Meaning of alleles, dominant, heterozygous, homozygous, and recessive?

Alleles: allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome. Alleles are called diploid in humans.

Dominant: In genetics, dominance is the phenomenon of one variant of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome.

Heterozygous: Zygosity is the degree to which both copies of a chromosome or gene have the same genetic sequence.

Homozygous: Homozygous is a word that refers to a particular gene that has identical alleles on both homologous chromosomes

Recessive: Recessive: A condition that appears only in individuals who have received two copies of a mutant gene.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

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