exam questions

• Name the enzymes used in DNA replication and state their function (2)

  -       DNA helicase breaks the hydrogen bonds between bases, unwinding the DNA molecule 

  -       DNA polymerase catalyses the reaction between the phosphate group and pentose sugar of adjacent nucleotides, forming phosphodiester bonds.
• Explain the role of free DNA nucleotides (1) 

  -       Line up next to DNA template via complementary base pairing to form a polynucleotide chain (complementary DNA strand)
• State 2 features of DNA and explain how each one is important in semiconservative replication (2) 

  -       Weak/easily broken hydrogen bonds between bases so 2 strands can unwind 

  -       2 strands so both can act as templates 

  -       Complementary base pairing so there is accurate replication