BCH223: Regulation of Gene Expression and Associated Diseases

Vocabulary flashcards covering molecular mechanisms of gene expression, epigenetics, mutations, and disease pathology from BCH223 Unit 1.

Epigenetics

Heritable changes in gene expression from parent cell to daughter cell that occur without altering the underlying DNA sequence.

Heterochromatin

Highly condensed DNA in eukaryotes that is associated with transcriptional repression and silenced genes.

Euchromatin

Less condensed, accessible DNA in eukaryotes that is actively transcribed by RNA polymerase.

Fragile X Syndrome

The most prevalent inherited form of intellectual disability and autism, caused by a trinucleotide repeat expansion $(CGG)_{>200}$ that induces CpG island methylation and transcriptional silencing of the FMR1 gene.

Missense Mutation

A point mutation in a protein-encoding gene that alters a single codon to specify a different amino acid, such as the $Glu \rightarrow Val$ substitution in sickle cell disease.

Nonsense Mutation

A point mutation that converts an amino acid-encoding codon into a premature termination (stop) codon, producing a truncated protein.

Frameshift Mutation

An insertion or deletion of nucleotides not in multiples of three within a gene's coding region, which shifts the translation reading frame and typically leads to premature termination.

Spinal Muscular Atrophy (SMA)

An inherited neuromuscular disorder caused by mutations or loss of function in the SMN1 gene, leading to motor neuron degeneration and progressive muscle atrophy.

Survival Motor Neuron (SMN) Protein

A essential protein needed to assemble components of the spliceosome; encoded by SMN1 and SMN2 genes.

Cystic Fibrosis

An autosomal recessive disease commonly caused by an in-frame deletion of phenylalanine 508 ($\triangle F508$) in the CFTR gene, resulting in misfolded chloride channels and thick mucus accumulation.

Huntington's Disease

An autosomal dominant progressive neurological disorder caused by an in-frame CAG trinucleotide repeat expansion in exon 1 of the HTT gene, leading to toxic huntingtin protein aggregation.

Familial Adenomatous Polyposis (FAP)

An inherited colorectal cancer syndrome caused by nonsense mutations in the APC gene (frequently in exon 15) that lead to truncated APC protein.

BRCA2 Gene

A tumor suppressor gene involved in homologous recombination DNA repair; frameshift mutations such as 6174delT increase susceptibility to inherited early-onset breast and ovarian cancers.

Amyloid Plaques

Extracellular protein deposits characteristic of Alzheimer's disease, formed by the aggregation of $A\beta$ peptides produced via Sequential cleavage of APP by $\beta$-secretase and $\tau$-secretase.

Neurofibrillary Tangles

Intracellular protein structures found in Alzheimer's disease neurons, composed of paired helical filaments of hyperphosphorylated Tau protein.

Zolgensma

An FDA-approved gene replacement therapy that uses an adeno-associated virus (AAV) vector to deliver functional SMN1 cDNA to treat spinal muscular atrophy in pediatric patients.