mRNA Processing and Protein Synthesis in Eukaryotes

mRNA processing

Modification of mRNA in eukaryotes post-transcription.

split genes

Genes containing both introns and exons.

exons

Expressed sequences of genes that code for proteins.

introns

Intervening sequences that are removed from mRNA.

5' capping

Addition of guanylyl residue to mRNA's 5' end.

heterogeneous nuclear RNA (hnRNA)

Newly transcribed RNA before processing occurs.

methylation

Modification of guanine at the 7-position.

3' polyadenylylation

Addition of adenine residues to mRNA's 3' end.

polyadenylylation signal

AAUAAA sequence indicating polyadenylylation site.

endonuclease

Enzyme that cleaves mRNA during polyadenylylation.

poly(A) polymerase

Enzyme adding 100-200 adenines to mRNA.

pre-mRNA

RNA with 5' cap and 3' poly-A tail.

spliceosome

Complex that splices pre-mRNA into mature mRNA.

splicing mechanism

Precise process of removing introns from pre-mRNA.

genetic code

System translating mRNA codons into amino acids.

adapter molecule

Molecule facilitating interaction between mRNA and amino acids.

tRNA

Transfer RNA reading mRNA codons and carrying amino acids.

triplet code

Three-base sequence coding for one amino acid.

start codon

AUG, initiating protein synthesis and encoding methionine.

stop codons

Codons signaling termination of protein synthesis.

codon degeneracy

Multiple codons can encode the same amino acid.

universal codons

Shared coding system across all organisms.