Colour Blindness | Genetics | NMDCAT 2021
20.9 هزار بار بازدید -
4 سال پیش
-
About This Video!:Genetics of colour-blindness
About This Video!
:Genetics of colour-blindness
Normal trichromatic colour vision is based on three diferent kinds of cone cells in
the retina, each sensitive to only one of the three primary colours, red, green or blue.
Each type of cone cell has speciic light absorbing proteins called opsins. The genes for
red and green opsins are on X chromosome, while the gene for blue opsin is present
on autosome 7. Mutations in opsin genes cause three types of colour-biindness. A
dichromat can perceive two primary colours but is unable to perceive the one whose
opsins are missing due to mutation. Protanopia is red blindness, deuteranopia is green
blindness, while tritanopia is blue blindness. Some people can detect red and green but
with altered perception of the relative shades of these colours. They have abnormal
but still partially functional opsins. They are protanomalous and deuteranomalous
for red and green weakness respectively. A monochromat can perceive one colour.
Monochromacy is true colour-blindness. Blue cone monochromacy is an X - linked
recessive trait in which both red and green cone cells are absent. That is why it is also
called red - green colour-blindness. It is a common hereditary disease. Like any sex
- linked recessive trait, it also zigzags from maternal grandfather through a carrier
daughter to a grandson. It never passes direct from father to son. This type of colour-
blindness is more common in men than women, because chances for a male to be
afected by it are muh more than a female.
Activity: A sex-linked recessive allele “c” produces red - blindness. Its normal dominant
allele is “C”. A normal woman whose father was red-blind, marries a red-blind man.
What proportion of their children can have normal colour vision?
:Genetics of colour-blindness
Normal trichromatic colour vision is based on three diferent kinds of cone cells in
the retina, each sensitive to only one of the three primary colours, red, green or blue.
Each type of cone cell has speciic light absorbing proteins called opsins. The genes for
red and green opsins are on X chromosome, while the gene for blue opsin is present
on autosome 7. Mutations in opsin genes cause three types of colour-biindness. A
dichromat can perceive two primary colours but is unable to perceive the one whose
opsins are missing due to mutation. Protanopia is red blindness, deuteranopia is green
blindness, while tritanopia is blue blindness. Some people can detect red and green but
with altered perception of the relative shades of these colours. They have abnormal
but still partially functional opsins. They are protanomalous and deuteranomalous
for red and green weakness respectively. A monochromat can perceive one colour.
Monochromacy is true colour-blindness. Blue cone monochromacy is an X - linked
recessive trait in which both red and green cone cells are absent. That is why it is also
called red - green colour-blindness. It is a common hereditary disease. Like any sex
- linked recessive trait, it also zigzags from maternal grandfather through a carrier
daughter to a grandson. It never passes direct from father to son. This type of colour-
blindness is more common in men than women, because chances for a male to be
afected by it are muh more than a female.
Activity: A sex-linked recessive allele “c” produces red - blindness. Its normal dominant
allele is “C”. A normal woman whose father was red-blind, marries a red-blind man.
What proportion of their children can have normal colour vision?
4 سال پیش
در تاریخ 1399/04/09 منتشر شده
است.
20,964
بـار بازدید شده