Reproduction in humans 1

What is the purpose of reproduction

To prevent extinction

Diploid

Full set of 46 chromosomes

What is produced in sexual reproduction

Specialised sex cells gamete are produced by gonads

Haploid

Contain half the genetic info. For example mobile sperm and stationary ovum

How are gametes produced

By mieosis

Fertilisation

The mobile sperm moves towards the stationary egg and fuse together forming a zygote

Zygote

First daploid cell of the organism

Mitosis

The process by which zygotes divides to form the new organism

Features of asexual reproduction

No specialised gametes, no fertilisation, cells in one part of the body divide and break away from the parent body, no genetic variation,

When is asexual reproduction useful

When the environment is stable

Stages of sexual reproduction

Gametes are produced, male gamete is transferred to female gamete, fertilisation occurs, zygote develops

Structure of a sperm

Have a flagellum that moves them through fluid, mid piece contains enzymes for aerobic respiration, contains acrosome

Acrosome

Sac that contains digestive enzymes that help sperm penetrate the jelly around the egg

Structure of the egg

Contains protective jelly layer, has a cell membrane to prevent sperm from entering after fertilisation, contains cytoplasm to supply nutrients for the zygote

External fertilisation (fish)

When some animals release their gametes for fertilisation to occur outside the body

Internal fertilisation

When fertilisation happens inside the females body

What happens to the zygote after

It divides by mitosis for different cells to specialize