29 第六章 含氮化合物代谢.ppt

第1页：Chapter 6 Nucleotides and Nucleic Acids

Chapter 6Nucleotides and NucleicAcidsFrancis Crick and James Watson point out features of their model for the structure of DNA.

第2页：DNA and RNA

deoxyribonucleic acid (DNA)andribonucleic acid (RNA)

第3页：Nitrogenous Bases图示

第4页：Nitrogenous Bases

6.1•Nitrogenous Bases

第5页：Nitrogenousbases

NitrogenousbasesBicyclicpurines:Monocyclicpyrimidine:Thymine (T) is 5-methyluracil (U)

第6页：BASESNUCLEOSIDESNUCLEOTIDES

BASESNUCLEOSIDESNUCLEOTIDESAdenine (A)AdenosineAdenosine 5’-triphosphate (ATP)DeoxyadenosineDeoxyadenosine 5’-triphosphate (dATP)Guanine (G)GuanosineGuanosine 5’-triphosphate (GTP)Deoxy-guanosineDeoxy-guanosine 5’-triphosphate (dGTP)Cytosine (C)CytidineCytidine 5’-triphosphate (CTP)Deoxy-cytidineDeoxy-cytidine 5’-triphosphate (dCTP)Uracil (U)UridineUridine 5’-triphosphate (UTP)Thymine (T)Thymidine/deoxythymidineThymidine/deoxythymidine 5’-triphosphate (dTTP)Comparisons of names of bases, nucleosides and nucleotidesPurine: A & G; Pyrimidine: C & T/U; (deoxy)-ribose,

第7页：Furanose structures—

Furanose structures—ribose and deoxyribose.6.2 The Pentoses of Nucleotides and Nucleic Acids

第8页：Nucleosides Are

6.3•Nucleosides AreFormed by Joining aNitrogenous Base to aSugar

第9页：Nucleoside示意图

第10页：Nucleoside结构图

第11页：Nucleoside

Nucleoside Conformation

第12页：Nucleotides Are

6.4•Nucleotides AreNucleoside Phosphates

第13页：Cyclic Nucleotides

CyclicNucleotides

第14页：Nucleoside

Nucleoside Diphosphatesand Triphosphates

第15页：Nucleic Acids Are

6.5•Nucleic Acids ArePolynucleotides

第16页：Structures

Structures

第17页：Classes of Nucleic

6.6•Classes of NucleicAcids

第18页：DNA Chargaff’s Rules

DNAChargaff’s Rules:[A] = [T]; [C] = [G]; [pyrimidines] = [purines]

第19页：Escherichia coli流程图

第20页：Escherichia coli模式图

第21页：Escherichia coli

Escherichia coli

第22页：RN Am RNA

RNAmRNA

第23页：Transfer RNA

Transfer RNA

第24页：r RNA

rRNA

第25页：Small Nuclear RN图解

第26页：Small Nuclear RN As

Small Nuclear RNAsSmall nuclear RNAs,or snRNAs,are a class of RNA molecules found in eukaryotic cells, principally in the nucleus. They are neither tRNA nor small rRNA molecules, although they are similar in size to these species. They contain from 100 to about 200 nucleotides, some of which, like tRNA and rRNA, are methylated or otherwise modified. No snRNA exists as naked RNA. Instead, snRNA is found in stable complexes with specific proteins forming small nuclear ribonucleoprotein particles,or snRNPs,which are about 10S in size.

第27页：Hydrolysisby Acid or

Hydrolysisby Acid orBase

第28页：RNA is relatively

RNA is relatively resistant to the effects of dilute acid, but gentle treatment of DNA with 1 mMHCl leads to hydrolysis of purine glycosidic bonds and the loss of purine bases from the DNA. The glycosidic bonds between pyrimidine bases and 2'-deoxyribose are not affected, and, in this case, the polynucleotide’s sugar-phosphate backbone remains intact. The purine-free polynucleotide product is called apurinic acid. DNA is not susceptible to alkaline hydrolysis.

第29页：Enzymatic Hydrolysis

Enzymatic Hydrolysis

第30页：Restriction Enzymes

Restriction EnzymesRestriction enzymes are classified into three types, I, II, or III. Types I and III require ATP to hydrolyze DNA and can also catalyze chemical modification of DNA through addition of methyl groups to specific bases. Type I restriction endonucleases cleave DNA randomly, while type III recognize specific nucleotide sequences within dsDNA and cut the DNA at or near these sites.

第31页：Type II Restriction

Type II RestrictionEndonucleasesEcoRI

第32页：Restriction图谱

第33页：Restriction Mapping

Restriction Mapping

第34页：THE END

THE END