Tell Me Why finals Flashcards

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During the war in Afghanistan in 2012, an army
corporal with type AB blood received a life-saving
transfusion from his sergeant, who had type O blood.
Later, the sergeant was involved in a traumatic
accident and needed blood desperately. The corporal
wanted to help but was told his blood was incompatible.
Explain why the corporal could receive blood from but
could not give blood to the sergeant.

The O blood type lacks two antigens (A and B) that can trigger an immune response, and it is therefore safe to give to a person of any blood type (this is why people with O blood type are sometimes referred to as "universal donors"). The corporal's blood carries both A and B antigens and will provoke an immune response in anyone who does not have both A and B antigens because their blood contains antibodies to one or both of the antigens.


Why can’t scientists use the postulates of Robert Koch
to determine the specific cause of Graves’ disease?

because they can not be grown alone in a cell-free culture


Two boys have autoimmune diseases: One has Bruton
-type agammaglobulinemia, and the other has
DiGeorge syndrome. On a camping trip, each boy is
stung by a bee, and each falls into poison ivy. What
hypersensitivity reactions might each boy experience
as a result of his camping mishaps?



Vaccines have drastically reduced the number of
cases of many diseases, such as measles and
whooping cough. Why should parents have their
children vaccinated given that there are so few



A diagnostician used an ELISA to show that a
newborn had antibodies against H IV in her blood.
However, six months later, the same test was
negative. How can this be?

The antibodies detected at the time of birth were maternal antibodies (IgG) that crossed the placenta. Human babies do not have a functional acquired immune system at birth and therefore do not have their own antibodies. When the maternal IgG antibodies were depleted, the test results were negative.


Why are the activities of B and T cells called

B and T cells to "adapt" and follow through the specific job that is needed to be done


Why are exogenous epitopes processed in vesicles
instead of in endoplasmic reticulum, as endogenous
epitopes are?

they enter the cell via phagocytosis


Why did scientists give the name perforin to a molecule secreted by Tc cells?

they are synthesized as monomers of cytotoxic granules of armed CTLs and NK cells.


Plasma cells are vital for protection against infection,
but memory B cells are not. Why not?

memory be cells provide more lifelong protection by producing antibodies and retaining that information, not actually fighting infections head on


Why is passive immunity effective more quickly than
active immunity?

Active immunity provides longer term protection. Once a person has been exposed to an antigen, specific B and T cells are activated and they then multiply, giving the person lasting protection due to immunological memory.


Why aren’t the body’s skin and mucous membrane
barriers significant factors in your resistance to infection by hyperthermophiles?

normal body temperature is too low to support growth of hyperthermophiles


Why doesn’t lysozyme released in tears harm a person’s eyes?

Lysozyme kills gram-positive bacteria, protecting the eye against pathogens.


Why are pathogen-associated molecular patterns (PAMPs) necessary for Toll-like receptors (TLRs) to fully

TLRs hold a key position in the first line of defense against pathogens because of their ability to recognize the conserved pathogen-associated molecular patterns (PAMPs), conserved structures of the pathogens, or the damage caused by the pathogens within the host


describe how DNA is packaged in both prokaryotes and eukaryotes. explain the central dogma of genetics

genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein.


Label steps in phagocytosis