MMI 1053 Final exam

COMPREHENSIVE

Which features are routinely examined in the clinical testing laboratory to establish the identity of a pathogenic bacterium in a patient sample:

Cell shape are arrangement, cell wall construction, and metabolic biochemical properties

What is the correct definition of commensalism?

type of symbiosis in which one organism benefits but the other is unaffected

Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light?

fluorescence microscope

What would be the total magnification of a sample viewed through a microscope using a combination of a 10x ocular and 40x objective lens?

400 X

A virus measures 50nm in length. What is its length in um?

0.05um

Which type of microscopy is best suited for examining thin, hair-like spirochete bacteria like Borrelia burgdorferi (the causative agent of Lyme disease)?

Phase contrast microscopy

Which organelle most closely resembles a prokaryotic cell?

mitochondria

After completing the Gram stain procedure, what color are the gram positive and gram negative cells?

purple and red

Which structure would you find in both prokaryotic and eukaryotic cells?

plasma membrane

What is the correct order of microbes according to size from smallest to largest?

virus, bacterium, protozoan, tapeworm

What are the two key features (parameters) of any microscope, important for a microbiologist to know?

magnification and resolution

The endosymbiotic hypothesis is a theory that proposes which two organelles evolved from free-living aerobic and photosynthetic bacteria taken up by an early eukaryotic cell?

mitochondria and chloroplasts

Which hair-like structures found on microbial cells has a different function to the others?

fimbriae

Which type of stain is most useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection?

gram stain

What is the infectious agent of prion based diseases such as kuru or mad cow disease (BSE)?

a protein

Which of the following group of individuals is most at risk from a life-threatening systemic fungal infection?

immunocompromised individuals

Protozoan and fungal diseases are most difficult to treat than bacterial infections because

their cells are structurally and functionally more similar to human cells than bacterial cells

Which media cannot be used to culture/grow viruses?

plain culture media

In which viral replication cycle does viral DNA integrate into the host cell's genome and is duplicated during subsequent cell divisions, while the host shows no sign of infection/disease?

lysogenic

A student is looking at a bacterial specimen using the oil immersion lens, but has forgotten to put immersion oil on the slide. The specimen will appear

somewhat fuzzy and have poor resolution

What do viruses NOT include?

ribosomes

What is the current treatment for prion caused diseases?

there is no cure for prion based diseases

What is a classic example of a latent viral infection?

Cold sores

What is a classic example of a persistent (long term progressive) viral infection?

HIV/AIDS

Which scientist was the first to observe microorganisms with a microscope?

van Leeuwenhoek

Some viruses have an external lipid envelope. At which stage of their life-cycle is it acquired?

Release

What structure is never found in prokaryotic cells?

80s ribosomes

Mycology is the study of

fungi

What was the major discovery made by Edward Jenner during his development of the first vaccination process?

exposure to a milder disease form can produce immunity to a related but more dangerous form

Which organism is NOT typically included in the study of microbiology?

insects

Which class of microorganism is most likely to be studied by a parasitologist?

protozoa

Which class of organisms does not have a cell wall?

animals

Into which group would you place a photosynthetic cell that lacks a nucleus?

bacteria

a multicellular organism that has a mouth and lives inside an animal host would most likely be a

helminth

Correctly order the five steps listed below in the process of pathogenesis?
1. microbes enter the host
2. cause damage
3. adhere to host tissues
4. avoid destruction by host defenses
5. exit host to continue chain of transmission

1,3,4,2,5

What is an example of a biological vector?

mosquito

Which of the following statements about exotoxins is FALSE?

they cannot be denatured or inactivated by heat

Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to the presence of

superantigens

What is the name of the science that deals with when diseases occur and how they are transmitted?

epidemiology

The causative agent of which disease did Dr. John Snow discover was being transmitted through the water supply?

cholera

The means of Cholera transmission in London in the mid-1800s (through the water supply) is called?

common vehicle transmission

What is the most frequently used portal of entry for human pathogens outside of the hospital setting?

mucous membranes of the respiratory tract

To which US government entity must physicians and medical professionals report every case of a patient which certain notifiable disease they encounter?

CDC

Many bacterial species organize genes encoding enzymes involved in the same metabolic pathway in a back-to-back cluster with a single promoter sequence. What is the correct scientific term for such a cluster of genes?

an operon

Blood may serve as a liquid vehicle for which of these pathogens?

Hepatitis B Virus (HBV)

Symptoms of disease differ from signs of disease in that symptoms

are changes felt by the patient

The passing of the rubella (German measles) virus from mother to unborn fetus is an example of what type of pathogen transmission?

vertical transmission

What is the most common type of nosocomial (hospital acquired) infection?

urinary tract infection

When a pathogen attaches and causes a disease at a single anatomical site, this is known as what type of infection?

local

What are four examples of reservoirs of infection?

a sick person, a healthy person, a sick animal, a hospital

What is NOT a communicable disease?

tetanus

Which of the following statements about nosocomial infections is FALSE?

the patient was infected before hospitalization

Influenza transmitted by an unprotected sneeze is an example of

droplet transmission

What is considered a zoonotic disease?

rabies

An infection obtained from an accidental needle stick is acquired through which route?

parenteral

What is a fomite?

an inanimate object that can transmit infections to a new host

In which process is a plasmid passed from one bacterial cell to another using a hair-like structure called a pilus?

conjugation

A group of people acquiring Legionnaire's disease from bacteria carried through air conditioning ducts is an example of

common vehicle transmission

What four things can contribute to a postoperative infections?

using syringes more than once, normal microbiota on the operating room staff, antibiotic resistance, errors in aseptic technique

What are four examples of predisposing factors of disease?

occupation, lifestyle, gender, climate

The location where a pathogen can survive and replicate until it can enter a new host is called the

reservoir

What is the best description of transcription?

an RNA molecule made from a DNA template

Genetic change in bacteria (which are asexual) can be brought about by what four things

conjugation, viral transduction, mutation, transformation

What is the process by which the information in mRNA is used to make proteins?

translation

Cytopathic effects observed in host cells are used as an indicator of which type of infection?

viral

What four factors influence the disease outcome after the entry of a microbe into a human?

host genetic factors, microbial virulence factors, the number of invading microbes, and the immune status of the host

What procedure did Dr. Ignaz Semmelweis introduce that saved the lives of new mothers in the Vienna hospital where he was a physician?

hand-washing by medical students in a chlorinated lime solution before assisting in childbirth

Which four medical conditions CAN be caused by bacterial endotoxin?

fever, acute respiratory distress syndrome, disseminated intravascular coagulation, septic shock

How does a nonsense mutation in DNA alter the final protein product?

it changes the affected codon into a stop signal thereby truncating (shortening) the final product

The tryptophan biosynthesis cluster of genes are a classic example of a feed-back loop, where excess product switches off their expression. As such, they are

repressible

Which of the following statements about bacterial endotoxin is true?

it is pyrogenic (induces a fever)

Example of an obligate anaerobe

Image: Example of an obligate anaerobe

Example of a facultative anaerobe

culture medium containing agar, human blood, and beef heart extract is an example of a

complex medium

A culture medium on which only gram-positive organisms grow and a yellow halo surrounds Staphylococcus aureus colonies but not colonies produced by other Staphylococcus species is called a(n)

selective and differential medium

Which of the following is NOT a direct method to measure microbial cell numbers?

turbidity readings with a spectrophotometer

All adhesive first aid dressings such as Band Aids now allow air to pass through them (breathable). Which disease/infection is this feature primarily designed to prevent?

tetanus

What is an advantage of the direct microscopic count?

it requires no incubation time

What was the first compound truly characterized as an antibiotic?

penicillin

Against which class of organisms do most of the currently available antimicrobial drugs work?

bacteria

Penicillin and cephalosporins interfere with the synthesis of which bacterial structure?

cell wall

Disease caused by which of the following classes of organisms are typically the most difficult to treat with antimicrobial drugs?

viruses

Which of the following concentrations of ethanol is the most effective bactericide?

70 percent

For years, people in Eastern countries stored water in copper containers. The belief was that this reduced the number of microbes in the water, making it safer to drink. To which of the following categories of antimicrobial agents does copper belong?

Heavy metals

Drug resistance occurs

when antibiotics are used indiscriminately

List four reasons why human patients contribute to the problem of antimicrobial resistance

1. failing to follow prescription instructions
2. self-administration of antimicrobial drugs left over from prior infection
3. asking health care providers for antimicrobial drugs when they are not needed
4. using drugs prescribed for someone else without seeing a medical professional

What is NOT an example of a physical method of controlling microbial growth?

use of an alcohol based gel

Which disinfectant is the most effective at stopping bacterial growth?

doom

Which disinfectant is bactericidal?

mortum

How are protein-containing solutions such as antisera or some vaccines typically sterilized?

filtration

What is the correct definition of "selective toxicity"?

use of drugs to kill or inhibit the growth of a pathogen without harming the host

An E-test is used in the clinical laboratory to determine

the minimum inhibitory concentration (MIC) of an antibiotic

What are four types of mechanisms employed by microbes to develop drug resistance?

1. alter the permeability of the cell to the drug
2. production of enzymes to degrade or modify the drugs chemical structure
3. a mutation to modify the drugs cellular target
4. up-regulation of efflux pumps to rapidly remove the drugs from inside the microbial cell

There are three major classes of antifungal drugs (azoles, polyenes, and echinocandins) routinely used for serious (non-superficial) infections. What are the major targets of these drugs?

unique structures within the fungal cell wall and membrane

Which section of a bacterial growth curve shows a phase where the number of cells dying equals the number of cells dividing?

C

What is the scientific name for the section of a bacterial growth curve labeled B?

logarithmic phase

Most bacteria grow best in which pH range?

pH 6.5-7.5

If a bacterial growth experiment began with 4 cells and ended with 128 how many generations (divisions) did the cells go through?

5

Most (human) disease causing microorganisms are classified into which of the following groups?

mesophiles

The biosafety level (BSL) for a clinical microbiology laboratory working with airborne pathogens such as tuberculosis bacteria or Coccidiodes fungus, which can cause disease in the heathy, is

BSL-3