D2.2 Flashcards
Define genotype and phenotype.
Genotype: An organism’s genetic makeup (alleles). Phenotype: Observable characteristics resulting from genotype and environment.
Define gene expression
The process of using information from a gene to synthesize a functional gene product (usually a protein). Involves transcription and translation.
List common stages of gene
- Transcription (DNA → mRNA); 2. RNA processing (eukaryotes only); 3. Translation (mRNA → protein); 4. Protein folding & modification.
Transcription regulation by transcription factors.
Transcription factors bind to promoter sequences. Activators enhance transcription; repressors inhibit it.
Compare enhancers and silencers.
Enhancers increase transcription; silencers decrease it. Both can be distant from the gene.
Compare repressor and activator transcription factors.
Repressors inhibit transcription; activators stimulate it.
Length of Poly-A tail and mRNA degradation.
Longer poly-A tails protect mRNA from degradation by nucleases, increasing protein synthesis.
mRNA degradation and translation regulation.
mRNA degradation controls protein levels; rapid degradation leads to lower protein levels.
Define epigenesis and epigenome.
Epigenesis: Heritable changes in gene expression without DNA sequence changes. Epigenome: The overall pattern of epigenetic modifications.
Compare genome, transcriptome, and proteome.
Genome: Complete DNA; Transcriptome: All RNA transcripts; Proteome: All proteins expressed.
Methylation of DNA in promoters.
DNA methylation (usually at CpG islands) in promoters typically represses gene expression.
Acetylation and methylation of histones.
Histone acetylation usually increases gene expression; histone methylation can increase or decrease it depending on the specific amino acid and number of methyl groups.
Air pollution and epigenetic regulation.
Air pollutants can cause epigenetic changes in immune system genes, affecting immune function.
Imprinting and gene expression.
Genomic imprinting: Gene expression depends on parental origin (monoallelic expression).
Epigenetic origins of liger/tigon size differences.
Size differences are partly due to genomic imprinting affecting growth genes.
Monozygotic twin studies and environment.
Monozygotic twins share the same genome; phenotypic differences are due to environmental effects on gene expression.
: Lactose regulation in E. coli.
lac operon: Lactose absence → repressor binds, blocking transcription. Lactose presence → repressor inactive, allowing transcription.
Estrogen regulation of endometrium genes.
Estrogen binds to receptors, forming a transcription factor complex that stimulates transcription of genes involved in endometrium development.
