Bio Notes 3-11-2016
Bio Notes 3-11-2016 BIOL 1014
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This 2 page Class Notes was uploaded by Crystal Florman on Saturday April 9, 2016. The Class Notes belongs to BIOL 1014 at University of Northern Iowa taught by Dr. Kurt Pontasch in Spring 2016. Since its upload, it has received 44 views. For similar materials see Life: Continuity and Change in Biology at University of Northern Iowa.
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Date Created: 04/09/16
Lecture Notes March 11 , 2016 Nondisjunction Sometimes during meiosis the chromosomes don’t separate properly Results in gametes lined up with too many/ too few chromosomes Frequency of this increases in women in their late 30’s Homologous chromosomes pairs in every cell are balanced against each other- when an individual has a double dose of some genes and a single dose of others shit happens o Down’s Syndrome- extra chromosome 21 47 total chromosomes in the zygote and in all other cells of the individual Low level of intelligence, thickened eye lids, faulty speech o Turner’s Syndrome Results when a person only has one X chromosome- 45 chromosomes in zygote One of the gametes was missing a sex chromosome Female, sterile, short, webbed neck, and have problems with math and special relationships o Klinefelter’s Syndrome Extra sex chromosome- 2X 1Y- 47 chromosomes Egg having 2X chromosomes Tall, sterile, male, often with a lowered mental capacity Hormonal Control Hormones- chemicals, usually proteins or steroids, produced by one part of the body (usually a gland) that alters the activity of another part of the body called the target organ Important to the bodily functions of many animals- focus on male and female hormones o Males- during embryotic development of the male, the testes produce small amounts of the male sex hormone- testosterone These small amounts result in the formation of male structures (differentiation) but no sperm is produced At puberty- the hypothalamus (part of the brain) begins to secrete Gonadotrophic Releasing Hormone- GnRH GnRH acts on the pituitary gland- which is a “master” gland near the brain- causes the pituitary gland to release a luteinizing hormone (LH) and follicle stimulating hormone (FSH) LH- causes the interstitial cells in the testes to produce more testosterone FSH- along with extra testosterone causes maturation of the seminiferous tubules and the production of sperm Once the LH causes more testosterone to be produced it causes the maturation of the accessory reproductive structures- penis and testes- testosterone triggers secondary sexual characteristics- pubic hair, beard growth, deeper voice, larger and stronger muscles o Females- reproductive cycle Lecture Notes As in the male- at puberty the hypothalamus releases GnRH which causes the pituitary gland to release LH and FSH FSH and LH causes the ovaries to mature and begin secreting the two female sex hormones estrogen and progesterone Estrogen- stimulates maturation of accessory reproductive structures- increases the size of the uterus and vagina- causes the development of secondary sexual characteristics- pubic hair, breasts, broadening of pelvis, redistribution of body fat, and some change in voice As the hormone balance changes the menstrual cycle is initiated Estrous Cycle- in most mammals the rhythmic changes in the female reproductive tract is called an EC- female receptive to the male only at certain times during EC- uterine lining build up is reabsorbed if fertilization does not occur Humans and other higher primates differ from other mammals in that: Female is somewhat receptive to the male at all times If fertilization does not occur the thickened uterine lined is shed during a period of bleeding known as menstruation o Human menstrual cycle is about 28 days
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