Answer: alleles
Explanation:
Alleles are different forms of a given gene. Alleles are mutated forms of a given gene which controls a particular trait. For instance, the gene that codes for hemoglobin is denoted with the letter A but the gene has another variant denoted by S. In abnormal hemoglobin S (sickle hemoglobin), glutamate is replaced by valine at position 6 in the amino acid sequence of the two beta chains of hemoglobin. This change in the amino acid sequence causes the red blood cells to have a sickle shape resulting in sickle cell disease. Therefore hemoglobin A and S are alleles of a given gene.
It is based on shared characteristics
<span>The answer is a certain required chemicals must be actively
transported. Blood brain barrier is a
selective membrane that separates blood circulating from the brain and the
fluid of extracellular in the central nervous system. This is also called a
filtering mechanism, the capillaries that carry blood to the brain and spinal
cord tissue blocking the path way of the certain substance.</span>
