Genetic recombination occurs between homologous chromosomes.
Answer: A
Genetic recombination is the formation of a new genotype by reassortment of genes following an exchange of genetic material between two different chromosomes that have similar genes at corresponding sites. These are called homologous chromosomes and are from different individuals.
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The physical nature of genomes is studied under
Answer: A
Correct answer: structural genomics
Structural genomics is concerned with the physical organisation of the genome - sequencing it, mapping it, and determining the structures of what it encodes. Functional genomics asks what the genes do, and comparative genomics what the differences between genomes signify.
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Proteomics is
Answer: D
Correct answer: the study of the entire collection of proteins expressed by an organism
The proteome is what the genome actually produces, and it differs between cells, conditions and moments in a way the genome does not. It also reflects processing and modification that the sequence cannot predict, which is why proteomics is a separate study rather than a corollary of genomics.
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What are bacteriocins?
Answer: A
Correct answer: proteins
Bacteriocins are proteins produced by one strain that kill closely related strains, usually by forming pores or degrading nucleic acid. They are typically plasmid-encoded, and the producing cell carries an immunity protein to protect itself - which is what makes the weapon usable.
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The flow of genetic material in microbial cells usually takes place from
Answer: C
Correct answer: DNA through RNA to proteins
This is the central dogma: DNA is transcribed to RNA and RNA translated to protein. Retroviruses reverse the first step with reverse transcriptase, but no mechanism translates protein back into nucleic acid, and it is that last impossibility which gives the dogma its force.
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Why Deinococcus radiodurans is able to survive massive exposure to radiation?
Answer: D
Correct answer: Because it has many copies of genes encoding DNA repair
Deinococcus radiodurans survives doses that shatter its chromosome into hundreds of fragments, and reassembles it within hours. Multiple genome copies provide the templates and an unusually efficient repair apparatus does the work - the resistance lies in repair rather than in any shielding.
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In the time since E. coli and Salmonella diverged evolutionarily
Answer: C
Correct answer: E. coli has acquired many genes via horizontal transfer
Comparison of the two genomes shows a substantial fraction of the E. coli chromosome differing in base composition and codon usage from the rest, which marks it as foreign in origin. Several hundred kilobases appear to have arrived by horizontal transfer since the two lineages separated, and much of what distinguishes the two species lies in that acquired material.
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The transfer of genes from one cell to another by a bacteriophage is known as __________________
Answer: C
Correct answer: Transduction
In transduction a bacteriophage packages host DNA by mistake and carries it into the next cell it infects. It is one of three routes for horizontal transfer: transformation takes up naked DNA from the surroundings, conjugation passes it through direct contact, and transduction uses a virus as the vehicle.
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Which of the following organisms has the smallest genome?
Answer: B
Correct answer: M. genitalium
Mycoplasma genitalium has about 580,000 base pairs and some 470 genes, among the smallest of any cell able to replicate independently. Its economy comes from parasitism - it takes most of what it needs from its host - which is why it has been used to investigate the minimum gene set for life.
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Transfer of genes between cells that are in physical contact with one another is known as transformation.
Answer: B
Correct answer: False
Transfer between cells in physical contact is conjugation, in which a pilus draws the cells together and DNA passes from donor to recipient. Transformation is the uptake of naked DNA from the surroundings and needs no donor cell present at all.
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