Cellular Reproduction

Mitosis
1. Interphase
  1. G1 (gap 1)
    1. cell growth begins
    2. increase amount of cytoplasm
  2. S (synthesis)
    1. DNA replication
  3. G2 (gap 2)
    1. organelles duplicate
    2. takes in need nutrients
    3. cell grow
2. Prophase
  1. Chromosomes condense
    1. this is when they first become visible in a light microscope
  2. Mitotic spindles form
    1. made up of microtubules
      1. called spindle fibers
    2. forms from a microtubule-organizing center
      1. centrosome
      2. contains a pair centrioles
    3. Polar microtubules
      1. push the poles of the cell away from each other
    4. Kinetochore microtubules
      1. pull chromosomes to the poles of the cell during mitosis
3. Premetaphase
  1. Nuclear envelope breaks down
  2. nucleolus disappear
  3. Kinetochore microtubules from ea. mitotic spindle attach to one sister chromatid of ea. chromosome
    1. attachment occurs in the centromere region at the kinetochore
4. Metphase
  1. Formation fo the mitotic spindle is completed
  2. motor proteins on the kinetochore microtubules
    1. pull ea. chromosome in opposite directions
    2. causing the chromosome to line up in the middle of the cell
  3. the imaginary plane is formed
    1. Metaphase plate
5. Anaphase
  1. Centromere split
    1. replicated chromosomes split
      1. into two identical sets of unreplicated chromosomes
  2. Sister chromatids are pulled by the spindle fibers toward opposite poles of the cell
    1. by motor proteins of polar microtubules
  3. as soon as they are no longer attached at the centromere
    1. sister chromatids become Daughter Chromosomes
6. Telophase
  1. a new nuclear envelope begins to form around ea. set of chromosomes
  2. mitotic spindle disintegrates
  3. chromosomes begin to decondense
  4. mitosis is complete
    1. when two independent nuclei have formed
7. Cytokinesis
  1. occurs immediately after mitosis
  2. the cytoplasm divides to form two daughter cells
  3. each daughter cell has its own nucleus & complete set of organelles
8. The two sister chromatids separate to form independent chromosomes
9. One copy of each chromosome goes to each of the two daughter cells
  1. called Somatic cells
    1. 46 chromosomes
    2. both are identical to the parent cell
    3. Diploid
10. Mitosis
11. Each daughter cell receives a copy of the genetic information that is contained in each chromosome
The Cell Cycle
1. Cells arise from pre-existing cells
2. 2 types of cell division
  1. Meiosis
    1. Gametes
      1. Sex cells
      2. Eggs
      3. Ovum
      4. Sperm
      5. daughter cells have half the amount of genetic materials as the parent cell
    2. Meiosis II is much like Mitosis
  2. Mitosis
    1. used for
      1. Asexual Reproduction
      2. Growth
      3. Wound Repair
    2. Body cells
    3. Somatic cells
      1. genetic material is copied & then divided equally
      2. daughter cells are genetically identical to the parent cell
    4. purpose
      1. to distribute chromosomes to daughter cells during cell division
  3. both forms go through cytokinesis
    1. the cytoplasm
3. Chromosomes
  1. contains a single long double helix of DNA
    1. deoxyribonuceic acid
    2. are wrapped around proteins
      1. Histones
  2. can be stained with dye
  3. observed under the light microscope
  4. chromosomes condense from long, thin filaments into compact structures that can be moved around the cell
  5. each chromosome is replicated before mitosis
    1. called a chromatid
  6. at the end of mitosis, one of the chromosome copies is distributed to each of two daughter cells
  7. Chromatids
    1. joined together along their entire length
    2. joined to together at a specialized region of the chromosome called the Centromere
    3. from the same chromosome are called Sister Chromosome
  8. Mitotic Phase
    1. dividing phase
  9. Interphase
    1. nondividing phase
    2. chromosome replication only in this phase
  10. Karyotype
    1. # and types of chromosomes present in an organism
  11. Homologous Chromosomes
    1. aka Homologs
    2. chromosomes of the same type
    3. carry the same gene
      1. in the same location
      2. but each one may contain different alleles
  12. carry Genes
    1. a section of DNA that influences one or more hereditary traits
    2. different versions of a specific gene are called Alleles
4. Cytokinesis
  1. occurs after mitosis or meiosis
  2. cytoplasm divides to form two daughter cells
    1. each daughter cell has its own nucleus & complete set of organelles
  3. Animals, Fungi, Slime Molds
    1. use Actin-Myosin ring
      1. causes the plasma membrane to begin pinching in
      2. cleavage furrow
      3. happening from inside cell
  4. Plants
    1. as vesicles are transported from the golgi apparatus to the middle of the dividing cell
    2. these vesicles fuse to form a cell plate
  5. Bacteria
    1. binary fission
5. Interphase
  1. Cell-Cycle Checkpoints
    1. G1 check
      1. cell size is adequate
      2. nutrients are sufficient
      3. social signals are present
      4. DNA is undamaged
      5. most important
    2. G2 check
      1. chromosome have replicated successfully
      2. DNA is undamaged
      3. activated MPF is present
    3. M-phase check
      1. chromosomes have attached to spindle apparatus
      2. chromosome have properly segregated & MPF is absent
      3. cell growth ceases during metaphase
      4. if the chromosomes are not properly attached to the mitotic spindle
      5. prevents incorrect chromosome separation
      6. could give daughter cells the wrong # of chromosomes
      7. prevents the division of cells that are damaged
      8. the growth of mature cells that should stay in the G0 state
Meiosis
1. Interphase
2. Early Prophase I
  1. nuclear envelope begins to break down
  2. spindle apparatus forms
  3. homolog pairs come together
    1. in pairing process called Synapse
      1. creating a structure called a tetrad
    2. chromatid of the homologs are called non-sister chromotids
  4. Chromosomes condense
3. Late Prophase I
  1. nuclear envelope broken down
  2. non-sister chromotids begin to separate
  3. exchange or Crossing Over between homologous non-sister chromotids
    1. where chiasmata are formed
      1. at the synapses
4. Metphase I
  1. tetrads line up at the Metaphase Plate
    1. Tetrad
  2. Independent Assortment (aka homologous recombination)
    1. the order of maternal and paternal chromosomes can be either way and is not controlled
5. Anaphase I
  1. homologs separate and begin moving to opposite poles of the spindle apparatus
    1. Anaphase I
6. Telophase & Cytokinesis I
  1. chromosomes move to opposite poles of the spindle apparatus
    1. spindle apparatus disassembles
  2. cell separates
    1. into 2 haploid cells
      1. each different genetically from each other & from the parent cell
7. Prophase II
  1. spindle apparatus forms
  2. one spindle fiber attaches to the centromere of each sister chromatid
8. Metaphase II
  1. chromosomes line up at middle of the spindle apparatus (metaphase plate)
9. Anaphase II
  1. sister chromatids separate
    1. begin moving to opposite poles of the spindle apparatus
10. Telophase & Cytokinesis II
  1. chromosomes move to opposite poles of the spindle apparatus
    1. spindle apparatus disassembles
  2. nuclear membrane forms around each haploid set of chromosomes
  3. each cell undergoes cytokinesis
11. Meiosis I
12. Meiosis II
13. happens to each of the of the 2 daughter haploid cells
  1. creating 4 haploid daughter cells
    1. Gametes
      1. 23 chromosomes
    2. completely unique form each other and the parent