AP Biology Unit 6: Gene Expression and Regulation — Tips & Strategies

The lac operon is an inducible system. When lactose is present (and glucose absent), the repressor is inactivated and CAP activates transcription of lactose-digesting enzymes.

Each new DNA molecule has one original strand and one new strand (semi-conservative). Replication proceeds in both directions from each origin of replication.

Transcription copies DNA to mRNA (in the nucleus). Translation reads mRNA to build a polypeptide (at ribosomes). This is the 'central dogma' of molecular biology.

Point mutations include silent, missense, and nonsense. Frameshift mutations (insertions/deletions) are usually most damaging because they alter every codon downstream.

Gene expression can be regulated at chromatin remodeling, transcription, RNA processing, mRNA stability, translation, and post-translational levels. Transcription factors are key.

PCR amplifies DNA exponentially. Gel electrophoresis separates DNA by size (smaller = farther). CRISPR-Cas9 allows precise gene editing. These techniques appear in experimental design FRQs.