Microfilaments
Microfilaments are fine, thread-like protein fibers, 3-6 nm in diameter. They are composed predominantly of a contractile protein called actin, which is the most abundant cellular protein. Microfilaments' association with the protein myosin is responsible for muscle contraction. Microfilaments can also carry out cellular movements including gliding, contraction, and cytokinesis.
Microtubules
Microtubules are cylindrical tubes, 20-25 nm in diameter. They are composed of subunits of the protein tubulin--these subunits are termed alpha and beta. Microtubules act as a scaffold to determine cell shape, and provide a set of "tracks" for cell organelles and vesicles to move on. Microtubules also form the spindle fibers for separating chromosomes during mitosis. When arranged in geometric patterns inside flagella and cilia, they are used for locomotion.
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Answer:
B
Explanation:
Amniotes develope a fluid filled sac within a shell or uterus
Is there any multiple choice questions?
Answer:
In the African savanna, more wildebeests are born than the environment can support. Which is most likely to happen over a period of years as a result? Individuals that are well suited to the environment reproduce, and those that have lesser adaptations die before they reproduce.
It is necessary to increase oxygen delivery in order to maintain sustained ATP production.
