A-Level Biology · Topic 8
The control of gene expression and gene technology: every key term you need (+ practice quiz)
16 flashcard terms for A-Level Biology Topic 8, written to match the course framework. Study them here, then drill them as interactive flashcards, or test yourself with the 8-question quiz — free, no account needed.
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Totipotent cell Can divide and differentiate into every cell type including extra-embryonic tissue. Only the earliest embryonic cells are truly totipotent.
Pluripotent cell Can become almost any body cell type but not extra-embryonic tissue. The basis of most therapeutic stem cell research.
Induced pluripotent stem cell An adult body cell reprogrammed to a pluripotent state using transcription factors, avoiding the ethical problems of embryonic sources.
Transcription factor A protein that binds a promoter region to switch transcription of a gene on or off, controlling which proteins a cell makes.
Oestrogen and gene expression Being lipid-soluble it diffuses in, binds a receptor to form a transcription factor complex, and activates target genes.
Epigenetics Heritable change in gene expression without any change to the base sequence, driven by environmental signals.
DNA methylation Adding methyl groups to a promoter prevents transcription factors binding, silencing the gene.
Histone acetylation Reduces the positive charge on histones so DNA is held less tightly, making genes more accessible for transcription.
RNA interference Small interfering RNA binds a complementary mRNA and targets it for destruction, so the protein is never translated.
Tumour suppressor gene Normally slows division and triggers apoptosis in damaged cells. Silencing it by mutation or hypermethylation allows tumours to develop.
Reverse transcriptase Builds complementary DNA from an mRNA template. Useful because the resulting gene contains no introns.
Restriction endonuclease Cuts DNA at a specific palindromic recognition sequence. A staggered cut leaves sticky ends that anneal to complementary ends.
Polymerase chain reaction Amplifies DNA in cycles of heating to separate strands, cooling to anneal primers, then extension by a heat-stable polymerase.
Marker gene Inserted alongside the desired gene so transformed host cells can be identified — by fluorescence or antibiotic resistance.
Gene probe A short labelled single-stranded DNA sequence that binds a complementary target, letting a specific allele be located.
Genetic fingerprinting Compares variable number tandem repeats between individuals. The more repeat regions match, the closer the relationship.
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