1. SEXUAL REPRODUCTION
Chapter 4 lesson 1
Part 1

2. Reproduction of Organisms
Why do living things reproduce?

3. Sexual Reproduction and Meiosis
What is sexual reproduction, and why is it beneficial?
What is the order of the phases of meiosis, and what happens during each phase?
Why is meiosis important?

4. sexual reproduction
a type of reproduction in which the genetic materials from two different cells combine, producing an offspring.

5. Gamete The cells that combines to form offspring A reproductive cell
A sex cell
Formed by meiosis
In most organisms meiosis produces 1 of 2 types of gametes

6. 2 types of gametes
Ova (singular-ovum) - female gametes; female sex cell(book calls them eggs)
Sperm - male gametes; male sex cell

7. 2 types of gametes
ovum
sperm

8. Where are gametes formed?
In reproductive organs
Testes – male reproductive organs
Ovaries – female reproductive organs
The female sex cell, an ovum, forms in an ovary.
The male sex cell, a sperm, forms in the testis.

10. Fertilization the formation of a zygote from the union of 2 gametes
The process when a sperm and an ovum join togther.

11. What is sexual reproduction? (cont.)
During a process called fertilization, an ovum cell and a sperm cell join together to create a zygote.

12. Zygote
The new cell that forms from fertilization

13. Diploid cells
Organisms that reproduce sexually form somatic (body) cells and germ (gametes; sex) cells.
In somatic cells of most organisms, similar chromosomes occur in pairs.
Diploid cells are cells that have pairs of chromosomes.

14. Diploid cells

15. Diploid cells
Pairs of chromosomes that have genes for the same traits arranged in the same order are called homologous chromosomes.
Because one chromosome is inherited from each parent, the chromosomes are not identical.
Different organisms have different numbers of chromosomes.

16. Homologous chromosomes

18. Haploid cells
Haploid cells are cells that have only one chromosome from each pair of chromosomes.
haploid
from Greek haploeides, means “single”

19. Haploid vs Diploid

20. Normal human cells have 23 pairs of chromosomes which is a total of 46 chromosomes.
Human diploid number is 46
Human haploid number is 23

21. Diploid & Haploid Examples
Honey bee 16 32
Crayfish
100
200
Rabbit 22 44
Watermelon 11
Corn 10 20