Additional Science B5 Growth and Development

Cell Reproduction:

Mitosis - a cell splits to create two identical copies of the original cell.

Meiosis - a cell splits to form new cells with half the number of chromosomes.
- they produce gametes for sexual reporoduction.

Fertilisation - a human sperm cell fertilizes an egg.
- their nuclei join up
- the fertilized egg (zygote) gets one set of chromosomes from each
parent.

DNA:

- The nucleus of each body cell contains enough information to determine the characteristics of the whole bodt.
- this information is the Genetic code.

- Long strands of DNA make up chromosomes.
- They are found in the nucleus of a cell.

- DNA is a large molecule.
- It contains two strands that are twisted together in a spiral.
- This is a double helix.

- Each strand is made of four bases - A, T, G, C
- The bases on the two strands of a DNA molecule always pairs up in the same way:
A and T, G and C
- This is base pairing.