{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter 14 HO

y sperm y yy yy yy yy f212

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ses! ! #!of!gamete!types!=!2n;!n=#!of!characters! Trihybrid\$Cross:\$\$\$\$ \$ \$\$\$\$\$\$PpYyRr)))x))Ppyyrr) 23!=!8!gamete!types!–!huge!cross!! ! p! ! P!P! ¼! P!p! ¼! Pp! ¼! p!p! ¼! F2:)¼)PP:))½)Pp:)¼)pp) ! y! ! ! y! ! Sperm! y! Y!y! ¼! y!y! ¼! Yy! ¼! y!y! ¼! )F2:)))1/2 Yy, 1/2 yy ) R! Sperm! r! ! r! ! Egg! Egg! ! P! ! Y! p! Egg! P! Sperm! R!r! r!r! ¼!! ¼!! ! !! rr! r! ! R!r! ¼!! ¼!! ! ! 1 F2:) ))/2 Rr, 1/2 rr What\$frac/on\$of\$the\$oﬀspring\$from\$this\$cross\$would\$be\$predicted\$to\$exhibit\$the\$recessive\$ phenotypes\$for\$at\$least\$two\$of\$these\$three\$characters?\$ ! !ppyyRr ! (1/4) * (1/2) !* (1/2) = 1/16 !! ! !ppYyrr !1/4!*!1/2!*!1/2!!=!1/16! ! !Ppyyrr !!(1/2) * (1/2) * (1/2) = 1/8 ! !PPyyrr !1/4!*!1/2!*!1/2!!=!1/16! ! !ppyyrr! !1/4!*!1/2!*!1/2!!=!1/16! Frac/on\$of\$oﬀspring\$with\$\$at\$least\$two\$recessive\$traits\$ 6/16 --> 3/8 Extending\$Mendelian\$Gene/cs\$for\$a\$Single\$Gene\$ ! Inheritance!of!characters!determined!by!a!single!gene!deviates!from!simple!Mendelian! paderns!when:! Alleles!are!not!completely!dominant!or!recessive! *! When a particular gene has more than two alleles When!a!single!gene!produces!mul<ple!phenotypes! ! 1.\$\$Incomplete\$Dominance:\$\$When!neither!allele!for!a!gene!is!completely!dominant! Is\$this\$evidence\$for\$the\$Blending\$Hypothesis?\$ ! No not enough you'd have to do another generation cross… but if you're right, you'd never see the parent alleles again… Incomplete --- BLENDING. F1!hybrids!have!a!phenotype!somewhat!between!the!parental!phenotypes! Set\$up\$an\$F1\$X\$F1\$cross\$ WE SEE WHITE AND RED PHENOTYPES!!! Which means Blending hypothesis is WRONG. PARTICULATE HYPOTHESIS is right. Phenotypes:)!!! red: !2 pink: 1 white ! 1 ! !Genotype:!!!1!CRCR;!2CRCW;!1!CWCW! What\$can\$you\$conclude\$from\$these\$results?\$ ! Segregation of the red allele from the white allele in the gametes produced by the pink parent supports PARTICULATE HYPOTHESIS. 2.  Codominance:!!Both!alleles!aﬀect!the!phenotype!but!in!separate!dis%nguishable!ways! Example:!!MN!blood!group!V!dis%nct!from!the!beder!known!ABO!blood!groups! ! ! M!allele!codes!for!M!type!glycoprotein!on!the!surface!of!a!RBC! M! ! RBC! ! N!allele!codes!for!a!N!type!glycoprotein!on!the!surface!of!a!RBC! RBC! N! Predic<on:) M! M! N! MM! MN! Results:) CO-DOMINANT….both alleles are expressed! ! M! M! RBC! N! N! RBC! RBC! RBC! N! MN! M! N! NN! Genotype:! 1 MM: 2 MN: 1 NN !!Both!alleles!are!expressed!! ! !!Even!when!only!one!copy!is!present! For\$any\$character,\$the\$observed\$dominant/recessive\$rela/onship\$of\$alleles\$depends\$on\$the\$ level\$at\$which\$we\$examine\$the\$phenotype\$ ! Example:!!TayVSachs!Disease!! (similar to POMPE disease) ! A!fatal!gene%c!disorder!caused!by!the!build!up!of!a!harmf...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online