#Question id: 3820
#Unit 3. Fundamental Processes
Meselson and Stahlʹs experiments involved growing E. coli on a medium containing 15N (heavy nitrogen) which increased the density of the bacterial DNA. Cells were then grown on a medium containing only 14N. DNA samples were obtained for analysis after one, two and three rounds of replication (generations) and centrifuged on a density gradient. The double-helical DNA forms bands in the gradient depending on its density. How many bands did Meselson and Stahl see after two generation of cells were grown on the 14N medium?
#Question id: 3821
#Unit 3. Fundamental Processes
Which mechanism contributes to accuracy during DNA replication?
#Question id: 3822
#Unit 3. Fundamental Processes
State whether the following statements is true/false regarding DNA replication.
1. Proteins bind to both origin sites and termination sites on DNA during DNA replication.
2. In the Sanger method for DNA sequencing, the gels are read from bottom to top, since the smallest fragments travel farthest in the sequencing gel.
3. DNA polymerase I which is inhibited by dideoxynucleoside triphosphates is used in the Sanger method for DNA sequencing.
4. Sanger DNA sequencing requires inhibition of DNA polymerization by a specific dideoxynucleoside every time it is copied in the replication process.
5. The Klenow fragment can be used for DNA sequencing if proteins such as SSB protein are added.
#Question id: 3823
#Unit 3. Fundamental Processes
Regarding DNA replication and DNA synthesis, which, if any, of the following statements is incorrect?
#Question id: 3824
#Unit 3. Fundamental Processes
State whether the following statements is true/false regarding DNA replication.
1. The polymerization of DNA is essentially irreversible due to the hydrolysis of pyrophosphate.
2. On average about twenty errors are made during each replication of the human genome.
3. DNA polymerase I possesses 5ʹ → 3ʹ exonuclease activity.
4. All DNA ligase enzymes use ATP as a cosubstrate.
5. The purpose of SSB is to prevent single-stranded DNA from folding back on itself to form double-helical regions.
#Question id: 3825
#Unit 3. Fundamental Processes
Telomeres are the repetitive sequence of T's and G's that are present in the eukaryotes to protect the random cleavage from nucleases. These telomeres are synthesized by the enzyme telomerase. Which of the following are the properties of enzyme telomerase?