Comments on: In humans, one of the genes determining color vision is located on the X? http://www.colorblindclub.com/facts51/in-humans-one-of-the-genes-determining-color-vision-is-located-on-the-x/ For People With Color Vision Deficiency Wed, 15 Jul 2009 07:22:07 -0400 http://wordpress.org/?v=2.8 hourly 1 By: mareeclar http://www.colorblindclub.com/facts51/in-humans-one-of-the-genes-determining-color-vision-is-located-on-the-x/comment-page-1/#comment-26 mareeclar Fri, 06 Apr 2007 21:02:28 +0000 http://www.colorblindclub.com/?p=51#comment-26 (Brace yourself for an old high school chemistry lesson here in case you forgot) ok we generally write this as Xc or XC (to show its linked to the X chromosome...the Y has nothing to do with it) Also note the c's are supposed to be superscript! The different genotpyes and phenotypes are XC XC = normal female XC Xc = carrier female, not affected Xc Xc = affected female XCY= normal male Xcy = affected male ok so a normal mae (XCY) + colour blind female (XcXc) Xc : Xc (female alleles) XC. XCXc XCXc Female all carriers Y . XcY XcY All males colourblind Note that its the mother that passes colourblindness to her sons (on the X , the Y is passed from his father and has no influence on the actual presence of the gene), if a male is colourblind then his maternal grandfather will probably also have been colourblind. Because males only get 1 copy, they are more often to be colourblind than females, which require 2 reccessive alleles (1 from each parent...which is statisically harder to achieve) (Brace yourself for an old high school chemistry lesson here in case you forgot)

ok we generally write this as Xc or XC (to show its linked to the X chromosome…the Y has nothing to do with it) Also note the c’s are supposed to be superscript!

The different genotpyes and phenotypes are
XC XC = normal female
XC Xc = carrier female, not affected
Xc Xc = affected female
XCY= normal male
Xcy = affected male

ok so a normal mae (XCY) + colour blind female (XcXc)
Xc : Xc (female alleles)
XC. XCXc XCXc Female all carriers

Y . XcY XcY All males colourblind

Note that its the mother that passes colourblindness to her sons (on the X , the Y is passed from his father and has no influence on the actual presence of the gene), if a male is colourblind then his maternal grandfather will probably also have been colourblind.
Because males only get 1 copy, they are more often to be colourblind than females, which require 2 reccessive alleles (1 from each parent…which is statisically harder to achieve)

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