Chapter 37- Translation Flashcards
How many nucleotides and coat proteins does the Tobacco necrosis satellite virus have?
Has 1200 nucleotides coding for 400 protein ( 1200/400 = 3)
DNA polymerase that polymerizes DNA from an RNA template
Reverse Transcriptase
What was the observation in bacteriophage T4?
That deletion of one or 2 base pairs resulted to synthesis of wrong proteins but deletion of 3 base pairs nagkukulang ng isang protein
What is the codon for Start?
AUG = methionine
What is the codon for STOP?
UAA, UAG, UGA
What are the chars of Genetic Code?
- Degeneracy - which can be found at 3rd bp
- Unambiguous - codon codes for only ONE AA
- Nonoverlapping - read in a continuous manner
- Universal - except for (some) mitochondrial DNA
What is the role of eIF 3 and eIF 1A?
delays the reassociation of the 43s to the 80s complex
When is eIF-2alpha phosphorylated?
When the cell is stressed or when the energy expenditure required for protein synthesis is deleterious
How does phosphorylation of eIF-2alpha blocks protein synthesis?
by binding tightly and inactivating the GTP-GDP recycling synthesis thus preventing formation of preinitiation complex
Where does the 3’ acceptor binds to?
Binds to the amino acid
What does the Ribothymidine pseudouridine cytidine arm binds to?
Binds the aminoacyl-tRNA to ribosomal surface
What is the function of the D arm?
One of the sites needed for recognition of accurate aminoacyl-tRNA synthetase
What is the function of the anticodon arm?
recognizes the codon of mRNA
Importance of WOBBLE position
Since the 1st and 2nd bp are highly specific, wobble position allows recognition of different codons coding for the same protein
Components of the cap binding protein complex (eIF-4F)
eIF -4E, eIF-4G-eIF4A complex
Initiation sequence for translation
Kozak consensus sequence
What is the action of peptidyltransferase?
Catalyzes peptide formation between alpha-amino group od new aminoacyl-tRNA in site A with the esterfied carboxyl group of the peptidyl-tRNA in the P site
What is the function of release factor RF1?
Recognizes stop codon
Component of RF1?
Release factor RF3 and GTP
Function of the signal peptide?
it prompts the transport mechanism to bring it to its specific destination
Multiple ribosomes on the same mRNA molecule?
Polysome
Importance of the polysome?
The proteins they synthesize maybe free or bound to RER. This proteins are extruded into the cisternal space then exported.
sdfs
sdfsdf
How does eIF-2A regulate translation?
Tight binding to eIF-2B prevents GTP-GDP recycling thus no formation of preinitiation complex—> defence against viruses or energy conservation mech during stress or nutrient deprivation
How does the Phosphorylation of 4E protein regulate translation?
Activation: increased binding of 4E to mRNA cap = enhanced protein synthesis *stimulated by synthesis + mitogenic growth factor
Inactivation via BP1(BP2 or BP3)
Is the inactivation of 4E by BP1 reversable? if yes how?
Yes by insulin
Rate limiting step in translation?
Recognition of mRNA cap by 4E
What is the initiating amino acid of prokaryote? eukaryote?
pro: formyl-methionine
euk: methionine
Differentiate Transition Mutation from Transversion
Transition = Mutation wherein one base pair is converted from a purine to a purine (or pyrimidine to pyrimidine)
Transversion = Mutation wherein one base pair is converted from a purine to a pyrimidine (or pyrimidine to purine)
Type of mutation wherein the codon containing the changed base codes for the same amino acid
Silent mutation
Changed base codes for a different amino acid?
Missense Mutation
Cganged codon codes for a termination?
Nonsense mutation
Differentiate acceptable, partially acceptable and unacceptable missense?
Acceptable = fully functioning protein
Partially acceptable = functioning but with abnormality
Unacceptable = protein is non-functional
Define Splice Site mutation
Improper removal of introns could cause aberrant protein product
Medicine used in cases of meningitis and typhoid fever? Mech of action?
Chloramphenicol - inhibits peptidyltransferase
Med that prevents translocation (prevents movement of peptidyl-tRNA from the A to P site)
Erythromycin
Medicine that distorts A site thereby initiating misreading of code? What is its complication?
Streptomycin. In high dosage can cause hearing loss
A reversible drug that is concentrated on the gut rather than the intestine? Mech?
Tetracycline - prevents the binding of aminoacyl-tRNA to A site at 30s
Medicine that irreversibly binds to 30s subunit?
Aminoglycosides
What are interferons?
Proteins that are synthesized by virus-infected cells. They trigger antiviral protein
