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Nucleic Acids

This text provides an overview of the structure, function, and importance of DNA and RNA, the two main types of nucleic acids. It covers topics such as nucleotide composition, sugar differences, base types, and nucleotide nomenclature. It also discusses the role of nucleic acids in storing and transferring genetic information. The text is written in English.

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Nucleic Acids

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  1. Nucleic Acids

  2. We have studied three other sets of Macromolecules: Carbohydrates, lipids, & proteins The 4th macromolecule used by organisms: Nucleic Acids

  3. Two main types: • DNA (deoxyribonucleic acid) - found in the nucleus • RNA (ribonucleic acid) – found all over the cell • DNA functions: • Store genetic information “blueprint” • Transfer genetic blueprint to other generations • Controls many cellular functions • RNA functions: • Carries genetic information out of nucleus • Builds proteins

  4. Both types are polymers The monomers are nucleotides RNA is a single strand DNA is a double strand Both have a helix structure

  5. The basic unit for DNA and RNA is a “nucleotide” • Composed of 3 parts: • a nitrogenous base (1 of 5 types) • a pentose sugar (1 of 2 types) • a phosphate

  6. Pentose Sugars DNA = deoxyribose RNA = ribose Difference is: Deoxyribose lacks an –OH at 2’ C. Note: 5th C sticks up from ring

  7. C atoms numbered for orientation: “Primes" distinguish them from atoms of nitrogenous bases. 1’-C –OH group is in a beta (b) configuration We will be referring to this number system a lot! Particularly note the 5’ and 3’ carbons

  8. Nitrogenous bases of nucleotides • Ring structures • of N & C • Plus side chains • Double rings • are purines • Single rings • are • pyrimidines • 5 types provide • variety in • nucleic acids Note where the carbonyl groups & amines are located

  9. Thymine is only in DNAUracil is only in RNA (but similar to thymine) 2 purine and 3 pyrimidine bases.

  10. Carbon numbering comparison: Purines start at upper left Nitrogen Then move counterclockwiseon 1st ring, clockwise on 2nd Pyrimidines start at bottom, central Nitrogen and move clockwise Sugars start at far right Carbon and move clockwise

  11. Nucleosides and nucleotides A  nucleoside forms by combining a nitrogenous base (A,T,C or G) with a pentose sugar. Purine bases:  glycosidic bond is N-9 of base and C-1' of the pentose. Pyrimidine bases:  glycosidic bond is N-1 of base and C-1' of the pentose.

  12. Nucleotide formation -OH group on 5’ carbon H atom on phosphate OH group

  13. Nucleotide formation H2O Condensation reaction or Dehydration synthesis

  14. Nucleotide nomenclature: "5'-monophosphate" suffix – phosphate group attached to 5’ C e.g. "adenosine 5'-monophosphate". Prefix describes the base: purines (double ring) end in –osine pyrimidines (single ring)end in –idine e.g. thymine = thymidine adenine = adenosine Ribose sugar = no additional prefix deoxyribose + adenine = deoxyadenosine Come on! Let it roll off the tongue!

  15. Deoxyadenosine 5' monophosphate Deoxythymidine 5 ' monophosphate

  16. Names of the Eight Nucleotides found in DNA and RNA.

  17. Artificial nucleotides in treating fast growing cancers: 5-Fluorouracil Tumor cells utilize uracil for DNA synthesis more efficiently than normal cells. Fluorinated pyrimidine inhibits DNA synthesis.

  18. Nucleotide monomers are linked using "phosphodiester bonds" between the 3' C of one sugar to the 5' C of another.

  19. An ester (-O-) is acondensation reaction product of an alcohol (sugars are "polyalcohols") and an acid ( PO43- is an acid). H2O is a byproduct “Diester" signifies the formation of two ester linkages by each phosphate

  20. The phosphate groups link to the sugars at the 3' and 5' carbons. This is the sugar-phosphate “backbone” of long nucleic acids - held together by covalent bonds

  21. Bases are perpendicular to the axis like the steps of a staircase

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