Exam One Study Guide
Exam One Study Guide BIOL 309
Popular in Genetics Lecture
Popular in Biology
This 5 page Study Guide was uploaded by Katlyn Burkitt on Friday September 16, 2016. The Study Guide belongs to BIOL 309 at Towson University taught by Dr. Bulmer in Fall 2016. Since its upload, it has received 173 views. For similar materials see Genetics Lecture in Biology at Towson University.
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Date Created: 09/16/16
Genetics Study Guide for Exam One Mitosis o Clonal Replication o For somatic cells o Stages Prophase Duplicated chromosomes condense into rods Metaphase Migrate to the equatorial plane of the cell Anaphase Centromere splits and sister chromatids separate (disjunction) from each other Telophase Chromosomes decadence and nuclear membrane forms around them Cytokinesis The splitting of the cytoplasm into two daughter cells Each daughter ceperates o Meiosis o Replication and pairing of homologous chromosomes with 2 rounds of division creating 4 daughter cells (Gametes) o Cells are haploid o Shuffles genetic composition o 50%/50% chance Aa genotype can produce two gametes, an A or an a. Cell cycle Characteristics of chromosomes o Heterochromatin o Euchromatin o Centromeres: Attaches the sister chromatids to each other, splits during anaphase o Telomeres Mendel’s principles o Dominance and Segregation: That a dominant allele can mask a recessive allele o Principle of independent assortment: That two heterozygous loci (Genes) can produce 4 gametes GgWw can produce, GW, Gw, gW, gw Dihybrid cross(GGWW x ggww) = a 9:3:3:1 ratio Dihybrid cross (AaBb x aabb) = a 1:1:1:1 Ratio Alleles o Different forms of a gene at a given locus o Dominant: Capital masks a recessive allele o Recessive: Lower case requires two alleles to be visible o Incomplete dominance: When a dominant allele does not completely mask the recessive allele. o Codominance: Heterzygote phenotype is a mixture of the homozygous phenotypes and both are expressed like blood types o Incomplete penetrance: Potential problem/wrong assignment of genotypes o Variable expressivity: ???????????? P: Parent generation F1 : The progeny of the cross between the P generation F2 : The progeny of the cross between the F1 generation Haploid: Containing only one chromosome, not pairs. In humans these are gamete cells Diploid: Containing pairs of the chromosomes in humans these are somatic cells o Genotype The genetic make up Heterozygous One dominant and one recessive allele Homozygous Two dominant or two recessive alleles o Phenotype The observable result of a genotype True Breeding: Homozygous for the trait Testing genetic hypotheses o Test cross is done to determine if a trait is Dominant, Recessive, Incomplete dominant, or codominant o Chi Squared test After performing a test cross you take the observed numbers (The actual results) and what would have been expected (Do a Punnet square or if you know the ratio take that, from there you multiply the total number by that ratio, ex, if the ratio is 1:1:1:1 and the total number is 100 you would expect 25 in each category for expected.) Then from here you plug these numbers in as O= observed & E= Expected and solve. You do this for each piece of the ratio, and add them together From here determine the degrees of freedom by taking he number of phenotypic categories minus one, ie. 4 phenotypic categories then the degrees of freedom are 3 From here use this chart to determine if it meets the 5% critical value, if it is below then the hypothesis is accepted, if it is above then you reject the hypothesis Epistasis: Two or more genes influencing the same trait Pleiotropy: One gene affects many phenotypic characteristics Binomial probability Human genetics o Rely on pedigree analysis o Some diseases follow mendelian patterns of genetics Sex linkage: Traits that are typically only found on an X chromosome, making them sex liked, such as color blindness. A female can be a carrier a male cannot Genes on Y (SRY): Produces Testis Determining Factor (Without it ovaries develop), having this gene will determine if you develop into a male or female. Dosage Compensation Barr bodies Haplodiploidy: The situation where the males of a species originate from unfertilized eggs and the females from fertilized eggs, making males haploid and females diploid Relatedness Cytogenetics???? Karyotypes: A “Photograph” of an individual’s chromosomes Polyploidy: Presence of more than 2 sets of chromosomes Euploidy: An abnormal amount of chromosomal pairs Examples of trisomy o XXY Trisomy (1/500 – 1/1000 boys) Klinefelters syndrome: Sexually underdeveloped (Low testosterone) long limbs and large hands and feet, may develop breast tissue, usually infertile, no mental retardation X-inactivation excluding a few genes in the pseudoautosomal region o Triple X syndrome (1/1000 girls) tallness, menstrual irregularities, slightly reduced intelligence when compared to XX siblings, fertile No unusual physical features or medical problems Only one X is active at a time o XYY Jacobs Syndrome (1/1000 boys) tallness, acne, and speech and reading problems in some cases Used to be associated (1960’s) with criminal behavior Usually occurs due to nondisjunction during meiosis II Not affected by advanced paternal or maternal age Aneuploidy: Having an abnormal amount of chromosomes (unpaired) Chromosomal rearrangements o Deletions – Hypoploidy for region deleted, typically lethal if the deletions occur on both chromosomes Cri-du-chat syndrome, 5p minus syndrome (1/20,000-50,000) Deletion of short arm of chromosome 5 Mental and physical impairment, cat like crying noises, <5year lifespan o Duplications of chromosome segments Hyperploidy partial trisomy for duplicated region o Rearrangements- no variation in chromosome number Inversions- Piece of a Chromosome detaches and rotates 180 degrees and reattaches to the same chromosome o Translocations Piece re-attaches to a non-homologous chromosome o Mosaicism Autosomal and sex chromosome aneuploidy only occurs during mitosis One daughter cell receives both chromosome duplicates or none o
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