Mitosis: GCSE Biology Exam

Mitosis and Meiosis (covered in another article) are key things to learn. I smell a possible six marker. Unlike someone I used to know... Oh yeah... you wont get that... He couldn't smell. MOVING ON. As with Biology it is a good idea to know definitions so get listening:

"Mitosis makes new cells for growth and repair."

There are lots of details unlikely to come up on the exam but a few things you might wanna know before I start rambling:

• Human body cells are diploid (2 versions of each chromosome, one from each parent)
• 23 pairs of chromosomes in in a human cell.

So:

Mitosis

Mitosis results in two identical cells. The cell gets the signal to duplicate the DNA in order to divide. The cells then have to go from being stringy things into pairs of arms to make chromosomes. In an x shape.

See? X shaped. Wasn't even lying this time.

WARNING: Although often depicted as different coloured arms of the chromosome the 2 arms of the chromosome are EXACT DUPLICATES.

Next comes the line-up. Like in the military and stuff. The chromosomes line up at the center of the cell and the cell fibres pull them apart. Not so much like the military. This is called the "Metaphase" but don't stress about that, not important!

The membranes form around the the new sets of chromosomes. These become the nuclei of the two cells. See where this is going?

Hehehehe... Cleavage.

Finally the cytoplasm divides! The chromomes return to their stringy origins within the new cells. There are now two new diploid cells with exactly the same DNA. This is called being "Genetically identical". Why? Because their genes are identical. Common sense people.

USEFUL FACT: Asexual reproduction uses Mitosis. You might get a question involving plant "runners". These plants use mitosis so when they produce new plants on the ends of these runners they will be genetically the same so are more likely to be the same size and have the same resistance to certain drugs as the original plant. Farmers often use this to breed larger plants by only killing smaller ones... Adds new meaning to the phrase "size matters" doesn't it?