Radioactive labels 32P for DNA and 35S for protein.32PDNAT2phagePhageswithInfectE.coli andgrow32p-labeledDNA.in32p-containingmedium.35sproteinPhages withT2phageInfectE.coliandgrow35s-labeledproteinin 35s-containingmedium.Fig.6.76-16
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 6-16 Radioactive labels Radioactive labels 32P for DNA and for DNA and 35S for protein. for protein. Fig. 6.7
Ghosts32PDNA中BlendbrieflyCellRadioactivityPhageswithrecovered in hostandIntroducephagesinto32p-labeledDNA.passed onto phageprogenybacteria culture.Ghosts35sproteinASBlendbrieflyCellRadioactivityPhages withrecoveredIntroducephagesinto35s-labeledprotein.inphageghostsbacteria culture.Fig.6.76-17
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 6-17 Fig. 6.7
Other evidence that supports DNA asthe genetic materiall.DNA exclusivelylocalized in the chromosomes.2.The amount of DNA and the number of sets ofchromosomes arecloselycorrelated.Organismn (picograms)2n(picograms)3.257.30Human1.262.49Chicken2.675.79Trout1.653.49CarpShad0.911.97SpermNucleatedprecursors to redblood cells6-18
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 6-18 Other evidence that supports DNA as Other evidence that supports DNA as the genetic material the genetic material 1. DNA exclusively localized in the chromosomes. 2. The amount of DNA and the number of sets of chromosomes are closely correlated. Organism Organism n (picograms picograms) 2n (picograms picograms) Human 3.25 7.30 Chicken Chicken 1.26 2.49 Trout 2.67 5.79 Carp 1.65 3.49 Shad 0.91 1.97 Sperm Nucleated Nucleated precursors to red precursors to red blood cells blood cells
3.DNA, but not protein, absorbs UV light more stronglyat260 nm,the wavelengththat has the strongestmutagenic effect.Action spectrumUV light is mostmutagenicat260nmwavelength.240250260270280290UVwavelength (2-nm)6-19
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 6-19 UV light is most mutagenic at 260 nm wavelength. Action spectrum 240 250 260 270 280 290 UV wavelength (-nm) Mutation frequency 3. DNA, but not protein, absorbs UV light more strongly at 260 nm, the wavelength that has the strongest mutagenic effect
DNA absorb UV light most strongly at260 nm butprotein at 280 nm.Absorption spectrumNucleic acidProteino240250260270280290UVwavelength (2-nm)6-20
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 6-20 DNA absorb UV light most strongly at 260 nm but protein at 280 nm. Absorption spectrum 240 250 260 270 280 290 UV wavelength (-nm) Absorption Nucleic acid Protein