Microbiology - Exam 3

Which of the following statements about fungal structure are TRUE?

1. A visible mass of fungal hyphae is called a mycelium. 2. The hyphae of parasitic fungi are called haustoria. 3. Some fungi can be both unicellular and multicellular.

Identify all the ways that helminths can be transmitted to humans.

1. Consuming helminth-contaminated food or water. 2. Some helminths can burrow under the skin. 3. Via insect bites.

In lytic phage infections, the early viral proteins are important for initial steps of phage multiplication. Which of the following are functions of these proteins?

1. Degrade host cell's ribosomes. 2. Activate bacteriophage's DNA polymerase for copying bacterial RNA.

Members of this group of microbes can break down glycogen deposited in the vaginal lining in response to estrogen. This helps to drop the pH in the area, preventing infections.

Lactic acid bacteria

Which of the statements about chemotrophs is FALSE?

Lactic acid bacteria such as Lactobacillus obtain their ATP by oxidizing glucose, using lactic acid as their terminal electron acceptor.

What term describes the type of bacteriophage infection in which the host bacteria are lysed and killed as a result of the infection?

Lytic

Which of the following is NOT a method of genotypic typing?

MALDI-TOF

Which of the following methods is used to help identify prokaryotes by examining how bacteria respond to different nutrients in the media?

Metabolic capability testing

Which of the following is NOT an obligate intracellular parasite?

Treponema pallidum

All coliforms are Enterobacteriaceae, but not all Enterobacteriaceae are coliforms.

True

Almost immediately upon entry, the viral nucleic acid alters the gene expression of the host cell.

True

Bacteriophage DNA directs the degradation of the bacterial host cell's DNA.

True

Both enveloped and non-enveloped (naked) viruses can enter a cell by endocytosis.

True

Both sexual and asexual reproduction are common in protozoa, and may alternate during the life cycle of some organisms.

True

PCR reactions are carried out in machines called thermocyclers?

True

Staphylococcus species can be distinguished from Streptococcus, Enterococcus, and Lactococcus species on the basis of catalase activity.

True

The enzyme lysozyme is used by the T4 phage to assist in the injection of its DNA into the target cell.

True

The evolution of shared characteristics in unrelated organisms such as fungi and water molds living in similar environments is called convergent evolution.

True

Please choose the statement that best describes the role of viral surface proteins or spikes.

Viral spikes provide means of attachment to host cell surface.

A man who had recently travelled to the Ohio River valley..... Based on this information, the likely cause of the infection was

a fungus.

The capsid of a virus is

a protein shell that surrounds the nucleic acid.

Which of the following is required to maintain a lysogenic state?

a repressor protein

The single-stranded ends of DNA molecules can be joined together by?

DNA ligase

What bacterial enzyme is used by the virus for replicating its nucleic acid?

DNA polymerase

Identify all the fungi that are considered medically important from the choices below.

Cryptococcus neoformans, Candida albicans, Aspergillus species that produce aflatoxins,

Which of the following is NOT a fungal disease?

Cryptosporidiosis

Arrange the following in the proper sequence in which they occur during a single PCR cycle.

1. Heat separation 2. Complementary base pairing 3.Addition of DNA nucleotide

Which of the following statements regarding the Enterobacteriaceae are TRUE?

1. They are Gram-negative rods that form part of the normal microbiota. 2. Their name derives from the fact that they reside in intestinal tracts of humans and animals. 3. Enterobacteriaceae called coliforms ferment lactose.

Which of the following are TRUE regarding coliforms?

1. They are used as indicators of fecal pollution 2. They are f. anaerobes 3. gram-negative 4. belong to the family of Enterobacteriaceae 5. characteristically ferment lactose

Hydrogen peroxide.... Identify two conclusions you can make about the bacterial cells:

1. break down hydrogen peroxide 2. are catalase-positive

Nematodes

1. cylinder tapered bodies 2. roundworms 3.example of pinworms 4. digestive tract including mouth and anus

Cestodes

1. flat ribbon shaped bodies 2. lack digestive system; absorb nutrients 3. intermediate hosts include cattle 4. example of tapeworm

Trematodes

1. flukes 2. flat-leaf shaped bodies 3. One opening for intake of nutrients and exits of waste 4.example of schistosomes

Which of the following statements about parasitic helminths are TRUE?

1. swimmer's itch is caused by flukes burrowing under the skin. 2. Ascaris lumbricoides may cause pulmonary symptoms. 3. Tapeworms are hermaphrodites, carrying both male and female reproductive structures.

Which of the rRNA molecules is most useful for bacterial identification?

16S

Which of the following is NOT a mode of entry for helminths?

Aerosol droplets

Which of the following about fungi is FALSE?

All fungi are unicellular.

Which of the following is NOT caused by a protozoan?

Athlete's foot

Match five methods used to characterize different strains of prokaryotes with their descriptions.

Biochemical typing: this type of testing relies on unique metabolic activities of the microbe. Serological typing: This type of testing relies on the use of specific antibodies to detect unique antigens on the microbe. Molecular typing: This type of testing relies on detecting specific differences in the microbe's DNA or DNA patterns. Phage typing: This type of testing relies on the use of specific bacteriophages to detect a particular microbe strain. Antibiograms: This type of testing relies on antibiotic susceptibility patterns generated by specific microbes.

Match the Clostridial species with the diseases they cause.

Clostridium difficile: Antibiotic-associated diarrheal disease. Clostridium perfringens: Gas gangrene: a disease characterized by necrotic tissue and the production of gas. Clostridium tetani: Tetanus: a disease characterized by painful muscle spasms. Clostridium botulinum: Botulism, a disease characterized by flaccid paralysis.

Which of the following is NOT a member of the Enterobacteriaceae family (Gram-negative rods, glucose fermenters, some members motile with peritrichous flagella, some members lactose fermenting)?

Corynebacterium diphtheriae

Identify which of the following genera have members that are disease-causing facultative anaerobes.

Corynebacterium, Escherichia, Staphylococcus

PCR requires all of the following EXCEPT

DNA ligase

Please choose the term that describes a virus that has a lipid bilayer (derived from the host cell) surrounding its capsid.

Enveloped virus

The T-even bacteriophages such as T2 and T4 infect

Escherichia coli.

Gram staining is never sufficient for diagnosis?

False

Haemophilus influenzae is a virus that causes the "flu."

False

In multilocus sequence typing (MLST), the sequences of all ribosomal subunits of an organism are determined and compared to those of other organisms.

False

In the lysogenic stage of phage replication, the host cell is lysed.

False

Once a phage becomes lysogenic, it will remain lysogenic and never be lytic again.

False

Restriction enzymes cut only at specific sites and therefore are not useful for microbial identification.

False

Match each of the following anaerobic chemotrophs with their descriptions.

Methanogens: Archaea, live in anaerobic environments with H2 and CO2. Sulfur and sulfate-reducing bacteria: Found in mud with organic material and oxidized sulfur compounds. Clostridium species: Generally in endospore form in soil, but will germinate to vegetative form when anaerobic conditions arise. Gram-positive rods. Lactic acid bacteria: Gram-positive, catalase-negative, grow in aerobic environments but only ferment, producing acidic conditions. Propionibacterium species: Gram-positive pleomorphic (irregular shaped) rods, fermenters, often used in Swiss cheese production.

Match each of the following obligate aerobic bacteria with its description.

Micrococcus species: Gram-positive cocci found in soil, dust particles, inanimate objects, skin; tolerates dry and moderately salty conditions. Mycobacterium species: Generally pleomorphic (variable shape) rods that stain poorly and resist destaining due to waxy lipids in their cell wall structure. Several species cause human diseases. Pseudomonas species: Gram-negative rods with polar flagella. Often produce pigments. Widespread in soil and water. Most are harmless, but some can be opportunistic pathogens of humans. Thermus species: Stain Gram-negative, but have an unusual cell wall. Survive well in high heat, due to their interesting heat-resistant enzymes. Deinococcus species: Stain Gram-positive, with an odd multilayer cell wall that lets the cells resist high levels of gamma radiation (also due to their extensive DNA repair enzyme activities).

Identify all the organisms that are protozoans from the choices below.

Plasmodium species, Giardia lamblia, Cryptosporidium parvum

Which of the following about protozoa is FALSE?

Protozoa are never motile.

Which of the following organisms is NOT classified as a facultative anaerobe?

Pseudomaonas aeruginosa

Select the TRUE statements about obligate aerobes.

Pseudomonas species are aerobes but can grow anaerobically if sulfate is present in the medium.

Which of the following phenotypic methods is used to help identify prokaryotes by analyzing antibody reactivity?

Serological testing

bacteriophage initially associates with which bacterial structure?

The bacterial cell wall

Members of the genus Mycoplasma have no cell wall, making them somewhat unique in the microbial world. How do they prevent osmotic lysis?

Their cytoplasmic membrane is rich in sterols to help provide added strength and rigidity.

What do the pathogens Plasmodium species, Toxoplasma gondii, Cryptospirdium parvum, and Cyclospora cayetenansis have in common?

They all have apical complexes.

Which of the following statements about members of the genus Mycoplasma are true?

They are unaffected by penicillin

The general steps in viral replication (in order) are

adsorption, penetration, synthesis, assembly, release.

Viral spikes

attach specifically to host cell receptors.

Place the steps of T4 phage replication into the correct sequence.

attachement - genome entry - synthesis - assembly - release

The stage of T4 replication that involves interaction between the protein fibers on the phage and receptors on the bacterial cell wall is the

attachment stage

Human DNA cut with restriction enzyme A can be joined to?

bacterial DNA cut with restriction enzyme A.

During PCR, which primer anneals to DNA with its 3' end toward the center of the sequence to be amplified?

both the forward primer and the reverse primer

An organism produces bubbles upon addition of hydrogen peroxide and causes the pH of the medium to become very acidic when grown in the presence of lactose. This organism is

catalase-positive and can ferment lactose.

Some protozoans can produce _____ during times of environmental stress.

cysts

very virus particle contains ______.

either DNA or RNA

Corynebacterium species and Enterobacteriaceae family members are examples of ______ anaerobes, meaning that they preferentially use aerobic respiration if O2 is available, but can ferment if it is not.

facultative

Only Gram-positive bacteria can form resting stage structures.

false

T-even phages can replicate independently of a host cell.

false

In viral entry by endocytosis

he host cell's cytoplasmic membrane surrounds the whole virion and forms a vesicle. Correct

How does bacteriophage DNA get into the host cell?

it is injected

The final step in T2 bacteriophage infection results in:

lysis of the bacterial cell and release of new viral particles.

What term describes the type of bacteriophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide?

lysogenic

Viral cycles that end in release of the new phages and immediate destruction of the host bacterial cell are referred to as ______.

lytic

When present, of what is the viral envelope composed?

mainly lipids

Loss of the apicoplast genome in T. gondii and Plasmodium sp. results in the death of the organisms. This information is important because

medications targeting the apicoplast genome may be used for treating diseases such as malaria and toxoplasmosis.

Once inside the host cell, viral DNA directs production of _______.

new viral particles

Methanogens are a group of archaea that generate ATP by

oxidizinng hydrogen gas, using carbon dioxide as a terminal electron acceptor

A major difference in the replication of animal viruses and bacteriophages is the ______ step.

penetration

Viral capsids are composed of ______.

proteins

The causative agent of malaria is what type of microbe?

protozoan

Match the type of genetic analysis used for microbial identification with its description.

rDNA sequence analysis: analysis of nucleotide sequence of small subunit rRNA genes. DNA hybridization: Measuring nucleotide sequence similarity. G + C content: Determining the number of Gs and Cs in the genome.

Which molecule was the basis for establishing the three-domain classification system?

rRNA

In the method shown in the figure, the probes used in detecting the nucleic acid sequences can be labeled with a

radioisotope or fluorescent dye.

Phage DNA encodes for the proteins of the viral capsid and

regulatory proteins that direct the production and assembly of the capsid proteins.

All of the following could serve as receptors for phage attachment EXCEPT

ribosomes

In the name E.coli O157:H7; "O157:H7" refers to the ______ of the organism.

serotype

The DNA of the unknown organism must be denatured to allow

single-stranded complementary probes to bind to the unknown DNA

E. coli or other coliform

stains pink in the Gram stain

When looking at the GC (or G + C) content, a researcher is studying?

the DNA of the organism.

Helminths are most commonly transmitted to humans by

the gastrointestinal route

In the figure, the probes in A do not bind to the denatured DNA because?

they are not complementary to the unknown DNA.

The G + C content can be measured by determining the temperature at which double-stranded DNA denatures.

true

Which of the following can cause a phage in the lysogenic stage to revert to the lytic stage?

ultraviolet light

Removal of the capsid to release the virus nucleic acid into the host cytoplasm is called ______.

uncoating