SEXUAL REPRODUCTION

Quiz 6B

sexual reproduction

• the joining of haploid gametes to form a diploid zygote, which develops into a new individual

• each offspring receives genes from both its parents

• get genetic variety

Information about genes

most organisms have 2 genes for every trait

Information about genes

genes are parts of chromosomes

Information about genes

most genes come in pairs

Information about genes

most chromosomes come in pairs

Diploid

•having 1 pair of each type of chromosome in an organism

•have 2 of every kind of chromosome

•symbol is 2n

Haploid

•a cell that has only 1 chromosome of every pair

•symbol is 1n

Diploid vs Haploid

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

Diploid & Haploid Examples

Haploid Diploid

Honey bee 16 32

Crayfish 100 200

Rabbit 22 44

Watermelon 11 22

Corn 10 20

Meiosis

•the process whereby 1 diploid cell forms haploid cells (gametes)

•a dividing process during which the # of chromosomes is cut by 1/2 in each resulting cell

•also called reduction division

Meiosis

Gamete•a cell that contains only 1 of each type of chromosome found in an organism

•a reproductive cell•in order to form a haploid cell (gamete)- meiosis occurs

•in most organisms meiosis produces 1 of 2 types of gametes

2 types of gametes

•Ova (singular-ovum) - female gametes; usually larger than the male gamete and does not have that power to move itself

•Sperm - male gametes; usually smaller than ova, but they have some means of moving themselves

2 types of gametes

sperm

ovum

Spermatogenesis

Oogenesis

Where are gametes formed?

• Testes – male reproductive organs

• Ovaries – female reproductive organs

In reproductive organs

Fertilization

the formation of a zygote from the union of 2 gametes

Zygote

a diploid cell formed by the union of 2 gametes