{"id":6212,"date":"2013-08-05T13:32:34","date_gmt":"2013-08-05T13:32:34","guid":{"rendered":"https:\/\/schooltutoring.com\/help\/?p=6212"},"modified":"2014-12-02T08:26:59","modified_gmt":"2014-12-02T08:26:59","slug":"biology-review-of-genetic-behavior","status":"publish","type":"post","link":"https:\/\/schooltutoring.com\/help\/biology-review-of-genetic-behavior\/","title":{"rendered":"Biology Review of Genetic Behavior"},"content":{"rendered":"

Overview:\u00a0 What Is Genetic Behavior?<\/strong>
\nMorgan’s discovery of gender-linked traits was further evidence that genes were located on chromosomes.\u00a0 However, other research indicated that the behavior of genes during meiosis was sometimes more complex than with gender-linked traits.\u00a0 With the development of more powerful techniques of observation, specific genes could sometimes be located.<\/p>\n

What Is Gene Linkage?<\/strong>
\nMorgan studied other traits in fruit flies besides eye color.\u00a0 One of his experiments involved crossing flies that had the genotype homozygous for gray bodies (G) and long wings (L), all showing the dominant pattern GGLL, \u00a0with flies that were homozygous for black bodies (g) and short wings (l), all showing the recessive pattern ggll.\u00a0 As was expected, the F1<\/sub> generation all had gray bodies and long wings.\u00a0 If body color and wing size were independent of each other, there should have been a mixture of genotypes in the 9:3:3:1 ratio in the F2<\/sub> generation, similar to the experiments with round melons and striped melons discussed with Mendelian inheritance.\u00a0 However, three-fourths of the flies in the F2<\/sub> generation had gray bodies and long wings, and one-fourth had black bodies and short wings, about what would be expected if the two traits were linked.\u00a0 When genes for a trait occur on the same chromosome, they are linked, and there are as many linkage groups as there are pairs of chromosomes.<\/p>\n

What Is Crossing Over?<\/strong>
\nSome flies had a mixture of dominant and recessive traits, such as gray bodies with short wings or black bodies with long wings.\u00a0 During meiosis, alleles for body color exchanged places with alleles for wing length so that both dominant traits or both recessive traits were not inherited together.\u00a0 When the cells completed division, the alleles were in different positions on the chromosomes of each daughter cell.\u00a0 Later experiments with other organisms showed that crossing over is a common phenomenon that accounts for genetic diversity within species.<\/p>\n

What Is Chromosome Mapping?<\/strong>
\nThe phenomenon of crossing over led scientists to believe that genes were located in fixed positions on chromosomes, similar to an arrangement of beads on a string.\u00a0 If their position was fixed, then it could be mapped, as more was discovered about genes and chromosomes.\u00a0 In addition, since crossing over results \u00a0when chromosomes break apart during meiosis, it is more likely to occur when chromosomes are further apart than when they occur close together. Because a mixture of dominant and recessive traits are found in the offspring of a testcross, the percentage of times the mixture occurs might be related to how far apart the genes are on the chromosome that contains them.<\/p>\n

What Are Giant Chromosomes?<\/strong>
\nIn most organisms, chromosomes are so small that only a few details about them can be seen with a microscope.\u00a0 However, the larval form of the fruit fly has giant chromosomes in the salivary glands, more than a thousand times larger than those same chromosomes in the mature adult.\u00a0 They are visible under a regular light microscope.\u00a0 When the cell is stained to show the chromosomes, dark and light bands correspond to the locations of specific genes.<\/p>\n

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 <\/p>\n","protected":false},"excerpt":{"rendered":"

Overview:\u00a0 What Is Genetic Behavior? Morgan’s discovery of gender-linked traits was further evidence that genes were located on chromosomes.\u00a0 However, other research indicated that the behavior of genes during meiosis was sometimes more complex than with gender-linked traits.\u00a0 With the development of more powerful techniques of observation, specific genes could sometimes be located. What Is […]<\/p>\n","protected":false},"author":22,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[3],"tags":[281,434,719],"class_list":["post-6212","post","type-post","status-publish","format-standard","hentry","category-biology","tag-chromosome-mapping","tag-crossing-over","tag-gene-linkage"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/6212","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/comments?post=6212"}],"version-history":[{"count":0,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/posts\/6212\/revisions"}],"wp:attachment":[{"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/media?parent=6212"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/categories?post=6212"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/schooltutoring.com\/help\/wp-json\/wp\/v2\/tags?post=6212"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}