Science - Cell Division

Why are new cells created?

• Growth and repair of body cells

• Production of specialised sex cells

Give facts about chromosomes

• Controls the functions of a cell

• Has instructions from the DNA to build up an adult from a fertilised egg cell

• carry DNA in a cell

• Must copy the DNA accurately

what is Meiosis, Mitosis and gametes?

Mitosis - A single cell divides twice to make 4 daughter cells, which carry half of the genetic information.

Meiois - A single cell divides into 4 cells

Gametes - another name for Sex cells

What is Chromatid?

A chromosome which has two distinctive halves

How many chromosomes does a sperm and egg cell have

23 chromosomes

How many cells does a human cell contain

46 chromosomes

What happens if there is an extra chromosome

Cell dies

Why does some people have genetic disorders like down syndrome?

Because they have an extra chromosome

Explain the stages of cell mitosis

Stage 1 - the single cell grows and develops, carries normal activities

Stage 2 - Chromosomes doubles into pairs

Stage 3 - Cell divides into two daughter cells which carry each parent DNA

Define Gene and DNA

Gene - Contains information (section of DNA) that forms the characteristics, appearance etc

DNA - Unique Chemical which contains genetic material

Suggest why it is important for chromosomes to stay the same when a cell divides to make other cells (3 Marks)

• Organism might die

• Lacks vital genes

• Cell wouldn’t work properly