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 cell compared to inside the cell. The readings are presented below: In the dark Inside of the cell [CGMP] = 14 mM -10mV Outside of the cell In the presence of light Inside of the cell [CGMP] = 4 μM -70mV Outside of the cell 11. Based on the cytosolic concentration of cGMP and the membrane potential readings in both conditions, what can you conclude about the role of cGMP during phototransduction? A. CGMP helps maintain a constant membrane potential B. Light increases the concentration of cytosolic cyclic-GMP (CGMP) C. Light decreases the concentration of cytosolic GMP D. CGMP increases the membrane potential (= depolarization from -70mV up to -10mV) E. CGMP decreases the membrane potential (= hyperpolarization from -10mV down to -70mV).
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 cell compared to inside the cell. The readings are presented below: In the dark Inside of the cell [CGMP] = 14 mM -10mV Outside of the cell In the presence of light Inside of the cell [CGMP] = 4 μM -70mV Outside of the cell 11. Based on the cytosolic concentration of cGMP and the membrane potential readings in both conditions, what can you conclude about the role of cGMP during phototransduction? A. CGMP helps maintain a constant membrane potential B. Light increases the concentration of cytosolic cyclic-GMP (CGMP) C. Light decreases the concentration of cytosolic GMP D. CGMP increases the membrane potential (= depolarization from -70mV up to -10mV) E. CGMP decreases the membrane potential (= hyperpolarization from -10mV down to -70mV).
Human Physiology: From Cells to Systems (MindTap Course List)
9th Edition
ISBN:9781285866932
Author:Lauralee Sherwood
Publisher:Lauralee Sherwood
Chapter6: The Peripheral Nervous System: Afferent Division; Special Senses
Section: Chapter Questions
Problem 2SQE
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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 cell compared to inside the cell.
The readings are presented below:
In the dark
O-10mV
Inside of the cell
[CGMP] = 14 mM
Outside of the cell
In the presence of light
0-70mV
"
Inside of the cell
[CGMP] = 4 μM
Outside of the cell
11. Based on the cytosolic concentration of cGMP and the membrane potential readings in both
conditions, what can you conclude about the role of cGMP during phototransduction?
A. CGMP helps maintain a constant membrane potential
B. Light increases the concentration of cytosolic cyclic-GMP (CGMP)
C. Light decreases the concentration of cytosolic GMP
D. CGMP increases the membrane potential (= depolarization from -70mV up to -10mV)
E. CGMP decreases the membrane potential (= hyperpolarization from -10mV down to -70mV).](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5750fa67-9049-4422-863b-3fef8ebd663f%2F939889e5-d28f-4259-a7ce-de4cd2a0e97c%2F31a1tyu_processed.png&w=3840&q=75)
Transcribed Image Text: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 cell compared to inside the cell.
The readings are presented below:
In the dark
O-10mV
Inside of the cell
[CGMP] = 14 mM
Outside of the cell
In the presence of light
0-70mV
"
Inside of the cell
[CGMP] = 4 μM
Outside of the cell
11. Based on the cytosolic concentration of cGMP and the membrane potential readings in both
conditions, what can you conclude about the role of cGMP during phototransduction?
A. CGMP helps maintain a constant membrane potential
B. Light increases the concentration of cytosolic cyclic-GMP (CGMP)
C. Light decreases the concentration of cytosolic GMP
D. CGMP increases the membrane potential (= depolarization from -70mV up to -10mV)
E. CGMP decreases the membrane potential (= hyperpolarization from -10mV down to -70mV).
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