The Reproductive Syste1

The Reproductive Syste1 - minutes Genetics Chromosomes o...

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The Reproductive System The First Year Following Birth Many important changes occur during the first year after birth. Many of these changes are linked to continued development of the brain. Life Stages The eight stages of life are: germinal period (fertilization to 14 days),embryo (14- 56 days after fertilization), fetus (56 days after fertilization to birth), neonate (birth-1 month), infant (1 month-1 or 2 years), child (1 or 2 years-puberty), adolescent (puberty to 20 years), adult (20 years to death). Aging Aging occurs as irreplaceable cells wear out and the tissue becomes more brittle and less able to repair damage. Atherosclerosis is the deposit of lipids in the arteries. Arteriosclerosis is hardening of the arteries. Death Death is defined as the absence of brain response to stimulation, the absence of natural respiration and heart function, and a flat electroencephalogram for 30
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Unformatted text preview: minutes. Genetics Chromosomes o Humans have 46 chromosomes in 23 pairs. o Males have the sex chromosomes XY and females have XX. o During gamete formation, the chromosomes of each pair of chromosomes separate; therefore half of a person's genetic makeup comes from the father and half from the mother. Genes o A gene is a portion of a DNA molecule. Genes determine the proteins in a cell. o Genes are paired (located on the paired chromosomes). o Dominant genes mask the effects of recessive genes. o Sex-linked traits result from genes on the sex chromosomes. o In incomplete dominance, the heterozygote expresses a trait that is intermediate between the two homozygous traits. o In codominance, neither gene is dominant or recessive, but both are fully expressed. o Polygenic traits result from the expression of multiple genes....
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