Genetic Variation

Genetics

Genetics is the study of inheritance.The passing on of characteristics/traits

from the birth mother & father to their offspring

Most life begins as a fertilised ovule called a zygote or embryo.

Animals:

Male gamete

Female gamete

Formed in:

Sperm Egg/OvuleZygote/embryo+

testes ovary

Plants:

Male gamete

Female gamete

Formed in:

Pollen Ovule Zygote+

anther ovary

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?

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.

Chromosomes

From Advanced Biology for You

Chromosomes

Chromosomes are found in nucleus of cellsThey come in pairs of similar shape and size

called homologous pairs.Exception – sex chromosomes, X & Y differ in

size and shapeFemales: XX Males: XY

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.

What does this tell us about human chromosomes?

The human karyotype

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

Complete the Table

Species Body Cell Male gamete

Female gamete

Human 23

Rat 19

Pea 14

Fruit Fly 4

Horse 66