Genetic Expression: Transcription and Translation

Vocabulary flashcards covering key concepts of transcription, translation, mutations, and eukaryotic vs. prokaryotic gene expression.

Gene expression

The process by which DNA directs the synthesis of proteins, serving as the essential link between genotype and phenotype.

Template strand

The specific DNA strand that is read in the $3'$ to $5'$ direction during transcription to serve as a pattern for ordering complementary nucleotides in an RNA transcript.

Coding strand

The non-template DNA strand whose nucleotide sequence is identical to the synthesized mRNA transcript, with uracil replacing thymine.

Promoter

A DNA sequence region located upstream of a gene that signals the transcription start point and initiates transcription.

TATA box

A specific eukaryotic promoter DNA sequence located upstream of the start point that plays a crucial role in forming the transcription initiation complex.

Transcription factors

Specialized regulatory proteins that bind to promoter regions such as the TATA box to guide and facilitate the binding of RNA polymerase.

RNA polymerase

An enzyme that pries apart the DNA double helix and synthesizes an RNA transcript complementary to the DNA template strand in the $5'$ to $3'$ direction.

Polyadenylation signal

A specific sequence on the template strand (such as TTATTT in eukaryotes) that signals the termination of transcription and causes the release of RNA polymerase.

Ribosome

A cellular structure composed of ribosomal RNA (rRNA) and proteins that carries out translation in the cytosol or attached to the rough endoplasmic reticulum.

Codon

A series of three consecutive nucleotides in mRNA that specifies a particular amino acid or signals translation termination.

Transfer RNA (tRNA)

An RNA interpreter molecule that carries a specific amino acid at one end and an anticodon triplet complementary to an mRNA codon at the other end.

Anticodon

A specific triplet of bases on a tRNA molecule that base-pairs with a complementary triplet codon on an mRNA strand.

Start codon

The mRNA codon AUG that signals the initiation of protein translation and specifies the amino acid methionine.

Point mutation

A mutation that involves a change in a single nucleotide pair within a gene.

Missense mutation

A nucleotide-pair substitution that alters a codon so that it codes for a different amino acid than the original sequence.

Nonsense mutation

A point mutation that converts an amino acid codon into a stop codon, usually generating a truncated and nonfunctional protein.

Silent mutation

A change in a nucleotide pair that transforms one codon into another codon specifying the exact same amino acid, resulting in no effect on the protein.

Decoupling of transcription and translation

The spatial separation in eukaryotic cells where transcription occurs in the nucleus and translation occurs in the cytoplasm, unlike in prokaryotes where both occur simultaneously in the cytoplasm.

Thymine vs. Uracil chemical roles

Thymine provides long-term stability suitable for permanent DNA storage, whereas uracil is utilized for temporary RNA messenger transcripts.

Central Dogma

The universal information flow pathway shared across cellular life where genetic information flows from DNA to RNA to protein.