chromosomes and mitosis

Question 1

What do our cells need to do in order for us to survive?

Answer 1

Our cells need to divide- which is the same for our DNA.

Question 2

What are chromosomes and where are they in a cell?

Answer 2

Chromosomes are found in the nucleus of our cells and are coiled up lengths of DNA molecules. Each one carries a large number of genes which control the development of different characteristics e.g hair colour.

Question 3

How many pairs of chromosomes are there in a human cell.

Answer 3

There are normally 23 pairs of chromosomes in a human cell.

Question 4

What happens to body cells in multicelluar organisms?

Answer 4

They divide in order to make new cells which multicellular organisms use to grow and devolop- this is called mitosis.

Question 5

What are the main stages of the cell cycle?

Answer 5

1) Before it divides the cell grows and increases the amount of sub cellular structures
2)The DNA is copied so there is a copy for each new cell
3)The DNA form x-shape chromosomes with each arm being the exact copy of the other
(cell is ready for dividing-mitosis)
4)The chromosomes now line up at the centre of the cell and its arms are pulled apart to the opposite ends of the cell causing the nucleus to divide.
5)Each set of chromosomes become the nucleus of a new cell
6)The cytoplasm and cell membrane divide
7)The cell has now produced two identical cells