DNA replication:

Question 1

Every time a cell underogoes cell division what happens?

Answer 1

= All the dna is copied
= DNA replication

Question 2

What happens in the first stage?

Answer 2

= enzyme DNA helicase attaches to the DNA molecule
= causes hydrogen bonds between the complementary base pairs to break
= causes 2 polynucleotide strands to seperate from eachother

Question 3

What happens secondly?

Answer 3

= free nucleotides line up with their complementary bases on the DNa strands
= held into place by hydrogen bonds between the complementary bases
= not bonded by phosphodiester bonds

Question 4

What are these free nucleotides called and what are they?

Answer 4

= activated nucleotides
= contains 3 phosphate heads
=

Question 5

What happens thirdly?

Answer 5

= a 2nd ezyme attaches
= DNA polymerase
= moves down the molecule and catalyses the formation of a phosphodiester bond between the activated nucleotides
= this causes the activated nuclotides to loose their 2 other phosphate heads- as they leave it provides energy for the reaction

Question 6

What are we now left with?

Answer 6

= two copies of double stranded dna molecule
= each contains one strand from the original DNA molecule+ brand new
= semi-conservative replication

Question 7

What is a mutation?

Answer 7

= when an incorrect base is inserted into the growing polynucleotide strand causes the DNA sequence to change
= effects the organisms
= random and occur spontanously
=