Biology 1002B Lecture Notes - Lecture 25: Dichromacy, Spectral Sensitivity, Opsin
6 Apr 2015
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One sensitive to short wavelength, one sensitive to medium, one sensitive to long. Importance of lysine at position 296 and glutamic acid at position 113: some amino acid sequences are highly conserved. 296 binds: when protein acquires tertiary structure, they fold and 113 and 296 come very close together. Top is short, medium is medium, bottom is long wavelength. Red = completely conserved (only when found in all three) Mw and lw highly conserved and very different than short (divergent compared to the other two) Subtle changes in retinal absorption gives rise to different types of sensitivity of different wavelengths: assocatiation between trichromacy, dichromacy, old world monkeys and new world monkeys. Medium and long wavelength genes on x chromosome, short wavelength are on chrome 7. M and l similar probs because they came from gene duplication: before they could have been dichromacy now we can see more colours. Trichromatic isn"t the top (other animals have more opsins than us)
