Which does not contribute to genetic variation mitosis, meiosis, crossing over, or random mating

You hate the smell of mercaptoethanol. since there are no disulfide bonds in intracellular proteins, you have convinced yourself that it is not necessary to treat a cytoplasmic homogenate with mercaptoethanol prior to sds-page. you heat a sample of your homogenate in sds and subject it to electrophoresis. much to your surprise, your gel looks horrible; it is an ugly smear! you show your results to your friend who is a chemistry major, and she suggests that you treat your sample with n-ethylmaleimide (nem), which reacts with free sulfhydryls. you run another sample of your cytoplasmic homogenate after treatment with nem and sds. now the gel looks perfect! if intracellular proteins don't have disulfide bonds (and they don't) why didn't your original scheme work? and how does treatment with nem correct the problem?

Which medullary index indicates a human hair? a. 0.653 b. 0.733 c. 0.516 d. 0.256

Prior to the development of dna fingerprinting, blood type could be used to determine possible parentage. although it might prove someone was not a parent, it could not show if someone was positively the parent, only that he or she might be a parent. which of the following is a true statement that can be made about parentage based on blood typing?