CHAPTER 25 NUCLEIC ACIDS AND PROTEIN SYNTHESIS 25.1 NTRODUCTION The nucleic acids, deoxyribonucleic (dna)and ribonucleic (RNA), are, respectively, the molecules that preserve here ditary information and that transcribe and translate it in a way that allows the synthesis of all the varied proteins of the cell 252 NUCLEOTIDES AND NUCLEOSIDES
CHAPTER 25 NUCLEIC ACIDS AND PROTEIN SYNTHESIS 25.1 INTRODUCTION The nucleic acids, deoxyribonucleic (DNA) and ribonucleic (RNA) , are, respectively , the molecules that preserve hereditary information and that transcribe and translate it in a way that allows the synthesis of all the varied proteins of the cell 25.2 NUCLEOTIDES AND NUCLEOSIDES
Mild degradations of nucleic acids yield their monomeric units compounds that are called nucleotides Heterocyclic base NI HO-POH,C B-N-Glycosidic HO-POH2C 9N"4N link OHOH OH OH A nucleotide Adenylic acid (核苷) (腺苷酸) Complete hydrolysis of a nucleotide furnishes 1. A heterocyclic base, either a purine or pyrimidine 2. a five-carbon monosaccharide, either D-ribose or 2-deoxy D-ribose 3.A phosphate ion
Mild degradations of nucleic acids yield their monomeric units, compounds that are called nucleotides. O POH2 C OH OH N O HO HO 1' 3' 2' 4' 5' Heterocyclic base -N-Glycosidic linkage O POH2C OH OH O HO HO 1' 3' 2' 4' 5' N N N N NH2 1 2 3 4 5 7 6 8 9 Adenylic acid ( 腺苷酸) A nucleotide (核苷) Complete hydrolysis of a nucleotide furnishes: 1. A heterocyclic base, either a purine or pyrimidine. 2. a five-carbon monosaccharide, either D-ribose or 2-deoxyD-ribose. 3. A phosphate ion
The central portion of the nucleotide is the monosaccharide and it is always present as a five-membered ring, that is, as a furanoside The nucleosides that can be obtained from dna all contain 2-deoxy D-ribose as their sugar component and one of four heterocyclic bases either adenine, guanine, cytosine or thymine NHA NH NH H H,C H N NH H H H Adenine Guanine Cytosine Thymine (腺嘌呤) (鸟嘌呤) (胞核嘧啶) (胸腺嘧啶) Purines Pyrimidines
The central portion of the nucleotide is the monosaccharide and it is always present as a five-membered ring, that is, as a furanoside. The nucleosides that can be obtained from DNA all contain 2-deoxyD-ribose as their sugar component and one of four heterocyclic bases, either adenine, guanine, cytosine, or thymine. N N N N NH2 H N N N N NH H H NH2 N N NH2 O O O H H3 C H H Adenine (腺嘌呤) Guanine (鸟嘌呤) Cytosine (胞核嘧啶) Thymine (胸腺嘧啶) Purines Pyrimidines
The nucleosides obtained from RNa contain D-ribose as their sugar component and either adenine, guanine, cytosine, or uracil as their heterocyclic base H Uracil (尿嘧啶) Nucleotides are named in several ways. Adenylic acid for example is sometimes called 5-adenylic acid, it is also called 5-phosphate or simply adenosine monophosphate(AMP)
The nucleosides obtained from RNA contain D-ribose as their sugar component and either adenine, guanine, cytosine, or uracil as their heterocyclic base. N N O O H H Uracil (尿嘧啶) Nucleotides are named in several ways. Adenylic acid, for example, is sometimes called 5’-adenylic acid, it is also called 5’-phosphate, or simply adenosine monophosphate(AMP)
The names and structures of the nucleoside found in dna and rna Thymine Cytosine NH2 H3C N N CH,OH CHoOH H OH H 2-Deoxvcvtidine 2-Deoxythymidine Guanine Adenine NH2 N CH,OH CHOH NH, O H H H OH OH H 2-Deoxyguanosine 2'-Deoxyadenosine (2-脱氧次黄苷) (2-脱氧腺苷)
The names and structures of the nucleoside found in DNA and RNA: N N N N NH2 O O O H3C H Cytosine Thymine O CH2OH OH H H H H H O CH2OH OH H H H H H 2'-Deoxycytidine 2'-Deoxythymidine Adenine Guanine O CH2OH OH H N N N N NH2 H H H H O CH2OH OH H N N N N O H H H H H NH2 2'-Deoxyadenosine (2'-脱氧腺苷) 2'-Deoxyguanosine (2'-脱氧次黄苷)