Gene Technologies

What Gene Technologies covers

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.

The 5 subtopics

Each one has its own page.

• Post-Transcriptional Editing of mRNARecall 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.Open →
• Genetic modification of bacteria and insulin productionRecall 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.Open →
• The polymerase chain reaction and gel electrophoresisRecall 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.Open →
• Haplotypes, SNPs, VNTRs and genetic engineering in eukaryotesRecall 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.Open →
• Gene therapy and RNA interferenceRecall 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.Open →

What you need to know

Answer each one before you reveal it.

Take Gene Technologies further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Restriction enzyme vs DNA ligase

  Restriction enzyme: a protein that cuts the double helix wherever a specific palindromic base sequence occurs, by hydrolysing the sugar-phosphate backbone of both strands. DNA ligase: a protein that seals two fragments together permanently by forming the phosphodiester bonds between their sugar-phosphate backbones.

• Sticky ends vs Blunt ends

  Sticky ends: short single-stranded overhangs of unpaired bases left by a staggered cut, which base-pair with any complementary overhang they meet. Blunt ends: a straight cut across both strands leaving no unpaired bases, so two fragments join only by chance and far less efficiently.

• Marker gene vs Gene of interest

  Marker gene: the extra sequence carried on a plasmid whose product shows which bacteria have taken the plasmid up, so transformed cells can be selected. Gene of interest: the length of DNA that the whole transfer exists to clone, because its protein product is the substance actually wanted.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is the primary transcript produced when a human gene is transcribed?

   Model answer

   It is pre-mRNA, a complete RNA copy of the gene that still contains both the introns and the exons.

2. 2

   Define the term intron.

   Model answer

   An intron is a non-coding section of a gene that is transcribed into pre-mRNA but is removed before the molecule is translated.

3. 3

   Define the term exon.

   Model answer

   An exon is a section of a gene that is transcribed and retained in the mature mRNA, and it carries the coding sequence that is translated into a polypeptide.

4. 4

   How is pre-mRNA converted into mature mRNA in a human cell?

   Model answer

   The introns are cut out and the exons are joined together in the nucleus, and a cap is added to the 5′ end and a tail of adenine nucleotides to the 3′ end.

5. 5

   What is added to the 3′ end of a mature mRNA molecule, and why?

   Model 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.

6. 6

   What is the function of the cap added to the 5′ end of mature mRNA?

   Model answer

   It protects the mRNA from digestion by enzymes and is recognised by the small ribosomal subunit, so it is needed for translation to begin.

What is inside Levo

Six ways to work the same material.

Gene Technologies revision questions

What does Gene Technologies cover in OCR A-Level Biology B?

5 subtopics: 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. Each one has its own page with questions and model answers.

How is Gene Technologies organised?

By the OCR H422 specification, subtopic by subtopic, so it matches the order you are taught it in.