《有机化学》课程PPT教学课件（Organic Chemistry with Biological Applications, 3th Edition, John McMurry, 2016）Chapter 24 Biomolecules - Nucleic Acids and Their Metabolism

CNGNGE JOHN MCMURRY CHAPTER 24 Biomolecules:Nucleic Acids and Their Metabolism Organic Chemistry with Biological applications

CHAPTER 24 Biomolecules: Nucleic Acids and Their Metabolism

Nucleic Acids Nucleic Acids are the chemical carriers of a cell's genetic information Deoxyribonucleic acid(DNA) Holds the information that determines the nature of a cell Controls cell growth and division Directs biosynthesis of the enzymes and other proteins required for cellular functions Ribonucleic acid (RNA) Nucleic acid derivatives such as ATP are involved as phosphorylating agents in many biochemical pathways Several important coenzymes,including NAD+,FAD,and coenzyme A,have nucleic acid components

Nucleic Acids are the chemical carriers of a cell’s genetic information ▪ Deoxyribonucleic acid (DNA) ▪ Holds the information that determines the nature of a cell ▪ Controls cell growth and division ▪ Directs biosynthesis of the enzymes and other proteins required for cellular functions ▪ Ribonucleic acid (RNA) ▪ Nucleic acid derivatives such as ATP are involved as phosphorylating agents in many biochemical pathways ▪ Several important coenzymes, including NAD+ , FAD, and coenzyme A, have nucleic acid components Nucleic Acids

24-1 Nucleotides and Nucleic Acids Nucleic acids are biopolymers -Composed of nucleotides which are joined together to form a long chain ·Nucleotide Composed of nucleosides bound to a phosphate group Nucleoside Composed of an aldopentose sugar linked through its anomeric carbon to the nitrogen atom of a heterocyclic purine or pyrimidine base DNA H20 Nuclease Base 0 Base Base O-POCH2 HOCH2 Nucleotidase Nucleosidase HOCH2 OHOH(or H) OHOH (or H) Nucleotides Nucleosides 0P032 OHOH(or H)

Nucleic acids are biopolymers ▪ Composed of nucleotides which are joined together to form a long chain ▪ Nucleotide ▪ Composed of nucleosides bound to a phosphate group ▪ Nucleoside ▪ Composed of an aldopentose sugar linked through its anomeric carbon to the nitrogen atom of a heterocyclic purine or pyrimidine base 24-1 Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids DNA Sugar component is 2'-deoxyribose (the prefix 2'-deoxy indicates that oxygen is missing from the 2'position of ribose) Contains four different amino bases Two substituted purines (adenine and guanine) Two substituted pyrimidines(cytosine and thymine) RNA Sugar component is ribose Contains adenine,guanine,and cytosine Thymine is replaced by a closely related pyrimidine base called uracil

DNA ▪ Sugar component is 2′-deoxyribose (the prefix 2′-deoxy indicates that oxygen is missing from the 2′ position of ribose) ▪ Contains four different amino bases ▪ Two substituted purines (adenine and guanine) ▪ Two substituted pyrimidines (cytosine and thymine) RNA ▪ Sugar component is ribose ▪ Contains adenine, guanine, and cytosine ▪ Thymine is replaced by a closely related pyrimidine base called uracil Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids The pyrimidines and purines found in DNA and RNA 5 HOCH2 OH HOCH2 OH 0 0 4 1 OH OH OH Ribose 2-Deoxyribose Purine Pyrimidine NH2 NH2 H Adenine(A) Guanine(G) Cytosine(C) Thymine(T) Uracil(U) DNA,RNA DNA,RNA DNA,RNA DNA RNA Cng Learing All Pights Reserved

The pyrimidines and purines found in DNA and RNA Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids Structures of the four deoxyribonucleotides NH2 15 OPOCH> OPOCH> NH2 04 0 Adenine Guanine OH OH 2'-Deoxyadenosine 5'-phosphate 2'-Deoxyguanosine 5'-phosphate Deoxyribonucleotides NH2 H3C OPOCH2 OPOCH2 Cytosine Thymine OH OH 2'-Deoxycytidine 5'-phosphate Thymidine 5'-phosphate Cengage Learning.All Rights Reservec

Structures of the four deoxyribonucleotides Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids Structures of the four ribonucleotides NH2 G FOPOCH2 OPOCH2 NH> Adenine Guanine OH OH OH OH Adenosine 5'-phosphate Guanosine 5'-phosphate Ribonucleotides NH> U 0 OPOCH2 Cytosine Uracil OHOH OH OH Cytidine 5'-phosphate Uridine 5'-phosphate Cengage Learing.All Rights Reserve

Structures of the four ribonucleotides Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids In naming and numbering nucleotides,positions on the sugars are given a prime superscript to distinguish them from positions on the amine base ▣ DNA and RNA differ dramatically in size Molecules of DNA have molecular weights up to 75 billion -Molecules of RNA are much smaller,containing as few as 21 nucleotides,and have a molecular weight as low as7,000

▪ In naming and numbering nucleotides, positions on the sugars are given a prime superscript to distinguish them from positions on the amine base ▪ DNA and RNA differ dramatically in size ▪ Molecules of DNA have molecular weights up to 75 billion ▪ Molecules of RNA are much smaller, containing as few as 21 nucleotides, and have a molecular weight as low as 7,000 Nucleotides and Nucleic Acids

Nucleotides and Nucleic Acids Nucleotides are linked together in DNA and RNA by phosphodiester bonds between the phosphate group at C5'on one nucleotide and the 3'-hydroxyl group of the sugar of another nucleotide C3'is one free hydroxyl group at the end of the nucleic polymer (the 3'end) C5'is another free hydroxyl group at the other end of the nucleic polymer (the 5'end) Sequence of nucleotides in a chain is described by starting at the 5'end and identifying the bases in order of occurrence(using G,C,A,T or U) 5end 5'end 日ase O=POCH Phosphate Sugar Base Phosphate Sugar Base 3'end 3end

▪ Nucleotides are linked together in DNA and RNA by phosphodiester bonds between the phosphate group at C5′ on one nucleotide and the 3′-hydroxyl group of the sugar of another nucleotide ▪ C3′ is one free hydroxyl group at the end of the nucleic polymer (the 3′ end) ▪ C5′ is another free hydroxyl group at the other end of the nucleic polymer (the 5′ end) ▪ Sequence of nucleotides in a chain is described by starting at the 5′ end and identifying the bases in order of occurrence (using G, C, A, T or U) Nucleotides and Nucleic Acids

24-2 Base Pairing in DNA:The Watson- Crick Model Samples of DNA isolated from different tissues of the same species have the same proportions of heterocyclic bases Samples of DNA from different species often have greatly different proportions of bases Composition of human DNA =30%each of adenine and thymine 20%each of guanine and cytosine Composition of the bacterium Clostridium perfringens 37%each of adenine and thymine 13%each of guanine and cytosine

Samples of DNA isolated from different tissues of the same species have the same proportions of heterocyclic bases Samples of DNA from different species often have greatly different proportions of bases ▪ Composition of human DNA ▪ 30% each of adenine and thymine ▪ 20% each of guanine and cytosine ▪ Composition of the bacterium Clostridium perfringens ▪ 37% each of adenine and thymine ▪ 13% each of guanine and cytosine 24-2 Base Pairing in DNA: The Watson￾Crick Model