Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic...

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Meiosis Sexual Reproduction

Transcript of Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic...

Page 1: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Meiosis

Sexual Reproduction

Page 2: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Why is meiosis important?

• Make eggs and sperm for reproduction• Genetic diversity – half DNA from father and

half from mother= new combination

Page 3: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

• Somatic cells – (any cell other than egg or sperm)-formed from mitosis only -– Have 46 chromosomes and divide to make

identical cells with 46 chromosomes– Diploid (2n)

• Gametes (egg and sperm) – formed from meiosis only– Have 23 chromosomes– Haploid (n)

Page 4: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

• Autosomes are the 22 pairs (44) of chromosomes that are not involved in determining gender

• Sex chromosomes are the pair (2) that determine gender

Page 5: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

• Homologous chromosomes- pair of chromosomes that are similar in size, shape, and genetic content- one in each pair comes from the father and the other from the mother.

• Humans have ____pairs of homologous chromosomes.

Page 6: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Chromosome Numbers in Cells• Diploid (2n) cell contains 2 sets of

chromosomes (somatic cell)• Haploid (n) cell contains 1 set of chromosome

(gamete)• What happens when 2 haploid cells fuse in

fertilization?

Page 7: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 8: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Homologous Chromosomes and Sister chromatids

Page 9: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Mitosis vs Meiosis

• Mitosis – used for Growth– Two daughter cells– genetically identical to parent cell– two full sets of chromosomes (diploid)– makes bigger organism

• Meiosis – used for Reproduction– Four daughter cells– genetically different from parent cell (and each other)– one full sets of chromosomes (haploid)– helps makes another organism (sexual reproduction)

Page 10: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Meiosis- two cell divisionsMeiosis preceded by an interphase (just like mitosis) – chromosomes replicated during the S phase.

Page 11: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 12: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Meiosis 1

Page 13: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Stages of Meiosis

Page 14: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Crossing Over

Page 15: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Crossing Over in ActionWhat is the advantage of crossing over?

Page 16: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 17: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

How does this differ from metaphase in mitosis?

Mitos is

Page 18: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Independent Assortment

Page 19: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 20: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 21: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

After the 1st Division

Page 22: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 23: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 24: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 25: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 26: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=
Page 28: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Mitosis versus Meiosis

Page 29: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

What happens to the possible combinations when crossing over occurs?

Page 30: Meiosis Sexual Reproduction. Why is meiosis important? Make eggs and sperm for reproduction Genetic diversity – half DNA from father and half from mother=

Sperm versus the Egg