Brief study of the two processes

1. Mitosis & Meiosis
Made By
Name: Carolyn Joseph
Reg.No: 16BCB0098
Course title: cell Biology and Biochemistry

2. Cell makes a copy of itself
1) Copy its DNA (part of a chromosome).
2) Copies are separated & sorted into two sides of the cell.
3) The cell then splits in two.
4) Part of each parent is carried to the two new cells.
5) Two EXACT daughter cells (same number of chromosomes)
Examples: skin, bones, internal organs
Mitosis
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3. ∗ Cell division that forms gametes (egg and sperm cells)
∗ GametesGametes have halfhalf the number of chromosomeschromosomes.
∗ Two divisionsTwo divisions (meiosis Imeiosis I and meiosis IImeiosis II).
∗ Part of each parent is carried to the four new cells.
∗ MeiosisMeiosis is similar to mitosismitosis with some chromosomal
differences.
Meiosis
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4. Mitosis: Meiosis:
Each resulting cell still has chromosomes from parent cellsEach resulting cell still has chromosomes from parent cells
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5. ∗ MITosis takes one cell and Makes It Two
∗ Meiosis has to do with sex
∗ From the cell’s point of view:
∗ mITosis results in Identical Twins CELLS
∗ mEioSis results in Egg and Sperm
Tips
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6. ∗ Interphase I
∗ Meiosis I and Meiosis 2
∗ Similar to Mitosis EXCEPT changes in chromosomes
Cell Division in Sex Cells
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7. ∗ Similar to mitosismitosis interphase.
∗ ChromosomesChromosomes replicate (S phase).(S phase).
∗ Each duplicated chromosomechromosome consist of two
identical sister chromatidschromatids attached at their
centromerescentromeres.
Interphase IInterphase I
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8. ∗ Cell divisionCell division that reduces the chromosomechromosome
number by one-half.one-half.
∗ Four phasesFour phases:
a.a. prophase Iprophase I
b.b. metaphase Imetaphase I
c.c. anaphase Ianaphase I
d.d. telophase Itelophase I
Meiosis I (four phases)Meiosis I (four phases)
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9. Prophase IProphase I
centrioles
spindle fiber
TETRAD
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10. ∗HHomologous chromosomesomologous chromosomes come
together to form a tetradtetrad.
∗TetradTetrad is two chromosomeschromosomes or four
chromatidschromatids (sister and nonsister
chromatids).
Prophase IProphase I
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11. Homologous chromosomes
sister chromatids
paternal
sister chromatids
maternal
Tetrad
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12. ∗ Crossing overCrossing over: segments of nonsister chromatidschromatids break and
reattach to the other chromatidchromatid.
∗ Crossing overCrossing over causescauses variationvariation
Prophase 1 – Crossing OverProphase 1 – Crossing Over
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13. Crossing Over - variationCrossing Over - variation
nonsister chromatids
chiasmata: site
of crossing over variation
Tetrad
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14. ∗ TetradsTetrads align on the in center of cell on spindle
∗ INDEPENDENT ASSORTMENT OCCURS:INDEPENDENT ASSORTMENT OCCURS:
1. Orientation of homologous pair to poles is random.
2. Variation
Metaphase IMetaphase I
OR
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15. ∗ Homologous chromosomesHomologous chromosomes separate and
move towards the poles.
∗ Sister chromatidsSister chromatids remain attached at their
centromerescentromeres.
Anaphase IAnaphase I
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16. ∗ Each pole now has haploidhaploid set of chromosomeschromosomes.
∗ CytokinesisCytokinesis occurs and two haploid daughter
cells are formed.
Telophase ITelophase I
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17. ∗ No interphase IINo interphase II
∗ Remember:Remember: Meiosis IIMeiosis II is similar to mitosismitosis
Meiosis IIMeiosis II
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18. ∗ same as prophaseprophase in mitosismitosis
Prophase IIProphase II
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19. ∗ same as metaphasemetaphase in mitosismitosis
Metaphase IIMetaphase II
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20. ∗ same as anaphaseanaphase in mitosismitosis
∗ sister chromatids separatesister chromatids separate
Anaphase IIAnaphase II
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21. ∗ Four haploid daughter cells producedFour haploid daughter cells produced
gametes = sperm or egggametes = sperm or egg
Telophase IITelophase II
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22. 2n
diploid
n haploid
n haploid
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