Introduction to Nucleic Acids Lecture # 1 Dr. Shumaila Asim

Learning Outcomes Knowledge; Define and explain nucleic acids Describe the types of nucleic acids Content Nucleic Acids Types Of Nucleic Acids

Nucleic acids Nucleic acids are the most important biological macromolecules found in abundance in all living things They are involved in encoding, transmitting and expressing genetic information Or we can say that information is conveyed through the nucleic acid sequence.

Brief history 1869: isolated DNA from salmon sperm (Friedrich Miescher) 1944: proved DNA is genetic materials (Avery et al.) 1953: discovered DNA double helix (Watson and Crick) 1968: decoded the genetic codes (Nirenberg) 1981: invented DNA sequencing method (Gilbert and Sanger) 1987: launched the human genome project 2001: accomplished the draft map of human genome

Deoxyribonucleic acid, DNA Ribonucleic acid, RNA

The distribution of nucleic acids in the eukaryotic cell DNA is found in the nucleus with small amounts in mitochondria and chloroplasts RNA is found throughout the cell

NUCLEIC ACID STRUCTURE Nucleic acids are polynucleotides Their building blocks are nucleotides

phosphate nucleic acid pentose nucleotides nucleosides bases

NUCLEOTIDE STRUCTURE NUCLEOTIDE BASE PURINES PYRIMIDINES Adenine (A) PHOSPATE SUGAR Ribose or Deoxyribose BASE PURINES PYRIMIDINES Adenine (A) Guanine(G) Cytocine (C) Thymine (T) Uracil (U) NUCLEOTIDE

Ribose is a pentose C1 C5 C4 C3 C2 O

RIBOSE DEOXYRIBOSE CH2OH H OH C O

BASES Two types of bases: 1. Purines are fused five- and six-membered rings Adenine A DNA RNA Guanine G DNA RNA 2. Pyrimidines are six-membered rings Cytosine C DNA RNA Thymine T DNA Uracil U RNA

Nucleic Acid Bases Pyrimidines Purines

Phosphate Groups Mono-, di- or triphosphates Phosphates can be bonded to either C3 or C5 atoms of the sugar

Nucleosides Result from linking one of the sugars with a purine or pyrimidine base through an N-glycosidic linkage Purines bond to the C1’ carbon of the sugar at their N9 atoms Pyrimidines bond to the C1’ carbon of the sugar at their N1 atoms

Nucleosides

Nucleosides in DNA Base Sugar Nucleoside Adenine (A) Deoxyribose Adenosine Guanine (G) Deoxyribose Guanosine Cytosine (C) Deoxyribose Cytidine Thymine (T) Deoxyribose Thymidine

Nucleosides in RNA Base Sugar Nucleoside Adenine (A) ribose Adenosine Guanine (G) ribose Guanosine Cytosine (C) ribose Cytidine Uracil (U) ribose Uridine

Nucleotides Result from linking one or more phosphates with a nucleoside onto the 5’ end of the molecule through esterification

Nucleotides in DNA and RNA dAMP Deoxyadenosine monophosphate dGMP Deoxyguanosine monophosphate dCMP Deoxycytidine monophosphate dTMP Deoxythymidine monophosphate RNA AMP adenosine monophosphate GMP guanosine monophosphate CMP cytidine monophosphate UMP uridine monophosphate

Naming Conventions Nucleosides: Nucleotides: Purine nucleosides end in “-sine” Adenosine, Guanosine Pyrimidine nucleosides end in “-dine” Thymidine, Cytidine, Uridine Nucleotides: Start with the nucleoside name from above and add “mono-”, “di-”, or “triphosphate” Adenosine Monophosphate, Cytidine Triphosphate, Deoxythymidine Diphosphate

THE SUGAR-PHOSPHATE BACKBONE The nucleotides are all orientated in the same direction The phosphate group joins the 3rd Carbon of one sugar to the 5th Carbon of the next in line.

The bases are attached to the 1st Carbon P G C A T ADDING IN THE BASES The bases are attached to the 1st Carbon Their order is important It determines the genetic information of the molecule

Functions of Nucleic Acids Direction of Metabolism Synthesis of Proteins Control of synthesis of Enzymes Transfer of Genetic information Essential substance of genes Causation of cancers (malignancies)