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