 Dear students, in this topic we shall discuss the color vision. The perception of colors is based on three types of cone cells. These cone cells have one of the three color pigments. A cone cell may have blue color pigment, it may have green or it may have blue red color pigment. As a result, these are three types of cone cells, blue, green and red. Each cone cell synthesizes only one of these three pigments, not all three. So each cone cell is selectively sensitive to a particular color range. Dear students, the three color pigments are called the photopsins. They are formed from the retinol, they are formed by the binding of the retinol to different three types of absence. Retinol is the same, but retinol binds with three different types of absence. So these three are different types of photopsins. These absence, which are used to make these pigments, these have slight differences which let each photo, each photopsin to absorb light optimally at a different wavelength, or different wavelengths come up with a different colors. Now, there are three basic colors are pigments in these cone cells, but we can perceive many intermediate colors how it is possible. It is possible because the absorption spectra of blue, green and red pigments in the three types of cones show peak absorbance at wavelengths of 445, 535 and 570 nanometers. But you can see here that the ranges of these spectra overlap. This overlapping enables the brain to perceive intermediate colors on simultaneous stimulation of two or more classes of cones. Dear students, when it comes to color vision, it also refers to a genetic disease, which is called color blindness. This color blindness has a genetic basis. The reason for this is that the three types of absence which are involved in the formation of three colored photopsins are encoded by three genes. The gene encoding for blue pigment or for the absence involved in the formation of blue pigment is located on an autosomal chromosome. However, the genes for red and green cone pigments are located on the X chromosome and are found in close proximity on this chromosome. Inki location b ek du se ke kareeb hai. Color blindness is caused due to a mutation in one of these cone obscen genes. Results in the absence of one type of pigment in these cone cells. A person which misses a single type of color receptive cones is unable to distinguish some colors. Primary color ko bhi ni distinguish kar sakega aur jo usse mille wale intermediate hues hai wo bhi differentiate nahi ho sakega, ish tarah se a color blind person, kahi tarah ke rang aapas me distinguish nahi kar sakega. The most common form of color blindness is the red-green color blindness. We can see that green, yellow and orange and red colors, they lie between the wavelengths of 525 and 675 nanometers. They are normally distinguished because of red and green cones. If any one of these two types of cones is missing, the person cannot distinguish these four colors. The person is especially unable to distinguish red from green. That is why this type of color blindness is called red-green color blindness. Dear students, a person which does not have the red cones is called a protonope. A protonope person has a condition which is called proteinopia. In proteinopia, the visual spectrum is reduced. It is shortened because red color's wavelength is long wavelength, it is 700 nanometer region and a person who does not have red cones, his visual color field is reduced and this is called proteinopia. A person which lacks green cones is called deuteronope. In deuteronopia, the overall visual spectrum lies within the normal range. We can see the blue and red as well. There is a green in the middle and that is the problem with the wavelengths. In overall, the color visual field is not disturbed according to the wavelengths and a person in this condition can see the colors of short and long wavelengths. This condition is called deuteronopia.