分子生物学(双语)1GenesAreDNA课件.ppt

1、分子生物学（双语）1 Genes Are DNAFigure CO:X chromosome in blue Science VU/DOE/Visuals UnlimitedFIGURE SO:Part I:Genes and ChromosomesPhoto courtesy of S.V.Flores,A.Mena,and B.F.McAllister.Used with permission of Bryant McAllister,Department of Biology,University of Iowa.FIGURE CO:Genes are DNA Mopic/Shutter

2、Stock,Inc.FIGURE 01:A brief history of geneticsFIGURE 02:A gene codes for an RNA,which may code for proteinDNA as the Genetic Material Pneumococcus pathogenicity tranferred to normal strain by transformation T2 bacteriophage genetic material is DNA Transfection of eukaryotic cells with TK+FIGURE 03:

3、Griffith experimentFIGURE 04:The DNA of S-type bacteria can transform R-type bacteria into the same S-typeFIGURE 06:The genetic material of phage T2 is DNAFIGURE 07:Eukaryotic cells can acquire a new phenotype as the result of transfectionBasic DNA Structure Nucleotide phosphate,sugar,base Bases pyr

4、imidines and purines Phosphodiester bonds phosphate/sugar backbone 5 to 3 direction,antiparallel double helix Base pairing Minor versus major groove in B-DNA 3.4 nm and 10.4 base pairs per turn Alternative DNA structuresFIGURE 08:A polynucleotide chain FIGURE 12:Flat base pairs lie perpendicular to

5、the sugar-phosphate backboneFIGURE 14:Base pairing provides the mechanism for replicating DNAFIGURE 13:The two strands of DNA form a double helix PhotodiscDNA Replication Basics Origins of replication Semi-conservative Denaturation,annealing,extension DNA Polymerases proofreading mutationsFIGURE 15:

6、Replication of DNA is semiconservativeFIGURE 16:The replication forkFIGURE 17:An endonuclease cleaves a bond within a nucleic acidFIGURE 18:An exonuclease removes bases one at a timeGene Expression Transcription Reverse transcription RNA processing Translation Post-translational modificationsFIGURE

7、19:The central dogmaControl of Gene Expression Processes affected by control Complexity from control Regulatory elementscis-actingtrans-actingFIGURE 20:Nucleic acids all replicate by synthesis of complementary strandsFIGURE 21:The amount of nucleic acid in the genome varies over an enormous rangeFIG

8、URE 22:Base pairingHybridization Nucleic acids hybridize by base pairing Denaturation is ds to ss Tm depends on sequence Renaturation is ds to ss Depends on complementarity Intermolecular or intramolecular Hybridization is the key to many methodsFIGURE 23:Denatured single strands of DNA can renature

9、 to give the duplex formFIGURE 24:Filter hybridizationMutations Point mutations Transitions versus transversions Chemical mutagens or misincorporation Reversions Insertions and deletions Frameshifts One gene,one polypeptide Loss-of-function or gain-of-function Complementation of mutations means diff

10、erent genesFIGURE 25:Mutation ratesFIGURE 26:Mutations can be induced by chemical modification of a baseFIGURE 27:Mutations can be inducedFIGURE 28:Point mutations and insertions can revert,but deletions cannot revertFIGURE 29:Spontaneous mutations are concentrated at a hotspotFIGURE 30:DeaminationFIGURE 31:DeaminationFIGURE 32:PSTV RNA