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Control of gene expression official content
Control of gene expression official content develops AQA A-Level Biology knowledge through Alteration of the sequence of bases in DNA can alter the structure of proteins, Most of a cell's DNA is not translated, Regulation of transcription and translation, Gene expression and cancer, Using genome projects, Recombinant DNA technology. Students should connect molecular detail, cell-level mechanisms, organism-level outcomes and ecological or genetic consequences where relevant, rather than treating each objective as an isolated definition. The topic overview should help learners locate every learning objective, recognise the main command words and prepare for data-led questions. Focus on precise biological vocabulary, cause-and-effect chains, and evidence from practical work or experimental observations. Useful revision links include Explain, base-sequence, changes, sequences., altered, sequences, protein, structure, function., mutations. Strong answers should state the biological principle, apply it to the named context, interpret any data carefully and finish with a clear consequence or evaluation. Common mistakes include giving GCSE-level descriptions, missing the scale of organisation, or using a correct term without explaining why it matters in this A-Level context.
34
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10
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10
Questions
90 min
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34 objective pages available
Alteration of the sequence of bases in DNA can alter the structure of proteins4 objectives
- Explain how base-sequence changes can alter amino acid sequences.
- Relate altered amino acid sequences to protein structure and function.
- Explain how mutations can affect phenotype.
- Interpret mutation information in unfamiliar contexts.
Most of a cell's DNA is not translated4 objectives
- Explain that cell specialisation results from translation of only part of the DNA.
- Distinguish totipotent, pluripotent, multipotent and unipotent cells.
- Explain induced pluripotent stem cells.
- Evaluate stem-cell use in treating human disorders.
Regulation of transcription and translation5 objectives
- Explain transcriptional stimulation and inhibition by transcription factors.
- Explain the role of oestrogen in initiating transcription.
- Explain epigenetic control through DNA methylation and histone acetylation.
- Explain RNA interference as inhibition of translation.
- Interpret and evaluate data on gene expression and phenotype.
Gene expression and cancer4 objectives
- Distinguish benign and malignant tumours.
- Explain roles of tumour suppressor genes and oncogenes in tumour development.
- Explain abnormal methylation and oestrogen links to cancer.
- Evaluate evidence linking genetic and environmental factors with cancer.
Using genome projects4 objectives
- Explain how genome sequencing can identify protein sequences in simpler organisms.
- Describe applications of genome information, including antigen identification for vaccine production.
- Explain why non-coding DNA and regulatory genes complicate proteome prediction in complex organisms.
- Recognise that sequencing methods are continuously updated and automated.
Recombinant DNA technology5 objectives
- Explain recombinant DNA technology as DNA transfer between organisms or species.
- Describe methods for producing DNA fragments, including cDNA, restriction enzymes and gene machines.
- Explain PCR as an in vitro method of amplifying DNA.
- Explain transformed host-cell culture as an in vivo method of amplifying DNA.
- Explain roles of restriction endonucleases, ligases, vectors, marker genes and transformed cells.
Differences in DNA between individuals of the same species can be exploited for identification and diagnosis4 objectives
- Explain how DNA differences between individuals can be used for identification and diagnosis.
- Describe use of DNA probes to locate specific alleles or sequences.
- Explain genetic screening in relation to inherited conditions.
- Interpret information on DNA-based diagnosis.
Genetic fingerprinting4 objectives
- Explain principles of genetic fingerprinting using DNA fragment patterns.
- Describe how DNA fragments can be separated and compared.
- Explain forensic and paternity applications of genetic fingerprinting.
- Interpret genetic fingerprinting evidence in context.
Key terms
Exam tips
- Use precise terminology: When describing mutations and their effects, use specific terms like 'substitution', 'deletion', and 'insertion' to convey your understanding clearly.
- Use diagrams to illustrate protein structure: When explaining how mutations affect protein function, draw diagrams of the primary, secondary, and tertiary structures.
Common mistakes
- Confusing mutations with all changes in protein structure: Clarify that not all changes in protein structure are due to mutations; some can occur due to environmental factors or post-translational modifications.
- Confusing mutations with all changes in DNA: Clarify that mutations specifically refer to changes that can affect protein coding sequences and potentially alter protein function.
Practice preview
- Which of the following best describes how a mutation in the DNA sequence can affect protein structure?
- Explain how a single base substitution in a gene can lead to a different protein being produced.
- A scientist observes that a mutation in a gene leads to a protein that is unable to bind to its substrate. Describe how this mutation might have occurred at the DNA level.
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