Translation

• Amino acids are the building blocks of proteins and have a central C (with H) amino group and carboxyl group.
• The R group in an amino acid determines its chemical properties and amino acids are usually ionized.
• Translation in prokaryotes can initiate at multiple locations on the mRNA, allowing for polycistronic mRNA that codes for several polypeptides.
• In prokaryotes, translation can initiate at multiple locations on the mRNA, allowing for polycistronic mRNA that codes for several polypeptides.
• Amino acids are categorized by whether the R group is hydrophobic or hydrophilic, and polar, non-polar, charged (acidic,basic).
• Proteins are formed by peptide bonds between amino acids, which are formed by dehydration synthesis.
• The shape of a protein determines its function and protein structure is defined at four levels: primary, secondary, tertiary, and quaternary.
• An example of protein shape/function is Sickle cell disease.
• Denaturation is a change in a protein’s structure that usually renders it biologically inactive due to changes in temperature, pH, ionic concentration, etc.
• The Gene is a sequence of DNA that codes for a protein.
• Transcription is the synthesis of mRNA from DNA.
• Translation is the synthesis of protein from mRNA.
• Codon is a 3 nucleotide sequence that specifies a particular amino acid.
• 61 codons code for the 20 amino acids and 3 codons signal “stop”.
• AUG (Met) signals “start”.
• mRNA is read 5’ to 3’.
• Ribosome translocates during elongation, tRNA in A site moved to P site.
• Termination in translation involves stop codon, A site accepts release factor instead of a charged tRNA, and breaks bond between tRNA and protein.
• The complex reaches an AUG, the large ribosomal subunit joins, placing the initial tRNA at the P site.
• tRNA structure includes a specific amino acid attached to 3’ end, anticodon, which is a sequence of 3 nucleotide bases that is the complement of an mRNA codon, and charging, which is when tRNA is matched to appropriate amino acid by aminoacyl-tRNA synthetase enzymes.
• Repeat for next codon during elongation.
• Empty tRNA in P site moves to E site, released during elongation.
• The genetic code is degenerate, meaning that some amino acids are specified by more than one codon.
• Initiation factors release during translation.
• Initiation in translation involves Small ribosomal subunit and Initiator tRNA (carrying Met) and scanning the mRNA for an AUG codon and binding to the mRNA.
• Types of transcribed RNA include Messenger RNA (mRNA), which carries information for making a protein from DNA to ribosome, Small nuclear RNA (snRNA), part of spliceosomes, Ribosomal RNA (rRNA), part of ribosomes, Transfer RNA (tRNA), which brings amino acids to ribosome during translation, Micro-RNA (miRNA) & small interfering RNA (siRNA), which are very small and their role is related to control of gene expression, and Small nuclear RNA.
• Ribosomes have 3 tRNA binding sites: A, which holds tRNA carrying next amino acid to be added, P, which holds tRNA carrying growing protein, and E, which is tRNA exit site.
• The genetic code is universal.
• Components dissociate and are reused during termination.
• Elongation in translation involves charged tRNA with matching anticodon entering A site, and peptide bond formed between new amino acid and growing protein.
• The genetic code is specific.
• tRNA becomes charged by animoacyl-tRNA sythase enzymes