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STEP 1 > HY Micro > Flashcards

HY Micro Flashcards

1
Q

Recombination can occur between 2 virus strains that have a _____ genome (Ex: Herpes)

A

nonsegmented (double stranded)

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2
Q

refers to the exchange of genes between 2 chromosomes via crossing over within homologous regions.

Progeny can have genomes with traits from both parent viruses.

A

Recombination

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3
Q

occurs when one virus inhibits replication and/or release of a second virus that is infecting the same cell.

A

Interference

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4
Q

Phenotypic mixing can occur when a host is ___ with 2 viruses.

A

coinfected

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5
Q

occurs when a host cell is coinfected with 2 viral strains and progeny virions contain parental genome from one strain and nucleocapsid (or envelope) proteins from the other strain.

A

Phenotypic mixing

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6
Q

Phenotypic mixing result in progeny acquiring additional traits (ex: enhanced ability to infect new host cells due to different nucleocapsid proteins). However, as the genome is _____, subsequent progeny would not retain these traits.

A

unchanged

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7
Q

Reassortment refers to changes in genomic composition that occur when a host is coinfected with 2 _____ viruses that exchange whole genome segments.

A

segmented

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8
Q

Reassortment can cause alterations in surface antigens of the _____ , making it mutagenic (Ex: Influenza)

A

viral progeny

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9
Q

Reassortment is for ______ genomes

Recombination is for ________ genomes

A

segmented

non-segmented

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10
Q

Direct uptake of extracellular DNA from a lysed cell or from free floating plasmids

A

Transformation

*typically causes no genomic change in progeny

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11
Q

They possess the surface proteins hemagglutinin (HA) and neuraminidase (NA), which are virulence factors required for infectivity

A

Orthomyxoviruses

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12
Q

refers to point mutations in HA and NA genes that slightly alter the product proteins, allowing them to evade immune recognition and possibly increasing infectivity of the virus.

A

Antigenic drift

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13
Q

a change in species-to-species transmission likely represents a major modification in protein structure that is better explained by RNA segment _____.

A

reassortment

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14
Q

occurs when 2 viruses infect the same cell and progeny viruses exhibit coat or envelope proteins not coded for by the genetic material packaged within them.

A

Phenotypic mixing

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15
Q

Influenza epidemics and pandemics are typically caused by reassortment of the RNA segments coding for hemagglutinin or neuraminidase proteins (major antigenic ____ ).

A

shifts

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16
Q

Bacterial mRNA can be polycistronic, meaning that ____ codes for several proteins.

A

one mRNA

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17
Q

The transcription and translation of the lac operon proteins is regulated by a single _____, operator, and set of regulatory elements.

A

promoter

mRNA is polycistronic

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18
Q

Parvovirus B19 replicates in _____ precursors in the bone marrow.

A

erythrocyte (RBC)

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19
Q

an enveloped virus containing partially double-stranded circular DNA.
An enzyme packed in its virion has RNA-dependent DNA-polymerase activity.

A

Hepatitis B

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20
Q

Orthomyxoviruses contain a segmented genome, and HA and NA are coded by separate RNA segments. This allows for ______ when 2 distinct strains infect the same cell.

A

genetic reassortment

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21
Q

Immune defense against Giardia involves CD4+ T helper cell induction of secretory __ production.

A

IgA

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22
Q

Secretory ___ helps prevent and clear infection by binding and impairing microbial or protozoal adherence to the mucosa.

A

IgA

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23
Q

IgA deficiency, X-linked agammaglobulinemia, and common variable immune deficiency have a predisposition to developing chronic ____ (protozoa)

A

giardiasis

*+/– Small-bowel biopsy = villous atrophy & crypt hyperplasia.

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24
Q

is able to obtain new genetic material (which codes for a capsule) from the environment that is released following the death and lysis of neighboring bacterial cells (Transformation) thus becoming VIRULENT.

A

S pneumoniae

25
Q

Bacteria that have the innate capacity to undergo transformation are said to be naturally competent and include :

A

Streptococcus (S pneumoniae, Viridans)
Haemophilus
Neisseria
Bacillus

26
Q

Transfer of infected Bacterial Host DNA to another newly infected bacteria via a Bacteriophage

A

Transduction

27
Q

While replicating within a host bacterium, a bacteriophage may accidentally incorporate host bacterial DNA into the phage particle.

A

Transduction

28
Q

By this mechanism, bacteria can acquire genes for virulence and antibiotic resistance from another bacteria.

A

Transduction (via a bacteriophage)

29
Q

Phage mediated DNA transfer

A

Transduction

30
Q

_____ form of one-way DNA transfer performed by bacteria carrying a plasmid with the fertility (F) factor.

A

Conjugation

31
Q

Pilus mediated DNA transfer

A

Conjugation

32
Q

The process begins with a pilus, forming a direct connection with the receiving bacterium.
Then transferring a single DNA strand with the F factor to the recipient.
After which, complementary DNA strands are synthesized.

A

Conjugation

33
Q

S. Viridans dextrans colonize/adhere to ____ at sites of endothelial trauma on heart valves

A

Fibrin- Platelet aggregates

34
Q

Spore-forming bacteria can survive boiling temperatures. ____ & _____ species are common pathogenic spore-forming bacteria.

A

Bacillus

Clostridium

35
Q

Endothelial surface glycoproteins mediate binding of ____ cells to endothelium

A

immune (Neutrophils)

36
Q

Subendothelial collagen and _____ form the subendothelial fibrous cap over the central core of an atherosclerotic plaque and are potent platelet activators.

A

glycosaminoglycans

37
Q

___ and ___ have a dormant hepatic phase (hypnozoite) that may reactivate several months after return from an endemic region (if not treated with primaquine).
In contrast, ____ does not have a dormant hepatic phase; it matures in (and is released from) the liver over 8-30 days.

A

P ovale
P vivax

P falciparum (not dormant)

38
Q

In Africa, where chloroquine-resistant _____ is endemic, common chemoprophylaxis regimens include atovaquone-proguanil, doxycycline, and mefloquine.

A

Plasmodium falciparum

39
Q

____ is a schizonticide that actively destroys replicating parasites within red blood cells. However, it is inactivated in the liver and has no efficacy against hepatic schizonts.

A

Mefloquine

*must be taken for 4 weeks after return to ensure liver parasites burst and inhabit RBCs

40
Q

Cases of P falciparum in Africa are usually resistant to.

A

chloroquine

41
Q

___ chemoprophylaxis for malaria must be continued for 4 weeks after return from an endemic region to ensure the elimination of hepatic schizonts (which develop in the liver over 8-30 days).

A

Mefloquine

42
Q

In the bloodstream, endotoxin causes a severe inflammatory response mediated by ___ & ___ from activated macrophages.

A

tumor necrosis factor-alpha

IL-1

43
Q

Intestinal ____ is a property of gastroenteritis caused by Salmonella, Shigella, EIEC, Campylobacter jejuni, & Entamoeba histolytica. This frequently leads to bloody or hemorrhagic diarrhea (due to mucosal cell necrosis).

A

invasion

44
Q

acts by inactivating the 60S ribosomal subunit in human cells, thereby inhibiting human cell protein production, leading to cell death.

A

Shiga Toxin

Shiga-like Toxin

45
Q

“Stacked-brick” intestinal adhesion is characteristic of ____.

These organisms adhere to human jejunal, ileal, and colonic mucosa in an aggregative, or stacked-brick, pattern and do NOT invade.

It causes persistent diarrhea in infants in developing countries and those with advanced immunosuppression (AIDS).

A

enteroaggregative E coli (EAEC)

46
Q

ETEC produces plasmid-encoded, ____ and ____ enterotoxins which cause watery diarrhea which self resolves in a few days.

A

heat-labile (LT, choleragen-like)

heat-stable (ST)

47
Q

ETEC, Heat-Labile toxin (LT) activates

A

adenylate cyclase, leading to increased intracellular cyclic AMP

48
Q

ETEC heat-labile (LT) toxin is similar to

A

Cholera- Like enterotoxin

49
Q

ETEC Heat-stable Toxin (ST) activates

A

guanylate cyclase leading to increased intracellular cyclic GMP

50
Q

non-Lactose fermenting bacteria turn what color on MacConkey Agar

A

White colonies

51
Q

During Glucose fermentation

____ produces acid & ____ produces gas.

A 
Shigella (Acid)
Escherichia coli (Gas)
52
Q

Generate Black Hydrogen Sulfide (2)

A

Salmonella

Proteus

53
Q

Do NOT Generate Black Hydrogen Sulfide

A

Shigella

54
Q

Lactose Fermenters

A 
E. coli
Enterobacter
Klebsiella
Serratia (slow)
Citrobacter (slow)
55
Q

Shigella is transmitted via the __ route and is never a component of the normal bacterial gut flora (non-motile).

A

fecal-oral

56
Q

Shigella INVADES the gastrointestinal mucosa, particularly via the M cells in the ____ .

After cell entry, Shigella is able to lyse its containment vacuole and enter the cytosol. It then can induce apoptosis and spread to adjacent cells via protrusions created through HOST-cell _____.

A

Peyer’s patches

actin polymerization

*Shiga toxin is NOT the main pathogenic factor. INVASION is.

57
Q

can cause inflammation and enlargement of the lymphoid tissue around the appendix and terminal ileum (“pseudoappendicitis”), leading to right lower quadrant pain that can be confused with acute appendicitis.

A

Y enterocolitica

proliferates in the LNs and grows in the cold

58
Q

_____ phosphorylates Acyclovir to its active form.

A

thymidine kinase

STEP 1 (88 decks)

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