B2.1.4 - Mitosis Flashcards
What is mitosis?
The process by which body cells divide
What does each cell divide to produce in mitosis?
Two identical daughter cells (clones to parents)
Why do body cells divide?
To replace worn out cells
To repair damaged tissue
To enable the organism to grow in size
What is the process of cell growth and division called?
Cell cycle
What are the 4 stages of the cell cycle?
DNA replication
Movement of chromosomes
Cytokinesis
The growth of the daughter cell
What must you do to replicate a chromosome?
Replicate its DNA molecule
How does DNA replicate?
It unzips itself forming 2 separate strands. The DNA bases on each strand are exposed. Free nucleotides in the nucleus line up against each of the strands following the rules of complementary base pairing. This forms DNA base pairs. When the strand is complete, you have 2 separate identical pieces of DNA.
How do the chromosomes move?
The chromosomes line up at the centre of the cell. The 2 identical copies of each chromosome, which was created by DNA replication, separate and move to opposite ends of the cell. Each end now contains a full set of identical chromosomes. 2 new nuclei then form.
Explain what happens during cytokinesis.
The cell membrane pinches inwards and separates the 2 new nuclei, and then pinches off to split the original cell into 2 identical daughter cells.
What happens once the daughter cells are created?
They grow quickly and will begin replicating their DNA, so the cycle can continue.
Why is mitosis important?
It constantly has to replace dying cells with new ones, and can heal our injuries.
Approximately how many cells die on a human per minute?
300 million
