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1 gene multiple effects

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Unformatted text preview: eVending!carbohydrates! Galactose) GalNAc) Galactose) 2 As 1 A, 1 none *! Each individual can only have 2 of these 3 alleles 2 Bs 1 B, 1 none 1 A, 1 B 2 nones Pleiotropy:$$when$a$gene$has$more$than$one$phenotypic$effect$ ! 1 gene, multiple effects Example:!!Cys%c!Fibrosis!is!caused!by!a!muta%on!to!a!single!gene,!however!this!single! allele!is!responsible!for!numerous!symptoms!!that!affect!an!individual’s!breathing!and! diges%ons! 2 Systems affected? DIGESTIVE & RESPIRATORY Muta%on!is!CFTR!gene!causes!cys%c!fibrosis! ! *!CFTR gene codes for a channel protein that transports chloride ! ions into & out of the cell Flow!of!ions!helps!control!movement!of!water!in!%ssues.!! Water!is!necessary!for!the!produc%on!of!normal!mucus! that!is!thin!and!freely!moving.! ! Muta%on!disrupts!the!func%on!of!chloride!channels!and! prevents!normal!flow!of!ClV!and!water! ! Cells!lining!the!lungs,!pancreas!and!other!organs! produce!abnormal!mucus!that!is!unusually!thick!and! s%cky! build up of mucus makes a GREAT enviro for bacteria & biofilms to build up… it also clogs up pancreatic duct so ! they dont make enzymes to digest food so they dont get *! as much nutrition…. PLEIOTROPY = EX: CYSTIC FIBROSIS! Mucus clogs airways of lungs & prevents release of digestive enzymes from the pancreas. Epistasis:$$A$gene$at$one$locus$can$alter$the$expression$of$a$gene$at$a$second$locus$ ! Multiple genes on separate loci interfere with each other (the presence of one alters or blocks the other) Gene!for!coat!(hair)!pigment:!!Black!Coat!(B)!vs!!brown!coat!(b)! ! BB!=!black!coat! Bb!=!black!coat! bb!=!brown!coat! ! Gene!for!Pigment!Deposi%on!into!hair!follicle:!!Deposi%on!(C)!!vs.!NonVdeposi%on!(c)! ! CC!=!pigment!deposited! Cc!=!pigment!deposited! cc!=!no!pigment!deposited!–!mouse!is!white!–!regardless!if!the!pigment!is!black!or!brown! ! ! ! ! ! ! *! Mate$two$black$mice$of$the$genotype$BbCc$ ! Predict!genotype!and!phenotype!for!this!dihybrid!cross:! ! How)many)mice)will)be:) ! Black!=!! 9 ! Brown!=! 3 ! White!=! 4 Any)mouse)with)cc)genotype)will) be)white))) $ The presence of "cc" BLOCKS the expression of any other gene. Can$answer$this$same$ques/on$–$by$breaking$the$dihybrid$cross$into$two$crosses$ Predic<on:) Bb$$x$$Bb$ ! B! b! Predic<on:) Cc$$x$$Cc$ ! C! c! B! BB! Bb! C! CC! Cc! b! Bb! bb! c! Cc! cc! Genotype:!!1/4!BB:!1/2!Bb:!1/4!bb!!! Genotype:!!1/4!CC:!!1/2!Cc:!!1/4!cc!! How$many$mice$will$be:$ Black))So must have 1 B, 1 C BBCC!=!1/4*1/4!!=!1/16! BbCC!=!1/2*1/4!=!2/16! BBCc!=!1/4*1/2!=!2/16! BbCc!=!1/2*1/2!=!4/16! Total$=$ 9/16 Brown))) least 1 C and no Bs @ bbCC!=!1/4*1/4!!=!1/16! bbCc!=!1/4*1/2!!=!2/16! Total$=$ 3/16 Must White))) have cc BBcc!=!1/4*1/4!!=!1/16! Bbcc!=!1/2*1/4!!=!2/16! bbcc!=!1/4*1/4!!=!1/16! Total$=! 4/16...
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