Imagine if you could tinker with any component of the signaltransduction pathway involved in vision in vertebrates. In thisproblem, you will predict the effect of a change in the activity ofa single component of the signal transduction pathway in vision.The rod cell secretes the neurotransmitter glutamate onto thebipolar cell as a function of its membrane potential – the moredepolarized, the more it secretes; the more hyperpolarized, theless it secretes. The bipolar cell in this case (ON bipolar) hasglutamate receptors that cause closure of cation channels,hyperpolarizing their membrane. They synapse with ON ganglion cellsand secrete acetylcholine into the synapse at a rate that increaseswith increased depolarization of the bipolar cell membrane. The ONganglions have acetylcholine receptors that are ligand-gated ionchannels. The ganglion cell responds by sending a train of actionpotentials to the brain; the frequency of these action potentialsis a function of the amount of acetylcholine that they sense. Inyour experiment, you will expose the rod cells to a controlledlight pulse (same length and intensity every time) and measure theoutput of the ON ganglion cells to which they are connected. Thenyou will repeat this in each perturbed system. In each case,predict whether the frequency of action potentials sent out by theON ganglion in response to light will be HIGHER or LOWER than theunperturbed system.

• You express a version of rhodopsin that stabilizes11-cis retinal relative to all-trans retinal                            [Select ]                      [\"HIGHER\", \"LOWER\"]     
• You mutate the transducin (G_t) beta subunit suchthat it has much higher affinity for the transducin (G_t)alpha subunit bound to GTP (G_tα-GTP)                            [Select ]                      [\"HIGHER\", \"LOWER\"]     
• You mutate the inhibitory subunit of cGMP phosphodiesterase(PDE) such that it has lower affinity for the catalytic subunit ofPDE.                            [ Select ]                     [\"HIGHER\", \"LOWER\"]      
• You add a drug that mimics the effect of cGMP: it binds to theligand-gated Na⁺/Ca²⁺ channel and opens it.However, this drug is not affected by PDE.                            [ Select ]                     [\"HIGHER\", \"LOWER\"]     
• You use CRISPR/Cas9 to delete the gene for rhodopsinkinase.