A stroke occurs when blood flow to a part of the brain stops. A stroke is sometimes called a brain attack.. If blood flow is cut off for longer than a few seconds, the brain cannot get nutrients and oxygen. Brain cells can die, causing lasting damage.
A cell is said to be homozygous for a particular gene when identical alleles of the gene are present on both homologous chromosomes. The cell or organism in question is called a homozygote. True breeding organisms are always homozygous for the traits that are to be held constant.
Confidence votes 38. It sounds like you are referring to homozygous vs heterozygous. If an organism has two identical alleles of the same gene, it is said to be homozygous. If an organism has two different alleles of the same gene, it is said to be heterozygous.