Chapter48

Chapter48 - Chapter 48 1) Asexual and Sexual Reproduction...

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Chapter 48 1) Asexual and Sexual Reproduction a) Asexual Reproduction is an efficient strategy i) Budding is where a small part of the parent’s body separates from the rest of the organism and develops into a new individual. ii) Fragmentation is a method seen in flatworms and other organisms that are capable of reproduction. iii) Parthenogenesis is a form of asexual reproduction where an unfertilized egg develops into an adult animal. (the adult is haploid) b) Sexual reproduction is the most common type of animal reproduction. i) This allows for genetic variation that can help t save a species if the environment undergoes dramatic change. 2) Human Reproduction: The Male a) The Testes Produce Gametes and Hormones. i) Spermatogenesis is the process of sperm cell production. ii) This occurs in the testes . iii) This takes place in the Seminiferous Tubules within the testes. iv) The process begins with undifferentiated spermatagonia . v) Some of these will enlarge and become primary spermatocytes , which undergo meiosis. vi) The first meiotic division produces secondary spermatocytes . vii)The second gives rise to spermatids . viii) FOUR spermatids are prodouced overall. ix) THE PROCESS: (1) Spermatagonium (2) Primary spermatocyte (3) Secondary Spermatocyte (two) (4) Spermatids (four) (5) Four Mature Sperm x) Each sperm has a head, midpiece, and tail (flagellum) xi) The head is nearly all nucleus, and is partially covered by the acrosome , a vesicle that contains proteins to help break down the egg’s membranes. xii)The midpiece holds the mitochondria, and the flagellum is in the typical 9 +2 arrangement. xiii) The Sertoli Cells that surround a developing sperm strip it of most of its cytoplasm. xiv) These sertoli cells also are responsible for generating hormones. xv) Sperm cells cannot develop at warmer temperatures. xvi) The scrotum is a flap of skin that keeps the testes away from the body. xvii) Undescended Testes cause sterility . xviii) The scrotum stays connected to the body cavity by the inguinal canals . b) A Series of Ducts Store and Transport Sperm. i) Developed sperm cells leave the seminiforous tubules and move into the epididymis , a large coiled tube. ii) During ejaculation, the sperm pass into the vas deferens .
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iii) These empty into an Ejaculatory Duct , which passes through the prostate gland and then into the single Urethra . iv) Pathway: (1) Seminiferous Tubules (2) Epididymis (3) Vas deferens (4) Ejaculatory duct (5) Urethra (6) Release From Body. c) The Accessory Glands Produce the fluid portion of Sperm. i) About 3ml of semen is ejaculated during climax. ii) The paired seminal vesicles secrete a nutritive fluid rich in fructose and prostaglandin into the vasa deferentia.
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This note was uploaded on 04/02/2008 for the course BIO 101 taught by Professor Martin during the Spring '08 term at Rutgers.

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Chapter48 - Chapter 48 1) Asexual and Sexual Reproduction...

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