Molecular Cell Biology and Genetic Module (CBG 1103) PDF

Molecular Cell Biology and Genetic Module (CBG 1103)  Overall Aims: The Module is designed to provide medical students with the basics of molecular biology and genetics, with brief description of different mechanisms which may control stability and structur...

Molecular Cell Biology and Genetic Module (CBG 1103)  Overall Aims: The Module is designed to provide medical students with the basics of molecular biology and genetics, with brief description of different mechanisms which may control stability and structure of genetic material. Utilizing some examples helping in under standing the cellular and genetic bases of some diseases. Finally applying such basic knowledge in in solving clinical problems. Structure and function of nucleotide, nucleoside BY: Dr/Shimaa Mohsen Elbeah Lecturer of Medical Biochemistry and Molecular Biology  ILOs Studying this topic should enable you to: 1. Identify nucleotides and nucleosides nomenclature & structure 2. List nucleotides of biological importance & their roles 3. Describe DNA structure & Explain phosphodiester bond formation  Learning outcome 1 Identify nucleotides and nucleosides nomenclature & structure  Nucleic acid chemistry Nucleic acids (DNA & RNA) are long chains of repeated subunits called nucleotides. Nucleotides ❑ building blocks of DNA and RNA. ❑ present in body as poly- nucleotide chain (DNA,RNA ) or free nucleotides.  Nucleotide Structure 1-Nitrogenous base : 2-pentose sugar : 3-phosphate(phosphoric acid )  A- Pentose sugar Two types of pentose sugar are present: a- Ribose (present in ribonucleic acid) b- Deoxyribose (Ribose from which an oxygen has been removed from carbon 2) (present in deoxyribonucleic acid DNA)  B- Phosphate Phosphoric acid (H3PO4) It attach to C5 of ribose by an ester bond  C- Nitrogenous bases We have two family of nitrogenous bases I- Purine bases: two rings Adenine:A Guanine:G II- Pyrimidine bases: one ring Cytosine: C Thymine: T (found in DNA) Uracil: U(found in RNA) Nitrogenous Bases Minor nitrogenous bases Other purine metabolites ,not usually found in nucleic acids, include Xanthine ,Hypoxanthine and uric acid.  Nucleosides Nucleosides are formed of covalently linking a base (N1 of pyrimidine and N9 of purine) to the number 1 carbon of a sugar by N- glycosidic bond. Nitrogenous base sugar Nucleoside  Nucleotides Nucleotides are formed when one or more phosphate group are attached to the 5 carbon of the nucleoside, nucleoside di- and triphosphates are high-energy compounds. Nitrogenous Phosphoric base sugar Nucleotide group  Nomenclature of Ribonucleotides Base Nucleoside Nucleotide Adenine Adenosine Adenylic acid Adenosine Adenosine Adenosine diphosphate triphosphate monopphosphate (ADP) (ATP) (AMP) Guanine Guanosine Guanylic acid Guanosine Guanosine Guanosine diphosphate triphosphate monoPhosphate (GDP) (GTP) (GMP) Cytosine Cytidine Cytidylic acid Cytidine Cytidine Cytidine Diphosphate Triphosphate monoPhosphate (CDP) (CTP) (CMP) Uracil Uridine Uridylic acid Uridine Uridine Uridine diphosphate triphosphate monoPhosphate (UDP( )UTP) (UMP) Hypoxanthine Inosine IMP Xanthine Xanthosine XMP Nomenclature of Deoxyribonucleotides Base Nucleoside Nucleotide Adenine DeoxyAdenosine DeoxyAdenylic acid DeoxyAdenosine DeoxyAdenosine DeoxyAdenosine diphosphate triphosphate monopphosphate (dADP) (dATP) (dAMP) Guanine DeoxyGuanosine DeoxyGuanylic acid DeoxyGuanosine DeoxyGuanosine DeoxyGuanosine diphosphate triphosphate monoPhosphate (dGDP) (dGTP) (dGMP) Cytosine DeoxyCytidine DeoxyCytidylic acid DeoxyCytidine DeoxyCytidine DeoxyCytidine Diphosphate Triphosphate monoPhosphate (dCDP) (dCTP) (dCMP) Thymine Deoxy Deoxy thymidylic Deoxy Deoxy acid thymidine thymidine thymidine Deoxy thymidine diPhosphate triPhosphate monoPhosphate (dTMP (dTTP) (dTMP)  Other important nucleotides S-adenosyl methionine (SAM):Methyle donner  Other important nucleotides Phosphoadenosine-phospho-sulfate (PAPS):sulphate donner Cyclic AMP (c.AMP):Second messenger for hormone action  Learning outcome 2 List nucleotides of biological importance & their roles  Functions of nucleotides 1-Building blocks of RNA and DNA 2-Source of energy : ATP ,GTP act as source of Energy. 3-Mediate action of hormone : c.AMP and c.GMP are second messenger 4- Co-enzymes : as NAD,FAD, Co-enzyme A.  Functions of nucleotides 5-Activation of chemical compounds ❖UDP- glucose synthesis of glycogen. ❖CDP-choline , CDP-ethanolamine synthesis of phospholipids. 6- Chemical group donors : ❖PAPS is a sulfate donor synthesis of sulfolipids. ❖SAM is a methyl donor transmethylation reactions.  E : 7- Synthetic Analogue E nucleotides analogues are prepared by altering the base ring or sugar part. Anti-cancer 5-flurouracil (pyrimidine analogue): ↓ thymine synthesis ↓ DNA synthesis ↓ growth of cancer cells. Anti-gout Allopurinol (hypoxanthine analogue ) used for treatment of gout