Dr. atef abdelmeguid Lecturer Faculty of Allied Medical Science Biochemistry Of Nucleic acids

By the end of the lecture, the students have the ability to: 1-Recognize the structure of nucleosides and nucleotide and differentiate between them. 3-Recognize the structure of DNA and RNA and differentiate between them. 2-Identify functions of nucleosides and nucleotides. 4-Identify the biological importance of DNA and RNA.

Difference between Purine & Pyrimidine of Nitrogenous Base The Nitrogenous Bases

Deoxyribose Sugar Ribose Sugar

are made of nitrogenous base bind to Ribose sugar.

Base FormulaBase (x=H) Nucleoside (x=ribose) Nucleotide (x=ribose phosphate) Adenine A Adenosine A Adenylic acid AMP Guanine G Guanosine G Guanylic acid GMP Cytosine C Cytidine C Cytidylic acid CMP Uracil U Uridine U Uridylic acid UMP Thymine T Deoxythymidine dT Deoxythymidylic acid dTMP

Nucleosides are glycosamine consisting of a nucleobase (often referred to simply base ) bound to a ribose or deoxyribose sugarvia a β-glycosidic bond. Nucleosides

consists of a nucleoside plus one or more phosphate groups.

Nucleotides are phosphate esters of nucleosides.

Common bases found in nucleic acids with corresponding nucleosides and nucleotides

Purine bases (adenine, guanine and hypoxanthine) Nucleosides are then formed by the addition of sugar moieties (deoxyribose or ribose) nucleotides are then formed by the addition of phosphate (mono-, di- and triphosphate)

FForming a Adenosine 5′-triphosphates ATP is central to energy metabolism, energy stores. pportion of several important coenzymes such as NAD+, NADP+, FAD and co A. AActivated intermediates in numerous biosynthetic reactions, as Sulfate donor (PAPS) in lipids synthesis. Methyl donor (SAM) in glycoprotein synthesis. CCyclic nucleotides are 2 nd messenger and regulators of many cellular metabolism. GGTP drives protein synthesis CCTP drives lipid synthesis UUTP drives carbohydrate metabolism

ATP

Nicotinamide adenine dinucleotide NAD+ Nicotinamide adenine dinucleotide ( NAD ) and nicotinamide adenine dinucleotide phosphate ( NADP ) are two important coenzymes found in cells.coenzymescells It acts as a coenzyme in redox reactions. A group of enzymes used NAD + to remove acetyl groups from proteins.acetyl groups as a donor of ADP-ribose moieties in ADP-ribosylation reaction ADP-ribosylation precursor of the second messenger molecule cyclic ADP-ribosesecond messengercyclic ADP-ribose nicotinamide adenine

SAM S-adenosyl methionine Methyl donor PAPS Phosphoadenosine-phosphosulfate Sulfate donor Adenine-ribose-phosphate-sulfateAdenine-ribose-methionine

UDP Conjugaton with bilirubin and some drugs as Aspirin Biosynthesis of Glycogen Biosynthesis of glycoprotein

Biosynthesis of phosphoglycerides,sphingosine, sphingomyelin. CTP OH

Thymidine tri-phosphate TTP Marker for DNA

cGMP 2 nd messengers in many signal transduction cAMP

They carry genetic informaton or form structures within cells. They are usually either single-stranded or double-stranded. They are polymers of nucleotides. They are built from three components, nitrogenous bases (purines and pyrimidines) 5-carbon sugars (Ribose in RNA or deoxyribose in DNA) phosphate groups. two types of nucleic acid in living organisms, DNA deoxyribonucleic acid RNA ribonucleic acid.

Structure of DNA  Double helix  The bases occupy the core of helix  Sugar –phosphate run along periphery.  Complementary base pairing ( G binds C)  (A binds T)  The length of DNA is measured by bp and Kb.  The two strand run anti-parallel.

Cytosine Thymine Adenine Guanine Bases of DNA

The structure of DNA is a double-stranded, antiparallel helix

FUNCTIONS of Nucleic acids - Carrying the genetic information for all biological functions of the cell e.g protein synthesis and metabolism.

Principles of Biochemistry, Donald J. Voet, Judith G. Voet, Charlotte W. pratt, 3 rd ed.,p Suggesting readings

ASSIGNMENTs The students are requested to prepare slides about the following topics: Students NameTopics Biological important of RNA and DNA Applications of DNA in laboratories. Disease related to disturbance of nucleotides structure.

Study Question  Write three points about :  i-Function of nucleotides  1-  2-  3-  Correct the incorrect word:  Nucleosides are made from a ring of nitrogen, carbon and oxygen atoms together with a six-carbon sugar.  DNA is polymer of nucleotides and contains ribose sugar.

1-Nucleotide consists of  a-Sugar+ Nitrogenous base+phosphate group  B- Nitrogenous base+phosphate group.  C- Sugar+ Nitrogenous base 2- DNA is polymer of a-Nucleoside b-Nucleotides c-Nitrogenous base Choose: