Question

Prokaryotic mRNA usually encodes for more than one protein while eukaryotic mRNA a single protein. Eukaryotic DNA is linear and bacterial and archaeal DNA is-linear. In prokaryotes, ribosomes attach to the mRNA and start protein synthesis even before transcription is completed. Eukaryotic mRNA, rRNA, and tRNA are all highway processed. Nuclear pore complexes control the entry and exit to and from the nucleus. They will not let mRNA exit the nucleus before it is full processed. Eukaryotic and archaeal DNA is associated with a large number of proteins whereas bacterial DNA is associated with few proteins. The cells that have the enzyme telomerase never run out of their telomere sequences. Prokaryotic ribosomes subunits do not add up. The direction of RNA synthesis is 5' to 3' in eukaryotes and prokaryotes. Eukaryotic RNA poymerases require transcription factors to find and bind to the promoter region. Which one of the following is incorrect about the genetic code? It is non-overlapping It is degenerate There is a single three-letter code per each amino acid It is fairly universal It is a triplet code Which one of the following is incorrect about DNA polymerase III? It also has 5' to 3' exonuclease activity It has 3' to 5' exonuclease activity to remove incorrectly placed nucleotides during elongation It is the major polymerase responsible from the bulk of DNA replication It functions in the nucleus It has 5' to 3' polymerase activity Which one of the following is incorrect about DNA? The non-coding regions of DNA has important regulatory functions. It is either in the nucleus (eukaryotes) or is localized to a certain area in the cell (prokaryotes) The number of base pairs in DNA shows great variation from one organism to the other It is replicated during the M phase of the cell cycle A very small percentage of DNA is actually expressed into protein Which one of the following is incorrect about DNA damage and repair? DNA is routinely damaged due to different factors like UV radiation Damaged area is removed by repair endonucleases The segment of DNA removed by repair endonucleases is repaired by DNA polymer in 3' to 5' direction using the intact strand as the template Damaged DNA is routinely detected and repaired If the detection and repair of mechanisms foil, we may end up with mutations or cancer

Answer 1

2. Eukaryotes have a double helical supercoiled DNA inside the nucleus. However, mitochondrial DNA, if present, is always circular in eukaryotes.

In prokaryotes such as archaea and bacteria, the DNA is circular and present inside the nucleoid.

9. RNA synthesis in both the eukaryotes and prokaryotes happens in 5' to 3' direction because the initiation of transcription mechanism is similar in both.

12. DNA pol 3 does not have a 5' to 3' exonuclease activity. This is because the polymerase activity and the exonuclease activity happens in opposite direction. The DNA pol 3 polymerase activity happens in 5' to 3' direction while the exonuclease activity happens in the 3' to 5' direction.

13. The non-coding areas of DNA i.e. the introns do not have direct regulatory functions. However, SNPs present in INTRONS in some cases such as aspirin-intolerant asthma can have the indirect effect.