Lecture Notes for Bio 106
Reproductive roles Male’s job is to get the sperm to the egg The sperm are specialized to deliver the male’s genes to the egg Female’s job is to produce a gamete (egg) containing the female’s genes Egg is specialized to nourish the embryo Egg is large and contains nutrients Egg must be moved along Female must also nourish and protect the embryo and fetus This is the job of the uterus Male reproductive strategy: Produce millions of gametes and hope that one makes it to the egg Female reproductive strategy: Invest heavily in one gamete and nourish and protect it Egg Cell (Ovum; 1 copy each chromosome) Sperm Cell (1 copy of each chromosome) MEIOSIS (a type of cell division that begins with a cell with 2 copies of each chromosome and ends with 4 cells with 1 copy of each chromosome) FERTLIZATION (Fusion of Egg and Sperm nuclei; creates a cell with 2 copies of each chromosome)
Zygote (cell formed by fusion of egg and sperm; has 2 copies of each chromosome; will develop into new individual) Ovary (in female) Testis (in male)
1
Gonads: a. Testes in male b. Ovaries in females 1. produce gametes Male = sperm Female = ovum or egg join zygote; new individual 2. produce sex hormones testosterone estrogen + progesterone Male Reproductive System Testes located in scrotum why? sperm don't survive well at body temperature is 3-4o F cooler temp kept constant by reflex how? – pass through the inguinal canal before birth hole usually closed over with connective tissue possible problems 1. cryptorchidism failure of the testes to descend if not corrected, results in sterility corrected by surgery or by administering hormones 2. inguinal hernia inguinal canal does not completely close intestine may push into opening correct with surgery more common in men but may occur in women
Inside Testes 1. seminiferous tubules about 1000 site where sperm are produced by a process called spermatogenesis produce 100 million+ sperm each day from puberty until death spermatogenesis A.
Zygote (cell formed by fusion of egg and sperm; has 2 copies of each chromosome; will develop into new individual) Ovary (in female) Testis (in male)
1
Gonads: a. Testes in male b. Ovaries in females 1. produce gametes Male = sperm Female = ovum or egg join zygote; new individual 2. produce sex hormones testosterone estrogen + progesterone Male Reproductive System Testes located in scrotum why? sperm don't survive well at body temperature is 3-4o F cooler temp kept constant by reflex how? – pass through the inguinal canal before birth hole usually closed over with connective tissue possible problems 1. cryptorchidism failure of the testes to descend if not corrected, results in sterility corrected by surgery or by administering hormones 2. inguinal hernia inguinal canal does not completely close intestine may push into opening correct with surgery more common in men but may occur in women
Inside Testes 1. seminiferous tubules about 1000 site where sperm are produced by a process called spermatogenesis produce 100 million+ sperm each day from puberty until death spermatogenesis A.