1. Genetic Variation

2. Genetics Genetics is the study of inheritance. The passing on of characteristics/traits from the birth mother & father to their offspring

3. Most life begins as a fertilised ovule called a zygote or embryo. Animals: Male gamete Female gamete Formed in: SpermEgg/Ovule Zygote/ embryo + testesovary

4. Plants: Male gamete Female gamete Formed in: Pollen Ovule Zygote + antherovary

5. Questions Does growth and development stop at fertilisation? … at birth? How does the one cell zygote know what to do to become a mature member of its species?

6. Genetic Code The genetic code is the instructions for how a zygote grows and develops into a mature organism. The genetic code is found in the nucleus of cells.

7. Chromosomes From Advanced Biology for You

8. Chromosomes Chromosomes are found in nucleus of cells They come in pairs of similar shape and size called homologous pairs. Exception – sex chromosomes, X & Y differ in size and shape Females: XXMales: XY

9. Each species has a unique number of chromosomes e.g. humans – 46 chromosomes Scientists arrange the chromosomes in pairs from longest to shortest. They call this pattern a karyotype.

10. What does this tell us about human chromosomes? The human karyotype

11. Gametes contain half the number of chromosomes found in the body cell. One from each homologous pair

12. Complete the Table SpeciesBody CellMale gamete Female gamete Human23 Rat19 Pea14 Fruit Fly4 Horse66