No, the sickle-cell anemia allele won't be eliminated by natural selection.
Sickle-cell anemia trait is controlled by a single gene and the allele (S) for sickle-cell anemia is a harmful autosomal recessive.
It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
Heterozygotes (AS) with the sickle-cell allele are resistant to malaria, a deadly tropical disease. It is common in many African populations.
In these areas, (S) carriers have been naturally selected, because their red blood cells, containing some abnormal hemoglobin, tend to be in sickle shape when they are infected by the malarial parasite.
Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.
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Answer:
Fusion of embryonic myoblasts, each having its own nucleus to many other myoblasts to form the multinucleated skeletal muscle fibers.
Explanation:
The multiple nuclei in skeletal muscle cells are as a result of fusion of embryonic myoblasts, each having its own nucleus to many other myoblasts to form the multinucleated skeletal muscle fibers. This gives rise to multiple copies of genes, allowing production of the large amounts of proteins and enzymes and ATPs needed for muscle contraction.
When exercise does not increase bone mass, it has been observed that the risk of bone fractures increases due to osteoporosis.
<h3>What are the benefits of exercise to bone mass and density?</h3>
Bone mass refers to the mass of the bones in a living organism as a result of the deposition of minerals within the bone.
An increase in bone mass is directly related to the strength of the bone.
Strong bones have high bone masses whereas weak bone have low bone mass.
Physical activity have been shown to improve bone mass by increase the mass of deposited minerals in the bone.
Exercise such as walking, running, jogging, and other forms of exercise have been shown to improve bone mass and hence, the strength of bones.
However, when exercise does not increase bone mass, osteoporosis is observed which results in bone fracture.
In conclusion, the strength of a bone is directly related to the bone mass which is directly related to the mass of minerals deposited within them.
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Answer:Organel
Explanation:
A lysosome (/ˈlaɪsəˌsoʊm/) is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane proteins, and its lumenal proteins.
Here, you go:
Answer:
<u><em>Generation of B Cells. The immune system is remarkable for its ability to respond to a great many antigens.</em></u>
Explanation:
<u><em>These cells make antibodies which defends and fights out viruses in our bodies.</em></u>
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<em>~Hope This Helps~</em>