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Chapter 9.1. Overview of Cell Division Mechanisms. AP Biology Fall 2010. Objectives. Determine the function of mitosis, meiosis, and prokaryotic fission Analyze the structural components of chromosomes . Mitosis, Meiosis, and Prokaryotes.

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chapter 9 1

Chapter 9.1

Overview of Cell Division Mechanisms

AP Biology

Fall 2010

  • Determine the function of mitosis, meiosis, and prokaryotic fission
  • Analyze the structural components of chromosomes
mitosis meiosis and prokaryotes
Mitosis, Meiosis, and Prokaryotes
  • Before cells reproduce, there must be a division of the nucleus and its DNA
mitosis meiosis and prokaryotes4
Mitosis, Meiosis, and Prokaryotes
  • Mitosis and meiosis are eukaryotic nuclear division mechanism that lead to the distribution of DNA to new nuclei in forthcoming daughter cells
  • Mitosis is used by multicelled organisms for growth by repeated divisions of somatic cells
  • Responsible for:
    • Increases in body size during growth
    • Replacement of worn out or dead cells
    • Tissue repair
  • Used by multicelled organisms
  • Plants, animals, fungi and single celled protists produce asexually by mitosis
  • Meiosis occurs only in reproductive cells that divide to form gametes or spores
  • Sexual reproduction
  • Gemetes kown as sperm and eggs develop from germ cells
  • Spores form in life cycle of protists, plants, and fungi
  • Prokaryotic cells reproduce asexually by an entirely different mechanism called prokaryotic fission
chromosome structure
Chromosome Structure
  • Each chromosome is a molecule of DNA complexed with proteins
  • Eukaryotic species have a characteristic number of chromosomes
  • Before cell enters nuclear division, duplicates every chromosome
    • Forms two sister chomatids held together by centromere
chromosome structure13
Chromosome Structure
  • During early stages of mitosis and meiosis:
    • Duplicated chromosomes coil back on itself into highly condensed form
chromosome structure14
Chromosome Structure
  • Proteins called histones tightly bind to DNA and cause spooling into structural units called nucleosomes
    • Prevent tangling during nuclear division
    • DNA winds twice around histones
chromosome structure15
Chromosome Structure
  • Nucleosome: consists of part of DNA molecule looped twice around a core of histone proteins
chromosome structure16
Chromosome Structure
  • Centromere: constricted region
    • Location is different for each type of chromosome, unique characteristic
  • Kinetochore: during nuclear division, located at centromere
    • Is docking station for microtubules that help move chromatids
  • What is the point of structural organization of chromosomes?
  • What is the function of mitosis?
  • Tight packaging keeps chromosomes from getting tangled, also between cell divisions nucleosome packaging can be loosened in specific regions (enzymes gain access to heredity information that cell requires).
  • The function of mitosis is to increase in body size during growth, replacement of dead or worn-out cells, and repair of damaged tissues.