which of the following is NOT a step in rod phototransduction by rhodopsin? activation of rhodopsin by photons conversion of cGMP to GMP by phosphodiesterase opening of cGMP-dependent ion channels and hyperpolarization of the membrane activation of phosphodiesterase by light-activated rhodopsin through Galphat, (couldn't add the alpha into that part

which of the following is NOT a step in rod phototransduction by rhodopsin? activation of rhodopsin by photons conversion of cGMP to GMP by phosphodiesterase opening of cGMP-dependent ion channels and hyperpolarization of the membrane activation of phosphodiesterase by light-activated rhodopsin through Galphat, (couldn't add the alpha into that part

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter36: Sensory Systems

Section: Chapter Questions

Problem 10RQ: Many diabetic patients are warned by their doctors to test their glucose levels by pricking the...

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To further investigate the cellular response in photoreceptor cells, we will now look at the actual effect of cGMP within the phototransduction pathway. Again, we will compare what happens in the dark and in the presence of light to understand how an electric signal is generated in either condition. Comparing both conditions (in the dark or under the light), researchers have measured the molar concentration of cytosolic cGMP and recorded the membrane potential of rod cells by placing micro-electrodes on either side of their plasma membrane (see figure below). A negative membrane potential means that there are more negatively charged ions inside the cell compared to outside the cell, or equivalently, that there are less positively charged ions inside the cell compared to outside the cell. ● A positive membrane potential means that there are more negatively charged ions outside the cell compared to inside the cell, or equivalently, that there are less positively charged ions outside the…
Researchers who study those rods cells have performed a series of experiments to better understand this phototransduction pathway and the role of this PDE protein in patients that suffer from night blindness. In one experiment, researchers have measured the cytosolic concentration of cGMP (cyclic- GMP) under different light intensities (exposure = 10 min) in both the presence and the absence of the PDE6i inhibitor. The results are as follow: the cytosolic concentration of cGMP (cyclic-GMP) decreases as light intensity increases, but only in the absence of the PDE6i inhibitor (see figure below). Without PDE6i cGMP concentration (A.U) 25 20 15- 10- 0 0 0.1 A.U (Arbitraty Unit) 0.2 0.3 Light intensity (A.U) 25 -20 -15 -10 -5 0.4 0 GMP concentration (A.U) cGMP concentration (A.U) 25 20- 15- 10 0- 0 0.1 With PDE6i 0.2 0.3 Light intensity (A.U) -20 C. The PDE protein is an oxidase that reduces GMP into a cGMP D. The PDE protein is a phosphodiesterase that converts cGMP into a GMP E. The PDE…
Researchers who study those rods cells have performed a series of experiments to better understand this phototransduction pathway and the role of this PDE protein in patients that suffer from night blindness. In one experiment, researchers have measured the cytosolic concentration of cGMP (cyclic- GMP) under different light intensities (exposure = 10 min) in both the presence and the absence of the PDE6i inhibitor. The results are as follow: the cytosolic concentration of cGMP (cyclic-GMP) decreases as light intensity increases, but only in the absence of the PDE6i inhibitor (see figure below). Without PDE6i cGMP concentration (A.U) 25 20 15- 0- 0 0.1 0.2 0.3 Light intensity (A.U) 25 0.4 20 15 - 10 5 0 GMP concentration (A.U) cGMP concentration (A.U) 25 20 15- o 0- 0 0.1 With PDE6i 0.2 0.3 Light intensity (A.U) 0.4 25 20 0 GMP concentration (A.U) 10. What is the likely function of the cytosolic cGMP in this phototransduction pathway? A. It is a competitive inhibitor of PDE B. It is a…
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The apical surfaces of hair cells are exposed to an unusual extracellular fluid called endolymph. Endolymph is relatively similar in ionic composition to cytoplasm: Select one: O O a. it is high in Na+ (-150 mM), low in K+ b. It is high in K+ (250 mM), low in Na+ c. it is high in K+ (150 mM), low in Na+ d. It is high in Ca 2+ (-250 mM), low in Na+ (-2 mM), and relatively low in Ca 2+ (100 μM). (-4 mM), and relatively low in Ca 2+ (150 µm). (2 mM), and relatively low in Ca 2+ (100 µm). (2 mM), and relatively low in K+ (150 M).
After establishing the importance of cGMP in the signaling pathway of the photoreceptor cells, the researchers wish to identify the exact target of cGMP. The researchers suspect that cGMP binds to an ion channel, causing the observed change in the membrane potential between the dark and the light conditions but they are not sure which one. The researchers determine the movement of three different ions (sodium, chloride and potassium) as a function of their respective electrochemical gradient across the plasma membrane: ● Sodium tends to enter the cell Chloride tends to enter the cell Potassium tends to leave the cell The researchers therefore propose three simple hypotheses for the effect of cGMP on the membrane potential of the rod photoreceptor cell: ● Hypothesis A: CGMP binds to a sodium-channel, that opens and lets sodium ions diffuse inside the cell. Hypothesis B: cGMP binds to a chloride-channel, that opens and lets loride ions diffuse inside the cell. Hypothesis C: cGMP binds to…
Describe phototransduction in detail, comparing this process both in the dark and in the light. For each cell involved in phototransduction, discuss what ion channels may be open/close and why they are open/close, whether the cell is hyperpolarized or depolarized, what cause it to hyperpolarize or depolarize, whether the cell releases any neurotransmitters, and whether graded potential or action potential is generated in each cell.
In most neurons, membrane depolarization leads to the opening of voltage-dependent ion channels, generation of an action potential, and, ultimately, an influx of Ca2+, which causes release of neurotransmitter at the axon terminus. Devise a cellular strategy by which hyperpolarization in rod cells could produce excitation of the visual pathway and passage of visual signals to the brain. (Hint: The neuronal signaling pathway in higher organisms consists of a series of neurons that relay information to the brain. The signal released by one neuron can be either excitatory or inhibitory to the following, postsynaptic neuron.)
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What does cGMP do inside of rod cells? Group of answer choices cGMP opens CNG channels to allow more positive ions into the rod cell cGMP powers active transport in the cell membrane cGMP stimulates Rhodopsin to turn into its active form, which allows light to be perceived cGMP is a neurotransmitter that is released from the rod cell and stimulates other cells
Which of the following occurs when light activates a photoreceptor? Choose all that apply. Glutamate will be released The cell will be depolarized Phosphodiesterase is inactivated [Sodium ions channels will be closed CGMP is present
The action potential generated in the squid giant axon requires voltage-gated potassium channels. Describe the shape of the action potential if these channels are blocked using TEA (Tetraethylammonium).