The Genetic Code and Transcription

Flashcards covering key vocabulary and concepts from the Genetics lecture, focusing on the genetic code and transcription.

Transcription

The process where DNA gene sequences are copied into RNA molecules.

Translation

The process where RNA molecules are used to create protein molecules.

Genotype

The DNA gene sequences that code for RNA.

Phenotype

The proteins and RNA produced from genes, resulting in a trait or function.

Codon

A sequence of three nucleic acids that codes for an amino acid.

Stop Codons

Codons that signal the end of translation (UGA, UAA, UAG).

Start Codon

A codon that signals the start of translation and codes for methionine (AUG).

Reading Frame

The correct sequence of codons that must be translated to synthesize proteins correctly.

Promoter

Sequence that recruits RNA polymerase to start transcription.

Terminator

Sequence that signals the end of transcription.

TATA Box

A region in the promoter sequence rich in T and A nucleotides.

Transcription Factors

Proteins that bind upstream of the transcription start site at a TATA box and recruit RNA polymerase.

RNA Polymerase

Adds nucleotides complementary to the template strand of DNA in the 5’ to 3’ direction during elongation.

Non-template Strand (Coding Strand)

The strand of DNA with the same sequence as the RNA transcript (except with U instead of T).

Polyadenylation Signal (AAUAAA)

Sequence in eukaryotes that signals termination and polyadenylation.

5’ Cap

Enzymes place a modified guanine nucleotide on the 5’ end of the mRNA.

Functions of the 5’ Cap

Protects the mRNA from degradation, promotes mRNA export, and promotes translation.

Cleavage enzyme related to Poly A tail

An enzyme binds to the polyadenylation signal (AAUAAA) and snips the end off of the mRNA molecule.

Polyadenylate Polymerase

An enzyme that adds between 100-200 “A” nucleotides to the 3’ end of the mRNA.

Functions of the 3’ Poly A Tail

Protects the mRNA from degradation, promotes mRNA export, and promotes translation.

Exons

Segments of RNA sequence that are maintained in the transcript; include coding regions for translation.

Introns

Intervening noncoding sequences interspersed between exons that are removed during splicing.

Spliceosomes

Complexes made of snRNA and snRNPs that carry out splicing.

snRNA

Small nuclear RNAs.

snRNPs ('snurps')

Small nuclear ribonucleoproteins that are part of spliceosomes.

Alternative Splicing

To yield different proteins from a single gene, this process can be directed by introns.

RNA Modifications

Enzymes alter the chemical structure of specific nucleotides within the RNA.

RNA Polymerase I

Generates certain rRNA in the nucleolus.

RNA Polymerase II

Generates mRNAs and certain non-coding RNAs.

RNA Polymerase III

Generates tRNAs and certain rRNAs.