{"id":198352,"date":"2025-03-08T16:21:38","date_gmt":"2025-03-08T16:21:38","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=198352"},"modified":"2025-03-08T16:22:27","modified_gmt":"2025-03-08T16:22:27","slug":"red-green-color-blindness-in-humans-is-a-sex-linked-trait-controlled-by-alleles-on-the-x-chromosome","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/03\/08\/red-green-color-blindness-in-humans-is-a-sex-linked-trait-controlled-by-alleles-on-the-x-chromosome\/","title":{"rendered":"Red-green color blindness, in humans, is a sex-linked trait controlled by alleles on the X chromosome"},"content":{"rendered":"\n<p>Red-green color blindness, in humans, is a sex-linked trait controlled by alleles on the X chromosome. Normal color vision (X+) is dominant to colorblindness (Xc). (NOTE: You could write this as XC for the normal allele and Xc for the recessive colorblind allele. Unfortunately, capital C and lowercase c are hard to tell apart as superscripts, especially in type. I will use C &#8212; &#8220;X-plus&#8221; &#8212; for the normal allele.) If a colorblind man marries a woman with normal vision and they have a colorblind son, what are the genotypes of the father and the mother?<\/p>\n\n\n\n<p><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-ast-global-color-6-color\"><strong>The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n<p>In this case of red-green color blindness being a sex-linked recessive trait, the key is to understand the genetic inheritance and how the alleles on the X chromosome determine the outcome.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Given information:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Colorblindness<\/strong> (Xc) is recessive and located on the X chromosome.<\/li>\n\n\n\n<li><strong>Normal color vision<\/strong> (X+) is dominant to colorblindness (Xc), and also located on the X chromosome.<\/li>\n\n\n\n<li>The man is colorblind, which means his genotype must be <strong>XcY<\/strong> (since males have one X and one Y chromosome).<\/li>\n\n\n\n<li>The woman has normal color vision, but she must be a <strong>carrier<\/strong> for colorblindness (X+Xc), as she has a colorblind son.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Genotypes:<\/h3>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Father&#8217;s Genotype: XcY<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Since the father is colorblind, his X chromosome must carry the colorblind allele, and he also has a Y chromosome, which does not carry an allele for color vision.<\/li>\n<\/ul>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Mother&#8217;s Genotype: X+Xc<\/strong><\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The mother has normal color vision but is a carrier of the colorblind allele. Therefore, one of her X chromosomes carries the normal color vision allele (X+), and the other carries the colorblind allele (Xc).<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Inheritance of the child:<\/h3>\n\n\n\n<p>The son must inherit his Y chromosome from his father (since only males inherit the Y chromosome from their father), and he must inherit one of the X chromosomes from his mother. Since the mother is a carrier (X+Xc), the possible X chromosome that the son could inherit from her is <strong>Xc<\/strong> (which is the colorblind allele).<\/p>\n\n\n\n<p>Thus, the son&#8217;s genotype is <strong>XcY<\/strong>, making him colorblind.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Summary of the family\u2019s genotypes:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Father: <strong>XcY<\/strong> (colorblind)<\/li>\n\n\n\n<li>Mother: <strong>X+Xc<\/strong> (normal vision but carrier)<\/li>\n\n\n\n<li>Son: <strong>XcY<\/strong> (colorblind)<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Explanation:<\/h3>\n\n\n\n<p>In sex-linked inheritance, the X chromosome is crucial because females have two X chromosomes while males have one X and one Y chromosome. The father can only pass on his Y chromosome to his son, while the mother passes one of her X chromosomes. Since the mother is a carrier, she has a 50% chance of passing on the colorblind allele to each child. This combination results in the son being colorblind, inheriting the Xc from his mother and the Y chromosome from his father.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/learnexams.com\/blog\/wp-content\/uploads\/2025\/03\/image-688.png\" alt=\"\" class=\"wp-image-198353\"\/><\/figure>\n\n\n\n<p>Here is the diagram illustrating the genetic inheritance of colorblindness in this family. It shows the genotypes of the father (XcY), the mother (X+Xc), and the son (XcY). The arrows indicate how the alleles are passed on from the parents to the child.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Red-green color blindness, in humans, is a sex-linked trait controlled by alleles on the X chromosome. Normal color vision (X+) is dominant to colorblindness (Xc). (NOTE: You could write this as XC for the normal allele and Xc for the recessive colorblind allele. Unfortunately, capital C and lowercase c are hard to tell apart as [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-198352","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/198352","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=198352"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/198352\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=198352"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=198352"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=198352"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}