REPRODUCTION :

Sexual vs Asexual

STUDENTS WILL:

• Define Reproduction and identify the 2 kinds of Reproduction.

• List 2 examples of Asexual Reproduction.

• Describe the stages of Meiosis.• Explain why Meiosis is important in

sexual reproduction.

VOCABULARY:

• Reproduction meiosis• Fertilization regeneration• Budding • Zygote• Diploid• Haploid

Reproduction?

• A process by which an organism produces their own kind.

2 kinds of Reproduction:1. Sexual Reproduction2. Asexual Reproduction

Reproduction Video

Sexual Reproduction

• Requires 2 organisms (same species)

2 SEX CELLS

egg sperm (female) (male)

Asexual Reproduction

• A new organism is produced from one organism

• Examples: 1. Budding2. Regeneration

Budding:

-A new organism is growing from the body of the parent organisms.-Ex. hydra

Regeneration

Re-grows body parts

BINARY FISSION (Cell Division)

• Mother cell is dividing into two daughter cells

• Examples: bacteria amoeba

Asexual or Sexual?

Reflection:

• What would you say is the most important difference between asexual reproduction and sexual reproduction?

• Which type of reproduction allow variety of organisms?

Major difference:

ASEXUAL• Cannot develop much

variety• Copying the original

organism almost exactly

SEXUAL• Allows great diversity• Zygote is a combination

of a mother’s egg and father’s sperm

• Greater chance of variation that allows the organism to adapt and survive changes in his environment

Zygote

-the cells formed as a result of fertilization.

Fertilization????

- The joining of an egg and sperm.

Fertilization Video

https://youtu.be/_5OvgQW6FG4

HUMAN BODY

body cells sex cells46 chromosomes 23 chromosomes(23 pairs)

Diploid Cells: Haploid Cells:cells having pairs cells that have the of similar half number of chromosomes. chromosomes.

NOTE:

• FOLLOWING CELL FERTILIZATION, CELL DIVIsION HAPPENS (Mitosis)….

Meosis Video

MEIOSIS

• A process of CELL DIVISION that produces haploid cells.

• (23 chromosomes)

• Meiosis is a sexual reproduction.

• 2 divisions (meiosis I and meiosis II).

MEIOSIS

MEIOSIS I• PROPHASE I• METAPHASE I• ANAPHASE I• TELOPHASE I

MEIOSIS II• PROPHASE II• METAPHASE II• ANAPHASE II• TELOPHASE II

PROPHASE I

• Chromosomes condense.• Spindle fiber begins to appear.• Nucleolus and nuclear membrane

disappears.• Synapsis occurs: homologous chromosomes come together to form a tetrad (2 chromosomes)

• CROSSING OVER happens!!!- exchange of segment.

Synapsis inProphase I

Homologous chromosomes

sister chromatids sister chromatidsTetrad

Prophase I

Metaphase 1

-Homologous pair align at the center.

-Centromere attach to the spindle fiber.

Metaphase I

- Homologous chromosomes separate and move towards the poles.

- Sister chromatids remain attached at their centromeres.

Anaphase I

Anaphase I

Telophase I

-Cytoplasm begins to divide

- 2 new cells are formed having duplicated chromosome.

Telophase I

MEIOSIS II

• Similar to Mitosis • Very short and no more DNA

duplication.

Prophase II

Metaphase II

Anaphase II

sister chromatids separate

Telophase II

Results of MEIOSIS:

-2 cells are formed duringMeiosis I

-Meiosis (I and II) resulted in 4 daughter cells.

-Each has 23 unpaired chromosome. (haploid cells)