Genetics Exam 1 Review I Chromosomes a Based on the centromere know what type of chromosome it is chart i Metacentric ii Submetacentric iii Acrocentric typically have ribosomal genes iv Telocentric mouse chromosomes b Chromosome content within the cell i 1n haploid gametes spores etc ii 2n diploid somatic cells c Homologous Chromosomes i Gene loci are in the same order in both ii One comes from father one from mother d Sister Chromatids i Arms in each chromosome II Terminology a Genotype set of alleles that are carried in an individual b Phenotype outward appearance what is expressed i Can t necessarily tell you the genotype c Allele variant forms of a gene i i e white vs red eye in drosophila d Homozygous both alleles are the same e Heterozygous both alleles are different i i i e BB i e Bb III Cell Cycle Chromosome Behavior a G1 S Phase G2 M Phase i G1 1 sister chromatid ii G2 2 sister chromatids b Mitosis somatic cell division i 2n 2n ii Growth and Development of an organism iii If a cell is terminally differentiated it enters G0 no growth c Meiosis gametic cell division i 2n 1n ii occurs in the ovum spermatozoa iii Go over stages for generating ovum spermatozoa i Crossing over occurs genetic exchange between homologous d Prophase I chromosomes ii Terms 1 Tetrad homologous chromosomes 2 Synapsed 3 Chiasma where the crossing over actually occurs 4 Non autonomous do not act independently e Be able to label different stages of meiosis i Prophase I ii Metaphase I iii Anaphase I iv Telophase I v Prophase II vi Metaphase II vii Anaphase II viii Telophase II IV Deviations from Mendel a Incomplete dominance the combination of heterozygous alleles are not dominant over one another i Yields intermediate phenotype hybrid of the two b Co dominance distinct phenotypes i MN Blood Groups ii AB blood type c Epistasis Expression of one gene can mask or modify the expression of a second gene d Multiple Genes contribute to a phenotype i A I B II C e Complementation Analysis i ii If you have a mutation in I then you cross that organism with one that has a mutation in II If you crossed it with an organism that a mutation in I it would not survive f Pleitropy mutations in a single gene multiple phenotypes g Imprinting parent specific gene expression i 2 types of syndromes Look in book V Sex Chromosomes a Male XY b Female XX c Y Chromosome i Determines maleness ii PAR pseudoautosomal regios that pair up X and Y Chromosomes iii SRY gene that determines maleness iv XX males XY females d Not all organisms use the SRY gene to determine maleness i Drosophila uses a ratio of X autosomes use book VI Human Pedigrees Is it autosomal dominant recessive a b Recessive Clue i Skips a generation c Dominant Clue i Occurs in every generation ii Affected individual will almost always have an affected parent d Autosomal Clue i Equal appearance in both sexes e Proband person with disease who went to the doctor VII Mendel a Mendel s Postulates i Unit factors exist in pairs ii Dominance Recessiveness iii Segregation iv Independent Assortment b Monohybrid Cross i P1 AA x aa ii F1 all Aa iii Aa x Aa iv F2 Genetypic Ratio 1 2 1 v F2 Phenotypic ratio 3 1 c Test Cross if an organism shows a dominant phenotype how do you know if it is AA or Aa Testcross cross it with homozygous recessive
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