is closely controlled by the genes inside every cell. Sometimes this control can go wrong. If that happens in just a single cell, it can replicate itself to make new cells that are also out of control. These are cancer cells.
