Microbiology exam 1

Rank the following levels of protein structure from primary to quaternary.

1. the sequence of the amino acids 2. the shape of the amino acid chain 3. the unique 3d structure of a single polypeptide 4.interactions between multiple proteins in complex

A cell's genome is 15% guanine. What is the percentage of thymine?

35%

Which of the following is NOT a trait that is shared by most types of bacteria?

A membrane-enclosed compartment that protects the genome of the cell

Once the process of DNA replication has begun, how soon can a bacterial cell begin a new round of DNA replication?

A new set of replication forks can begin to form while the DNA strand is still being replicated by the first set of replication forks.

Which of the following statements correctly describes the structure of the bacterial chromosome?

A single circular chromosome is much greater in circumference than the cell itself, so it is twisted back on itself and coiled up within the cytoplasm.

How did the work done by Nightingale contribute to controlling infectious disease?

A. By developing methods for reducing hospital-acquired infections

Which of the following best describes the structure of DNA?

A. Double-stranded DNA consists of two complementary strands of DNA that are twisted around each other and held together by hydrogen bonds.

Which of the following organisms would be considered the most virulent, based on their infectious dose (ID50)?

A. Rickettsia rickettsii, ID50 = 1

Doorknobs, shared utensils, and computer keyboards have the potential to harbor common cold viruses. Under which of the following disease transmission categories does this fall?

A. Vehicle transmission

Successful pathogens must do which of the following?

A.Grow and multiply within a host B.Enter and exit a host E.Avoid the host's immune system

Which of the following groups of microorganisms does NOT cause disease?

Archaea

Which of the following is not one of the cellular functions of an adenosine nucleotide?

As a structural component of the cell membrane

In what way do symptoms of disease differ from signs of disease?

B. Symptoms are changes felt by the patient.

Which of the following organisms has an oral portal of entry?

B.RotavirusC.Salmonella bacteria

Bacillus anthracis (anthrax) and severe acute respiratory syndrome (SARS) virus are classified in which biosafety risk group?

C. Risk Group III

Cholera toxin has the ability to kill a patient by causing massive fluid and electrolyte loss. Oral rehydration therapy is the main treatment option for patients with cholera; however antibiotics can be useful in the recovery process. What considerations should physicians have in mind regarding antibiotic use when treating a cholera patient?

C.Antibiotic use can lead to drug resistance.D.Antibiotics can cause additional nausea and vomiting.

What three elements are used to form sugar molecules?

Carbon, hydrogen, and oxygen

Carbohydrates fulfill a number of cellular roles. Which of the following functions could NOT be carried out by a type of carbohydrate molecule?

Catalysis of chemical reactions

spread from the initial site of infection

Consider the image shown below. A strain of Listeria monocytogenes that has lost the ability to polymerize actin (perhaps through a mutation in the responsible gene, ActA) would most likely be unable to do which? A. be cultured outside of host cellsB. spread from the initial site of infectionC. survive passage through the stomachD. attach to and invade host enterocytesE. escape from host vacuoles

If you became sick with influenza after a co-worker sneezed next to you in an elevator, which of the following types of transmission would apply?

D. Aerosol transmissio

What is an infection transmitted from a health care worker to a patient called?

D. Iatrogenic infection

If endospores had been present in Pasteur's growth medium, would the outcome of his experiments with swan-necked flasks have been the same? A. Yes, but only if he had plugged the ends of the swan-neck flasks (because all life needs oxygen).B. No, fungal colonies would have soon developed at the interface of the liquid and air.C. Yes, the broth would have remained sterile because endospores are killed by boiling.D. No, the broth would have eventually become cloudy from bacterial growth.

D. No, the broth would have eventually become cloudy from bacterial growth.

How does cellular RNA differ from cellular DNA?

DNA is double stranded, whereas RNA is single stranded.

unsaturated fatty acids characteristics

Double bond between carbons membrane more fluid in cold climates typically liquids at room temperature

sterile environment-A cells collect in here-c airflow-b

Identify the components by dragging the labels to their targets in the image of the swan-necked flask below. the scientist Louis Pasteur used this type of glassware to disprove spontaneous generation.

Assume that you have a substance capable of diffusing slowly across the plasma membrane. Which of the following changes would increase the diffusion rate of this substance?

Increase the concentration of the substance outside the membrane.

Which of the following is NOT a function of membrane-embedded proteins?

Membrane-embedded proteins can store important inheritable information that is needed by the cell.

Which of the following molecules are the sugars needed for the synthesis of bacterial cell walls?

N-Acetylmuramic acidD.N-Acetylglucosamine

Which of the following is expected to cross a lipid bilayer composed solely of phospholipids (i.e., no transport proteins are present) the fastest?

N2

Why must a cell use energy to bring nutrients into the cell?

Nutrients are usually found in a low concentration outside the cell and must be transported against their concentration gradients. Energy is required whenever something is moved against its concentration gradient.

agent 1

One way to measure virulence is to calculate the lethal dose 50% (LD50): the number of pathogens required to kill 50% of an experimental group of animal hosts. Which agent in the figure below is more virulent?

Amino acids can exist in one of two forms that are mirror images of each other, like your left hand and your right hand. These two chiral forms are called isomers. Each amino acid is either an L-isomer or a D-isomer. What amino acid isomer would be used by ribosomes to create proteins?

Only L-amino acids are used by the ribosomes in all types of cells

The fungus Pneumocystis jirovecii easily infects people, but rarely causes disease in healthy people. What is this type of pathogen called?

Opportunistic pathogen

Which of the following tasks would be a possible function of a bacterial pilus?

Pili allow cells to adhere to surfaces so that they do not get washed away from a favorable environment.D.Pili are hollow so they can form a tube that connects the cytoplasm of two cells and allow for the transfer of genetic material between them.

The distinctive smell of rotting meat comes, in part, from the production of a polyamine molecule called cadaverine. What are polyamines, and what purpose do they serve in bacterial cells?

Polyamines are small organic molecules with a positive charge that help stabilize negative charges within the cell.

Where does the process of DNA replication begin?

Replication of the DNA begins at a sequence of DNA called the "origin of replication."

Iron deficiency is a problem for many patients with cancer and chronic kidney disease. In many cases, replacement therapy through iron supplementation is advised to stimulate red blood cell and hemoglobin production. Consider the illustration below and predict how this strategy might affect a patient who was also battling a bacterial infection.

The bacteria would produce fewer siderophores and would increase their rate of cell division.

a carboxyl group

The functional group shown is a(n)

Which of the following is true of sugars?

They contain multiple hydroxyl groups

hypertonic, leave

This figure illustrates a cell in a solution. The dots represent solute. The solution is _________ in relation to the cell, and water will _________ the cell by osmosis.

eukaryotic protozoan

This organism is most likely __________ and could be identified as a/an _____________ cell.

Intravenous solutions must be prepared so that they are isotonic to red blood cells. A 0.9% salt solution is isotonic. What will happen to a red blood cell placed in a 0.6% salt solution?

Water will enter the red blood cell.

D.Mitochondria are descended from ancestral endosymbiotic proteobacteria.E.Having mitochondria is a prerequisite for acquiring chloroplasts.

Which of the following statements is supported by the model illustrated below?

A.5-carbon sugarsB.phosphate group

Which of the following structural characteristics do DNA and ATP both possess?

Which of the following would NOT be considered a polymer?

a fatty acid

Which of the following is NOT directly attached to an amino acid's central alpha carbon?

a hydroxyl group

Which of the following structures are needed to create a nucleotide?

a nucleobase a phosphate group a pentose sugar

Which of the following is NOT a type of carbohydrate molecule?

a triglyceride

Symptoms develop rapidly in which type of infection?

acute infection

Lipids are composed mainly of ________________.

alkane group

Which of the following molecules would the cell be most likely to move through the membrane using the process of efflux?

antibiotics

which of the following is a microbial function directed by humans? nutrient cycling all choices are correct bioremediation energy capture

bioremediation

glucose molecules that are covalently linked together to form chains can be found in

carbohydrates

All lipid molecules are primarily composed of which two elements?

carbon and hydrogen

In which of the following infections do symptoms develop gradually, over weeks or months, and then resolve slowly, taking three months or more?

chronic infection

a cell that looks like a sphere would be described as

coccus

The type of chemical reaction joining the glycerol and fatty acid subunits in this figure is known as a __________________ reaction. The bonds formed are called __________________.

condensation, ester linkages

A peptide bond that holds amino acids together is an example of which of the following types of chemical bonds?

covalent bond

In 2000, on a farm in North Dakota, 67-year-old Caleb helped bury five cows that had died of anthrax. Wearing heavy leather gloves, Caleb placed chains around the heads and hooves of the carcasses and moved them to the burial site. Four days later, he noticed a small lump on his left cheek. Over 2 days, the lump enlarged, and a lesion opened. Caleb then sought medical attention. The physician reported a firm, superficial nodule surrounded by a purple ring, with an overlying black eschar. The physician prescribed ciprofloxacin, the standard antibiotic for cutaneous (skin-affecting) anthrax. Testing the patient's serum with a bacterial antigen revealed the presence of antibodies, confirming the diagnosis of anthrax. The ciprofloxacin was continued, and the patient slowly improved over several weeks How did Caleb contract the Bacillus anthracis infection? What sign did Caleb exhibit that is typical of such an infection? Why did Caleb recover?

cutaneously skin lesions He was prescribed an antibacterial medication.

A cell's hereditary material is

dna

eukaryotic cells characteristics

dna in a nucleus wide range of cell sizes contain mitochondria multiple membrane enclosed organelles linear chromosomes

Characteristics of prokaryotic cells

dna is the nucleoid region small cell size circular chromosome very few intracellular membranes cell walls containing peptidoglycan

the Virginia department of health sends out a bulletin to inform the public of a sudden surge in cases of toxoplasmosis. The case count is much higher than normal. Surprisingly, the new cases are tightly clustered around Richmond, and aren't observed elsewhere in the state. What term should the department use to describe this set of cases?

epidemic

ells need to be able to move particles of a variety of different sizes through the membrane and into the cell. Rank the following methods of transmembrane movement based on how large the particles brought into the cell can be.

freely permeable through the bilayer membrane transport channels endocytosis phagocytosis

which of the following is least directly associates with digestion by protists?

golgi

if you forget to use safranin in the gram staining procedure, then

gram negative cells will be clear

Louise was an 80-year-old woman who, until recently, had led an active life despite diabetes. Following a stroke however, she was admitted to the hosptial and was fighting for her life. Upon admission, an indwelling urinary catheter was inserted to drain her bladder, and unfortunately the device became colonized by Pseudomonas aeruginosa. This bacteria quickly entered her bloodstream. Unlike certain enteric species (e.g., E. coli, Klebsiella, and Proteus), Pseudomonas aeruginosa is not a common cause of UTI; it is, however, an important opportunistic pathogen in health care settings and is notorious for forming biofilms on catheters, ventilators, mechanical heart valves, and stents. Antibiotics were not successful in resolving Louise's infection, and in fact, they seemed to worsen her condition. She died the following day of endotoxic shock. Endotoxic shock results from the body's overreaction to lipopolysaccharide, and thus it is a potential consequence of infections caused by What portion of lipopolysaccharide is responsible for its toxicity? What possible role did antibiotics play in the outcome of this specific case?

gram-negative lipid a Antibiotic-induced lysis of the cells caused the release of LPS.

compared to a chronic disease, an acute disease will

have shorter time between incubation and illness

Salmonella enterica, the bacteria that causes typhoid fever, can infect only humans. Therefore, which quality of Salmonella enterica is very limited?

host range

which of the following was not necessary for developing the germ theory of disease?

identification of B. anthracis spores

Which of the following occurs when a pathogen or parasite enters or begins to grow on a host?

infection

Endosomes and phagosomes are intracellular compartments lined with

lipids

Membranes are composed mainly of ________________.

lipids and proteins

characterization of a newly identified bacterial pathogen identifies porin proteins. What other type of molecules do you expect to find associated with this pathogen?

lipopolysacharide

A mutualistic relationship exists between human hosts an

microbiota

Which of the following eukaryotic structures most closely resembles a prokaryotic cell?

mitochondrion

bacterial flagella rotate as result of

movement of protons across the membrane

characteristics of saturated fatty acids

no double bonds between carbons membrane more stable in hot climates typically solids at room temperature

pathogen A has an LD50 of 500, and pathogen B has an LD50 of 100.Which of the following is true? pathogen a and b are equeally virulent pathogen a is more virulent than b pathogen b is more virulent than a there is no way to judge the relative virulence of the organisms

pathogen b is more virulent than a

which of the following protects Gran(-) cell from osmolysis?

peptidoglycan

What are pathogenic microbes like Shigella flexneri, which causes bacillary dysentery in healthy people, called?

primary pathogens

The phase is the infectious disease stage during which the number of organisms rises in the body until the immune system recognizes that an invader is present.

prodromal

a cell wall

protects the cell from osmotic shock ions pass freely ridged and holds its shape components are covalently linked together mainly made of polysaccharide

Mad Cow Bad CowJason, a 54-year-old Canadian, began to feel ill after coming home from a business trip. He exhibited symptoms of dementia and had loss of body control. It was determined that he suffered from a prion (infectious protein) disease. At some point in his life, he must have eaten meat from a farm where control measures were not in place and where farmers were feeding cattle meat-and-bone meal that contained prion-infected products. Pions are infectious agents composed entirely of a _________ material. Prions cause disease by which mechanism?

protein inducing irreversible conformational change in proteins

The plasma membrane of a bacterial cell is composed primarily of which two types of organic molecules?

proteins and lipids

which of the following type of microbe is the largest? yeast prion bacteria protist

protist

Which of the following is an INCORRECT pairing?

protozoa: multicellular

Which of the following has a low virulence?

rhinovirus

which of the following is not a function of the cell membrane?

ribosome production

septum formation during binary fission

separates replicated genomes

pick the pair of words that will make the following sentence correct. A_______________is a disease manifestation that can be observe by clinicians, whereas a _____________disease manifestation that cab only be felt by the patient

sign, symptom

Jennifer, age 23, had just graduated from college with a Fulbright fellowship to study sociology in Africa. Before leaving the United States, she obtained a routine physical exam at a large city hospital. Upon returning home from the hospital, she developed a swelling in her leg. When she returned to the hospital, she was told that the swelling represented an allergic reaction and was given anti-inflammatory agents. The swelling grew and within a day, the skin ruptured with a bloody discharge. Upon her return to the emergency room, Jennifer at last received a correct diagnosis of methicillin-resistant Staphylococcus aureus infection. A nurse commented that hospital visitors can acquire MRSA; the infectious agent is endemic in many hospitals in the United States and is very difficult to eradicate. She showed Jennifer a micrograph of the bacteria, Staphylococcus aureus, which septate in alternating division planes, thus forming clusters of cells. Jennifer required many weeks of treatment with the antibiotics doxycycline and clindamycin before the infection resolved, and she had to postpone her fellowship for a year. The name of the bacterial species that caused Jennifer's infection is Staphylococcus aureus. Based on this information, what shape would you expect the cell to be? The infection that Jennifer had was caused by a strain of Staphylococcus aureus called methicillin-resistant Staphylococcus aureus, also known as MRSA. As the name suggests, this organism cannot be killed with the drug methicillin, which is a member of the penicillin family of antibiotics. What part of the bacterial cell does methicillin target?

spheres Methicillin inhibits peptidoglycan synthesis in the bacterial cell wall.

prolaryotic flagella

spins to move cell contains a single filament made of flagellin monomers anchored in the membrane and extends out of the cell

What part of a bacterium does penicillin target?

the cell wall

You and your immunocompromised neighbor both consume undercooked meat containing a pathogenic strain of E. coli. Your neighbor becomes ill (but eventually recovers), whereas you never experience any symptoms. Which of the following is true?

the escherichia coli strain ingested was an opportunistic pathogen

which of the following statements about lipids is not correct?

they form bilayers due to interactions between amino acids

which of the following does not apply to a case of an individual who is bitten by a tick and then exhibits a rash on both arms and legs, consistent with Rock Mountain spotted fever? viremia vector acute systemic

viremia

Imagine you are working on an organic farm and notice one day that the cucumbers are yellowing and bumpy, and their leaves are wrinkled and withered. You contact the agricultural extension agent at the local university and she offers to help identify the cause. After collecting leaves from affected plants, she returns to her lab to process the samples. Several days later, she calls to explain that the infectious agent appears to be microbial, although she cannot visualize it with her light microscope. The organisms also do not grow on standard laboratory media, but preparations of nucleic acid yielded single-stranded RNA. Because you have taken microbiology, you are not surprised when she tells you that a ___________ is the probable cause of cucumbers' condition.

virus

eukaryotic flagella

whips back and forth to move cell contains multiple filaments made of tubulin monomers entirely enclosed within the membrane

a cell membrane

will be ruptured by osmotic shock impermeable to ions thin and flexible components are not covalently linked mainly made of lipids and proteins