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Expert: Florence M Rollwagen - 11/16/2008


Question
why aren't all the sperm in a human genetically identical?

Answer
Hi Beverly:  Thanks for your question.  In gametogenesis  (sperm and egg) the chromosomes are distributed to the gametes in random fashion.  Each gamete ends up with only half the correct number of chromosomes (haploid) so that when the egg is fertilized, the correct number of chromosomes is reinstated.

The chromosomes sort independently into the gametes.  For example, if a woman has a blue chromosome and a red chromosome, the egg could contain two blue, one blue and one red, or two red chromosomes after gametogenesis (meiosis).

Here's an interactive tutorial that may explain better.  I can't paste pictures into this format, so go to this website and play the video:

http://www.cellsalive.com/meiosis.htm

Hope this helps.  Write back if you have more questions.

FM Rollwagen, PhD

Biology

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Florence M Rollwagen

Expertise

I can answer questions in biology, microbiology and immunology on the undergraduate or graduate level. I can also address medical and health concerns regarding alternative medicine, autoimmune diseases (lupus, MS) liver disease and intestinal problems.

Experience

I have over 20 years experience in research and teaching at the medical/graduate level, and 5 years teaching college biology and microbiology. My expertise is in microbiology and immunology, specifically the biology of cytokines and soluble immune response modifiers. I also carried out original research in blood substitutes and shock/trauma.

Organizations
American Association of Immunologists (AAI) American Association for the Advancement of Science (AAAS)

Publications
Journal of Experimental Medicine, Journal of Immunology, Cytokine, Shock, Experimental Hematology

Education/Credentials
BS biology 1966 MS biology 1968 PhD immunology 1979

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