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