Micro MCQ Exam II

At the molecular level, how is a proton gradient generated by the quinone loop?

A. Electrons in the quinone are excited by light, and end up in NADH, which creates the PMF.

B. The quinone, which is located in the periplasm, accepts H+ from the cytoplasm.

C. The quinone donates both H+ and electrons, but FeS proteins only accept electrons.

D. The quinone donates 2 protons to O2 to make water, which leaves the cell.

E. Light causes the quinone to "flip" a proton to the outside of the membrane.

The quinone donates both H+ and electrons, but FeS proteins only accept electrons

Which of the following uses mainly fats and oils as carbon sources, producing acids and CO2 by fermentation?

A. Caulobacter

B. Pseudomonas

C. Propionibacterium

D. Clostridium

E. Rhizobium

Propionibacterium

Place the following organisms in order from HARDEST to kill to EASIEST.

(1) naked viruses

(2) Pseudomonas cells

(3) Bacillus endospores

(4) Giardia cysts

A. HARDEST (1) > (4) > (2) > (3) EASIEST

B. HARDEST (4) > (3) > (1) > (2) EASIEST

C. HARDEST (3) > (1) > (2) > (4) EASIEST

D. HARDEST (3) > (4) > (1) > (2) EASIEST

E. HARDEST (1) > (3) > (2) > (4) EASIEST

HARDEST (3) > (4) > (1) > (2) EASIEST

An inducer used with a positive regulatory system_________________

A. binds directly to the DNA instead of to a protein.

B. prevents the repressor protein from binding to the DNA.

C. helps the activator protein bind to the DNA.

D. binds directly to the DNA instead of to a protein.

E. is impossible - inducers are used only with negative regulatory systems.

helps the activator protein bind to the DNA

A disease called Paralytic Shellfish Poisoning is caused by ____________

A. larvae of a fish tapeworm.

B. a fungal spore.

C. a fungal toxin.

D. an algal zoospore.

E. an algal toxin.

an algal toxin

Why are purple sulfur bacteria considered metabolically unique?

A. They make oxygen as a byproduct of photosynthesis.

B. They produce a PMF from photosynthetic electron transport.

C. They use only one photosynthetic reaction center.

D. They must perform reverse electron transport to make NADH.

E. They use H2S as an electron donor.

They must perform reverse electron transport to make NADH

Using chlorox bleach, it takes 20 minutes to decontaminate a water bottle with 104 Cryptosporidium cysts in it. The decimal reduction time for this procedure is 10 minutes. Using the same method, how long would it take to decontaminate the water bottle if it had 108 Cryptosporidium cysts?

A. 20 minutes

B. 40 minutes

C. 60 minutes

D. 80 minutes

E. There is not enough information to answer this question

60 minutes

In protein synthesis, the transpeptidation reaction __________________

A. makes a peptide bond AND transfers the protein to the tRNA in the A-site.

B. makes a peptide bond AND releases the protein from the ribosome.

C. brings a new tRNA to the A-site of the ribosome.

D. releases an uncharged tRNA from the E-site.

E. moves the ribosome toward the 5' end of the mRNA.

makes a peptide bond AND transfers the protein to the tRNA in the A-site

A Shine-Dalgarno sequence for translation serves the same function as a ________ for transcription

A. start codon

B. terminator

C. RNA polymerase

D. sigma factor

E. promoter

promoter

During oxygenic photosynthesis, the terminal electron acceptor for the electron transport chain involving photosystem II and plastoquinone is __________.

A. ATP

B. H2O

C. the reaction center of photosystem I

D. NADP+

E. oxygen

the reaction center of photosystem I

How would you treat an implantable cardiac defibrillator before installing it in a patient?

A. Sterilize it with ethylene oxide

B. Sterilize it with iodine

C. Disinfect it with a quaternary amine

D. Wash it in 70% alcohol

E. Disinfect with UV light

Sterilize it with ethylene oxide

What is one way plant viruses differ from animal viruses?

A. They do not carry any nucleic acid, just protein.

B. They cannot cause tumors; animal viruses can.

C. They have a special outer layer called the plasmodesmata.

D. Neither membrane fusion nor endocytosis can get them into a plant cell.

E. They are all RNA viruses.

Neither membrane fusion nor endocytosis can get them into a plant cell

DNA is extracted from a patient's blood sample and denatured. Upstream and downstream primers specific for a Staphylococcus aureus gene are added, followed by DNA polymerase. The denaturing, priming and polymerase steps are repeated 40 times. The product of the reactions is run on an electrophoretic gel, but no bands are visible. Why not?

A. The patient is not infected with Staphylococcus aureus.

B. RNA polymerase should have been used since the template was DNA.

C. The denaturing step should have been done after primer addition, not before.

D. There should have been only one primer used.

E. The denaturing step should have only been done once.

The patient is not infected with Staphylococcus aureus

The free-living nitrogen fixing bacterium Azotobacter has a much higher rate of cellular respiration than other bacteria. Why?

A. It needs oxygen in large amounts for the metabolically active cysts.

B. It gives much of its energy to a parasitic symbiont.

C. To protect the enzyme nitrogenase from oxygen.

D. Its respiratory chain is less efficient than usual, since it does not donate electrons to O2.

E. It has a much larger need for ATP than other bacteria.

To protect the enzyme nitrogenase from oxygen

What provides the energy for the DNA polymerase reaction?

A. The reaction is spontaneous, therefore, no energy source is necessary.

B. Making hydrogen bonds between the bases of the template and the new strand.

C. DNA polymerase hydrolyzes ATP in addition to carrying out the replication reaction.

D. The reaction is coupled to pyrophosphate (P-P) hydrolysis.

E. The PMF via a rotary motor called the DNA synthase.

The reaction is coupled to pyrophosphate (P-P) hydrolysis

What is the mode of action of the fluoroquinolone antibiotics such as ciprofloxacin?

A. interfere with the assembly of the cell membrane

B. interfere with the action of DNA gyrase

C. collapse the bacterial PMF

D. inhibit cell wall cross-linking

E. inhibit protein synthesis

interfere with the action of DNA gyrase

How does a phagocyte "know" not to phagocytose your own cells?

A. The pathogen sends phagocytosis signals to the phagocyte before it is engulfed.

B. The phagocytes antibodies cannot bind to your own cells.

C. The phagocyte must be activated by a TC cell before it can engulf other cells.

D. The phagocytes that recognize self antigens are clonally deleted.

E. Your cells do not have PAMPs for the phagocyte to recognize

Your cells do not have PAMPs for the phagocyte to recognize

Some bacteria contain a large piece of circular DNA called the Ti plasmid. What is the purpose of this plasmid?

A. to form cysts that allow the bacteria to survive harsh environmental conditions

B. to make an infected plant produce nutrients for the bacterium

C. to increase the number of replication origins so that DNA replication is faster

D. to form symbiotic root nodules for nitrogen fixation

E. to protect nitrogenase from the toxic effects of oxygen

to make an infected plant produce nutrients for the bacterium

It is now easy to make mutations in any bacterial gene we choose. What technique can we use to make designer mutations?

A. Southern blotting of cloning vectors

B. Microarrays with labeled cDNA from two different species

C. Colony hybridization with radioactive probes

D. Restriction digestion with two different enzymes

E. Probes with sequence mismatches used as replication primers

Probes with sequence mismatches used as replication primers

Place the steps in the replication of an acute DNA virus, after attachment, in the correct order.

A. DNA replication, proteins synthesis uncoating, assembly, membrane fusion, budding

B. budding, DNA replication, protein synthesis, assembly, uncoating, membrane fusion

C. uncoating, DNA replication, protein synthesis, membrane fusion, assembly, budding

D. membrane fusion, uncoating, DNA replication, protein synthesis, assembly, budding

E. DNA replication, protein synthesis, budding, membrane fusion, uncoating, assembly

membrane fusion, uncoating, DNA replication, protein synthesis, assembly, budding

Ringworm is a __________.

A. filarial worm

B. cutaneous fungus

C. fluke

D. tapeworm

E. nematode

cutaneous fungus

The mechanism whereby a cryptic gene is inserted downstream of an active promoter, as occurs in Neisseria gonorrhoeae, is called ________________.

A. exon shuffling

B. quorum sensing

C. cassette switching

D. two-component regulation

E. promoter induction

cassette switching

Which of the following DNA replication enzymes is NOT correctly matched with its function?

A. Polymerase - dimeric enzyme that copies both the leading and lagging strands.

B. Primase - begins replication of each Okazaki fragment.

C. Helicase - rewinds the DNA helix that the gyrase opens up.

D. Gyrase - relieves coiling tension ahead of the replication fork.

E. All of the enzymes listed are correctly matched with their functions.

Helicase - rewinds the DNA helix that the gyrase opens up

Which of the following is a desirable property for a new antibiotic to have?

A. It should be strong enough to "clean out" (kill) the native flora as well as the infection.

B. It should be bacteriolytic for Gram-negative bacteria.

C. It should be able to be recognized by antibodies.

D. It should have a high therapeutic index

E. It should be acid-sensitive.

It should have a high therapeutic index

How can a single eukaryotic transcript be used to make more than one protein?

A. Different exons can be combined during splicing of the transcript.

B. Its translation can be coordinated with its transcription.

C. Its genes can be arranged in an operon.

D. It can contain more than one ribosome binding site.

E. It cannot. Only prokaryote genes can do that.

Different exons can be combined during splicing of the transcript

The zwf gene is constitutive. Which of the following is true?

A. There is always the same amount of zwf mRNA in the cell.

B. There is always the same amount of Zwf protein in the cell.

C. The rate of zwf mRNA production is always the same.

D. zwf must have two competing regulatory proteins that cancel each other's effects.

E. zwf may possibly be a gene involved in amino acid biosynthesis.

The rate of zwf mRNA production is always the same

A 2008 Nobel Prize was awarded to the discoverers of the GFP reporter gene. What is a reporter gene?

A. A gene used to isolate pieces of another organism's chromosome to begin the process of gene cloning.

B. A constitutive gene that is used to activate another gene that would otherwise be repressed.

C. A mutagenic gene used in cloning to make random mutations in other genes.

D. A gene with a visible product used to report the activity of another gene's promoter.

E. A gene used as a probe to report the position of another gene.

A gene with a visible product used to report the activity of another gene's promoter

The lac operon is ______________________.

A. always transcribed, but not translated until lactose is present

B. both inducible and repressible

C. inducible with two different inducers

D. constitutive

E. repressed by glucose binding to the lac operon's DNA

inducible with two different inducers

Which of the following is carried out by the spliceosome?

A. removal of introns from eukaryotic RNA

B. removal of exons from prokaryotic RNA

C. removal of introns from eukaryotic DNA

D. removal of exons from eukaryotic RNA

E. removal of introns from prokaryotic DNA

removal of introns from eukaryotic RNA

A chronic virus __________________.

A. is continually being released from the host cell for a long time period

B. causes a new infection after a long time without symptoms

C. usually lyses an infected host cell quickly

D. uses reverse transcriptase

E. is Snoop Dogg's favorite type of virus

is continually being released from the host cell for a long time period

Most antiviral drugs target ________________.

A. viral metabolism

B. an unusual glycosidic bond in capsid carbohydrates

C. assembly of new virions

D. viral protein synthesis

E. viral nucleic acid synthesis

viral nucleic acid synthesis

Wobble pairing allows _________________.

A. an amino acid to interact with more than one codon

B. a ribosome to recognize more than one tRNA at a particular position

C. the 5' base of the anticodon to recognize more than one 3' base of the codon

D. more than one reading frame to be used for translation

E. more than one amino acid to attach to a particular tRNA

the 5' base of the anticodon to recognize more than one 3' base of the codon

Which of the following is an example of a biological vector?

A. a worm attaches to the intestinal lining and releases cysts

B. a mite causes inflammation when it burrows into skin

C. a flea must take a blood meal to transmit an infection

D. a louse carries bacteria which enter the skin when scratched

E. a fly carries bacterial spores on its legs

a flea must take a blood meal to transmit an infection

How does the lactoferrin secreted by human cells help to prevent bacterial colonization of a human host?

A. It does not. It aids colonization by probiotic native flora.

B. It makes the skin pH too basic for bacteria to grow.

C. It makes the skin too moist for bacterial cells to adhere well.

D. It reduces iron availability preventing bacteria from synthesizing cytochromes.

E. It breaks down peptidoglycan in the bacterial cell wall.

It reduces iron availability preventing bacteria from synthesizing cytochromes

What happens after prions cause protein misfolding?

A. Death of infected cells leads to inflammation of tissues.

B. Neuron death leads to brain tissue becoming porous.

C. Protein synthesis in a host cell is inhibited.

D. Neurons can proliferate uncontrollably resulting in a tumor.

E. The growth of the infected host can become stunted.

Neuron death leads to brain tissue becoming porous

Which of the following is prescribed to treat both anaerobic bacterial infections and infections caused by flagellated protozoans such as Giardia?

A. Metronidazole

B. Sulfa drugs

C. Penicillin

D. Neuraminidase inhibitors

E. Cubicin

Metronidazole

Which of the following best describes the role of polymorphonuclear neutrophils (PMNs) in the immune response?

A. Spaces between them allow leukocytes to spread from capillaries into infected tissues.

B. They secrete complement proteins in response to an infection.

C. They are phagocytes that also secrete cytokines.

D. They seek out and destroy infected "self" cells.

E. They produce antibodies, especially after a second exposure to an infectious organism.

They are phagocytes that also secrete cytokines