Once a cis-retinal molecule (the absorbing form of retinal molecules) absorbs a photon, it undergoes a conformational change. When enough of these molecules within rhodopsin have undergone this change, an electrical signal is initiated to the brain. On average, approximately 2.0 x 10-17J of energy is needed to initiate this signal. How many cis-retinal molecules must simultaneously absorb photons of 450nm to initiate a nerve signal?
The energy of each photon E = hc/lambda
where h = Plancks constant, c= velocity of light and lambad = wavelength of photon
Thus E = 6.625x10-34 J.sec x 3.0x108 m.sec-1 / 450x 10-9 m
= 4.417x10-19 J
Each cis-retinal absorbs 4.417x10-19 J energy
To initiate the signal the energy necessary = 2.0x10-17 J
The number of molecules required to give this energy = total energy required / energy of each absorption
= 2.0x10-17 J /4.417x10-19 J
= 45.279 molecules
Once a cis-retinal molecule (the absorbing form of retinal molecules) absorbs a photon, it undergoes a...
The human eye contains a molecule called 11 - cis - retinal that changes shape when struck with light of sufficient energy, which results in an electrical signal being sent to the brain. The minimum energy required to change the conformation of 11 - cis - retinal within the eye is 164 kJ/mol. Calculate the longest wavelength (in nm) visible to the human eye.