Chromosomes and cell division

The nucleus of a cell contains chromosomes.

Chromosomes are made up of tightly wound DNA molecules. 

Each chromosome carries many genes, which are small sections of DNA containing instructions for making specific proteins. 

In most body cells, chromosomes are found in pairs.

How DNA is wound up up into chromosomes

Cell division

Cells divide through a series of stages known as the cell cycle.

The cell cycle includes:

1. Growth Phase: The cell grows and increases the number of sub-cellular structures, such as ribosomes and mitochondria, needed to support two cells.

2. DNA Replication: The DNA replicates, creating two copies of each chromosome to ensure both new cells receive identical genetic material.

3. Mitosis:

   • One set of chromosomes is pulled to each end of the cell.

   • The nucleus divides, followed by the division of the cytoplasm and cell membrane, resulting in two identical cells.

The process of cell divison by mitosis