How are selective media used in studying bacterial recombination?
What will be an ideal response?
Selective media permits certain bacteria to grow while suppressing the growth of other bacteria. During bacterial recombination, you can accurately assess transfer of genes using selective media in two ways.
First, you can use selective media to identify bacteria that have acquired a resistance gene and are recombinant. For example, E. coli can be transformed with a plasmid containing your gene of interest and a selectable marker, often an antibiotic resistance gene. You can add antibiotic to a bacterial culture and only the bacteria that have taken up the plasmid will be resistant. This will allow for identification of sequences which have been transferred between bacteria.
Second, you can use selective media to identify bacteria that have a mutation in a metabolic pathway by looking for mutants that are unable to complete normal metabolic processes. For instance, let's say you are studying a metabolic pathway and wish to identify bacteria that have mutations in this pathway. You can grow the bacteria in media with and without the final product
of the pathway. If the pathway is mutated and one of the enzymes is absent, the bacteria must be supplemented with certain nutrients to be able to grow. This will allow you to identify transformants, or mutants of interest.
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Which statement is TRUE about Streptococcus pneumoniae and the lung infection it causes?
A) Streptococcus pneumoniae can spread from the focus of infection as a bacteremia. B) Penicillin and erythromycin are the "last chance" drugs for treatment of streptococcal pneumonia. C) Infection with any strain of encapsulated virulent Streptococcus pneumoniae provides long-lasting immunity to all encapsulated virulent strains. D) Streptococcal pneumonia is not as serious as most people think; if left untreated, it usually runs its course in about a week to ten days.
What affects the rate of diffusion through a selectively permeable membrane?
I. concentration gradient II. temperature III. molecular size
a. I only b. II only c. I and II d. II and III e. I, II, and III
Keystone species:a
are always symbionts. b. are typically not the most abundant species in the community. c. illustrate secondary succession. d. always form the base of a food chain. e. are only found in tropical communities.
The term used when specifically discussing how common a particular allele is in a population is
A. population frequency. B. population number. C. allele number. D. allele frequency.