Protein Synthesis and Course Policies Vocabulary

Vocabulary flashcards covering concepts of protein synthesis including transcription, mRNA processing, translation, cellular structures, and related mechanisms from the lecture transcript.

Transcription

The first step of protein synthesis that physically takes place in the nucleus of the cell.

Transcription Factor

A regulatory protein activated by a cellular stimulus that translocates into the nucleus and binds to a specific spot on the DNA strand upstream of a target gene.

Histone

Spool-like proteins around which DNA is wrapped and cross-linked to keep it safe and inactive.

Helicase

A non-specific enzyme that acts as an unzipper by separating two DNA strands approximately $15$ to $20$ base pairs ahead of the RNA polymerase.

RNA Polymerase

A non-specific enzyme that acts as a copy machine to read open DNA sequences and transcribe them into RNA.

Messenger RNA (mRNA)

The reverse complement single-stranded copy of a DNA gene sequence that carries genetic information out of the nucleus.

Transcription Terminator

A discrete mechanism, such as a hairpin loop on DNA or a protein-attracting RNA sequence, that physically impedes RNA polymerase and releases the DNA and newly made RNA.

Poly-A Tail

A stretch of roughly $200$ adenine nucleotides added to the tail end of mRNA to protect it from enzymatic degradation.

Seven-Methylguanosine Cap (7-mg Cap)

A modified cap added to the leading end of mRNA that protects against enzymatic degradation and acts as a homing beacon for the ribosome.

Splicing

The process of cutting out unneeded mRNA sequences and rejoining the remaining exon segments before translation.

Chaperone Proteins

Proteins that attach to fragile mRNA molecules to guide and protect them as they migrate to the ribosome.

Rough Endoplasmic Reticulum (Rough ER)

An organelle studded with ribosomes where mRNA arrives via simple diffusion to undergo translation.

Ribosomal RNA (rRNA)

The nucleic acid type that forms the structural bulk of the two subunits of a ribosome.

Codon

A three-nucleotide reading sequence on messenger RNA that codes for a specific amino acid.

Start Codon

The specific mRNA sequence $AUG$ where translation begins, which codes for the amino acid methionine.

Transfer RNA (tRNA)

A clover-shaped RNA molecule that delivers a specific amino acid to the ribosome based on its anticodon sequence.

Anticodon

A three-nucleotide sequence on a tRNA molecule that forms a reverse complement with a corresponding mRNA codon.

Stop Codon

One of three specific three-base mRNA sequences that lack a corresponding tRNA, allowing water to enter and terminate polypeptide chain synthesis.

Polypeptide Chain

The newly assembled string of amino acids released upon completion of mRNA translation before post-translational processing.

Golgi Apparatus

The cellular organelle (also called the Golgi complex) where newly formed polypeptide chains are transported in temporary vesicles for processing.