3.14) Chromosome

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

Chromosomes are the genetic information in cells.

Cell ---> Nucleus ---> Chromosomes ---> DNA

The structure of a Chromosome

A chromosome is composed of DNA (deoxyribonucleic acid) which formed the shape known as the "double helix."

Each section of a chromosome is called genes. A chromosome contains thousands of genes. Each genes carry the information for the construction of protein.

Protein gives us the characteristic associated with the genes. For example, blood group.

Different organisms have different number of chromosomes per cell. 

- Cat - 38

- Chick - 78

- Chimpanzee - 42

- Human - 46 

Chromosomes operate in pairs known as the homologous pairs.

The homologous nature is based on the length of the chromosome. 

Some of the homologous pairs within an organism.

Gene loci are the specific locations or DNA sequence on a chromosome. 

If we go to the same position on the other chromosome in a homologous pair, we found the same gene loci (which contains another gene). Therefore we have 2 versions of each genes for one characteristic. These characteristics are called alleles, which is the variant of DNA sequence at a given locus.

Homologous chromosomes and gene loci

Question: Since there are 46 chromosomes per cells, is each chromosomes responsible for genes of different characteristic?