BSCI222 EXAM 1 REVIEW o Lecture 1 Material Chromosomes Mitosis Meiosis o Chapters 1 2 5 6 7 8 11 13 14 18 19 21 22 23 25 28 33 o o Features of the Cell Cycle Stage G0 Phase Interphase G1 Phase Chromosomes 4 DNA 4 S Phase Chromosomes 4 DNA 4 8 G2 Phase Chromosomes 4 DNA 8 M Phase Prophase Chromosomes 4 DNA 8 Prometaphase Chromosomes 4 DNA 8 Metaphase Chromosomes 4 Major Features Stable nondividing period of variable length Growth and development of the cell G1 S checkpoint Synthesis of DNA Preparation for division G2 M checkpoint Chromosomes condense and mitotic spindle forms Nuclear envelope disintegrates and spindle microtubules anchor to kinetochores Chromosomes align on the metaphase plate spindle assembly DNA 8 Anaphase Chromosomes 8 DNA 8 Telophase Chromosomes 4 DNA 4 Cytokinesis Chromosomes 4 DNA 4 Event Cell Division Chromosome reduction Genetic variation produced Crossing over Independent assortment Metaphase Anaphase checkpoint Sister chromatids separate becoming individual chromosomes that migrate toward spindle poles Chromosomes arrive at spindle poles the nuclear envelope re forms and the condensed chromosomes relax Cytoplasm divides cell wall forms in plant cells o Comparison of Mitosis Meiosis I and Meiosis II Mitosis Yes No No No No Meiosis I Yes Yes Meiosis II Yes No Yes Yes Yes No No No Individual chromosomes line up Chromatids separate Homologous pairs line up Homologous chromosomes separate Individual chromosomes line up Chromatids separate o Sources of Genetic Variation in Meiosis Crossing Over PROPHASE 1 OF MEIOSIS Exchange of genes between nonsister chromatids chromatids from different homologous chromosomes Shuffles alleles on the same chromosome into new combinations Crossing over is the basis for recombination o Creating new combinations of alleles on a chromatid Segregation Mendel s first law ANAPHASE 1 OF MEIOSIS Of homologs Each individual diploid organism possessed two alleles for any particular characteristic These two alleles segregate separate when gametes are formed and one allele goes into each gamete Each individual possessed two alleles encoding a trait alleles separate when gametes are formed alleles separate in equal proportions Independent Assortment Mendel s second law ANAPHASE 1 OF MEIOSIS Alleles at different loci separate independently The random assortment of maternal and paternal chromosomes shuffles alleles on different chromosomes into new combinations o Structure of Chromosomes Telomere centromere two sister chromatids kinetochore spindle microtubules Bivalent Tetrad each homologous pair of synapsed chromosomes consists of 4 chromatids Metacentric centromere in middle Submetacentric centromere gradually moving up Acrocentric Telocentric centromere at top Cohesion controls the separation of chromatids and chromosomes in mitosis and meiosis Chiasma Chiasmata the physical exchange of DNA between homologous chromosomes o Ploidy 1n 2 and 2n 4 o Spermatogenesis the production of gametes in a male animal Spermatogonium 2n Primary spermatocyte 2n Secondary spermatocyte 1n Spermatids 1n o Oogenesis the production of gametes in a female animal Oogonium 2n Primary oocyte 2n First polar body Secondary oocyte 1n the secondary oocyte completes meiosis II producing an ovum and a second polar body which also disintegrates Second polar body Ovum 1n in some animals meiosis II takes place after the sperm has penetrated the secondary oocyte o Sperm and ovum fuse at fertilization and produce a diploid 2n zygote o Lecture 2 Material Basics o Chapters 2 3 1 2 5 8 10 11 14 15 16 20 22 25 29 36 o Gene a factor responsible for a characteristic o Locus location of a gene in the genome o Allele form of gene o Dominant recessive Mendel s peas o Monohybrid cross Rr x Rr o Dihybrid cross RrGg x RrGg 16 combinations Following two loci on different chromosomes no crossing over o If you know the genotype phenotype relationship then you can predict ratios of phenotypes o Lecture 3 Material Basics Genotype Phenotype relationships o Chapters 3 5 1 2 3 4 12 13 14 15 17 18 19 22 25 26 28 29 30 31 37 39 o Ch 3 Probability The law of and multiplication P x and y p x p y What is the probability of flipping a coin twice and getting heads both times o Probability of getting heads o 1 4 The law of or addition P x or y p x p y What s the probability of throwing either a 3 or a 4 when you roll a die o Probability of rolling a 3 1 6 o Probability of rolling a 4 16 o 1 6 1 6 1 3 Multilocus Problems unlinked loci AABbDdEeGg x AaBbDdEeGg o What is the probability of AABBddEegg o 25 gamete types from each parent 1024 gamete combinations o p AA p BB p dd p Ee p gg o 1 256 Data often do not match expectations exactly Chi Square Goodness of fit chi square test o if you expected a 1 1 ratio and produced 22 brown and 18 yellow you wouldn t be surprised that it s not perfect 1 1 o Reasonable to assume that chance produced the deviation between the expected and observed results X2 Observed Expected 2 Expected Observed observed data in each category o Numbers not fractions or frequencies Expected expected data in category based on the experimenter s hypothesis model Degree of freedom n 1 P value o A measure of how significant the calculated value is stands for probability o A big p value means that the calculated value could probably have happened by chance process o A small p value means there s only a small probability that the calculated value arose If p value is less than 0 05 a significant difference exists between the observed and the expected values in a chi square test P 0 05 threshold Reject the null hypothesis if x2 calc x2 crit o Types of Dominance Complete dominance DD and Dd D phenotype D completely masks the d allele Incomplete dominance Dd phenotype between D and d Phenotype of the heterozygote is intermediate falls between the phenotypes of the two homozygotes Ex red and white flower pink flower Co dominance D phenotype and d phenotype The heterozygote expresses the phenotypes of both Ex MN bloodtypes blood type antigens Ex red horse and white horse roan horse red and homozygoyes white Dominance Series involves multiple alleles Rabbit coat color C cch ch ca o Ch 5 Penetrance and Expressivity Penetrace is defined as the percentage of individual organisms having a particular genotype that express the expected phenotype Incomplete penetrance product the expected phenotype the genotype does not always Expressivity is the degree to which a character is expressed Variable