Chapter 3 - DNA replication/genetic code

Question 1

what is the process of semi conservative replication?

Answer 1

1) DNA helicase unzips the section of DNA - strands separate
2) separations of strands complete - free activate nucleotides attract to their complementary base
3) activated nucleotides line up - joined together by DNA polymerase
4) all nucleotides joined up - form polynucleotide chain - two identical molecules of DNA formed - each with one original strand and one new strand

Question 2

what are the roles of enzymes in replication?

Answer 2

• DNA helicase=unwinds and separates the 2 strands of DNA by catalysing the break down of hydrogen bonds between complementary bases
• DNA polymerase=catalyses the formation of phosphodiester bonds between nucleotides

Question 3

what are replication errors?

Answer 3

• incorrect sequences occurring in newly copied strand
• occur randomly and spontaneously
• lead to a mutation

Question 4

what is the genetic code?

Answer 4

• DNA must code for a sequence of amino acids

Question 5

what is the triplet code?

Answer 5

• the code in the base sequence in DNA is a triplet code
• a sequence of 3 bases (codon)
• each codon codes for an amino acid
• gene=section of DNA that contains complete sequence of bases that codes for a protein

Question 6

what is the degenerate code?

Answer 6

• many amino acids can be coded for by more than one codon