BIOL 2040 Lecture 3: Chapter 3 Notes and Terms
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Locus: the location on a given chr where any particular gene occurs is called locus. Such crosses are used to detect sex linkage, maternal inheritance, or cytoplasmic inheritance: test cross: the cross of an organism with an unknown dominant genotype with an organism that is homozygous recessive for that trait. To perform an actual test cross with our black guinea pig, we would need a guinea pig (of the opposite se(cid:454)(cid:895) that is ho(cid:373)oz(cid:455)gous re(cid:272)essi(cid:448)e (cid:894)(cid:862)(cid:271)(cid:271)(cid:863)(cid:895). I(cid:374) other (cid:449)ords, (cid:449)e (cid:449)ould (cid:374)eed a (cid:449)hite gui(cid:374)ea pig to (cid:373)ate with our black guinea pig. Dizygotic twin pairs can be girl/girl, boy/boy, or girls/boy. Other words for dizygotic twins are also fraternal or non-identical twins. Monozygotic twins result from the fertilization of one egg and one sperm. The fertilized embryo then splits within days after fertilization resulting in two individuals which usually share the same chromosomes.