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Title: In bacteria, plasmids can be transferred from one cell to another by Post by: alatq33 on Nov 7, 2010 1. Temperate phages have genes for
a. enzymes c. repressors b. capsomeres d. all the above 2. Site - specific recombination is similar to homologous recombination because a. enzymes are required in both b. recombination proteins recognize a certain sequence of nucleotides in both DNA molecules c. single strands of DNA participate in both d. both are required in binary fission 3. Homologous recombination between two double stranded DNA molecules requires which order of events (from left to right). a. pairing of two chromosomes to form a four stranded structure, action of recombination enzymes to separate the four strands into two double stranded molecules. b. generation of circular molecule, nicking of one strand for transfer to the recipient c. formation of a single stranded fragment with a 3’ end, invasion of double stranded molecule by the 3’ end of the fragment. d. DNA ligase action to generate a partially single stranded fragment of DNA, invasion of double stranded molecule by the single stranded fragment 4. Transformation in bacteria a. is the transfer of DNA from one bacterium to another by use of a phage b. is able to convert mutants into wild-type organisms c. is a primitive sexual mechanism dependent on the fertility factor d. is limited to genes adjacent to prophage attachment sites 9. In bacteria, plasmids can be transferred from one cell to another by a. conjugation c. restriction b. deletion d. all the above 13. Conjugation a. is one example of a mechanism of transferring DNA from one cell to another b. involves male and female cells c. does not necessarily require homologous recombination d. all the above 14. DNA restriction a. is the breaking of double stranded DNA at specific nucleotide sequences b. preceeds plasmid DNA transfer in conjugation c. cuts the chromosome to form transducing phage particles d. all the above Title: In bacteria, plasmids can be transferred from one cell to another by Post by: duddy on Nov 7, 2010 4. Transformation in bacteria
a. is the transfer of DNA from one bacterium to another by use of a phage b. is able to convert mutants into wild-type organisms c. is a primitive sexual mechanism dependent on the fertility factor d. is limited to genes adjacent to prophage attachment sites Transformation in bacteria is regarded as a complex process that includes the following stages: fixation of DNA molecules by the recipient cell; penetration of DNA into the cell; inclusion of fragments of the transforming DNA in the chromosome of the host cell; and formation of pure transformed variants. The fixation of DNA occurs on a limited number of receptors located on the cell surface. The DNA bonded to the receptors remains sensitive to the enzyme deoxyribonuclease added to the medium. This leads to the decomposition of the DNA by the enzyme. Less than one minute after fixation, part of the DNA penetrates the cell 9. In bacteria, plasmids can be transferred from one cell to another by a. conjugation c. restriction b. deletion d. all the above 13. Conjugation a. is one example of a mechanism of transferring DNA from one cell to another b. involves male and female cells c. does not necessarily require homologous recombination d. all the above 14. DNA restriction a. is the breaking of double stranded DNA at specific nucleotide sequences b. preceeds plasmid DNA transfer in conjugation c. cuts the chromosome to form transducing phage particles d. all the above |