Nucleic acids

Question 1

Describe semi conservative replication?

Answer 1

• Before cell divides DNA strands unwind and is separated
• Each strand makes a new partner by adding the matching nucleotides
• As a result there is 2 double stranded DNA molecules in the nucleus so when the cell divides each nucleus contains identical DNA

Question 2

Stages of semi conservation replication?

Answer 2

1. DNA double helix unwinds and is separated by breaking the H bonds between the bases with the enzyme helicase
2. Each separated strand is now a template for new strands
3. Free nucleotides bind to the template stands and form H bonds with their complementary base pairs. A pairs with T and C with G. This is done by the enzyme DNA polymerase
4. The new DNA strands rewind to form a double helix
5. The new DNA molecule is identical to the initial one

Question 3

Explain the significance of complementary base paring in the conservation of the base sequence of DNA

Answer 3

• A always pairs with T and G always pairs with C
• As DNA replication is semi conservative this complementary base pairing allows the two DNA moleules to be identical to each oter as tey have the same base sequence
• The new strands formed are complementary to thei template strands but also identical to the other template.

Question 4

Function of mRNA?

Answer 4

• Carries DNA sequence info to ribosomes

Question 5

Function of tRNA?

Answer 5

• Provides a link between mRNA and amino acids, transfers amino acids to ribosomes

Question 6

Function of rRNA?

Answer 6

• Structural component of ribosomes

Question 7

What are exons?

Answer 7

• Regions of DNA that code for proteins

Question 8

What are introns?

Answer 8

• Regions of non coding DNA between exons found in eukaryotes

Question 9

What is RNA splicing?

Answer 9

• Cutting out introns from mRNA before mRNA leaves the nulcues