PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Mitosis and Meiosis Lectures 1 2 Chapter 2 Know the essential differences between mitosis and meiosis what homologous chromosomes are and how they behave in mitosis and meiosis Homologous Chromosomes Chromosomes that synapse or pair during meiosis are identical with respect to their genetic loci centromere placement Mitosis Converts a diploid cell two diploid daughter cells that are genetically identical to the parent cell Meiosis Each daughter cell gets 1 chromatid from each chromosome Formation of gametes sex cells 1 diploid 2n cell divides twice forms 4 haploid n cells Each daughter cell gets 1 chromatid from each pair of homologous chromosomes Reduces the genetic content number of chromosomes to half Understand the concept of the cell cycle and know what happens during S phase Cell Cycle The events that occur from the completion of one division until the beginning of the next division Interphase o G1 o S Phase Replication of the DNA of each chromosome occurs o G2 Mitosis 1 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Be able to name the stages of mitosis and know what events take place in each Interphase Prophase Metaphase Anaphase Telophase Chromosomes are extended uncoiled forming chromatin Chromosomes condense Centrioles divide move apart Prometaphase Chromosomes are clearly double structures Centrioles reach the opposite poles Spindle fibers form Centromeres align on metaphase plate Centromeres and daughter chromosomes migrate to opposite poles Daughter chromosomes arrive at the poles Cytokinesis begins 2 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Know what sister chromatids are Sister Chromatids The two parallel parts of the chromosome a double structure joined at the centromere that are exact duplicates of each other Understand the term diploid and haploid and know what homologous chromosomes are how they are similar to each other and how they differ from nonhomologous chromosomes Diploid 2n A condition in which each chromosome exists in pairs having 2 of each chromosome Haploid n When a cell or organism has one member of each pair of homologous chromosomes Equal to the diploid number Homologous Chromosomes Chromosomes that synapse or pair during meiosis are identical with respect to their genetic loci centromere placement Know the important events that occur in meiosis and understand how meiosis differs from mitosis Meiosis differs from mitosis in that the chromosome number genetic content is are reduced and it produces haploid gametes sex cells that have genetic variability while the diploid cells produced in mitosis are genetically identical to the parent cell 3 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Meiosis I 1st division DNA is replicated during interphase Homologous chromosomes align Chromosome recombination crossing over occurs Homologous chromosomes are separated into different daughter cells Result two haploid daughter cells 4 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Meiosis II 2nd division NO DNA replication occurs before meiosis II Sister chromatids are separated into different daughter cells Result four haploid daughter cells Understand the terms tetrad chiasmata crossing over and recombination Tetrad The 4 chromatids that make up paired homologs in the prophase of the first meiotic division Chiasmata The crossed strands of nonsister chromatids Crossing Over The exchange of chromosomal material parts of chromosomal arms between homologous chromosomes by breakage reunion Exchange of material between nonsister chromatids basis of genetic recombination Recombination The process that leads to the formation of new allele combinations on chromosomes Review of Mendel s Principles Lectures 3 5 Chapter 3 Be able to state Mendel s postulates Random Segregation and Independent Assortment and understand their significance Random Segregation During the formation of gametes the paired unit factors separate or segregate randomly so that each gamete receives one or the other with equal likelihood Ex If an individual has two unlike alleles one for tall and one for dwarf then each gamete has a 50 chance of receiving either the tall or the dwarf allele 5 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Independent Assortment Genes for different traits are inherited independently they assort independently into the gametes All possible combinations of gametes are formed in equal frequency Ex The chance of any plant having yellow or green seeds is not at all influenced by the chance that this plant will have round or wrinkled seeds Know and be able to use the terms phenotype genotype homozygous heterozygous dominant recessive allele true breeding or pure breeding parental generation F1 generation F2 generation F1 hybrid monohybrid cross dihybrid cross Phenotype The physical expression of a trait Genotype The genetic makeup of an individual Homozygous Both alleles for a trait are the same Heterozygous Two different alleles for a trait are present Ex AA or aa Ex Aa Dominant The trait typically observed when the organism is homozygous or heterozygous can mask a recessive trait Denoted by a capital letter Ex BB or Bb Denoted by a lowercase letter Ex bb Recessive The trait typically observed only when the organism is homozygous for it Alleles Alternative forms of single genes True Breeding Pure Breeding An organism that always passes down a certain phenotypic trait to its offspring Organism must be homozygous for the trait Parental P1 Generation The original parents F1 Generation Offspring of the parental P1 generation F2 Generation The individuals resulting from the selfed F1 generation F1 Hybrid The first filial generation of offspring of distinctly different parental types Ex Crossing pure bred round seed plants with pure bred wrinkled seed plants Test Cross Cross between an organism of dominant phenotype with one that is recessive 6 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Monohybrid Cross A cross that involves one pair of contrasting traits Made by mating true breeding individuals from 2 parent strains each exhibiting one of the 2 contrasting forms of the character under study Dihybrid Cross A cross that involves two pairs of contrasting traits Ex Pea plants having yellow seeds that are round are bred with pea plants having green seeds that are wrinkled 7 PCB3063 General Genetics Exam 1 Study Guide Fall 2014 Understand how Chi Square is used to determine
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