Meiosis (Ch 11.4)

Meiosis (Ch 11.4)

Meiosis (Ch 11.4) Background Chromosome = package form of DNA in a cell Genes = genetically inherited traits Genes normally have two alleles per gene (there are some exceptions like ABO blood type) Genes are carried on chromosomes from the parents to the offspring that ride on gametes (sex cells: sperm or egg) Genes can be found in specific locations on the chromosomes

Chromosome Number Homologous Chromosomes: each set of chromosomes that come from the parents Example: Fruit Flies 8 chromosomes (4 from dad and 4 from mom) Diploid: a cell that contains both sets of homologous chromosomes from the parents (2N) N = the single set of chromosomes coming from one parent 2N = the complete set of homologous chromosomes from mom and dad Haploid: a single set of chromosomes (N) Example: Fruit Flies 2N = 8 chromosomes (4 from mom and 4 from dad) N = 4 chromosomes coming from each parent

Phases of Meiosis Meiosis: the process during sexual reproduction where chromosomes are split in half through the separation of homologous chromosomes The two divisions creates the four haploid cells one haploid cell from mom (23 chromosomes = 11 pairs egg) will join with a haploid cell from dad (23 chromosomes= 11 pairs sperm) in the offspring (46 chromosomes = 23 pairs) 2 divisions Meiosis I / Meiosis II

Meiosis I Before Meiosis, the cell goes through interphase (G1 / S / G2) Prophase I Each replicated chromosome pairs with the corresponding homologous chromosome (tetrad) Each tetrad contains 4 chromatids Crossing-over: the chromatids cross over one another -- then the chromatids (contain alleles) are exchanged Spindle fibers form and attach to the tetrads

Meiosis I (Cont.) Metaphase I Spindle fibers pull the homologous chromosomes to line up across the center Anaphase I Spindle fibers pull the homologous chromosome pairs towards opposite ends of the cell Telophase I The nuclear membrane forms, spindle fibers disappear, and the cells begin to pinch off Cytokinesis

Meiosis I Meiosis II The two cells now undergo a second cell division to get from 2N N Prophase II Chromosomes become visible -- chromosomes do not need to form tetrads because they already crossed over in Prophase I Spindle fibers form from centrioles Metaphase II

Spindle fibers pull the chromosomes to line up at the center of the cell Meiosis II Anaphase II Spindle fibers pull the sister chromatids apart Telophase II The nuclear envelope begins to form, spindle fibers disappear, and the two cells begin to pinch off Cytokinesis

The two cells pinch off completely to form four haploid cells (N) Meiosis II Gametes Zygotes Meiosis II = 4 haploid cell (N) = gametes male gametes = sperm (23 chromosomes 11 pairs) female gametes = eggs (23 chromosomes 11 pairs) When the female gamete and the male gamete come together, fertilization begins to form the zygote

Zygote mitosis forms a new organism Mitosis vs. Meiosis Mitosis asexual reproduction Both Interphase Meiosis

sexual reproduction similar chromosomes in the daughter cells homologous chromosomes move to separate daughter cells = genetic variation 2N parent cell 2N daughter cells (8 chromosomes)

2N parent cells N daughter cells (4 chromosomes) 2 daughter cells = identical 4 daughter cells = genetically different 1 division

2 divisions Gene Linkage Mendel independent assortment: genes located on different chromosomes separate independently of each other Morgan Drosophilia = fruit flies 1.Each chromosome is a group of linked genes 2.Mendels principle of independent assortment holds true 3.Gene linkage: alleles of different genes tend to be

inherited together when the genes are located on

Recently Viewed Presentations

  • Concussion and Sports: Gambling with our children's brains

    Concussion and Sports: Gambling with our children's brains

    pathophysiology. CONCUSSION IS A BRAIN INJURY. Alteration in electrical system of brain. Brain cells become depolarized; they fire all neurotransmitters at once, flooding the brain with chemicals and deadening certain receptors linked to learning and memory
  • Big Data Tutorial on Mapping Big Data Applications

    Big Data Tutorial on Mapping Big Data Applications

    Multiple users performing interactive queries and updates on a database with basic availability and eventual consistency (BASE = (Basically Available, Soft state, Eventual consistency) as opposed to ACID = (Atomicity, Consistency, Isolation, Durability) ) Perform real time analytics on data...
  • Chapter 3 Nuclear Radiation - HCC Learning Web

    Chapter 3 Nuclear Radiation - HCC Learning Web

    49Mn 49Cr + 0e 25 24 +1 Gamma Radiation In gamma radiation energy is emitted from an unstable nucleus, indicated by m following the mass number. the mass number and the atomic number of the new nucleus are the same.
  • Introduction to Gaming - University of South Alabama

    Introduction to Gaming - University of South Alabama

    Before we can discuss how to create a basic computer game we need to know what exactly a game it - so we know what we need to include in our game So What is a Game A computer game...

    Of Mice and Men: A few miles south of Soledad, the Salinas River drops in close to the hillside bank and runs deep and green. The water is warm too, for it has slipped twinkling over the yellow sands in...
  • Elements of Art -

    Elements of Art -

    Elements of Art Basic components or building blocks Tender Loving Care For Someone Very Special Texture Line Color Form Shape Value Space TEXTURE The way something feels or appears to feel.
  • Shout To The Lord My Jesus, my Savior

    Shout To The Lord My Jesus, my Savior

    Shout To The Lord My Jesus, my Savior Lord there is none like You All of my days, I want to praise the wonders of Your mighty love My comfort, my shelter Tower of refuge and strength Let every breath,...
  • New Employee Orientation Ii

    New Employee Orientation Ii

    Hays-Caldwell Women's Center Attorney for Students Texas State faculty and staff are "responsible employees": technical term meaning reporting responsibilities