When these combine through a chemical reaction, they form inactive rhodopsin. • Active Rhodopsin - When light is introduced, rhodopsin takes on its trans form (it's straight chain form): this form is active! - Rhodopsin then breaks down to the trans-isomer of retinal and also opsin. - The trans-form of retinal isomerizes back to the cis-isomer, which is again ready to combine with opsin. phototransduction along the photoreceptor cell membrane Site of activity is a photoreceptor cell, in its outer segment, which is the site of the rod disc. • Step 1: Light activates rhodopsin. • Step 2: Activated rhodopsin activates transducin (a G-protein). • Step 3: Transducin activates phosphodiesterase (PDE). • Step 4: The transducin/PDE combination converts cGMP to GMP. When cGMP attaches to a sodium channel it is open. Sodium ions enter the cell, which serves to make the intracellular space more positive (less hyperpolarized). When the transducin/PDE combination converts cGMP to GMP, th..." />
When these combine through a chemical reaction, they form inactive rhodopsin. • Active Rhodopsin - When light is introduced, rhodopsin takes on its trans form (it's straight chain form): this form is active! - Rhodopsin then breaks down to the trans-isomer of retinal and also opsin. - The trans-form of retinal isomerizes back to the cis-isomer, which is again ready to combine with opsin. phototransduction along the photoreceptor cell membrane Site of activity is a photoreceptor cell, in its outer segment, which is the site of the rod disc. • Step 1: Light activates rhodopsin. • Step 2: Activated rhodopsin activates transducin (a G-protein). • Step 3: Transducin activates phosphodiesterase (PDE). • Step 4: The transducin/PDE combination converts cGMP to GMP. When cGMP attaches to a sodium channel it is open. Sodium ions enter the cell, which serves to make the intracellular space more positive (less hyperpolarized). When the transducin/PDE combination converts cGMP to GMP, th..."/>
When these combine through a chemical reaction, they form inactive rhodopsin. • Active Rhodopsin - When light is introduced, rhodopsin takes on its trans form (it's straight chain form): this form is active! - Rhodopsin then breaks down to the trans-isomer of retinal and also opsin. - The trans-form of retinal isomerizes back to the cis-isomer, which is again ready to combine with opsin. phototransduction along the photoreceptor cell membrane Site of activity is a photoreceptor cell, in its outer segment, which is the site of the rod disc. • Step 1: Light activates rhodopsin. • Step 2: Activated rhodopsin activates transducin (a G-protein). • Step 3: Transducin activates phosphodiesterase (PDE). • Step 4: The transducin/PDE combination converts cGMP to GMP. When cGMP attaches to a sodium channel it is open. Sodium ions enter the cell, which serves to make the intracellular space more positive (less hyperpolarized). When the transducin/PDE combination converts cGMP to GMP, th...">
When these combine through a chemical reaction, they form inactive rhodopsin. • Active Rhodopsin - When light is introduced, rhodopsin takes on its trans form (it's straight chain form): this form is active! - Rhodopsin then breaks down to the trans-isomer of retinal and also opsin. - The trans-form of retinal isomerizes back to the cis-isomer, which is again ready to combine with opsin. phototransduction along the photoreceptor cell membrane Site of activity is a photoreceptor cell, in its outer segment, which is the site of the rod disc. • Step 1: Light activates rhodopsin. • Step 2: Activated rhodopsin activates transducin (a G-protein). • Step 3: Transducin activates phosphodiesterase (PDE). • Step 4: The transducin/PDE combination converts cGMP to GMP. When cGMP attaches to a sodium channel it is open. Sodium ions enter the cell, which serves to make the intracellular space more positive (less hyperpolarized). When the transducin/PDE combination converts cGMP to GMP, th...">