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. 

TLS Online TPP Program

#Question id: 20003

#Unit 12. Applied Biology

In plants proline is preferentially produced from ornithine under normal conditions. However, under stress it is made directly from 

TLS Online TPP Program

#Question id: 15521

#Unit 4. Cell Communication and Cell Signaling

Rearrangement of the β, γ, and δ loci begins during the

TLS Online TPP Program

#Question id: 11096

#Unit 7. System Physiology – Animal

In which structure does diffusion of oxygen to capillaries not play a major role?

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#Question id: 5240

#Unit 8. Inheritance Biology

If bacteria grow in the presence of a large amount of DNase, which of the following recombination process completely inhibited?

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#Question id: 24489

#Unit 3. Fundamental Processes

Two transesterification reactions takes place for 2 exon -1 intron configuration. Choose the correct  statement 

a. First transesterification is always caused by exon 1 -3’OH

b. second transesterification is catalysed variably either by external G or branch point while .

c. First transesterification is catalysed variably either by external G or branch point while 

d. second transesterification is always caused by exon 1 -3’OH.