5 interactive labs · AS & A Level Biology 9700
· Obtain a gene, cut it with a restriction enzyme, join it into a plasmid, add a promoter and a fluorescent marker, then edit a gene at one site.
Obtain a gene, cut it with a restriction enzyme, join it into a plasmid, add a promoter and a fluorescent marker, then edit a gene at one site.
You will be able to
Syllabus learning outcomes: 19.1.1, 19.1.2, 19.1.3, 19.1.4, 19.1.5, 19.1.6, 19.1.7
· Step through denaturation, annealing and extension, count every strand for three cycles, then test the polymerase, the primers and the efficiency.
Step through denaturation, annealing and extension, count every strand for three cycles, then test the polymerase, the primers and the efficiency.
You will be able to
Syllabus learning outcomes: 19.1.8
· Run cut DNA, a ladder and controls through a gel, reverse the polarity, then size an unknown band and read a sickle cell test.
Run cut DNA, a ladder and controls through a gel, reverse the polarity, then size an unknown band and read a sickle cell test.
You will be able to
Syllabus learning outcomes: 19.1.9
· Hybridise labelled DNA and cDNA from liver and muscle to a microarray, then search a mock sequence database and judge what a match shows.
Hybridise labelled DNA and cDNA from liver and muscle to a microarray, then search a mock sequence database and judge what a match shows.
You will be able to
Syllabus learning outcomes: 19.1.10, 19.1.11
· Follow recombinant proteins, genetic screening, gene therapy and GM crops and salmon, then build a reasoned argument scored on its evidence, not its opinion.
Follow recombinant proteins, genetic screening, gene therapy and GM crops and salmon, then build a reasoned argument scored on its evidence, not its opinion.
You will be able to
Syllabus learning outcomes: 19.2.1, 19.2.2, 19.2.3, 19.2.4, 19.3.1, 19.3.2
Each link is a piece of biology that carries an idea from one lab into another. Follow one to use what you found here in a new setting.
A single base substitution in the HBB gene changes one codon. Follow it through the protein and the phenotype to inheritance and a genetic test.
The codon GAG becomes GTG. What type of mutation is this, and what changes in the polypeptide?
A substitution, and a missense one: one amino acid (glutamic acid) is replaced by another (valine); the reading frame is not shifted.
Why can one amino acid change alter how haemoglobin behaves?
The new R group is non-polar, so it changes the interactions on the molecule's surface: at low oxygen the molecules stick together into fibres that distort the red blood cell.
Which phenotype does a person with two copies of the allele have?
Sickle cell anaemia: the HBB gene codes for β-globin, the altered β-globin gives abnormal haemoglobin and sickled cells.
Two parents each carry one copy (HbᴬHbˢ). What is the probability that a child is HbˢHbˢ?
0.25 for each child, independently: the Punnett square gives 1 HbᴬHbᴬ : 2 HbᴬHbˢ : 1 HbˢHbˢ as expected proportions, not a guaranteed family pattern.
A test amplifies the region by PCR and cuts it with a restriction enzyme whose site the mutation removes. How would the gel show the allele?
The normal allele is cut into two shorter fragments, which travel further towards the positive electrode; the sickle allele stays one longer fragment, so a carrier shows both patterns.
