……………………………….BIOL114 Example short answer test marking scheme
1. Genomic DNA (1), cDNA (1)
2. Any 3 from:
cut double-stranded (1) DNA
recognise sequences with 2-fold rotational symmetry (1). Accept recognise palindromic
sequences
cut DNA at defined/specific (1) sequences
isolated/purified from bacteria (1)
can generate complementary/“sticky ends” (1)
Do not accept “cut DNA” without reference to dsDNA, recognition sites or sticky ends
3. a) DNA polymerase (1)
b) primer (1). Accept oligonucleotide
dNTPs/deoxyribonucleotides (1). Do not accept NTPs, nucleotides, bases, ddNTPs
c) A dideoxynucleotide (1) is incorporated which lacks a 3’ OH (1)
d) Detects fluorescence (1) from fluorescently labelled/tagged (1) ddNTPs
4. Taq polymerase is heat resistant/isolated from thermophilic bacteria/ bacteria that live in
hot springs (1) and so will not be destroyed/denatured (1) during PCR
5. The genetic code is degenerate (1) and different organisms favour different codons (1) to
encode specific amino acids.
6. Any 2 from:
To make them easier to purify (1)
1. Genomic DNA (1), cDNA (1)
2. Any 3 from:
cut double-stranded (1) DNA
recognise sequences with 2-fold rotational symmetry (1). Accept recognise palindromic
sequences
cut DNA at defined/specific (1) sequences
isolated/purified from bacteria (1)
can generate complementary/“sticky ends” (1)
Do not accept “cut DNA” without reference to dsDNA, recognition sites or sticky ends
3. a) DNA polymerase (1)
b) primer (1). Accept oligonucleotide
dNTPs/deoxyribonucleotides (1). Do not accept NTPs, nucleotides, bases, ddNTPs
c) A dideoxynucleotide (1) is incorporated which lacks a 3’ OH (1)
d) Detects fluorescence (1) from fluorescently labelled/tagged (1) ddNTPs
4. Taq polymerase is heat resistant/isolated from thermophilic bacteria/ bacteria that live in
hot springs (1) and so will not be destroyed/denatured (1) during PCR
5. The genetic code is degenerate (1) and different organisms favour different codons (1) to
encode specific amino acids.
6. Any 2 from:
To make them easier to purify (1)
