Reese Fulton Ap Biology X Linked Color Blindness
X-linked colour blindness (also known as color vision defect) is a condition which affects the individual’s perceptions of color. Colour Blind Awareness reports that around 1 in 12 men and 1 out 200 women are affected, with Red-Green the most prevalent. Blue cone monochromacy, a less common but more serious form of color vision impairment, causes severe visual acuity problems and reduced color vision. There are three distinct types of color receptors found in the eye. Each is sensitive to different wavelengths. Normal color is produced when the light enters all three rods. Color vision deficiency can be caused by mutations in OPN1LW and OPN1MW genes. Instructions are given by the OPN1LW and OPN1MW genes to make the three opsin pigment protein cones.
These proteins are crucial for color vision. One or more cones may not function when color blindness is present. The rare disorder tritanomaly, which causes color blindness in the rarest cases, is caused by a lack of the blue cone or S cone. This can lead to difficulty distinguishing between blue and green shades. The color blindness of color is passed from mother-to-son on the 23rdchromosome. This is also known to be the sexchromosome as it is involved in determining sex. The genes that cause color blindness in males are at Xq28 of the Xchromosome. Males are blessed with two Xchromosomes, while females can have both Xchromosomes. A male must have the mutation on his Xchromosome, while a female must have it on both Xchromosomes. A male cannot pass the colorblindness gene to his son. You can have dominant or recessive genes on theX chromosome. They are expressed differently in males and females. Tritanomaly occurs as an autosomal dominating defect that is not fully penetrated. Autosomal dominant treatment is red/green color blindness.
Most variation can be attributed to differences in the amino acids that are used in the tuning of the spectra for the green and red cone pigments. Ser180Ala is a source of variation. This is because it accounts for two red pigments. It also determines the severity and normal color vision. This polymorphism probably results from the gene conversion of the green pigment gene. Another common source is the existence many different types of green/red pigment. On the Xchromosome, there is a red-pigment-gene array that runs from head to tail. It has one green-pigment-gene followed by another. These genes have high homology which has made it more common for red/green genetic hybrids to form or to be deleted. Recombination between the genes is common because they are closely related and highly homologous. This can result in irregular pigments.
Rearrangements lead to duplications between the red-green genes. Most people are born with extra pigment genes. These events are the leading cause of color vision problems in red-green. The color vision phenotype is only caused by the expression of the first two pigment gene genes in the red/green array. Red-green color vision problems are more severe than those caused by a difference in the wavelengths at which the photopigments encoded. This is because the array’s first two genes have the highest wavelengths. It is possible to see more colors if you are heterozygous for the genes that encode red and/or green pigments.
