more questions

[BombayBombshell]

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hey guys....hate to pick your brains like this but here are a couple more q's for you...

1. a bacterium has 15,000 bp that encodes resistance to tet and amp segregates mutants that lose resistance to either drug. each indep. mutant plasmid appears to incr. in size by approx. 5200bp. why??
a. plasmid concatemers (huh WTF?) b. plasmid dimers c. homologous recomb. d. insertion of transposon e. slip-stranded dna rep.


2. a 5yo boy w/ recurrent ear infections receives a booster immunization against DPT..his response to tetanus toxoid is well below NML. Periph B and T count and function WNL. Ab he makes is pos. in both passive hemagglutination and complement-mediated lysis of tt-coated RBCs. Abs don't opsonize tt-coated latex particles for phagocytosis and do not directly ppt it efficiently. what's the problem?
a. affinity maturation of immunoglobulins
b. immunoglob. isotype switching
c. recombination of heavy chain variable genes
d. recombination of light chain variable region genes
e. somatic mutation of immunoglob. genes...

hmmmm ok there you go...thanks!! 😍

oh btw i read a post about someone wondering if it was a good idea to wait after 3 yr to take step 1...my answer: an emphatic NOOOOO!! my school also lets me take the step 1 whenever i want....so, i thought i would take it after 3rd yr...big mistake! the test sucks whenever you take it and some of the stupid little pesky details that the board tests just aren't relevant in the clinics and, besides, who the hell (in their right minds 🙂 ) remembers stuff from freshman yr anyway? just my personal opinion as i struggle w/ stuff that may very well have been a little fresher in my mind had i taken it last yr...

brin

 

[Idiopathic]

I went with transposons in the first example...the only real way that a functional chromosome could increase in size that much and still function.

For the second one, I went with isotype switching. This looks like Wiskott-Aldrich(?)...its been so long already. He can fix complement and D and T are WNL, which means that the lymphocytes are quantitatively okay and that IgM is being made. BUT, since there is no opsonization, IgG is not being made. Thus, no class switching.

 

[DarksideAllstar]

I couldnt remember what I put for the first one--probably marked transposons because I didnt know what a couple of the choices were and a couple didnt make sense (I actually forgot that I had that question) and I put the same as Idiopathic for the second one for the same line of reasoning.
Guess I wasnt as half asleep during my exam as I thought.