Splicing & Exporting RNA & Reading the Genetic Code

Flashcards covering key vocabulary terms from the lecture notes.

Splicing

Process that occurs in eukaryotic cells where introns are removed from pre-mRNA and exons are joined to form mature mRNA.

snRNA

Small nuclear RNA molecules that complex with proteins to form snRNPs and are involved in splicing.

Spliceosome

A large complex composed of snRNPs that catalyzes the splicing of pre-mRNA.

Exon

Expressed sequences in eukaryotic genes that are interspersed with non-coding regions called introns.

Intron

Intervening sequences in eukaryotic genes that are removed during RNA splicing.

Lariat

A loop-like structure formed during splicing when an intron is excised.

Cryptic splice site

Sequences within pre-mRNA that are similar to splice site consensus sequences and can be mistakenly selected during splicing.

Exon junction complex (EJC)

A protein complex that marks a newly completed splicing event.

RNA exosome

A complex that degrades RNA in the nucleus.

Nuclear transport receptor

Proteins that help guide completed RNA through channels in the nuclear membrane, created by nuclear pore complex proteins.

Ribosome

A protein-synthesizing machine that directs the elongation of polypeptides and is composed of rRNA and proteins.

rRNA

Ribosomal RNA; a type of RNA that is a component of ribosomes.

Svedberg unit (S)

A measure of the sedimentation rate during centrifugation, affected by both mass and shape of a molecule.

Nucleolus

A nuclear structure where rDNA clusters come together and ribosome biosynthesis occurs.

snoRNA

Small nucleolar RNAs; associated with proteins to form snoRNPs and involved in rRNA processing.

tRNA

Transfer RNA; responsible for decoding mRNA to create proteins and carries specific amino acids.

Codon

A set of three nucleotides that 'codes' for a single amino acid.

Reading frame

The way a nucleotide sequence is divided into codons for translation.

Frameshift mutation

A mutation that changes which reading frame is used, leading to a different sequence of amino acids.

Wobble base-pairing

The flexibility in codon/anti-codon pairing at the third base position, allowing a single tRNA species to base pair with more than one codon.

Aminoacyl-tRNA synthetase

The enzyme that catalyzes charging a tRNA with an amino acid.

Ribozyme

An RNA molecule that has catalytic activity.

Silent mutation

A mutation that alters the nucleotide sequence but still encodes the same amino acid.

Nonsense mutation

A mutation that leads to a stop/termination codon.