Mitosis cell division review
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Mitosis/Cell Division Review. A. B. C. D. E. Meiosis . Produces gametes or sex cells (sperm and egg cells) Occurs ONLY in the reproductive organs. Products of Meiosis = 4 new cells. AND. Divides the chromosome number in half. For Example: . Parent Cell. 4 daughter cells.

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  • Produces gametes or sex cells (sperm and egg cells)

  • Occurs ONLY in the reproductive organs

Products of Meiosis = 4 new cells


Divides the chromosome

number in half

For Example:

Parent Cell

4 daughter cells

2 Sets of Divisions

1st division is exactly like mitosis

except sister chromatids stay together

Before the 1st division takes

place DNA MUST replicate

Prophase I

  • Chromosomes condense

  • Homologous chromosomes pair together

  • Crossing over occurs

Metaphase I

  • Homologous pairs are moved to the equator (middle) of the cell

Anaphase I

  • Homologous pairs separate

  • Chromatids remain together

  • Genetic material has been recombined

Telophase I

  • Chromosomes gather at poles

  • Cytoplasm divides


DNA replication



Prophase 2

  • New spindles form around chromosomes

  • Crossing over – does not occur!

Metaphase 2

  • Chromosomes align along with equator (middle) of the cells

Anaphase 2

  • Sister chromatids (now called chromosomes) divide and move to opposite poles

Telophase 2

  • Chromosomes gather at the poles

  • Nuclear envelope forms and cytoplasm divides

4 new daughter cells, each genetically DIFFERENT, are formed and are all haploid

Sexual Reproduction

  • Haploid cells join to make diploid cells

  • Increase in genetic variation

  • Leads to change or evolution

Females: meiosis occurs before birth

Each month, one egg is matured

and released for possible fertilization

Males: meiosis begins at puberty

and continues until death

Asexual Reproduction

  • Single parents pass genes to offspring

    • Clones

    • Prokaryotes, yeast, hydra

    • Faster to produce offspring, but no genetic variation


  • The chromosome a gamete will receive depends on the way it lines up at the equator



The Importance

  • Lead to the evolution of a species

  • Increase survival


  • Cells have checkpoints to determine if they are healthy enough to divide

  • If those checkpoints are faulty, cells can divide and grow uncontrollable – can form a tumor and lead to cancer

What’s the problem

with more cells?

1.) Steal nutrients from healthy cells which eventually die

Causes of Cancer

  • Exposure to chemicals or toxins

  • Radiation

  • Viruses

  • Your Own Genetics