REPRODUCTION AND SEXUAL

DIVISIONCompare and contrast:

Asexual and sexual reproductionSomatic cells and Asomatic cells

Mitosis and Meiosis

Asexual Reproduction: Mitotic Division

Copyrighted for http://www.arhp.org/uploadImages/cloning_3.gif

Asexual Reproduction: Mitotic Division

(Cloning)

Asexual Reproduction:

Budding in a Hydra

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Asexual Reproduction: Fragmentation or Regeneration

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Asexual Reproduction: Parthenogenesis of a water

flea

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Asexual Reproduction: Fission in bacteria

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Asexual Reproduction:

Vegetative Propagation

Somatic cells vs. Asomatic Cells

SOMATIC CELLS ASOMATIC CELLS

Cells that are produced for use by the body.

The cells have a diploid (2n) chromosome.

Produced during mitosis.

Also known as the parent cells.

Cells that are produced for the use in reproduction.

The cells have a haploid (n) chromosome.

Produced during meiosis.

Also known as male or female gametes.

Chromosome Numbers of Common Organisms

Organism Body Cell (2n)

Fruit fly 8Garden pea 14Corn 20Tomato 24Leopard Frog 26 13Apple 34Human 46Chimpanzee 48Dog 78Adder’s tongue fern 1260

Gamete (n)47

1012

17232439

630

This table shows the diploid and haploid number of chromosomes of some species.

Diploid and haploid cellsDiploid and haploid cells

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On homologous chromosomes, these genes are arranged in the same order, but because there are different possible alleles for the same gene, the two chromosomes in a homologous pair are not always identical to each other.

Homologous chromosomesHomologous chromosomesHomologous Chromosome 4

a A

Terminal Axial

InflatedD Constrictedd

Tall

TShort

t

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Meiosis consists of two separate divisions,known as meiosis I and meiosis II.

Meiosis I begins with one diploid (2n) cell.

By the end of meiosis II, there arefour haploid (n) cells.

Why meiosis?Why meiosis?

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Meiosis: Asomatic Cell Division

http://www.biochem.s.u-tokyo.ac.jp/yamamoto-lab/images/meiosis.jpg

Female gamete

Male gamete

There must be another form of cell division that allows offspring to have the same number of chromosomes as their parents.

This kind of cell division, which produces gametes containing half the number of chromosomes as a parent’s body cell, is called meiosis.

Why meiosis?Why meiosis?

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These haploid cells are called sex cells—gametes.

Male gametes are called sperm.

Female gametes are called eggs.

When a sperm fertilizes an egg, theresulting zygote once again has the diploid number of chromosomes.

Why meiosis?Why meiosis?

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NondisjunctionNondisjunctionMale parent (2n)

Female parent (2n)

Meiosis

Nondisjunction

Meiosis

Nondisjunction

Abnormalgamete (2n)

Abnormalgamete (2n)

Zygote(4n)

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