{"id":61721,"date":"2020-09-14T19:52:56","date_gmt":"2020-09-14T19:52:56","guid":{"rendered":"https:\/\/www.mometrix.com\/academy\/?page_id=61721"},"modified":"2026-03-28T11:36:10","modified_gmt":"2026-03-28T16:36:10","slug":"genotype-vs-phenotype","status":"publish","type":"page","link":"https:\/\/www.mometrix.com\/academy\/genotype-vs-phenotype\/","title":{"rendered":"Genotype vs. Phenotype"},"content":{"rendered":"\n\t\t\t<div id=\"mmDeferVideoEncompass_fb3XS3STvBk\" style=\"position: relative;\">\n\t\t\t<picture>\n\t\t\t\t<source srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.webp\" type=\"image\/webp\">\n\t\t\t\t<source srcset=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.png\" type=\"image\/jpeg\"> \n\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" loading=\"eager\" id=\"videoThumbnailImage_fb3XS3STvBk\" data-source-videoID=\"fb3XS3STvBk\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/01\/circle-play-duotone.png\" alt=\"Genotype vs. Phenotype Video\" height=\"464\" width=\"825\" class=\"size-full\" data-matomo-title = \"Genotype vs. Phenotype\">\n\t\t\t<\/picture>\n\t\t\t<\/div>\n\t\t\t<style>img#videoThumbnailImage_fb3XS3STvBk:hover {cursor:pointer;} img#videoThumbnailImage_fb3XS3STvBk {background-size:contain;background-image:url(\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2023\/02\/1691-genotype-vs-phenotype-2.webp\");}<\/style>\n\t\t\t<script defer>\n\t\t\t  jQuery(\"img#videoThumbnailImage_fb3XS3STvBk\").click(function() {\n\t\t\t\tlet videoId = jQuery(this).attr(\"data-source-videoID\");\n\t\t\t\tlet helpTag = '<div id=\"mmDeferVideoYTMessage_fb3XS3STvBk\" style=\"display: none;position: absolute;top: -24px;width: 100%;text-align: center;\"><span style=\"font-style: italic;font-size: small;border-top: 1px solid #fc0;\">Having trouble? <a href=\"https:\/\/www.youtube.com\/watch?v='+videoId+'\" target=\"_blank\">Click here to watch on YouTube.<\/a><\/span><\/div>';\n\t\t\t\tlet tag = document.createElement(\"iframe\");\n\t\t\t\ttag.id = \"yt\" + videoId;\n\t\t\t\ttag.src = \"https:\/\/www.youtube-nocookie.com\/embed\/\" + videoId + \"?autoplay=1&controls=1&wmode=opaque&rel=0&egm=0&iv_load_policy=3&hd=0&enablejsapi=1\";\n\t\t\t\ttag.frameborder = 0;\n\t\t\t\ttag.allow = \"autoplay; fullscreen\";\n\t\t\t\ttag.width = this.width;\n\t\t\t\ttag.height = this.height;\n\t\t\t\ttag.setAttribute(\"data-matomo-title\",\"Genotype vs. Phenotype\");\n\t\t\t\tjQuery(\"div#mmDeferVideoEncompass_fb3XS3STvBk\").html(tag);\n\t\t\t\tjQuery(\"div#mmDeferVideoEncompass_fb3XS3STvBk\").prepend(helpTag);\n\t\t\t\tsetTimeout(function(){jQuery(\"div#mmDeferVideoYTMessage_fb3XS3STvBk\").css(\"display\", \"block\");}, 2000);\n\t\t\t  });\n\t\t\t  \n\t\t\t<\/script>\n\t\t\n<p><script>\nfunction HCQ_Function() {\n  var x = document.getElementById(\"HCQ\");\n  if (x.style.display === \"none\") {\n    x.style.display = \"block\";\n  } else {\n    x.style.display = \"none\";\n  }\n}\n<\/script><\/p>\n<div class=\"moc-toc hide-on-desktop hide-on-tablet\">\n<div><button onclick=\"HCQ_Function()\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.mometrix.com\/academy\/wp-content\/uploads\/2024\/12\/toc2.svg\" width=\"16\" height=\"16\" alt=\"show or hide table of contents\"><\/button><\/p>\n<p>On this page<\/p>\n<\/div>\n<nav id=\"HCQ\" style=\"display:none;\">\n<ul>\n<li class=\"toc-h2\"><a href=\"#Alleles\" class=\"smooth-scroll\">Alleles<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Genotype_and_Phenotype_Examples\" class=\"smooth-scroll\">Genotype and Phenotype Examples<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Effects_on_Inheritance\" class=\"smooth-scroll\">Effects on Inheritance<\/a><\/li>\n<li class=\"toc-h2\"><a href=\"#Review\" class=\"smooth-scroll\">Review<\/a><\/li>\n<\/ul>\n<\/nav>\n<\/div>\n<div class=\"accordion\"><input id=\"transcript\" type=\"checkbox\" class=\"spoiler_button\" \/><label for=\"transcript\">Transcript<\/label>\n<div class=\"spoiler\" id=\"transcript-spoiler\">\n<p>Hi, and welcome to this review of genotypes and phenotypes!<\/p>\n<p>What exactly is a genotype? How are genotypes and phenotypes related? How can we apply these terms to real-life situations?<\/p>\n<p>In this video, we\u2019re going to answer all of those questions. We\u2019ll compare and contrast genotypes and phenotypes to help us understand what purpose they serve in the world of genetics.<\/p>\n<h2><span id=\"Alleles\" class=\"m-toc-anchor\"><\/span>Alleles<\/h2>\n<p>\nBefore we can fully understand genotypes and phenotypes, we first have to understand <a class=\"ylist\" href=\"https:\/\/www.mometrix.com\/academy\/genes\/\">alleles<\/a>.<\/p>\n<p>Genes occur at specific locations on each <a class=\"ylist\" href=\"https:\/\/www.mometrix.com\/academy\/chromosomes\/\">chromosome<\/a> and are made up of a specific chemical sequence of adenine, guanine, cytosine, and thymine bases.<\/p>\n<p>However, the sequence of a gene on one copy of a chromosome may vary a little from the sequence on the other copy of the chromosome. If that\u2019s the case, this sequence variant for the same gene is our allele.<\/p>\n<p>An allele is a variant of a gene on a chromosome that helps determine the heredity of an organism. Since we have two copies of each gene (one from mom and one from dad), that means that all somatic cells have two alleles for each trait. Together, these two alleles determine the trait you inherit.<\/p>\n<h2><span id=\"Genotype_and_Phenotype_Examples\" class=\"m-toc-anchor\"><\/span>Genotype and Phenotype Examples<\/h2>\n<h3><span id=\"Phenotypes\" class=\"m-toc-anchor\"><\/span>Phenotypes<\/h3>\n<p>\nLet\u2019s take height for example. Although there are a few different factors that contribute to height, we\u2019ll keep it simple and say someone can either be tall or short.<\/p>\n<p>Let\u2019s say the gene that codes for height on one chromosome has a sequence that reads like this: A<strong>C<\/strong>GTC. Let\u2019s say this allele codes for \u201ctall.\u201d The gene that codes for height on the other chromosome has a sequence that reads: A<strong>G<\/strong>GTC. This allele codes for \u201cshort.\u201d<\/p>\n<p>Again, because the gene is slightly varied (one sequence has a cytosine as the second base, while the other has a guanine) this is considered an allele. We can assign arbitrary upper and lowercase letters to our alleles to keep them organized.<\/p>\n<p>Let\u2019s keep it simple and go with a capital T for \u201ctall\u201d and a lowercase t for \u201cshort\u201d like this:<\/p>\n<table class=\"ATable\" style=\"margin: auto;\">\n<thead>\n<tr>\n<th>Allele<\/th>\n<th>Sequence<\/th>\n<th>Phenotype<\/th>\n<\/tr>\n<tbody>\n<tr>\n<td>T<\/td>\n<td>A<strong>C<\/strong>GTC<\/td>\n<td>tall<\/td>\n<\/tr>\n<tr>\n<td>t<\/td>\n<td>A<strong>G<\/strong>GTC<\/td>\n<td>short<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\n&nbsp;<br \/>\nSo we can have the same gene coding for the same trait on both chromosomes, but the sequence variant, or allele, is what produces different phenotypes. Therefore, a phenotype is the physical trait that is determined by the present alleles.<\/p>\n<p>Phenotypes help us observe and analyze genetic mutations, especially when we are thinking about an experiment to track inheritance of a trait. If we want to know if the dumpy wing trait will appear in the offspring of a male and female fruit fly, all we have to do is look for this trait in their progeny.<\/p>\n<h3><span id=\"Genotypes\" class=\"m-toc-anchor\"><\/span>Genotypes<\/h3>\n<p>\nSometimes just seeing the phenotype isn\u2019t enough. Maybe we want to know the exact allele pairing that caused that trait. This is where the genotype comes in.<\/p>\n<p>A genotype is the allele pairing inherited for a particular gene that produces a specific phenotype. In reality, genotype refers to all the genes in an organism and phenotype refers to all observable traits of an organism, but in practice they\u2019re usually used to refer to a single gene in question. <\/p>\n<h2><span id=\"Effects_on_Inheritance\" class=\"m-toc-anchor\"><\/span>Effects on Inheritance<\/h2>\n<p>\nNow let\u2019s bring everything together and look at how genotypes and phenotypes actually affect inheritance.<\/p>\n<p>Remember that being a diploid organism means you don\u2019t have just one copy of an allele to contend with, you have two! Different combinations of those two alleles are what lead to the observable phenotype, or trait. An individual with two copies of the same allele is said to be homozygous for that trait and an individual with one copy of one allele and another copy of another allele is said to be heterozygous for that trait.<\/p>\n<p>So going back to our height example, an individual would be homozygous for height if he or she had the TT genotype or the tt genotype. An individual with a Tt genotype is therefore heterozygous. \u201ctT\u201d is understood to be the same as \u201cTt\u201d so that is why there is only one option here.<\/p>\n<p>This is important because whether an individual is homozygous or heterozygous for a trait can mean the difference between passing on an inherited mutation or not. Some alleles have been identified to be mutant alleles, meaning they contain a mutation that could cause a change or disease. If an allele is not a mutant allele, it is called a wildtype allele. This type of allele is considered to be \u201cnormal.\u201d<\/p>\n<p>So how do we know if a mutant allele will cause a change or not? It depends on the way it pairs with the second allele for that gene. Another way to say this is that it depends on if the alleles are dominant or recessive. <\/p>\n<p>Mutant alleles can be dominant, meaning they will override another allele, or recessive, meaning they will not override another allele. Dominant alleles are usually represented with a capital letter, and recessive alleles are represented by a lowercase letter.<\/p>\n<p>Let\u2019s look at this in more detail using a dimple mutation. Let\u2019s say the dominant allele means you have dimples, so we\u2019ll assign it the capital letter \u201cD.\u201d And let\u2019s say the recessive allele means you don\u2019t have dimples. We\u2019ll assign it the lowercase \u201cd.\u201d If we draw a simple Punnett square, we can determine a genotypic and phenotypic ratio for dimples. For this example, we have mom and dad who are both heterozygous for dimples with the genotype \u201cDd\u201d.                            <\/p>\n<p>If we fill in the Punnett square by dragging each allele down and across for each box, this is our result.<\/p>\n<p>Let\u2019s start with the genotypic ratio. We have one offspring that is homozygous dominant \u201cDD,\u201d two offspring that are heterozygous \u201cDd,\u201d and one that is homozygous recessive \u201cdd\u201d so the ratio is 1:2:1. Since the dominant allele is \u201cD,\u201d offspring with the genotypes DD and Dd will all have dimples because the \u201cD\u201d allele overrides the recessive allele.<\/p>\n<p>We also have one homozygous recessive offspring where there is no dominant allele, so this combination will yield no dimples. With this we can say the phenotypic ratio is 3:1 dimples to no dimples. We can also say that 75% of the offspring will have dimples while 25% will not.<\/p>\n<p>This example shows how the genotype and phenotype, while related, can give us different, but equally important, information about inheritance. <\/p>\n<hr>\n<h2><span id=\"Review\" class=\"m-toc-anchor\"><\/span>Review<\/h2>\n<p>\nThat\u2019s really all there is to it! Let\u2019s go over a quick review question to test your knowledge.<\/p>\n<p>Which of these correctly describes a main difference between genotypes and phenotypes?<\/p>\n<ol style=\"list-style: upper-alpha;\">\n<li>Genotypes are coding genes while phenotypes are non-coding genes<\/li>\n<li>Genotypes are recessive alleles while phenotypes are dominant alleles<\/li>\n<li>Genotypes are genetic information while phenotypes are environmental information<\/li>\n<li>A genotype is an organism\u2019s set of genes while a phenotype is its physical traits<\/li>\n<\/ol>\n<div style=\"text-align: center; margin-bottom: 20px;\">\n   <button class=\"buttontranscript\" onClick=\"toggle('Answer1')\">Show Answer<\/button>\n<\/div>\n<div id=\"Answer1\" class=\"showanswer\">\n   <strong>The correct answer is D!<\/strong><\/p>\n<p style=\"text-align: left;\">The genotype of an organism is all of its genes, right down to the specific allelic sequence they carry, while the phenotype is all of the organism\u2019s physical characteristics. A change in the genotype can alter the phenotype, but not the other way around because the phenotype is the result of the genotype. Remember that in some examples, we might be looking at a gene in isolation. So when we consider the genotype and phenotype, we are talking about the genotype and phenotype for the specific alleles present for that gene. <\/p>\n<\/div>\n<p>\n&nbsp;<br \/>\nI hope this review was helpful! 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