2006-07-20 06:50:39 · 96 answers · asked by Aroura 3 in Science & Mathematics ➔ Biology
The reason is the gene is located on the X-chromosome. Since men only posses one X-chromosome they are more likely to be affected as they only need to have 1 defective gene. Considering women have 2 X-chromosomes they would need to have the defective gene on BOTH chromosomes to suffer from colour blindness.
As for the above responses: Women have 2 X-chromosomes there is no garuntee which one she pass to her son, so the only way a women will know for sure if she is passing on colour blindness to her son/daughter is if she herself is colour blind (ie 2 defective genes)
2006-07-20 06:59:40 · answer #1 · answered by KRISTY 2 · 151⤊ 12⤋
1
2017-01-22 05:43:00 · answer #2 · answered by ? 2 · 0⤊ 0⤋
The reason is that the defective gene that directs production of the defective pigment is carried on the same pair of chromosomes that determines the sex of the child. In a female child (who has two X sex chromosomes), a defective gene on one X chromosome is almost always counteracted by a normal gene on the other X chromosome; as a result, the girl is born with normal color vision.
In a male child (who has an X and a Y sex chromosome), there is no matching normal gene to block the defect on the only X chromosome the boy has; the boy is, therefore, born color-blind.
Red-green color blindness cannot be passed from a father to his sons, nor will his daughters be color-blind, unless the mother carries the defective gene as well. However, his daughters will all be carriers of the defective gene, and the daughters' sons will have a 50 percent chance of being color-blind.
2006-07-20 16:26:11 · answer #3 · answered by dranagar 5 · 1⤊ 0⤋
Color blindness is an inability to distinguish certain colors. By far the most common type is inherited red-green color blindness, which affects 8 percent of men and boys but only 0.5 percent of women and girls.Total color blindness, which is very rare, and pastel-shade color blindness are believed to be inherited. Other types, including blue-yellow color blindness and red-green color blindness, can be either inherited or acquired. Disease or injury affecting the retina may also be the cause of color blindness.
Why is red-green color blindness inherited by boys more often than by girls? The reason is that the defective gene that directs production of the defective pigment is carried on the same pair of chromosomes that determines the sex of the child. In a female child (who has two X sex chromosomes), a defective gene on one X chromosome is almost always counteracted by a normal gene on the other X chromosome; as a result, the girl is born with normal color vision.
In a male child (who has an X and a Y sex chromosome), there is no matching normal gene to block the defect on the only X chromosome the boy has; the boy is, therefore, born color-blind.
Red-green color blindness cannot be passed from a father to his sons, nor will his daughters be color-blind, unless the mother carries the defective gene as well. However, his daughters will all be carriers of the defective gene, and the daughters' sons will have a 50 percent chance of being color-blind.
2006-07-21 04:09:26 · answer #4 · answered by DDS, MS 4 · 1⤊ 0⤋
Color Blindness Chromosome
2016-11-11 05:56:32 · answer #5 · answered by ? 4 · 0⤊ 0⤋
It is more frequent in boys because it is a sex-linked trait, and if the mom is a carrier (Xx) ( so the gene for color blindness is on the x chromosome) then, when it is paired with the Y chromosome from the dad it will result in a boy xY, with the gene for color blindness from the mom or and normal boy with no gene for color blindness XY.
Now, if the guy xY is color blind and he has a daughter with a woman who is a carrier Xx his daughter could be
be either color blind xx or a carrier for the trait Xx.
Note: X means this allele does not have the gene for color blindness (Dominant trait) , x means this allele has the gene for color blindness (recessive), and Y is the chromosome that defines/decides if the baby is a boy or not. Female (XX or Xx) and Male (XY or xYor xy). Dominant pairs XX or XY tend to have no color blindness gene. Recessive pairs xx or xY or xy do have the gene for color blindness. Heterzygous Pair ( 2 different pairs) Xx or Xy tend to be carriers. Note that since the color blindness gene comes from the female, the reason males are more likely to get it is because males have only one X chromosome and only one Y chromosome, so if the X which comes from the mom is recessive (x) then the boy is likely to have colorblindness because it doesn't have another (Dominant X) X chromosome to repress it.
2006-07-20 15:02:34 · answer #6 · answered by monavyas15 4 · 13⤊ 0⤋
There are several diseases found more in male than female. This is because male gene is X and Y. But female gene is X and X. So, because female has 2 identitical genes or chromosomes (what is the correct term - sorry!), a defect in one X can be mask by the other X. So, the disease does not really show up this case... unless both X's have are defected.
However, the male has only one X. A defect in the X will show up since the other is just Y gene/chromosome.
2006-07-20 16:44:33 · answer #7 · answered by teddybear1268 3 · 2⤊ 0⤋
Color blindness, or color vision deficiency, in humans is the inability to perceive differences between some or all colors that other people can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals. The English chemist John Dalton in 1794 published the first scientific paper on the subject, "Extraordinary facts relating to the vision of colours", after the realization of his own color blindness; because of Dalton's work, the condition is sometimes called Daltonism, although this term is now used for a type of color blindness called deuteranopia.
Color blindness is usually classed as a disability; however, in select situations color blind people have advantages over people with normal color vision. Color blind hunters are better at picking out prey against a confusing background, and the military have found that color blind soldiers can sometimes see through camouflage that fools everyone else. Monochromats may have a minor advantage in dark vision, but only in the first five minutes of dark adaptation.
2006-07-20 15:45:23 · answer #8 · answered by Sunil 1 · 2⤊ 3⤋
Because color blindess is an X-linked trait. Meaning that if a mother has a hidden trait for color blindness, the son has a fifty fifty percent chance at getting it, because males have one Y and one X while a female has two X's. A x-linked infected trait will automatically take over the Y the guy has, but a girl has a backup...I know why...I'm just not good at explaining this, because I'm not sure on how much you know about genetics.
2006-07-20 13:40:15 · answer #9 · answered by poetic_lala 5 · 8⤊ 1⤋
Color blindness is an inherited disorder that is carried on the X chromosome. All people have 2 sex chromosomes...if you're female you have XX and if you're male you have XY. That's the only GENETIC difference in boys and girls. Since colorblindness is carried on the X chromosome, girls have less of a chance of inheriting it (50/50 shot if both parents pass it on to them) but boys only have one X chromosome, so if both parents pass it to him, he WILL be colorblind. Great question!
2006-07-20 15:44:10 · answer #10 · answered by rdnck_grl_ms_007 3 · 2⤊ 0⤋
Kristy gave a great explanation. It is an X-linked genetic defect. Men only have one X-chromosome so if that gene is defective...it will be fully expressed (color-blind). Females can still express from the other X chromosome but pass on the defective gene to sons.
2006-07-20 15:19:06 · answer #11 · answered by embem171 4 · 0⤊ 2⤋