Biology · Continuity and change
D2.2 — Gene expression
Biology · SL / HL · syllabus-mapped notes
D2.2.1
Gene expression as the mechanism by which information in genes has effects on the phenotype
Explain the three stages by which a genotype produces a phenotype.
D2.2.2
Regulation of transcription by proteins that bind to specific base sequences in DNA
Explain how transcription factors bind enhancers and silencers to regulate transcription.
D2.2.3
Control of the degradation of mRNA as a means of regulating translation
Explain how the poly-A tail controls mRNA degradation and therefore translation.
D2.2.4
Epigenesis as the development of patterns of differentiation in the cells of a multicellular organism
Explain epigenesis, and why epigenetic tags change phenotype but not genotype.
D2.2.5
Differences between the genome, transcriptome and proteome of individual cells
Distinguish the genome, transcriptome and proteome of a cell.
D2.2.6
Methylation of the promoter and histones in nucleosomes as examples of epigenetic tags
Explain methylation of promoters and of histone tails as epigenetic tags.
D2.2.7
Epigenetic inheritance through heritable changes to gene expression
Explain how epigenetic tags are inherited, and the limits of transgenerational inheritance.
D2.2.8
Examples of environmental effects on gene expression in cells and organisms
Give examples of environmental effects on gene expression, including phenotypic plasticity.
D2.2.9
Consequences of removal of most but not all epigenetic tags from the ovum and sperm
Explain genomic imprinting as a consequence of incomplete removal of epigenetic tags.
D2.2.10
Monozygotic twin studies
Explain how twin studies separate genetic from environmental influence.
D2.2.11
External factors impacting the pattern of gene expression
Explain how nutrients, hormones and development alter the pattern of gene expression.