rman
Forum Senior
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The cystic fibrosis transmembrane conductance regulator (CFTR) consists of a single peptide chain with transmembrane segments and extracellular and intracellular regions. Which of the following peptide segments of CFTR is most likely located in a transmembrane segment?
A ) Asp-Val-Leu-Thr-Glu-Lys-Glu-Ile
B ) Glu-Glu-Thr-Glu-Glu-Glu-Val-Gln
C ) Ile-Phe-Val-Leu-Ile-Trp-Cys-Leu
D ) Lys-Ile-Lys-His-Ser-Arg-Gly-Arg
E ) Ser-Thr-Gly-Ala-Gly-Lys-Thr-Ser
C because it looks pretty hydrophobic??
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| rman
Forum Senior
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Second question:
During the first meiotic division of human oogenesis, nondisjunction occurs between a pair of homologous chromosomes. If fertilization occurs, which of the following is the possible number of chromosomes contributed by the female pronucleus?
A ) 21 or 23
B ) 21 or 25
C ) 22 or 23
D ) 22 or 24
E ) 23 or 24
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| rman
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Third Question:
6. A 17-year-old girl has hemophilia A. Her older brother also has hemophilia A, but neither of their parents is affected. Which of the following is the most likely explanation for the development of hemophilia in this girl?
A ) Aneuploidy
B ) Balanced autosomal translocation
C ) Inheritance of defective factor VIII alleles from both parents
D ) Skewed X-chromosome inactivation
E ) Unequal recombination
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| Cedrick
Esculapio
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1.-C
2.-E
3.-D
we already this this there is tread you can look up
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| robin082006
Forum Hero
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1. C
2. D this has been discussed
3.D
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| robin082006
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http://www.prep4usmle.com/forum/comments.php?id=33928&highlight=During%20the%20first%20meiotic%20division%20of%20human%20oogenesis&findpost=170814#post170814
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| nadiabarati
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in CF there isn't Phe. So how C?!!!
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| robin082006
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Nadia that is the key to answer the question, the question asks about normal CTFR.
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| nadiabarati
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oh my God. You are right.
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| rman
Forum Senior
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Is that how you discovered the answer? What is the mutation again in CF? PHe-Val?
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| raves
Forum Elite
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exactly right robin
rman its a three base deletion at position 508 that codes for phe.
so a normal CFTR is the one that has phe n theres only one choice with phe in there.
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