bio172

cDNA

DNA synthesized from mRNA using Reverse Transcriptase; represents only the expressed, exon-only parts of a genome.

Retrotransposon (LINEs)

"Jump" via an RNA intermediate; they code for Reverse Transcriptase and Integrase to insert themselves into new genomic locations.

Telomerase

An enzyme that extends the ends of linear chromosomes (telomeres) using its own RNA template.

Open Reading Frame (ORF)

A sequence of DNA that begins with a start codon and ends with a stop codon, potentially coding for a protein.

AAV (Adeno-Associated Virus)

A gene therapy vector where the therapeutic DNA stays episomal (does not integrate) and is not replicated by the host.

RTV (Retrovirus)

A vector that integrates the therapeutic gene into the host genome, allowing for permanent expression in dividing cells.

CRISPR-Cas9

A system using a gRNA to target a specific DNA sequence and Cas9 to create a double-strand break for editing.

Complementation

Adding a functional copy of a gene to a cell to "fix" the phenotype caused by a recessive loss-of-function mutation.

Proofreading

DNA Polymerase’s ability to detect and fix a mismatched base during replication (3′→5′ exonuclease activity).

Mismatch Repair (MMR)

A repair system that fixes errors missed by proofreading after replication is complete.

Thymine Dimers

Covalent links between adjacent Thymines caused by UV light; repaired by Nucleotide Excision Repair.

Germline vs. Somatic

Mutations in germline cells are passed to offspring; somatic mutations stay within the individual.

Alternative Splicing

Producing different mRNA isoforms from a single gene by including/excluding different exons; increases protein diversity.

miRNA & RISC

Small RNAs that pair with the RISC complex to target and degrade specific mRNAs or inhibit their translation.

Ubiquitin-Proteasome Pathway

Proteins are "tagged" with ubiquitin by ubiquitin ligase and sent to the proteasome for degradation.

Kinase / Phosphatase

Enzymes that add (kinase) or remove (phosphatase) phosphate groups, often acting as "on/off" switches for protein activity.

Chromatin Remodeling

The process of changing chromatin structure (condensed vs. open) to allow or prevent access to DNA for transcription.

Histone Acetylation (HAT)

Addition of acetyl groups to histone tails by HATs; neutralizes positive charge, loosening DNA-histone binding (Promotes Transcription).

Histone Deacetylation (HDAC)

Removal of acetyl groups by HDACs; makes DNA wrap tighter around histones (Represses Transcription).

Regulatory Transcription Factors

Proteins that bind to enhancers or silencers to control the rate of transcription for specific genes in specific cells.

Mediator Complex

A large protein complex that acts as a bridge between regulatory TFs (at enhancers) and general TFs/RNA Polymerase at the promoter.

X-Inactivation

The process in female mammals where one X chromosome is condensed into a Barr body to equalize gene dosage.

Endomembrane System

A group of membranes/organelles (ER, Golgi, Lysosomes, Nuclear Envelope) that work together to modify, package, and transport lipids and proteins.

Signal Sequence

An amino acid sequence that directs a protein to its specific destination (e.g., the ER or mitochondria).

Signal Recognition Particle (SRP)

A protein-RNA complex that recognizes the signal sequence on a nascent protein and directs the ribosome to the ER.

Nuclear Pore

Large protein complexes that cross the nuclear envelope, allowing selective transport of RNA out and proteins (like TFs) in.

Topology

The orientation of a protein relative to the membrane; determined during translocation into the ER.