Micro lecture quiz 3

Which of the rRNA molecules has proven the most useful in taxonomy/identification? -5S -16S -23S -805

16S

In 1970 Stanier proposed that classification be based on -evolution. -Gram stain. -physiology. -DNA sequence.

DNA sequence

The Ames test is useful as a rapid screening test to identify those compounds that -will respond to chemical agents. -are mutagens. -respond to the deletion of DNases. -will protect an organism from cancer. -will respond to chemical agents AND will protect an organism from cancer.

Are mutagens

Chemical mutagens that mimic the naturally occurring bases are called -nitrogen mustards. -alkylating agents. -base analogs. -nitrous oxide.

Base analogs

The point at which two organisms diverged from a common ancestor -can be determined by comparing the nucleic acid sequences. -depends on translational control. -depends on metabolism. -is determined on Mac Conkey's media.

Can be determined by comparing the nucleic acid sequences

All fungi have ______ in their cell walls. -cellulose -pectin -peptidoglycan -chitin

Chitin

The site in a photosynthetic eukaryotic cell where photosynthesis occurs is the -nucleus. -carotenoid. -mitochondria. -chloroplast.

Chloroplast

Planar molecules used as chemical mutagens are called -nitrous oxide. -base analogs. -alkylating agents. -intercalating agents.

Intercalating agents

Protozoan classification used to be based on their means of -locomotion. -growth. -reproduction. -obtaining nutrients.

Iocomotion

A clever technique that streamlines the identification of auxotrophic mutants is -gas chromatography. -replica plating. -direct selection. -reversion

Replica plating

The more closely related two organisms are, -the less they look alike. -the more similar the nucleic acid sequence. -the less similar the nucleic acid sequence. -the more they are phenotypically similar. -the more similar the nucleic acid sequence AND the more they are phenotypically similar.

The more similar the nucleic acid sequence

Direct selection involves inoculating cells onto growth media on which -the mutant but not the parental cell type will grow. -the mutation will be reversed. -the nutrients necessary for mutation to occur are present. -the mutagen is present

The mutant but not the parental cell type will grow

When DNA probes are used to identify bacterial DNA similarities by hybridization, the probe DNA is heated and the template DNA is treated to separate the two strands.Why would the probe DNA be heated? -This is the only way to properly label the probe DNA. -The probe may contain portions that are double-stranded. Heating it up breaks any possible hydrogen bonds that may have formed allowing the single-stranded sequences to hybridize with their complementary targets. -Heating it up activates the tag on the probe DNA before it hybridizes to the bacterial template DNA. -DNA hybridization can only take place at high temperatures, so all the DNA must be heated up prior to hybridization.

The probe may contain portions that are double-stranded. Heating it up breaks any possible hydrogen bonds that may have formed allowing the single-stranded sequences to hybridize with their complementary targets.

The F plasmid carries the information for -antibiotic resistance. -recipient cell DNA replication. -the Y chromosome. -the sex pilus. -antibiotic resistance AND the Y chromosome.

The sex pilus

Why would all protozoa be expected to require large amounts of water in their habitats? -They require water to avoid dehydration and death. Without being in water, they would quickly dehydrate (due to their small size) and die. -They require water to help them during photosynthesis by providing an electron source. -They require water to move around in to seek food particles. Without water, they would be unable to move at all. -All of the above are correct.

They require water to avoid dehydration and death. Without being in water, they would quickly dehydrate (due to their small size) and die.

Competent cells -are able to take up naked DNA. -are antibiotic resistant -occur naturally. -can be created in the laboratory. -are able to take up naked DNA, occur naturally, AND can be created in the laboratory.

are able to take up naked DNA, occur naturally, AND can be created in the laboratory.

X-rays -have no effect on DNA. -cause thymine trimers. -cause single and double strand breaks in DNA molecules. -make the DNA radioactive.

cause single and double strand breaks in DNA molecules.

Thymine dimers are dealt with by -no repair mechanisms. -photoreactivation repair. -SOS repair. -excision repair. -photoreactivation repair AND excision repair.

photoreactivation repair AND excision repair

Woese -was involved in determining rRNA sequences. -proposed breaking prokaryotes into two groups. -proposed breaking eukaryotes into Domains Archaea and Bacteria. -was involved in refining the Gram stain for classification purposes. -was involved in determining rRNA sequences AND proposed breaking prokaryotes into two groups.

was involved in determining rRNA sequences AND proposed breaking prokaryotes into two groups.

Bacteria that have properties of both the donor and recipient cells are the result of -UV light. -SOS repair. -frame shift mutations. -genetic recombination.

Genetic recombination

Which technique(s) is/are used to help identify and classify bacteria? -Microscopic examination -Culture characteristics -Biochemical tests -Nucleic acid analysis -All of the choices are correct

All of the choices are correct

On which of the following DNA strands would UV radiation have the most effect? -AACCGGG -TATATACG -AUAUCGAU -AATTAGTTC -TATATACG AND AATTAGTTC

AATTAGTTC

DNA transfer by conjugation is more efficient in a liquid medium setting, subjected to very mild agitation (stirring), rather than on an agar plate format. Why? -Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the plate format than in the fluid format (especially for relatively non-motile types of bacteria). -Direct cell-to-cell contact isn't required for this process, so the ability to secrete the DNA into the surrounding fluid medium makes the process more efficient than the dry surface of an agar plate. -Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the fluid liquid format than on an agar plate (especially for relatively non-motile types of bacteria). -Trick question-it can take place with the same degree of efficiency on either format. It doesn't matter

Direct cell-to-cell contact is required for this process, and this is more likely to be achieved in the fluid liquid format than on an agar plate (especially for relatively non-motile types of bacteria).

Why would it be more difficult to treat diseases in humans caused by members of the Eukarya than diseases caused by the Bacteria? -Multicellular organisms always have their own immune systems to contend with-so any treatment we develop needs to overcome this built-in protection mechanism in such organisms. -Since bacteria are so much simpler (being single-celled), they are inherently easier to kill off than multi-cellular eukaryotic microbes. -Eukaryotic microbes use many of the same enzymes and systems as humans-so we lose the ability to target certain molecules that might be present ONLY in the cell type we want to eliminate. There's too much overlap when both organisms are eukaryotic. -Eukaryotic microbes (unlike prokaryotes) often secrete compounds that breakdown and eliminate drugs used against them. This makes them much harder to effectively eliminate than bacteria.

Eukaryotic microbes use many of the same enzymes and systems as humans-so we lose the ability to target certain molecules that might be present ONLY in the cell type we want to eliminate. There's too much overlap when both organisms are eukaryotic

The return of carbon dioxide to the atmosphere and nitrogen to the soil is due to the action of -viruses and plants. -bacteria and viruses. -fungi and bacteria. -fungi and viruses.

Fungi and bacteria

Double-stranded DNA enters the recipient cell during transformation. True or False

False

Fungi are often capable of locomotion through the use of flagella. True or False

False

To maximize the number of thymine dimer mutations following UV exposure, should you keep human cells in tissue culture in the dark, in the light, or does it matter at all? -The dark-light will activate the photorepair systems that can break thymine dimers induced by UV light. -The light-it's important to keep on producing the thymine dimers by keeping the plate exposed to light as much as possible. -It's best to alternate light and dark every hour to increase the chances that thymine dimers will form in the human cells, but still keep the photorepair systems from correcting them as they are formed. -It doesn't matter-human cells don't possess the enzymes needed for photorepair of thymine dimers.

It doesn't matter-human cells don't possess the enzymes needed for photorepair of thymine dimers.

Which is not true about mismatch repair? -It utilizes an endonuclease. -It requires DNA polymerase and DNA ligase. -It utilizes the state of methylation of the DNA to differentiate between strands. -It removes both strands in the mismatch area.

It removes both strands in the mismatch area

Algae are important environmentally as -major producers of carbon dioxide. -major producers of oxygen. -local flora. -local contaminants.

Major producer of oxygen

The source of variation among microorganisms that were once identical is -antibiotic resistance. -virulence factors. -sigma factors. -mutation.

Mutation

A tangle of fungal hyphae is generally known as a -bud. -mycelium. -germ tube. -spore.

Mycelium

The mechanism by which genes are transferred into bacteria via viruses is called -ellipsis -replica plating. -transformation -transduction. -conjugation.

Transduction

Segments of DNA capable of moving from one area in the DNA to another are called -base analogs. -intercalating agents. -transposons. -inverted repeats

Transposons

DNA polymerase is able to proofread the DNA sequence. True False

True

F plasmids and oftentimes R plasmids are both able to code for production of a pilus. True False

True

Horizontal DNA transfer may make it more difficult to construct phylogenetic trees. True or False

True

Nucleic acid techniques have great power as diagnostic tools because they may be -very specific. -quick and easy to perform. -used to enhance the growth of bacteria. -used to selectively inhibit the growth of certain bacteria

Very specific

Phage typing -is useful for determining eukaryotic cell types. -is used to extract DNA from cells. -is used to distinguish bacterial strains. -is dependent on the type of eukaryotic cell. -is used to distinguish bacterial strains AND is dependent on the type of eukaryotic cell.

is used to distinguish bacterial strains.

Dimorphic fungi -may grow as mycelia or yeast. -are often associated with disease in humans. -are mushrooms. -are strictly hyphae. -may grow as mycelia or yeast AND are often associated with disease in humans.

may grow as mycelia or yeast AND are often associated with disease in humans.