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ECU BIOL 1050 - More Genetics and Sex Genes
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BIOL 1050 Lecture 20 Outline of Last LectureI. Human Genetics Outline of Current LectureI. GeneticsII. Sex genesCurrent LectureI. Geneticsa. Mendel’s law of segregation i. Only one of the two alleles for a gene is put into a gamete. At fertilization, offspring receive from each parent one allele for each geneb. Incomplete dominancei. In which the heterozygote appears to be intermediate between the two homozygotesii. Ex. When you cross red and white flowers they will all be pink, mixing pink flowers results in pink, red (heterozygous), and white (homozygous). c. Codominancei. In which the heterozygote displays characteristics of both homozygotesii. Ex. Red and white flower combined would result in a flower with both red and white, instead of pink d. Multiple allelesi. Occurs when there are three or more alleles for a gene within a population.An individual still inherits only two alleles, one from each parent.ii. Ex. Blood types. Red blood cells have 6different genotypes (AA, AO, BB, BO, AB, OO) these genotypes result in 4 different phenotypes (A, B, AB, O)e. Polygenici. A polygenic trait is a trait that is influenced by many different genesf. Pleiotropic genesi. Occurs when one gene influences multiple different traitsii. Ex. Sickle-cell diseaseII. Sex genesa. What determines your sex?i. Individuals have two copies of the sex chromosomes in every cellii. When the sperm carries an x the baby will have two x chromosomes and will develop as a femaleThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iii. When the sperm carries a Y the baby will have an x and a y and develop as a maleb. Sex-linked disorders i. Same disorders result from recessive alleles on x chromosomes1. Disorders expressed more by men than women because women have other x chromosome to balance outa. ex. Hemophilia=disease where blood won’t clot correctlyb. red-green color blindness2. Females can have a. XB XB (normal color vision)b. XB Xb (normal color visionc. Xb Xb (color blindness)3. Males can havea. XB Y (normal color vision)b. Xb Y (color blindness)c. Pedigreei. A useful tool to document a trait of interest across multiple generations of family membersd. Other disordersi. Many genetic diseases caused by alleles at one or more genesii. But other disorders caused by having an abnormal number of chromosomesiii. Abnormal chromosome number caused by a nondisjunction1. Members of a chromosome pair fail to separate in meiosis2. Result is gametes with abnormal number of chromosomes3. Causes for this are unknown 4. Leads to zygote with abnormal chromosome numbera. A human embryo with an abnormal number of autosomesi. Usually miscarried before birthb. Those that survive have a characteristic set of symptoms or asyndrome i. Down syndrome1. Have an extra chromosome 212. Also called trisomy 213. Incidence of down syndrome increases with the age of the mothera. Don’t know why risk goes up with moms ageb. But meiosis begins in ovaries before birth but does not continue until time of ovulationc. Longer time lag means increased risk for errorsiv. Too many or too few sex chromosomes1. Could result in a. Turner syndromeb. Klinefelter syndromec. Super malesd. Meta females 2. In generala. 1 y chromosome is enough to produce “maleness” even if several x’s are presentb. absence of a y chromosome results in


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ECU BIOL 1050 - More Genetics and Sex Genes

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