Gene Technologies | OCR A-Level Biology B (Advancing Biology) (H422)
Gene Technologies
- 81 questions
- 5 subtopics
- Biology content, examined on all three papers
- Component 01, Component 02 and Component 03
Gene Technologies is examined in all three written papers — the specification states that Components 01, 02 and 03 can each assess content from any of the five modules, so nothing is confined to one paper.
It covers post-Transcriptional Editing of mRNA, genetic modification of bacteria and insulin production, the polymerase chain reaction and gel electrophoresis, haplotypes, SNPs, VNTRs and genetic engineering in eukaryotes and gene therapy and RNA interference.
Sample questions from Gene Technologies
Answer each one closed book first, then open the answer.
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Post-Transcriptional Editing of mRNA
What is added to the 3′ end of a mature mRNA molecule, and why?
Show the answer
A poly(A) tail of many adenine nucleotides is added, which protects the molecule from being broken down by enzymes in the cytoplasm and so extends the time over which it can be translated. -
Post-Transcriptional Editing of mRNA
How does alternative splicing allow the human genome to code for far more proteins than it has genes?
Show the answer
Each different combination of exons is translated into a different polypeptide, so one gene can give rise to many related proteins, often with different roles in different tissues. -
Genetic modification of bacteria and insulin production
What are sticky ends, and how are they produced?
Show the answer
Sticky ends are short single-stranded overhangs of unpaired bases, produced when a restriction enzyme makes a staggered cut across the two strands of the double helix. -
Genetic modification of bacteria and insulin production
How is an antibiotic resistance gene used to identify transformed bacteria?
Show the answer
All the bacteria are grown on agar containing that antibiotic, and only the cells that have taken up the plasmid carry the resistance gene and survive to form colonies. -
The polymerase chain reaction and gel electrophoresis
Besides the template DNA, the primers and Taq polymerase, which other components must a PCR mixture contain?
Show the answer
It must contain a supply of the four free DNA nucleotides and a buffer providing magnesium ions and a suitable pH. -
The polymerase chain reaction and gel electrophoresis
What does agarose gel electrophoresis separate DNA fragments according to?
Show the answer
It separates them according to their length, because all DNA fragments carry a similar charge per unit length. -
Haplotypes, SNPs, VNTRs and genetic engineering in eukaryotes
Outline how a genetic profile is produced from a small sample of DNA.
Show the answer
The chosen VNTR loci are amplified by PCR, the products are separated by agarose gel electrophoresis according to their length, and the resulting pattern of bands is visualised and compared. -
Haplotypes, SNPs, VNTRs and genetic engineering in eukaryotes
What is a knockout mouse?
Show the answer
A knockout mouse is one in which a particular gene has been deliberately inactivated, so that the function of that gene can be worked out from the effects on the animal.
The 5 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Post-Transcriptional Editing of mRNA | Recall questions on pre-mRNA as the primary transcript, introns and exons, splicing, the 5′ cap and poly(A) tail, where editing happens, alternative splicing, why bacteria cannot splice human genes, and making cDNA with reverse transcriptase. | 12 |
| Genetic modification of bacteria and insulin production | Recall questions on reverse transcriptase and insulin mRNA from β cells, restriction enzymes, palindromic sites and sticky ends, DNA ligase and plasmid vectors, transforming bacteria, marker genes and antibiotic resistance selection, and the advantages and limits of insulin made by bacteria in fermenters. | 15 |
| The polymerase chain reaction and gel electrophoresis | Recall questions on the three stages of a cycle and their temperatures, primer design, copy-number calculations and log plots, and how fragment length is estimated from a gel. | 18 |
| Haplotypes, SNPs, VNTRs and genetic engineering in eukaryotes | Recall questions on SNPs and haplotypes, VNTRs and genetic profiling for identity and paternity, tracing human migration, genotyping patients for clinical trials, the ethics of genetic databases, knockout mice, clotting factors from farm animals, and genetically modified crops and their risks. | 18 |
| Gene therapy and RNA interference | Recall questions on somatic and germ line gene therapy, delivery by viruses and liposomes, gene therapy for cystic fibrosis and SCID and their difficulties, the ethics of germ line therapy, and RNA interference by siRNA and miRNA as a possible treatment. | 18 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Biology B (Advancing Biology) Active Recall Guide
Every topic, not just this one. 2,895 questions with their answers.