DNA and the Genome

Question 1

What is DNA?

Answer 1

DNA is a polymer made up of two long strands of small units that repeat throughout the structure, called nucleotides.

Question 2

What holds two strands of DNA together?

Answer 2

The attraction between the bases.

Question 3

What is a genome?

Answer 3

The genome is the entire genetic material of an organism. (Within a genome, there are lots of levels of organisation.)

Question 4

What is a gene?

Answer 4

A gene is a segment of DNA.

Question 5

What is the genome made up of?

Answer 5

• 23 pairs of chromosomes
• Double helix shape
• DNA contained in chromosomes

Question 6

What is mitosis?

Answer 6

When an organism grows it needs to make more cells. To do this the existing cells divide making identical copies of themselves. This process is called mitosis and is used to make all cells in an organism, with the exception of sex cells (gametes).

It is important that the chromosomes are copied before the cell divides, otherwise the amount of genetic information would decrease.

Question 7

What is meiosis?

Answer 7

In order to keep the number of chromosomes in a cell the same after sexual reproduction a different kind of cell division is needed. Meiosis reduces the number of chromosomes in the production of sex cells. (gametes)