Protein processing Flashcards
What is the RNA start codon for translation and what does it code for?
AUG- Methionine
What are the three RNA stop codons
UAA, UAG, UGA
What is a silent mutation?
A mutation that does not result in a change in the amino acid
What is a missense mutation?
A mutation that results in a change in the AA that can either have no effect or drastic change in protein folding
What is a nonsense mutation?
A mutation that changes the codon to a stop codon resulting in premature termination of protein synthesis
What is a frameshift mutation?
A mutation that causes multiple changes to the codon sequence
What is the mutation in sickle cell anemia and the physiological effect?
Glu (hydrophilic) to Val (hydrophobic) at the human beta globin gene. This results in deformed proteins that are rod-like and will aggregate. These cells have poor oxygenation and will clog arteries.
What kind of mutation results in sickle cell anemia?
a missense mutation- Glu for Val- results in misfolded protein
What is Duchenne Muscular Dystrophy?
Dystrophin gene is dysfunctional due to an out of frame mutation- Leads to muscle wasting and death
What kind of mutation results in Duchenne Muscular Dystrophy?
An out of frameshift mutation that leads to non functioning dystrophin gene
What kind of mutation results in Becker Muscular Dystrophy?
An in frame mutation of the dystrophin gene that results in a truncated dystrophin protein
What two things are added to mRNA to “protect” the sequence?
5’cap and poly A tail
What is the secondary structure and two crucial sites of the tRNA?
Shaped like a cloverleaf with an anticodon region to pair with complementary strand and 3’CCA terminal region that binds the AA for corresponding codon
How do tRNAs become activated?
Through aminoacyl synthetases- uses ATP to bond tRNA to the COOH end of the AA
What are the ribosomal subunits in prokaryotes?
50S large subunit and 30S small subunit- 70s when combined
What are the ribosomal subunits in eukaryotes?
60s large subunit and 40s small subunit- 80s when combined
What are the three sites of ribosome complex?
A- acceptor
P- peptidyl
E- exit
What are the steps involved in the initiation process of protein synthesis? Name the proteins involved
Met-tRNA is bound to GTP and loaded into the p site of the small subunit of the ribosome- other TF are added- (eIFs for euk and IFs for prok)- The large subunit will then bind and translation begins.
What are the steps involved in the elongation process of protein synthesis? Name the proteins involved and bonds formed
Aminoacyl tRNA is bound to a GTP elongation factor then loaded into the A site of ribosome. GTP hydrolysis and release of factor occur then peptidyl transferase will form a peptide bond between AA of a site and p site.
What are the steps involved in the termination process of protein synthesis? Name the proteins involved
RFs will recognize the stop codon at A site of ribosome and bind. Cleavage of the ester bond between the c terminus of peptide chain and tRNA. This releases the protein and GTP hydrolysis causes complex to disassociate.
polysomes
cluster of ribosomes that will translate a strand of mRNA simultaneously. Allows for increased protein production
What is the effect of streptomycin on protein synthesis?
Binds to the 30s subunit of prokaryotes to disrupt initiation- fmet-tRNA binding and association of 50s and 30s subunits
What is the effect of Tetracycline on protein synthesis?
Binds to the 30s subunit of prokaryotes to disrupt elongation- prevents entry of animoacyl tRNA to ribosome complex
What is the effect of Chloramphenicol on protein synthesis?
inhibits peptidyl transferase during elongation (prokaryotes)
