BIS 2A Lecture Notes - Cytoskeleton, C-Terminus, Purine
Translation and Protein Synthesis
• Translation: mRNA into protein
o Requires ribosome binding site, translation initiation site (start codon) and
translation termination site (stop codon)
• Protein synthesis machinery
o General functions of the translation machinery are the same across species but
the composition of the components are not
▪ mRNA template and open reading frame (ORF), amino acids, ribosomes,
tRNAs, energy, enzymes and small molecules
o Ribosomes catalyze the process of translation
▪ Composed of structural and catalytic rRNAs and protein
▪ Found in cytoplasm of prokaryotes and cytoplasm/endoplasmic reticulum
of eukaryotes
• Mitochondria and chloroplasts also have ribosomes which are
similar to bacterial ribosomes
▪ Disassociated into small and large subunits and only assemble during
initiation of translation
▪ Catalyze formation of peptide bonds between amino acids
▪ Draw structure of ribosome and components of translation
o tRNAs physically pair amino acids with the correct codon
▪ Originally single-stranded RNA molecule that folded on itself and formed
stem loops (base-paired region)
• 3’ ed otais the attahed aio aid
• Loop structure contain the anticodon (complementary to the
codon on the mRNA)
• Draw one
▪ Aminoacyl tRNA synthetases: enzymes that attach the correct amino acid
to the tRNA
• Active site contains tRNA binding site which can recognize
anticodons and allosteric sites that can bind to reactants
• Bind and hydrolyze ATP to form amino acid-AMP bond
• Specific amino acid activated and transferred to tRNA and AMP
released
• Charged tRNA released from the active site
• Draw the process
o Energy source
▪ Requires external energy source: elongation factors hydrolyze GTP
• Advances the ribosome complex along the mRNA
▪ Peptidyl transferase: enzyme integrated in the large subunit that
catalyzes formation of peptide bonds between amino acids
• Formation of peptide bonds between amino acids (between
amino group of one and carboxyl group of another) involves
dehydration synthesis/condensation reaction
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