• Only about 20 AA produced by sequence of 3 bases in mRNA called a codon

• Several Codons call for the same AA to be used during translation
  • ie: CUU, CUC, CUA, CUG encode leucine

• There is only 1 start codon: AUG (in most prokaryotes)

• UAA
• UAG
• UGA

• tRNAs aminoacetlyated: each carries specific amino acid
• Anticodon diversity< codon diversity

• Cytosine, uracil, or adenine (allows for degeneracy)

• it plus proteins form ribosome structure and translation occurs within this complex

• Serves as recipe for polypeptide chain

• Polypeptide is SLOWER than mRNA synthesis
  • transcription 900 residues per min
  • translation 110 residues per min

• Increases it by using polysomes
  • More than 1 ribosome translates the mRNA at same time
  • Results in multiple copies of polypeptide being produces per mRNA molecule.

• 70S whole ribosome (50S and 30 S subunits)

f- Met carried into ribosome by tRNA and binds to free 30 S subunit of rRNA

• positioned at what will become P-site of Active Ribosome Complex

mRNA attaches to 30S subunit

• It allighns itself so AUG intiator godon is @ translation domain of 30S subunit site
• Initiator codon complexes with complementary tRNA anti-codon (UAC)

Complete active ribosome complex forms

• mRNA binds to 50S subunit
• Energy required: GTP--> GDP + inorganic Phosphate (1ATP equivalent)

• Helps bind 30S and 50S subunits together
• Helps release IF-2/GDP from ribosome
• Blocks tRNA from binding to A site (aminoacyl site, also known as acceptor site)

• Used as an energy source with GTP (GDP produced)
• Makes sure fMet tRNA binds to P site

Transpeptidation occures between adjacent amino acids in P and A sites

• Elongation of Polypeptide chain
• Peptidyl transferase creates peptide bond between adjacent amino acids

the P-site

• Long polypep begin to exit ribosomes translational domain via e-site
• tRNA which have donated their amino acid also exit ribosome via e-site

• Only tRNA carring N-fmet binds here during initiation
• During elongation, growing chain is moved here

• Empty at start of translation
• Fills during elongation

• Also called translocase
• GTP used to 'move' the ribosome to next codon

• Require 1 GTP to bind to aminoacyl-tRNA in A site
• Require 1 GTP to translocate ribosome
• 2 GTP/codon of elongation

• No tRNA anticodons avaliable to undergo complementary binding to mRNA stop codons
• Translation stalls out

• Frees polypeptide and tRNA to leave ribosome

Ribosome subunits dissociate from 1 another and from mRNA

• Subunits remain as free entities in cyto
• IF-3 rebinds to 30 S subunit to keep them apart again.

Other ribosomes of polysome finish translating mRNA to stop codon

• After last ribosome finishes, mRNA can be degraded back to individual nucleotides by cytoplasmic nucleases

aid ribosome in recognizing the stop codons

specific roles currently undetermined

• 1 GTP to bind the initial N-fmet to P site
• 2 GTP/codon during elongation and translocation
• 1 GTP at termination

Native proteins under go folding

1. Exits ribosome in promary structure
2. folds into secondary and tertiary shapes
3. Joins other tert. proteins to produce quarternary structures

• DNaK and DnaJ
• GroEL and Gro ES
• GrpE

• DNaK and DnaJ

• GroEL and Gro ES

1. ATP/GTP hydrolysis
2. Proton Motive Force

• Occurs in Gram + and Gram -
• Transports only across cytoplasmic mem
• Transported as pre-proteins w/ single pep at N-term and then sec B chaperone recognizes signal

• Gram - and Gram + Bacteria
  • C term used for recog of new proteins
  • Spans cyto and outer membrane
• No sec-dependent transport needed
• Transports things other than proteins
• expels drugs from cyto

• Gram - only
• Common in pathogens
• Transports : cellulases, pectinases, proteases, lipases, toxins across outher membrane from periplasmic space by Sec-dependent and Tat pathways

• Gram - only
• Transports proteins periplasmic--> outer membrane
• uses sec-dependent
• some autotransporters, some require helper protein

• Gram - bacteria only
• Transports directly cyto--> cell exterior
• No sec needed
• Transports: toxins, phagocytosis inhibitors, apotopsis promoters, secretion reg. proteins

• Gram + and Gram - Bacteria
• Secretes both proteins and DNA from cyto--> outside cell

• Binding to 30S or 50S subunit- prevents active ribosome mRNA complex from ever forming and hence, prevent translation
• Interfering w/ ribosomes ability to bind to DNA, thus prevents transcription

• Binding to 30S or 50S subunit- prevents active ribosome mRNA complex from ever forming

• Interfering w/ ribosomes ability to bind to DNA

Eukaryotes have different types of rRNA subunits and RNA polymerases

• prokaryotic seq. in rRNA recognizable by antis not present in euk 
• Different polymerases