Chromosomes

3.14 Recall that the nucleus of a cell contains chromosomes on which genes are located.

Chromosomes= Genetic information of the cell.
If you opened a nucleus up you would find chromosomes

It is composed of a molecule called DNA (Deoxyribo nucleic acid) which forms a shape known as the double helix.


Sections of this molecule are called genes. And one chromosome will have many genes (possibly thousands)
Each gene contains the information for the construction of a protein. The protein gives the characteristic associated with the genes (e.g. blood group).


Different organisms have different number of chromosomes.
Cat 38, Chicken 78, Chimp 42 and human 46.


Chromosomes are known to operate in pares known as homologous pairs. 
 
If you go to the same loci on the homologous pair you'll find the same gene.


So there are 2 versions of each gene for 1 characteristic.
These versions are called Alleles.