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?