 Get out homework (phases of meiosis worksheet)  Fill in Meiosis Mitosis Venn Diagram  Please try to think of at least four differences for each and two things they have in common

How meiosis is different in males and females.

 Meiosis in males, process used to create sperm  Males create four sperm cells for each single spermatogonium  Remember the original spermatogonium is diploid, while the resulting four sperm are haploid (have half the DNA)  This process occurs in the seminiferous tubules which make up the testes

 Seminiferous tubules are the little tubes that curl around to create the testes  If stretched out these could reach 300 to 350 meters  Men can produce an infinite number of sperm in their life time.  They begin producing sperm at puberty because that is when the tubes become hollow

 The spermatogonium starts on the outside of the tube  As it moves its way to the inner portion of the tube it undergoes meiosis  The four sperm are then released into the inside of the seminiferous tubule.

 Oogenesis is meiosis in females and produces one egg cell.  Each round of meiosis creates one mature egg cell that can be fertilized and three polar bodies, which cannot be fertilized.  This process occurs in the follicles of the ocary

 Each female has about 400,000 primary follicles in her ovary at birth.  A female starts producing egg cells at puberty and cannot possibly produce more egg cells than she has follicles  Most female produce about 400 mature eggs in her lifetime  During ovulation the egg is released from the ovary so it can be fertilized

SpermatogenesisOogenesis  Creates four mature sperm  Occurs continuously  Occurs throughout entire life after puberty  Occurs in males  Sperm are smaller and motile  Creates one mature egg and three polar bodies  Occurs once a month  Stops occurring once menopause is reached  Occurs in females  Egg is much larger and not motile

 Both are forms of meiosis  Both create sex cells used in sexual reproduction  Both occur in the gonads  Both start with a diploid cell and end up with haploid cells.  Both occur in plants (pollen or spores and egg instead of sperm and egg) and animals

 Most issues during gamete formation occur during meiosis I  As a woman gets older there become more and more genetic abnormalities in her eggs, which is why the chances of bearing a child with birth defects increase as a woman gets older.  Sometimes during meiosis the chromosomes do not separate causing the egg or sperm to either have 46 or 0 chromosomes  Sometimes only one pair of chromosomes does not separate causing the egg or sperm to have 47 or 45 chromosomes.

 Sometimes sperm do not form properly  When this occurs it can lead to infertility  Even though sperm are being produced, they might be slow or not motile.  This causes them to die before they could possible reach the egg