storing and using genetic information

Question 1

structure of DNA

Answer 1

DNA is a polymer of nucleotide monomers arranged in a double helix shape which has two antiparallel strands.

Question 2

process of DNA replication

Answer 2

1. DNA strands are ‘unzipped’
2. DNA polymerase then acts on the strand, adding nucleotides from the 5’ to 3’ end of the DNA strand.
3. this is continuous on the leading strand but is caried out in fragments on the lagging strand, these are then joined together by DNA ligase.

Question 3

process of transcription

Answer 3

1. DNA is unzipped
2. RNA polymerase works from 5’ to 3’ end of chain producing an RNA chain with a base sequence complementary to that on the DNA.

Question 4

post-transcriptional modification of RNA

Answer 4

Introns are removed form the primary RNA strand and the exons are spliced together to form the mature RNA strand.

Question 5

process of translation

Answer 5

1. mRNA makes its way out of the nucleus to a ribosome
2. tRNA molecules are bound to a specific amino acid
3. they bring this amino acid to the ribosome. The tRMA contains an anticodon which is complementary to the codon on the mRNA. This allows amino acids to joined together in a polypeptide chain according to the sequence of bases on mRNA (and DNA)

Question 6

what is meant by DNA replication is semi-conservative?

Answer 6

after replication one strand is old and one is new