Molecular Biology
Translation
Actual synthesis of a protein under the direction of mRNA.
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mRNA is translated into the amino acid sequence of a protein
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mRNA- template for translation (information)
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Ribosome- coordinate recognition & catalyze bond formation
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tRNAs- physical interface between amino acid & codon
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Aminoacyl-tRNA synthetases- Couples amino acid to tRNAs
mRNA: "messenger" RNA
Carries the code for protein from DNA
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Codon: an ordered series of 3 nucleotide-long unit in the protein coding region of the mRNA or DNA

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Open Reading Frame (ORF): protein coding region of mRNA located within the mRNA
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Start Codon: 1st amino acid; defines the reading frame
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Stop Codon: Termination; defines the end of the ORF
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tRNA: "transfer"RNA
Transports amino acids to ribosomes during translation
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Provides the physical interface between the amino acids being added to the growing polypeptide chain & the codons in the mRNA

rRNA: Ribosomal ribonucleic acid or Ribosomal RNA
RNA component of the ribosome
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Structural component
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Directly responsible for the key functions of the ribosome
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provides a mechanism for decoding mRNA into amino acids
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interacts with tRNAs during translation by providing peptidyl transferase activity
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Prokaryotes- Ribosome-binding site (RBS)
Eukaryotes- 5' cap
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Untranslated Region (UTR): untranslated sequences located in eukaryotic mRNA
Ribosome:
RNA + Proteins= functional ribosome
Composed of 2 Subunits:
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Large Subunit: contains the peptidyl transferase center for the formation of peptide bonds
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Small Subunit: contains the decoding center for charged tRNAs read or decode the codon units of the mRNA

Aminoacyl-tRNA Synthetases:
"Charging" the tRNA with the amino acid
Enzyme that catalyst of the esterification of a specific amino acid to 1 or more its compatible cognate tRNAs to form an aminoacyl-tRNA.
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Amino acid react with ATP to become adenylylated with the release of AMP- Adenyllation of amino acid
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Transfer of the adenylylated amino acid to tRNA

Translation Steps
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Initiation
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Formation of an initiation complex in which the ribosome is bound to the specific initiation (start) site on the mRNA while the initiator tRNA is annealed to the initiator codon & bind to the ribosome
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Elongation
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Amino acids join to the growing polypeptide chain according to the sequence specified by the mRNA.
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Same steps are repeated over & over again until the termination codon is reached in the mRNA.
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Termination
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Termination codon gives the signal to release the ready-made protein from the ribosome.
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Ribosome Recycling
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Critical last step in translation after the release of the polypeptide chain
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