IBDP>CORE>TOPIC 3.4> DNA replication
ASSESSMENT STATEMENTS
3.4.1 Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase, followed by formation of the new complementary strands by DNA polymerase.
3.4.2 Explain the significance of complementary base pairing in the conservation of the base sequence of DNA.
3.4.3 State that DNA replication is semi- conservative.
3.4.2 Explain the significance of complementary base pairing in the conservation of the base sequence of DNA.
3.4.3 State that DNA replication is semi- conservative.
3.4.1. Explain how DNA is replicated within the cells of living organisms. 8 marks
helix is unwound; two strands are separated; helicase (is the enzyme that unwinds the helix separating the two strands);
by breaking hydrogen bonds between bases; new strands formed on each of the two single strands; nucleotides added to form new strands; complementary base pairing; A to T and G to C; DNA polymerase forms the new complementary strands; replication is semi-conservative; each of the DNA molecules formed has one old and one new strand; |
production of new DNA;
semi-conservative; one old strand and one new strand; double helix unwound/separated; by breaking of H-bonds; by helicase (enzyme);single strand acts as a template / blueprint; free bases form H-bonds with complementary bases / A with T, C with G; nucleotides linked; by DNA polymerase;daughter DNA molecules rewind; daughter strand identical to parent strand; |
3.4.2. Outline the significance of complementary base-pairing in DNA. 5 marks
when DNA replicates the 2 strands separate;
each single strand acts as template/serves as a base for base-pair matching;
free nucleotides of adenine/A bond only with thymine/T / vice versa and free nucleotides of cytosine/C bond only with guanine/G / vice versa; thus copying the opposite strand of the original DNA molecule;
replication is semi-conservative;
original order of bases is maintained/conserved;
new DNA identical to parent molecule;
(significance of base-pair matching) is that the information encoded in one DNA molecule is passed to others;
DNA structure indicates the manner of DNA replication;
each single strand acts as template/serves as a base for base-pair matching;
free nucleotides of adenine/A bond only with thymine/T / vice versa and free nucleotides of cytosine/C bond only with guanine/G / vice versa; thus copying the opposite strand of the original DNA molecule;
replication is semi-conservative;
original order of bases is maintained/conserved;
new DNA identical to parent molecule;
(significance of base-pair matching) is that the information encoded in one DNA molecule is passed to others;
DNA structure indicates the manner of DNA replication;