One isomer of retinal is converted to a second isomer by the absorption of a photon: CH3 H CH3 H H;C CH; H CH3 H H;C CH; H C=0 H,C H,C' H H;C´ _H H2C_ CH2 H H H2C "CH2 H `CH3 `CH3 H This process is a key step in the chemistry of vision. Although free retinal (in the form shown to the left of the arrow) has an absorption maximum at 376 nm, in the ultraviolet region of the spectrum this absorption shifts into the visible range when the retinal is bound in a pro- tein, as it is in the eye. (a) How many of the C=C bonds are cis and how many are trans in each of the preceding structures? (When assigning labels, consider the relative positions of the two largest groups attached at each double bond.) Describe the motion that takes place upon absorption of a photon. (b) If the ring and the -CHO group in retinal were replaced by -CH; groups, would the absorption maximum in the molecule shift to longer or shorter wavelengths?

One isomer of retinal is converted to a second isomer by the absorption of a photon: CH3 H CH3 H H;C CH; H CH3 H H;C CH; H C=0 H,C H,C' H H;C´ _H H2C_ CH2 H H H2C "CH2 H `CH3 `CH3 H This process is a key step in the chemistry of vision. Although free retinal (in the form shown to the left of the arrow) has an absorption maximum at 376 nm, in the ultraviolet region of the spectrum this absorption shifts into the visible range when the retinal is bound in a pro- tein, as it is in the eye. (a) How many of the C=C bonds are cis and how many are trans in each of the preceding structures? (When assigning labels, consider the relative positions of the two largest groups attached at each double bond.) Describe the motion that takes place upon absorption of a photon. (b) If the ring and the -CHO group in retinal were replaced by -CH; groups, would the absorption maximum in the molecule shift to longer or shorter wavelengths?

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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