Reproduction Notes

I. Asexual Reproduction Definition – reproduction without sex! A

partner is not needed and there is no exchange of DNA.

Benefit – fast and easy!

Drawback – no genetic diversity; your offspring are identical to you EVERYTIME!

Examples of Asexual Reproduction

A. Regeneration

B. Formation of Spores

C. Plant Asexual Reproduction

II. Sexual Reproduction

Definition – creating an organism by combining the genetic material of 2 organisms. Fusion of gametes.

Gametes are reproductive cells (sperm or egg)

Benefits – produces DIVERSITY in a species

Drawback - slow and sometimes difficult

Examples of Sexual Reproduction

BACK TO HUMANS

Sperm Cells Contribute half of father’s DNA (23 chromosomes) Formed during a process of cell division called

meiosis The combination of genes is different in every

single sperm

Egg Cells (Ova) Contribute half of mother’s DNA (23

chromosomes) Also formed during meiosis Each egg is different!

Fertilization fusion of egg and sperm forms a cell called a zygote

(egg) 23 chromosomes + (sperm) 23 chromosomeszygote with 46 chromosomes

Identical Twins One sperm One egg Zygote splits in 2 Same DNA

Fraternal Twins 2 eggs 2 sperm Each develops into

a baby with a unique set of genes and traits!

Formation of the Fetus The zygote goes through a series of cell

divisions called mitosis. Cells eventually differentiate into different cell

types.

Gender Father determines baby’s gender Men XY and Women XX

50% chance of either!