29 Questions
What is the function of the 3'OH end of the primer in DNA replication?
To provide a nucleophilic attack site for the incoming nucleotide
What is the direction of DNA replication in the leading strand?
Continuous
What is the function of SSBPs in DNA replication?
To protect single-stranded DNA from degradation
What is the function of the dnaA gene product?
To recognize the origin of replication
What is the function of DNA topoisomerase in DNA replication?
To relax DNA supercoils
What is the direction of DNA replication in the lagging strand?
Discontinuous
What is the primary function of RNA polymerase during transcription?
To add ribonucleotide units to the 3'OH end of the RNA chain
What is the term for the DNA sequence that corresponds to the first RNA nucleotide added by RNA polymerase?
Start cite (+1)
What is the region of DNA that is close to the promoter?
Proximal region
What is the term for the DNA sequence that does not code for an RNA?
Intron
What is the direction of RNA synthesis during transcription?
5'-3' direction
What is the frequency of error made by RNA polymerase during transcription?
1 error per 10^4-10^6 nucleotides
What is the primary function of guanidine isothiocyanate in RNA isolation?
To denature proteins and eliminate RNase activity
What is the purpose of adding a buffer such as Tris-HCl during tissue homogenization?
To maintain a stable pH and optimize enzymatic activity
Which of the following is NOT a method of surface decontamination?
Incubation at 37°C
What is the primary mechanism by which chaotropic agents like guanidine isothiocyanate disrupt protein structure?
By disrupting non-covalent interactions
What is the purpose of adding a reducing agent like β-mercaptoethanol during tissue homogenization?
To reduce the activity of RNases and other enzymes
What is the primary function of monovalent cations like sodium and potassium during nucleic acid precipitation?
To alter the solubility of nucleic acids and facilitate precipitation
What is the primary function of the enzyme responsible for adding approximately 20 nucleotides of DNA to the RNA primer during elongation in eukaryotes?
to extend the RNA primer
What is the role of the accessory protein that holds DNA polymerase tightly to the template in eukaryotes?
to control the processivity of DNA polymerase
What is the purpose of the 23 bp consensus sequence in termination of replication?
to bind the ter protein
What is the error rate of DNA polymerase due to pre-synthetic error control?
once every 10^4-10^5
What is the overall observed spontaneous mutation rate in bacteria?
10^-9-10^-10
What is the correct statement about DNA replication in eukaryotes?
no eukaryotic DNA polymerase has 5' → 3' exonuclease activity
What is the primary function of the 7-methylguanosine cap at the 5'-end of the mRNA?
To prevent degradation of the mRNA
What is the primary function of the poly-A tail at the 3'-end of the mRNA?
To stabilize the mRNA
What is the enzyme responsible for adding the 7-methylguanosine cap to the 5'-end of the mRNA?
Guanylyl transferase
What is the purpose of the AAUAAA conserved sequence in polyadenylation?
To direct polyadenylation
What is the consequence of having multiple polyadenylation sites in a single transcript?
Variability in protein expression
This quiz covers the steps involved in nucleic acid isolation, including preparation of DNase/RNase-free materials, sterilization methods, and general steps in NA isolation.
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