Question

I-Upon heavy damage to the cell'S DNA, the normal y stall when encountering replicative DNA polymerases ma damaged DNA, triggering the use of backup translesion polymerases. These backup polymerases (2 marks) A. have 5'-to-3' exonucleolytic proofreading activity B. are substituted by the replicative polymerases after adding only a few nucleotides. C. can generate mutations only on undamaged DNA D. may identify specific D NA damage and add the suitable nucleotide to restore the original sequence. E. All of the above F. None of the above 2- In meiosis, a crossover in one position is thought to inhibit crossing-over in the neighboring regions. This regulatory mechanism... A. results in a very uneven distribution of crossover points along each chromosome B. ensures that even small chromosomes undergo at least one crossover C. controls how the Holliday junctions are resolved. (2 marks) D. All of the above E. All of the above F. None of the above 3- DNA-only transposons...(2 marks) A. can be identified by the presence of short inverted repeats at each end. B. often encode a kinase that mediates the transposition C. D. cnot move by a cut-and-paste mechanism. process. leave single-strand breaks in the donor chromosome E. All of the above.

Answer 1

ans:-) 3) ans a is correct option

DNA Traansponse is a transponsable element taht caan move in the DNA of an organismmvia a single or a double strand and the prossess of DNA transposition require mainly three sites in a DNA that are found as 2 at end of transposon that is known as transposon inverted repeat and the last one is found at the target site .Many times to perform any reaction the researcher completely excise it from the donor site and insert it into the target DNA when it is called CUT AND PASTE .the process is not mediated by kinase it is specialized by a specialized recombinase or a transponsase that mediate specific recognition of transponsable element and t also facilitate the joining and the breaking process of DNA strand .The single strand break is not left in the donor chromosome