Chromosomes and Mitosis Flashcards
What is the genetic material inside a nucleus called?
It is called chromosomes.
What are chromosomes?
They are coiled up lengths of DNA molecules.
How are different characteristics formed?
Each chromosomes carries a large number of genes. Different genes control the development of different characteristics.
How many chromosomes are there in a human cell?
There are 23 pairs meaning there are 46.
What are the two main stages in the cell cycle?
Growth and DNA replication - Mitosis
What happens in the first stage of the cell cycle - Growth and DNA replication?
1) In a cell that is not dividing - the DNA is all spread out in long strings.
2) Before dividing - the cell has to grow and increase the amount of subcellular structures like mitochondria and ribosomes.
3) It then duplicates the DNA - so there is one copy for each cell - the DNA is copied and forms X-shaped chromosomes - each ‘arm’ of the chromosome is an exact duplicate of each other.
What happens in mitosis?
1) The chromosomes line up at the centre of the cell and cell fibres pull them apart. The two arms of the chromosome go to opposite ends of the cell
2) Membranes form around each sets of chromosomes. These become the nuclei of the two new cells - the nucleus has divided.
3) Lastly, the cytoplasm and cell membrane divide.
After mitosis what does the cell produce?
It produces 2 new daughter cells - they contain the exact same DNA (identical) and their DNA is also identical to their parent cell.
