MCAT Basics (from MedSchoolCoach) Genetics: Gene Expression
Oct 3, 2025
Delve into the intricacies of genetics, exploring X-linked and autosomal trait inheritance with real-life examples like color blindness. Understand the impact of epigenetic changes, DNA methylation, and genomic imprinting on gene expression. Discover the complexity of transcriptional control in prokaryotes and eukaryotes, including operons and chromatin remodeling. Learn about essential genetic lab techniques like PCR and FISH that aid in gene analysis and diagnostics, crucial for aspiring medical students.
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Parent‑Of‑Origin Expression
- Genomic imprinting silences one parental allele so expression depends on parent of origin.
- Imprinted genes express only the active parental copy, making them vulnerable to mutations and parent-specific inheritance patterns.
Linkage And Recombination Frequency
- Genetic linkage violates independent assortment because closely located genes tend to be inherited together.
- Recombination frequency (0–50%) measures how often crossover occurs between two genes; lower frequency means tighter linkage.
Operon Logic In Bacteria
- Prokaryotic genes often exist in operons: co-transcribed gene clusters under a single promoter.
- Repressors bind operators to reduce transcription and activators bind enhancers to increase it.