Cell Biology. Stephen R. Bolsover

dimerFrom the list of processes on the left, select the one described in each of the statements below.a hydrolysis reaction creating a uracil base in a DNA strandaddition of a ‐CH3 group to adenine bases on a DNA strandhydrolysis of the bond between the deoxyribose moiety and a guanine basehydrolysis of the bond between the deoxyribose moiety and an adenine baseloss of the NH2 group on the 4th carbon of a cytosine basethe formation of a covalent bond between adjacent bases on a DNA strand

      2 4.2 Theme: DNA replicationbreaking of base–base hydrogen bondsconnection of adjacent Okazaki fragmentsformation of an RNA sequence complimentary to the DNA chainhydrolysis and removal of a DNA strandincorporation of deoxyribonucleotide monomers into both the leading and lagging strandincorporation of deoxyribonucleotide monomers into the lagging strand but not into the leading strandin eukaryotes, removal of an RNA sequence complimentary to the DNA chainFrom the above list of processes, select the one performed by each of the enzymes below.DNA ligaseDNA polymerase IDNA polymerase IIIexonuclease Iexonuclease VIIhelicaseprimaseribonuclease H

      3 4.3 Theme: Regions within eukaryotic chromosomesexongene familyintronlong interspersed nuclear elementpseudogenesatellite DNAtandemly repeated DNAFrom the above list of DNA regions within eukaryotic chromosomes, select the region described by each of the descriptions below.a section of DNA that, read in triplets of bases, encodes successive amino acids in a polypeptide chaina section of DNA with a sequence similar to a working gene but which no longer encodes a functional proteina section of DNA within a gene that is transcribed into RNA but which does not encode amino acids and which must be removed from the RNA before it leaves the nucleusa series of identical or almost identical genes all of which are transcribed so as to generate identical or almost identical RNA products and, in the case of protein coding genes, identical proteinsa type of DNA with a presumed structural role that makes up much of the chromosome in the centromere regionan extragenic DNA sequence that is repeated more than a million times

THOUGHT QUESTION

      1 The bacteriophage PBS2 is very unusual in that its DNA uses uracil in place of thymine and therefore runs the risk of being “corrected” by the deamination enzymes of the bacterium that it infects. It therefore injects an inhibitor of bacterial uracil DNA glycosidase to prevent this from happening. Consider a section of the bacterial chromosome with the structure and suppose that at around the same time that it is infected by PBS2 a deamination event converts the cytosine to a uracil. Given that with uracil DNA glycosidase deactivated the bacterium cannot repair the error by base excision repair, can it repair the error using mismatch repair enzymes? If the error is not corrected, suggest what will happen to the DNA sequence (i) when the bacterium replicates its DNA and generates two daughter cells (ii) when these cells replicate their DNA to generate four second generation cells?