Protein Synthesis Flashcards
What is the complete set of proteins expressed in a cell
Proteome
Which codon is the start codon of translation?
AUG
What are the three termination codons
UAA
UAG
UGA
Which other enzyme has editing function apart from DNA polymerase?
Aminoacyl-tRNAs
The direction of RNA translation
5’ to 3’ direction
Translation begins at the
Start codon
Which codon codes for tryptophan?
UGG
Codons that code for amino acids are known as
Sense codons
The three stop codons are termed as
Nonsense codons
Leucine is coded for by how many different codons
6
What codes for methionine?
AUG
What is needed for protein synthesis?
Ribosome
Aminoacyl-tRNA
Mature mRNA
Soluble protein factors
Transcription is not coupled to translation in bacteria True /False
False
They are coupled
What codon is the first in protein synthesis?
Methionine codon
Why is the genetic code degenerate?
This is because more than one codon codes for each amino acid
Which codon codes for histidine?
CAU
What happens when there is a mutation in the first two nucleotides of a codon?
There is a change in the amino acid formed
The genetic code is not degenerate.True/ False
False
This is the change in the DNA sequence within a gene
Mutation
In which mutation is there a change in a single base pair of DNA?
Point mutation
In this type of mutation there is a change in DNA but protein expression is unaffected
Silent mutation
In this mutation, change in DNA leads to a change in an amino acid
mis-sense mutation
In this mutation,change in DNA creates a termination codon
Nonsense mutation
In this mutation, changes in DNA eliminates termination codon to add new sequences.
Read-through mutations
In this mutation, changes in DNA removes or introduce bases thereby change the frame of codon usage
Insertion or deletion mutations
Which amino acids have 6 codons that code for each of them?
Serine
Arginine
Leucine
The two parts of ribosomes
The small subunit
Large subunit
Protein translation is initiated on which subunit of ribosomes
The smaller subunit
The three binding sites of ribosomes
Aminoacyl-tRNA site
Peptidyl-tRNA site
Exit site
The movement of the ribosome one codon at a time is called
Translocation
The 3’ end of tRNA always has what kind of sequence?
CCA
20% of bases are covalently modified. True/False?
True
What are the adaptor molecules in translation?
tRNAs
Which component of ribosomes have catalytic activity
The rRNA component
Which drug confirms the presence of a tetrahedral intermediate being formed during protein synthesis?
Yarus inhibitor
Which drug leads to the termination of translation in both prokaryotes and eukaryotes?
Puromycin
What sequence is responsible for prokaryotes being considered as Polycistronic?
The Shine- Dalgarno sequence in the mRNA
How is formylmethionine able to find the correct AUG in prokaryotes?
The Shine-Dalgarno sequence forms complementary base pairs with the 3’ end of the 16S rRNA
How is the right AUG found by initiator methionine tRNA in eukaryotes?
By locating the Kozak consensus. This is because the AUG codon is found in the Kozak consensus
Due to the nature of the initiation signal on the mRNA, eukaryotes are considered as
Monocistronic
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IF3 is also know as
Dissociation factor
What is the function of IF3?
It binds to the small subunit of the ribosome to prevent the premature association of the 50S subunit
What is the function of IF1?
It binds to the A site of the ribosome
What is the function of IF2?
It binds to the fMet-tRNA and positions it at the P-site
What is the function of elongation factor Tu?
It binds to aminoacyl-tRNA with GTP to position the aminoacyl-tRNA at the A site.
What is the function of EF-Ts?
It displaces GDP from EF-Tu
What is the function of EF-G?
It promotes translocation by binding with GTP to the ribosome
What is the function of EF-G?
It promotes translocation by binding with GTP to the ribosome
What is the most abundant protein in bacteria?
EF-Tu
During termination in Prokaryotes Release Factor(RF) 1 recognizes which stop codons?
UAG and UAA
During termination in prokaryotes RF2 recognizes which stop codon?
UGA
What is the corresponding EF of EF-Tu in eukaryotes?
eEF1alpha
What is the corresponding EF of EF-Ts in eukaryotes?
eEF1B
What is the corresponding EF of EF-G in eukaryotes?
eEF2
Which release factor is the only factor that is used in protein termination in eukaryotes?
eRF1
How is translation regulated in eukaryotes?
When eEF-2 is phosphorylated
What substance inactivates eEF-2?
Diphtheria toxin
What is the function of release factor 3 of prokaryotes
It recognizes RF1 and RF3 and unbinds them from their stop codons
