Which of the enzymes are used to cut the recipient DNA?
Answer: A
Correct answer: endonuclease
An endonuclease cuts within the DNA strand, which is what is needed to open the recipient chromosome so that donor material can be inserted. An exonuclease trims from the ends, ligases join, and polymerases synthesise - the four together being the toolkit for recombination and for genetic engineering.
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Which of the following theory is supported by the genomic sequence of the obligate intracellular parasite Rickettsia prowazekii ?
Answer: C
Correct answer: Mitochondria have evolved from endosymbiotic bacteria
Rickettsia prowazekii is an obligate intracellular parasite whose genome is small and whose retained genes for aerobic energy generation resemble those of mitochondria more closely than any other bacterium’s. That similarity is strong evidence that mitochondria descend from an alpha-proteobacterial endosymbiont.
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Which of the following is concerned with the management and analysis of biological data using computers?
Answer: B
Correct answer: Bioinformatics
A single bacterial genome is millions of bases and a comparison spans many genomes, so the analysis is only possible by computer. Bioinformatics supplies the databases, the alignment and search algorithms, and the statistical methods, and it has become inseparable from the experimental work it serves.
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The word, used for the small solid supports onto which are spotted hundreds of thousands of tiny drops of DNA that can be used to screen gene expression, is
Answer: C
Correct answer: DNA microarrays
A microarray carries thousands of DNA spots on a slide, and labelled sample nucleic acid hybridises to whichever spots match it. The pattern of binding shows which genes are being expressed, so the transcription of a whole genome can be surveyed in one experiment.
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Why the bacterium Treponema pallidum is difficult to culture?
Answer: C
Correct answer: Because it lacks the genes needed for TCA cycle and oxidative phosphorylation
The genome of Treponema pallidum shows it cannot make its own amino acids, nucleotides or fatty acids, and lacks a complete respiratory chain, so it depends on the host for compounds no ordinary medium supplies. The sequence explained a difficulty that had defeated bacteriologists for a century.
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The cell in which the F factor carries along with it some chromosomal genes are known as ____________
Answer: C
Correct answer: F’ cell
An F factor integrated into the chromosome may excise imprecisely and carry adjacent chromosomal genes away with it, giving an F prime plasmid. Conjugation then transfers those genes at high frequency, which made F prime strains a valuable tool for mapping and for constructing partial diploids.
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What is the range of minimum set of genes required for life?
Answer: B
Correct answer: 250-350 genes
Comparisons of the smallest genomes, together with experiments knocking genes out one at a time, put the minimum for an independently replicating cell at around 250 to 350. The figure is not fixed, since what is essential depends on how rich the environment is, but it is far below the few thousand a free-living bacterium carries.
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