Chapter 17: From Gene to Protein

Comprehensive vocabulary flashcards covering the key terms, mechanisms, and molecular components of transcription, RNA processing, and translation from Chapter 17 (From Gene to Protein).

Gene Expression

The process by which DNA directs protein synthesis, consisting of two main stages: transcription and translation.

Transcription

The synthesis of RNA using information in DNA, producing messenger RNA (mRNA).

Primary Transcript

The initial RNA molecule (transcript) synthesized from any gene prior to RNA processing.

Translation

The synthesis of a chain of amino acids, forming a polypeptide, using information encoded in mRNA.

Central Dogma

The concept that genetic information in cells flows through a cellular chain of command: $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{protein}$.

Template Strand

The one DNA strand that always runs in the $3' \rightarrow 5'$ direction and provides the template for ordering the sequence of complementary nucleotides in an RNA transcript.

Coding Strand

The non-template DNA strand that contains the identical nucleotide sequence to the RNA strand, except uracil (U) substitutes for thymine (T) in RNA.

Codon

A series of nonoverlapping, three-nucleotide codes in mRNA that specify a particular amino acid to be placed along a polypeptide chain or signal translation termination.

Reading Frame

The correct grouping of codons read in the $5' \rightarrow 3'$ direction during translation to synthesize the intended protein.

RNA Polymerase

An enzyme that pries the DNA strands apart and bonds RNA nucleotides together during transcription.

Promoter

The DNA sequence where RNA polymerase attaches and signals the transcriptional start point, usually extending several dozen nucleotide pairs upstream.

Transcription Unit

The stretch of DNA that is transcribed into an RNA molecule.

Transcription Factors

Regulatory proteins that assist the binding of RNA polymerase to DNA to initiate transcription.

Transcription Initiation Complex

The completed assembly of transcription factors and RNA polymerase II bound to a promoter.

TATA Box

A eukaryotic promoter DNA sequence composed of adenines and thymines that is crucial in forming the transcription initiation complex.

Terminator

A DNA sequence in bacteria that signals the end of transcription, causing RNA polymerase to release the mRNA without further modification.

Polyadenylation Signal Sequence

A eukaryotic RNA sequence ($\text{AAUAAA}$) transcribed by RNA polymerase II that directs the RNA transcript to be released $10\text{--}35$ nucleotides downstream.

5' Cap

A modified nucleotide added to the $5'$ end of a pre-mRNA molecule during post-transcriptional RNA processing.

Poly-A Tail

A chain of adenine nucleotides added to the $3'$ end of a pre-mRNA molecule during RNA processing.

Introns

Noncoding, intervening stretches of nucleotides located between coding segments in eukaryotic genes and primary transcripts that are excised during RNA splicing.

Exons

Coding regions of eukaryotic genes and primary transcripts that remain after splicing and are expressed into a polypeptide.

RNA Splicing

The stage of RNA processing that cuts out noncoding introns and joins exons together, yielding an mRNA with a continuous coding sequence.

Spliceosome

A large complex consisting of proteins and small nuclear ribonucleoproteins (snRNPs) that carries out pre-mRNA splicing by recognizing splice sites and excising introns.

Ribozymes

Catalytic RNA molecules that function as enzymes to carry out biological reactions, such as self-splicing.

Alternative RNA Splicing

A regulatory mechanism where different segments of a primary transcript are treated as exons during splicing, allowing a single gene to encode multiple distinct polypeptides.

Essential Amino Acids

The $9$ amino acids that cannot be synthesized by the human body and must be acquired through the diet.

Transfer RNA (tRNA)

A single RNA strand about $80$ nucleotides long that transfers specific amino acids to a growing polypeptide chain within a ribosome.

Anticodon

A triplet of nucleotides on a tRNA molecule that base-pairs complementarily with an mRNA codon.

Aminoacyl-tRNA Synthetase

An enzyme that catalyzes the covalent attachment of a specific amino acid to its corresponding tRNA molecule using ATP.

P Site (Peptidyl-tRNA Binding Site)

The ribosomal binding site that holds the tRNA carrying the growing polypeptide chain.

A Site (Aminoacyl-tRNA Binding Site)

The ribosomal binding site that holds the incoming tRNA carrying the next amino acid to be added to the growing chain.

E Site (Exit Site)

The ribosomal binding site where discharged tRNAs without amino acids leave the ribosome.

Release Factor

A protein that binds directly to the stop codon in the A site of the ribosome, adding a water molecule instead of an amino acid to release the finished polypeptide.

Polyribosome (Polysome)

A cluster of several ribosomes translating a single mRNA molecule simultaneously, allowing rapid production of multiple copies of a polypeptide.

Signal Peptide

A sequence of leading amino acids on a growing polypeptide that targets the ribosome-polypeptide complex to the endoplasmic reticulum.

Signal-Recognition Particle (SRP)

A protein-RNA complex that recognizes and binds the signal peptide, escorting the ribosome and growing polypeptide to a receptor protein on the ER membrane.

Gene

A region of DNA that can be expressed to produce a final functional product, either a polypeptide or an RNA molecule.