Lifson Quizes 4 a, b, c

How do normal flora protect us?

a. they produce acid that discourages growth of pathogens b. they kill other microbes including pathogens with poisonous compounds c. they prevent pathogens from adhering d. diminish available nutrients making it difficult for pathogens to survive

siderophores

allow absorption of an essential

kinases and hyaluronidase

allow the microbes to spread through the host

Opportunistic pathogens

are microbes that in their normal habitat in contact with a normal host do not cause disease

mutalism

both benefit

Which of the following is true? a. viruses do not divide b. viruses do not have a cell membrane c. mature viral particles have only one type of nucleic acid viruses are small d. all of the above are true

d. all of the above are true

Which of the following is not true of viruses? a. viruses contain DNA or RNA but never both b. viruses contain a protein coat c. viruses use the anabolic machinery of the cell d. viruses use their own catabolic pathways for ATP production

d. viruses use their own catabolic pathways for ATP production

IgA proteases

detroy an important host resistant factor

What is the mechanism of transmission for a Chlamydia (sexually transmitted) infection?

direct contact

Lipid A from lipopolysaccharide from the outer membrane of Gram - bacteria is called

endotoxin

The chromosome of a virus can be

for some viruses DNA for others RNA

Referring to the previous question, the reservoir is

humans

The reservoir for the hepatitis C virus is?

humans

Order the appearance of viral nucleic acid from a retrovirus following uncoating from the following list. 1. DNA 2. DNA/RNA hybrid 3. single stranded RNA

3, 2, 1

Put the following in the correct order for virus replication: 1 - Maturation (assembly), 2 Biosynthesis, 3 - Attachment, 4 - Penetration, 5- Release, 6- Uncoating

3,4,6,2,1,5

In recent years there has been significant attention turned to the amount of gastrointestinal illness that is contracted on cruise ships. The most common type of virus linked to gastrointestinal illness is the Norwalk-like Virus (NLV) or norovirus, which gained notoriety from a 1968 outbreak in Norwalk, Ohio. Noroviruses are the leading cause of gastrointestinal illness with an estimated 23 million cases a year, according to the U.S. Centers for Disease Control & Prevention (CDC). After an outbreak a cruise ship will undergo extensive sanitization, yet there is often more outbreaks on subsequent cruises. It is suspected that infected crew members are the sources of continued outbreaks. Although a few cases of the virus have been due to contaminated seafood, most of the problem has been due to ill people vomiting in public places, having diarrhea in the public lavatories and handling all the railings and elevator buttons with unwashed hands. What is the method of transmission?

indirect contact

Probiotics are

microbes that are ingested to antagonize pathogens

parasitism

one benefits, one is harmed

commensalism

one benefits, one is unaffected

The envelope of a virus is made up of

partly the membrane of the host and partly viral proteins

Exotoxins which can be found in Gram + or Gram - (!) bacteria is easily denatured by heat because it is

protein

The capsid coat of a virus is made up of what material?

protein

An envelope is acquired during which of the following steps?

release

Endotoxin has low toxicity, however, when their is a septicemia (infection of the blood) there is so much bacteria that are being lysed either by the action of your immune system or due to the action of antibiotics that the toxin can kill. The action that causes death is by

release of immune factors that can cause lethal shock

capsules, M proteins of Steptococcus pyogenes and A protein of Staphylococcus aureus

resist phagocytosis

What type of chromosome does a +RNA virus have?

single stranded mRNA

What is the first biosynthetic event after un-coating for a +RNA virus?

translation

Borrelia burgdorferi causes Lyme disease in humans, an accidental host. The normal host is deer and deer mice. Ticks carry the microbe from one host to another including the accidental host. What is the mode of transmission for this disease?

vector

Salmonella Saint Paul is an unusual strain that has sickened many people in the US in the Spring of 2008. It is believed that a common source of transmission has been tomatoes from Mexico or Florida. What is the likely mechanism of transmission?

vehicle