Diagram a cell with four chromosomes going through

meiosis.

Mitosis vs. Meiosis

Mitosis• One division• 2 diploid

daughter cells• Identical to

parent cell

Mitosis• Two divisions• 4 haploid

daughter cells• Genetically

different from parent cell

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__how_meiosis_works.html

Nucleus chromosomes

• Get one small, one medium and one large of each color chromosome.

• What do the colors represent? • The Beads?

• Pair up chromatids with same size and color

• Pair up chromatids with same size and color• What does this represent?• What stage?• Haploid or diploid?

• Match homologous chromosomes

• Match homologous chromosomes• What are homologous chromosomes.

Carry the same traits Each

homologous pair has one from each parent

Demonstrate crossing over during prophase.

Demonstrate crossing over during prophase.

• Demonstrate metaphase

Demonstrate metaphase

• Demonstrate the first division • Anaphase I and Telophase I

• Demonstrate the first division • Anaphase I and Telophase I

• Move your cells through the second division.

• Move your cells through the second division.

• How many daughter cells do you have?• Are the daughter cells haploid or diploid?• Are the cells genetically Identical or different

from the parent cell?

4Haploid Daughter Cells

Daughter Cells

Parent Cell

Possible Combinations of chromosomes

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__random_orientation_of_chromosomes_during_meiosis.html

2nWhat does n represent?What was our haploid number of chromosomes?What is the possible number of combinations? 8In people possible 8388608 combinations.

Sexual Reproduction

• Combines the genetic material of two organisms.• Introduces new gene combinations in a population.• Leads to genetic Variability in the population.• Gametes produced in meiosis fuse to form a zygote.

– Gamete-reproductive cell that contains the haploid set of chromosomes…..sperm and egg

– Zygote- Cell formed from fusion of gametes that contains the diploid set of chromosomes.

Sexual Reproduction Methods

• External Fertilization: the eggs are fertilized outside of the body

• Internal Fertilization: the eggs are fertilized within the female reproductive tract

• Conjugation: cells exchange genetic material– Prokaryotes

Asexual Reproduction

• Offspring arise from a single parent. • Offspring genetically identical to parent. • More likely to inherit mutations. • Leads to less diversity. • Mitosis

Asexual ReproductionMethods

• Budding – offspring grows out of the body of the parent.

• Spores – a reproductive cell capable of developing into a new individualwithout fusion with another reproductive cell.

• Fission– separation of the body into two new bodies

Quiz

• Compare and contrast sexual and asexual reproduction.