Making New DNA

Question 1

What happens when a cell divides?

Answer 1

The chromosomes split length ways and each half enters the new cell.

Question 2

Why is this specific split important?

Answer 2

Each new cell must have the same chromosome number as the parent cell. If the chromosomes are not able to make exact copies of themselves then so must the genes and so must DNA. Otherwise the new cells would not have all the correct genetic information that they need.

Question 3

Before a cell divides the amount of DNA in it’s nucleus, doubles. But how does this happen?(5)

Answer 3

• Firstly the hydrogen bonds holding the bases together break
• Them the DNA double helix unwinds to give 2 single strands
• Each single strand attracts separate nucleotides present inside the nucleus
• These nucleotides line up along each single DNA strand following the rule of base pairing. So C lines up alongside G and A alongside T.
• The nucleotides join up and so two DNA molecules are formed and each one is an identical copy of the parent cell’s DNA

Question 4

To make a protein, lots of ______ ______ join together.

Answer 4

Amino Acids

Question 5

What determines what the protein will be like?

Answer 5

The type and sequence of the amino acid. For example it could be an enzyme , hormone or a protein in muscle.

Question 6

Where are proteins made?

Answer 6

In ribosomes, which are found the cytoplasm of a cell

Question 7

How does the information get from the nucleus to ribosomes?(How DNA controls protein synthesis)

Answer 7

• The m-RNA copies the base sequence on DNA and carries it out of the nucleus through a nuclear pore to the ribosomes
• t-RNA picks up amino acids and carries them to the ribosomes
• t-RNA slots into the m-RNA and gives up its amino acid
• The amino acids bond together forming a long chain- the protein
• Each amino acid is then coded for by a sequence of 3 bases
• The sequence of bases on DNA that codes for a protein is called the genetic code