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TLS Online TPP Program

#Question id: 14685

In dark-adapted rod cells, a high level of cGMP keeps cGMP-gated nonselective cation channels open, leading to hyperpolarization of the plasma membrane and neurotransmitter release. 
B - Light absorption generates activated rhodopsin, R*, which binds inactive, GDP-bound Gαt protein and mediates the exchange of GDP for GTP . 
C- The free Gαt∙GTP activates PDE by binding to its inhibitory γ subunits and dissociating them from the catalytic α and β subunits . Relieved of their inhibition, the α and β subunits of PDE hydrolyze GMP to cGMP . 
D- The resulting decrease in cytosolic cGMP leads to dissociation of cGMP from the cation channels in the plasma membrane and the closing of those channels . 
E- The membrane then becomes transiently hyperpolarized, and neurotransmitter release is reduced. 

#Unit 4. Cell Communication and Cell Signaling
  1. B , D and E       
  2. A, B, and E
  3. B, C, and D       
  4. C, D, and E
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TLS Online TPP Program

#Question id: 15817

#Unit 8. Inheritance Biology

You and your lab partner have isolated 20 new mutant yeast strains that are defective in synthesis of threonine, an amino acid. These Thr- mutants do not grow on minimal medium, but they do grow on minimal medium supplemented with threonine. Ten of your Thr- mutants (numbered 1 through 10) were isolated in a strain of mating type a (MAT a). The other 10 Thrmutants (numbered 11 through 20) were isolated in a strain of mating type α (MAT α). You and your lab partner cross each of the MAT a strains to each of the MAT α strains, and you include crosses to the appropriate wild-type strains. Your experimental observations are shown in the table below, where (-) indicates diploids that did not grow on minimal medium and (+) indicates diploids that did grow on minimal medium

Based on these experiments, what is the minimum number of genes required for threonine synthesis?
TLS Online TPP Program

#Question id: 15818

#Unit 8. Inheritance Biology

You and your lab partner have isolated 20 new mutant yeast strains that are defective in synthesis of threonine, an amino acid. These Thr- mutants do not grow on minimal medium, but they do grow on minimal medium supplemented with threonine. Ten of your Thr- mutants (numbered 1 through 10) were isolated in a strain of mating type a (MAT a). The other 10 Thrmutants (numbered 11 through 20) were isolated in a strain of mating type α (MAT α). You and your lab partner cross each of the MAT a strains to each of the MAT α strains, and you include crosses to the appropriate wild-type strains. Your experimental observations are shown in the table below, where (-) indicates diploids that did not grow on minimal medium and (+) indicates diploids that did grow on minimal medium.

What is the maximum number of genes that these 20 mutants could represent?
TLS Online TPP Program

#Question id: 15819

#Unit 8. Inheritance Biology

Being a well-rounded geneticist, you also maintain a colony of chickens. In a cross between a female chicken from a true-breeding strain with three toes per foot and a male from a true-breeding strain with seven toes per foot, all of the F1 progeny have five toes per foot.
Based on the information that toe counts should appear in the F2 generation and at what frequencies?
TLS Online TPP Program

#Question id: 15820

#Unit 8. Inheritance Biology

Your friends Ben and Jane are contemplating having children and seek your genetic counsel. Ben and Jane are unrelated, but both have younger brothers with the same, extremely rare genetic trait. (In fact, Ben and Jane met at a support group meeting for children and families of children with this rare disorder.) Ben’s parents and Jane’s parents are all unaffected.          
Assume that the trait is autosomal recessive with complete penetrance. What is the probability that Ben and Jane’s first child will be affected with the trait? If not affected, what is the probability that the child is a carrier?
TLS Online TPP Program

#Question id: 15821

#Unit 8. Inheritance Biology

Your friends Ben and Jane are contemplating having children and seek your genetic counsel. Ben and Jane are unrelated, but both have younger brothers with the same, extremely rare genetic trait. (In fact, Ben and Jane met at a support group meeting for children and families of children with this rare disorder.) Ben’s parents and Jane’s parents are all unaffected.          
Assume that the trait is autosomal recessive with 80% penetrance. What is the probability that Ben and Jane’s first child will be affected?
TLS Online TPP Program

#Question id: 15831

#Unit 8. Inheritance Biology

Your friends Ben and Jane are contemplating having children and seek your genetic counsel. Ben and Jane are unrelated, but both have younger brothers with the same, extremely rare genetic trait. (In fact, Ben and Jane met at a support group meeting for children and families of children with this rare disorder.) Ben’s parents and Jane’s parents are all unaffected.        
 Assume that the trait is X-linked recessive with complete penetrance. What is the probability that Ben and Jane’s first child will be affected? What is the probability that the first child will be a carrier?