Meiosis Presentation PDF

Label the Diagram: (Maternal and Paternal Chromosomes, homologous chromosomes, Centromere, sister chromatids) What is n? Based on the number of sets of chromosomes what phase is this cell in? Describe what a homolog is. What is n? The number of chromosomes in a set Based on the number of sets...

Label the Diagram: (Maternal and Paternal Chromosomes, homologous chromosomes, Centromere, sister chromatids) What is n? Based on the number of sets of chromosomes what phase is this cell in? Describe what a homolog is. What is n? The number of chromosomes in a set Based on the number of sets of chromosomes what phase is this cell in? 4n, after S of interphase but before Meiosis I. Describe what a homolog is. Terms! Gene - A unit of heredity Ex: The eye color gene Allele - The different types or versions of that gene Ex: The blue eye color allele Trait - The characteristic that is determined by the gene Ex: Blue eyes Locus (loci) - The location of the gene on a chromosome Homologous Chromosomes Chromosomes in organisms that carry the same genes but come from a different parental source. *Same genes but different alleles 22 autosomal chromosomes (autosomes) 1 sex chromosome.  Spermatogenesis and Oogenesis - Meiosis The formation of Stem gametes (Sperm and Cells Ovum) 4 sperm are formed through meiosis of the male sex cells (spermatocyte) 1 ovum and 3 polar bodies are formed from meiosis of the female sex cells (oocyte) Overview of Meiosis vs Mitosis Come up with a list of events that are unique to Meiosis. Is Meiosis I or II more similar to Mitosis? Justify your response. Overview of Meiosis List the unique events that occur during Meiosis I 1. Separation of homologous chromosomes 2. Synapsis in Prophase 1(crossing over) 3. Products are haploid cells. Which of these is more similar to Mitosis? Explain Meiosis II is more like Mitosis due to the fact that it is the separation of sister chromatids like Mitosis.  Chiasmata- where the homologous chromosomes attach during crossing over Synapsis = the formation of the tetrad Tetrad = a structure in which 4 chromosomes are held close together Crossing Over Leads to Genetic Variation The product of Meiosis is 4 haploid cells that are completely different from each other. What are the other characteristics of sexual reproduction that lead to genetic variation?  Independent Assortment Which side the homologs migrate to during Meiosis 1 is random. Random Mating Any of the gametes could be used in Fertilization What is Genetic Variation? Traits that differ between members of the same species Increasing variation results in the increased ability for species to survive. Videos to explain the 3 sources of variation that occur during Meiosis Genetic Mutations are another source of variation. - These are random changes to the DNA sequence. - They are not always BAD! Most of the time they don’t Video have any effect on the individual. - Mutations can lead to new characteristics in an individual. - Mutations can be passed down from parent to offspring if the mutation occurs in germ cells. - Mutations can also occur by exposure to mutagens (ie UV rays) and some viral infections (ie Herpes Viruses). What happens when Meiosis Goes Wrong? Nondisjunction Aneuploidy - the incorrect number of chromosomes Typically Lethal Few trisomies are viable in humans Nondisjunction Video Things to Remember Interphase still occurs whether the cell undergoes Mitosis or Meiosis cells cannot do both! Only germ cells will do meiosis. (formation of gametes) Sexual reproduction requires Meiosis to occur. Asexual reproduction is achieved through mitosis. Organisms can have different ploidiness (different number of sets of chromosomes) and different numbers of chromosome in each set. Strawberries are octoploidy (8n) Cats have 2 sets of 19 chromosomes (2n)(n=19) Today: - Pearson Assignment for Homework - Chi2 Edpuzzle Extra image beyond the scope of the course. This illustrates the differentiation of Spermatogonium to spermatocytes