Exam 3 Review OutlineChapter 9:1. Control of the Cell cycle- 3 checkpoints- G1(Restriction) Checkpoint- G2 Checkpoint- Metaphase Checkpoint2. Mitotic Cell Division- Prophase- Early Prophase:- Nucleolus fades- Chromosomes condense- Spindle apparatus forms- Spindle consists of microtubules between two microtubule organizing centers containing pair of centrioles- Late Prophase:- Nuclear envelope disappears- Microtubules attached to kinetochores of chromosomes- Centrioles are at opposite poles- Polar microtubules radiate toward the cell’s equator- Spindle microtubules capture chromosomes at centromeres- Metaphase - Centrioles positioned at opposite ends (poles) of the cell- Chromosomes move to and align on the equator of the cell- Anaphase - Movement of the chromosome is accomplished by depolymerization of the microtubules at the kinetochore- Cell begins to elongate because the polar microtubules grab onto each other and push the poles apart as they lengthen.- Telophase-Polar microtubules elongate (pushing out on the ends of the cells) helps cause the formation of the cleavage furrow.- Daughter nuclear envelopes form- Chromatin begins de-condensing--By the end of Telophase – replication of the nucleus is complete and two genetically identical daughter nuclei are present.- Cytokinesis-The division of the cytoplasm that forms 2 separate daughter cells each containing a single nucleus.- The division of the nucleus is usually followed quickly by cytokinesis- End result- 2 identical daughter cells (Diploid)3. Meiotic Cell Division- Crossing Over-When the maternal and paternal chromosomes (of a homologous pair) have exchanged the genetic material. This exchange of DNA is called crossing over.- Pairs are held together by chiasmata- Independent Assortment- Which side (maternal or paternal) faces which pole is random– This randomness is called independent assortment- End result- Four haploid cells (Gametes)- Meiosis I – First Division- Meiosis II – Second Division (very similar to mitosis)4. Genetic Diversity: - The level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.5. Life Cycles- Haploid- One set of chromosomes (we have 23)- (Eggs and Sperm)-Two haploid gametes unite during fertilization to form a zygote- Diploid- All of our cells are diploid. Meaning the chromosomes are in pairs (2 sets of chromosomes), not singular- Diploid is the condition in which cells contain two sets of chromosomes, abbreviated 2n. Fig. 9.17- (Zygote)- Alternation of Generations (also known as alternation of phases)a. Metagenesis- A term primarily used to describe the life cycle of plants. A multicellular gametophyte, which is haploid with nchromosomes, alternates with a multicellular sporophyte, which is diploid with 2n chromosomes, made up of n pairs.Chapter 10:1. Gene vs. AlleleAllele: are alternative forms of a gene that occupy a specific position (locus) on a specific chromosome.-Each homologous pair of chromosomes has the same genes at the same place (locus), but they can have different alleles for the same gene2. Homozygous v. heterozygous- Homozygous: both the alleles are the same of a given trait- Homozygotes are true-breeding- Heterozygous: the two alleles are different for a given trait- Heterozygotes are not true-breeding3. Phenotype v Genotype- Phenotype: is an organism’s expressed traits - What it looks like- Genotype: is an organism’s genetic traits4. Mendel’s Experiment- True Breeding - Varieties in which self-fertilization leads to offspring which are the same type as parent- F1 (Generation)- First generation offspring- F2 (Generation)- Second generation offspring5. Test Cross- According to the law of independent assortment, genes for different characters are inherited independently of each other- The parental crosses that Mendel did in his earlier experiments involved parental varieties that differed in a single trait (i.e., monohybrid crosses)6. Two trait cross- Consider two traits for pea:- Color: Y (yellow) and y (green)- Shape: R (round) and r (wrinkled)- Each dihybrid plant produces 4 gametes types of equal frequency.- YyRr (adult) four gametes types: YR, Yr, yR, or yr- A dihybrid is an individual that is heterozygous at two genes (YyRr)- Mendel designed experiments to determine if two genes segregate independently of one another in dihybrids- First constructed true breeding lines for both traits (YYRR & yyrr)- Crossed them to produce dihybrid offspring (YyRr)- Examined the F2 for parental or recombinant types (new combinations not present in the parents)7. Linked Genes- Tend to be inherited together because they are located on the same chromosome.- Linked genes two different genes that are on the same chromosome- Linked genes don’t assort independently8. Sex Linked Genes- Traits unrelated to sex are on the sex chromosomes-In humans, “sex-linked” usually means “X chromosome linked”-X chromosome is bigger and therefore more genes possible-Most X chromosomes have no homologous loci on the Y chromosome (i.e., can’t be homozygous or heterozygous at these loci)-Fathers pass X to daughters-Mothers pass X to sons and daughters9. Incomplete Dominance: is the present when the heterozygote genotype hasa unique phenotype that is intermediate between the two parental phenotypes; neither allele dominates.- Sounds like blending theory but it’s not!- Example of incomplete dominance: snapdragons10. Co Dominance- The pattern of inheritance characterized by full expression of both alleles in the heterozygous genotype.11. Polygenic Inheritance (Quantitative Inheritance)- P.I. is a mode of inheritance in which the additive effect of two or more genes determines a single phenotypic trait.Examples of human polygenic traits:Eye Color: is determined by several genesDetermined by two factors:1. The pigmentation of the eyes’ iris – from light brown skin to black only2. The scattering of light in the stroma of the irisHeightSkin Color: Punnett square Fig. 10.1912. Pleiotropy – genes that affect many traits (opposite of what we were just talking about)Pleiotropy is the ability of a single gene to have multiple phenotypic effectsExamples:-Sickle cell anemia-Albinism – single cell mutation has effects on different organ systems13. Non disjunction - At meiosis I or II Fig. 10.25Chapter 11:1. DNA discovery- By the
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