BMS 141 Lecture 1 Free Nucleotides (Amira Haleem) PDF

BMS: 141 Lecture No: 1 Title: Describe structure and functions of free nucleotides of biological significance Instructor Name: Dr Amira Abdel Haleem Medicine and Surgery Program Fall 2024  Intended Learning Outcomes of...

BMS: 141 Lecture No: 1 Title: Describe structure and functions of free nucleotides of biological significance Instructor Name: Dr Amira Abdel Haleem Medicine and Surgery Program Fall 2024  Intended Learning Outcomes of lecture At the end of this lecture, the students will be able to: 1- Describe the nucleic acids chemical structure 2- List Examples for physiologically active nucleotides and nucleosides 3- Study the chemistry of nucleic acids and their biological importance.  Nucleic Acid Def.: Polymer (repeated subunits) of nucleotides linked together by phosphodiester bond. Function: Storage and expression of genetic information. Types: There are two types of nucleic acids (a) Ribonucleic acid (RNA) (b) Deoxyribonucleic acid (DNA) Nucleotides & Nucleosides Nucleotides are organic compounds composed of a nitrogenous base linked to a pentose sugar to which phosphate group is also attached. Nucleosides are organic compounds composed of nitrogenous base linked to a pentose sugar  Nitrogenous base + pentose sugar + P group =Nucleotide Nitrogenous base + pentose sugar = Nucleoside So, (Nucleotide = Nucleoside + P group ) A. Nitrogenous Bases We have two family of nitrogenous bases Purine or Pyrimidine. I- Purine bases: It include (Adenine and guanine bases) (A and G) II- Pyrimidine bases: It include (Cytocine, thymine and uracil bases) (C,T and U respectively)  B- Pentose sugar Two types of pentose sugar 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)  C- Phosphate Posphoric acid (H3PO4) It attach to C5 of ribose by an ester bond N:B: - In nucleotide and nucleosides the nitrogenous base (N1 of pyrimidine and N9 of purine) is linked to C1 of sugar by N- glycosidic bond.  Nomenclature of nucleotides and nucleosides Nucleotide= nucleoside Nucleotide Nucleoside (NB+PS) Pentose sugar (PS) Nitrogen base (NB) monophosphate(NMP) (NB+PS+P) Adenosine Adenylic Adenosine Ribose Adenine monophosphate Acid (AMP) (Adenosinemonophosp hte) d.AMP d. Adenylic acid Deoxyadenosine d.ribose Adenine Guanosine Guanylic Guanosine Ribose Guanine monophosphate Acid (GMP) (Guanosine monophosphate) d.GMP d. Guanylic acid Deoxyguanosine d.ribose Guanine  Nomenclature of nucleotides and nucleosides Nucleotide= nucleoside Nucleotide Nucleoside Pentose sugar (PS) Nitrogen base (NB) monophosphate(NMP) (NB+PS+P) (NB+PS) CMP Cytidylic acid Cytidine Ribose Cytosine (Cytosine monophosphate) dCMP d.Cytidylic acid d. Cytidine d.ribose Cytosine UMP Uridylic acid Uridine Ribose Uracil (Uridine monophosphate) TMP Thymidylic acid Thymidine d.ribose Thymine (Thymidine monophosphate)  Importance of nucleotide and nucleosides 1- Building units of nucleic acid (DNA and RNA) 2- A high energy source (ATP) 3- Constituents of coenzyme (FAD, NAD) 4- Serve regulatory functions (e.g. cAMP, cGMP) 5- Synthetic nucleotide analogues used as chemotherapeutic drugs 6- Pyrimidines are precursors of some important intermediates in metabolism as (UDP-glucose, CDP-choline)  Polymerization of Nucleotides The nucleotides of a nucleic acid are linked together by 3’ , 5’ phosphodiester bond (the pentose sugar of one nucleotide is attached by its 3’to the phosphate group of the next nucleotide. So there is a phosphate group attached by 2 ester bonds to carbon 3’ and 5’ of two successive nucleotides. The phosphodiester bonds can be enzymatically hydrolyzed by enzymes called nucleases.  Thus every polynucleotide will have Two terminals: -Free 3′ hydroxyl (-OH) at one end called 3′-end - Free 5′ phosphate group at other end called 5′-end.....Polarity of Nucleic Acids..... While representing the nucleotide base sequence of DNA or RNA on paper it is represented in the 5 ′→ 3′ direction 5՝- A - A - T - C - T - G - G - C - A - C - T - 3՝ ⚫The sugar molecule present in nucleotide is a) triose Answer: b) tetrose c c) pentose d) Hexose ⚫Purine base found in RNA is Answer: a) Cytosine c b) Thymine c) Guanine d) Uracil ⚫ Find the correct statement about phosphodiester linkage between adjacent nucleotides in nucleic acids a)3'-phosphate of one nucleotide joins the 3'-hydroxyl of the next nucleotide b)3'-phosphate of one nucleotide joins the 5'-hydroxyl of the next nucleotide c)5'-phosphate of one nucleotide joins the 5'-hydroxyl of the next nucleotide d)3'-hydroxyl of one nucleotide joins the 5'-phosphate of the next nucleotide Answer: d  References for further readings Lippincott Illustrated Review Integrated system Lippincott Illustrated Review 6th edition Oxford Hand book of Medical Science 2nd edition Clinical Key Student THANK YOU