MITOSIS, CYTOKINESIS, MEIOSIS AND APOPTOSIS Michelle Gehringer Department of Biochemistry and Microbiology, University of Port Elizabeth, South Africa Keywords: Cell cycle, checkpoints, growth factors, mitosis, meiosis, cyclin, cyclin dependent protein kinases, G1 phase, S phase, spindle, prophase, anaphase, metaphase,
Summary: At the end of meiosis, 4 daughter cells are formed = eggs or sperm. Each contains half as many chromosomes as the parent cell (n); each cell is genetically different from its parents and from its siblings. Fertilization of an egg by a sperm restores the chromosome number to 2n.
About 1 month before conception: Almost all adult males produce thousands of spermatozoa (a.k.a. gametes or male germ cells) each second. Through a process called meiosis the number of chromosomes in each spermatozoon produced is half the normal number -- 23 instead of 46. Some spermatozoon will have an X sex chromosome; others will have a Y sex chromosome. It would take about 500 of them lined up in a row to total 1 inch in length.