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Cell Reproduction

Explore the world of cell division in this comprehensive guide covering chromosomes, mitosis, and cell cycle stages. Learn about genetic disorders, haploid and diploid cells, binary fission, and the intricate process of cytokinesis.

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Cell Reproduction

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Presentation Transcript

  1. Cell Reproduction Chapter 8

  2. Chromosomes = rod-shaped structures made of DNA and proteins Histone = protein that helps maintain the shape of chromosomes and aid in the tight packing of DNA

  3. Chromatid = each half of the chromosome, exact copies that have been replicated Centromere = point where 2 chromatids are attached Chromatin = DNA that is less tightly coiled

  4. Sex chromosomes = determines the sex of an organism; humans have either an X or Y Autosomes = all of the other chromosomes • Every organism is produced by sexual reproduction has 2 copies of each autosome. Homologous chromosome = homologues = same size, shape, and carry genes for same traits

  5. Karotype = photomicrograph of chromosomes = 46 chromosomes exist as 22 homologous pairs of autosomes and 2 sex chromosomes

  6. Genetic Disorder A disease or condition caused by an absent or defective gene or by a chromosomal aberration

  7. Diploid = cells having 2 sets of chromosomes (2n) Haploid = cell having 1 set of chromosomes (1n) = sperm and egg cells • approximately 2 trillion cells (25 million cells per second) are produced by an adult human body everyday

  8. Cell division = process by which cells produce offspring cells Binary Fission = division of a prokaryote cell into 2 offspring cells Asexual reproduction = production of offspring from one parent

  9. Mitosis = cell division in Eukaryote cells; new cells with genetic material that is identical to the first (original cell) - Occurs in organisms undergoing growth, development, repair or asexual reproduction

  10. Cell Cycle • Interphase- time between cell divisions; cell spends most of its time • G1 phase – grow to mature size • S phase – DNA copied (synthesized) • G2 phase – prepares for cell division • Go phase – usually after G1; does not copy DNA, does not divide • Mitosis – nucleus divided • Cytokinesis – cytoplasm divides

  11. Stages of Mitosis

  12. Prophase • shortening & tight coiling of DNA into rod-shaped chromosomes • nucleolus & nuclear envelope breaks down • centrosomes & centrioles appear in animal cells • only centrosomes appear in plant cells • spindle fibers = made of microtubules radiate from centrosomes in preparation of the next phase • mitotic spindle = array of spindle fibers; serves to equally divide chromatids between 2 offspring cells • made up of kinetochore fibers – attached to a disk shaped protein and to one of the chromosomes and polar fibers extend from centrosome to centrosome Kinetos means moving choros means place

  13. Metaphase • kinetochore fibers move chromosomes to center (equator)

  14. Anaphase • chromatids separate at centromere & slowly move toward opposite poles

  15. Telophase • spindle fibers disassemble; chromosomes return to a less tightly coiled chromatin state • nuclear envelope forms around each set of chromosomes; as well as a nucleolus

  16. Cytokinesis (in animals) • begins with the cell membrane pinching inward in the middle between 2 poles (cleavage furrow)

  17. Cytokinesis (in plants) • vesicles from Golgi apparatus join together at the midline to form cell plate • cell wall will eventually form from cell plate

  18. Checkpoints

  19. Crossing over occurs…

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