PredicttheresultsofacrossbetweenPPTT andpptt parents,IFDihybridcrosses,MitosisandMeiosis
ALLELESOFDIFFERENTGENESDONOTSTAYTOGETHER.ParentalgenotypesPPTTppttGamete genotypes:Gametegenotypes:F1 offspringfromcross:
Gametes produced by F parents:GametesproducedbyF1 parents:
F2 offspringfromselfing:
RatioofF2 phenotypes:
Mendels actual results (seed color and seed shape cross);Mendel sactualresults(seedcolorandseedshapecross);Y =yellow,y =greenR =round;r =wrinkled
YYRR x yyrrYYRR xyyrrF1sallmakeyellow,roundseeds(YyRr)
WhenF1sareselffertilized,phenotypesofF2 offspringare:
yellowround:greenround:yellowwrinkled
i kl dgreenwrinkled
TOTAL:TOTAL:
Note:othercombinationsoftwotraitsbehavedthesameway.
Mendelsconclusion:Thesegregationofallelesofdifferent genes occursdifferentgenesoccurs
Thisistheprincipleof
TounderstandthephysicalbasisofMendelsrulesandhowgeneticvariationisgeneratedin
l ti d t i t t f llpopulations,weneedtoexaminetwotypesofcelldivisionthatwerefirstdescribedinthelate1800s.
I.Mitosis:Theprocessresponsibleforasexualreproductionandgrowthinmulticellularorganisms.g g
Howdoesithappen?
Focusonchromosomes(coloredb di ) i id th lbodies)insidethenucleus
Chromosomescomeindifferenttypes,distinguishedbysizeandshape(morphology)
Inmanyorganisms,thereare2ofeachtypeof
Pairsofsimilarchromosomesaresaidtobe
Keynotation:
Usen toindicatethenumberofdifferenttypesofchromosomesfoundinaspecies
Useanumeralbeforethen toindicatethenumberofeach type presenteachtype present.
Whichistheploidy?Whichisthehaploidnumber?
d h h diff bAndwhatsthedifferencebetweenachromosomeandachromatid?
Drawahaploidsetofunreplicated chromosomesin
i h 6aspecieswheren =6.
Drawtheunreplicatedchromosomesofadiploidcellina species where n = 5 2n = 10aspecieswheren =5,2n =10.
Drawthereplicatedchromosomesofadiploidcellin
i haspecieswheren =3,2n =6.
Anoverviewofmitosisn =2;2n =4
Chromosomesreplicate
Chromosomeslineup
Sisterchromatids separate
ll di idCelldivides
AnoverviewofmeiosisIn =2;2n =4Chromosomesreplicate
Homologs synapse;Homologs synapse;Crossingoveroccurs
Homologs lineup
Homologs pullapart
Celldivides
AnoverviewofmeiosisII(sameinbothdaughters)
Chromosomeslineup
Sisterchromatidspullapart
Celldivides
h h f d ?Whataretheconsequencesofmitosisandmeiosis?MitosisMeiosis
Start:
End:
Chromosomessameordifferentasparentcell?