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Unit 2 Biology (Higher) > Cell Division > Flashcards

Flashcards in Cell Division Deck (8)
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How many chromosomes does a human have?

46 chromosomes; 23 pairs of each chromosome.


How many chromosomes does a gamete have?

23 chromosomes.


What is a gamete?

A sex cell, like Sperm and Eggs.


Define mitosis.

When a cell reproduces itself by splitting to form two identical offspring.


Explain how mitosis divides cells.

DNA is copied and forms X-Shaped chromosomes where each 'arm' is a duplicate of the other; there are now 92 chromosomes. Cell fibres then pull the chromosomes apart and each arm goes to opposite ends of the cell; there are now 46 chromosomes on each end. Membranes then form around the chromosomes to create nuclei and finally, the cytoplasm divides.


Define meiosis.

The production of cells which have half the normal number of chromosomes.


Explain how meiosis divides cells.

DNA is duplicated into X-Shaped chromosomes so there are now 92 chromosomes. The chromosomes then move to the middle of the cell and the cell splits in two. The two new cells have 46 chromosomes each. The chromosomes in each cell move to the middle and are pulled apart by cell fibres so each side has only 23 chromosomes. The cell then splits in two so the new cells all have 23 chromosomes and are all unique. This is how sex cells are produced.


What kind of cell division does asexual reproduction use?