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Understanding Nucleic Acids: Structure, Function, and Importance in Genetics

Nucleic acids, including DNA and RNA, are essential biomolecules responsible for storing and transmitting hereditary information. They are composed of monomers known as nucleotides, which consist of a nitrogenous base, a pentose sugar, and a phosphate group. DNA's double helix structure, proposed by Watson and Crick, features complementary base pairing that is crucial for replication and genetic fidelity. RNA serves various roles in protein synthesis. Understanding their structure and functions provides insight into genetics, cell reproduction, and the basis of life.

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Understanding Nucleic Acids: Structure, Function, and Importance in Genetics

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  1. HELIXHELIX

  2. Nucleic Acids Informationstorage

  3. Nucleic Acids • Function: • store & transmit hereditary information • Examples: • RNA (ribonucleic acid) • DNA (deoxyribonucleic acid) • Structure: • monomers = nucleotides

  4. Nucleotides • 3 parts • nitrogen base (C-N ring) • pentose sugar (5C) • ribose in RNA • deoxyribose in DNA • phosphate(PO4)group Are nucleic acidscharged molecules?

  5. RNA & DNA • RNA • single nucleotide chain • DNA • double nucleotide chain • N bases bond in pairs across chains • spiraled in a double helix • double helix 1st proposed as structure of DNA in 1953 by James Watson & Francis Crick(just celebrated 50th anniversary in 2003!)

  6. Types of nucleotides • 2 types of nucleotides • different nitrogen bases • purines • double ring N base • adenine (A) • guanine (G) • pyrimidines • single ring N base • cytosine (C) • thymine (T) • uracil (U)

  7. Building the polymer

  8. Nucleic polymer • Backbone • sugar to PO4 bond • phosphodiester bond • new base added to sugar of previous base • polymer grows in one direction • N bases hang off the sugar-phosphate backbone Dangling bases?Why is this important?

  9. Pairing of nucleotides • Nucleotides bond between DNA strands • H bonds • purine :: pyrimidine • A :: T • 2 H bonds • G :: C • 3 H bonds Matching bases?Why is this important?

  10. Information polymer • Function • series of bases encodes information • like the letters of a book • stored information is passed from parent to offspring • need to copy accurately • stored information = genes • genetic information Passing on information?Why is this important?

  11. T G A C T A C A G G A T C

  12. DNA molecule • Double helix • H bonds between bases join the 2 strands • A :: T • C :: G H bonds?Why is this important?

  13. Copying DNA • Replication • 2 strands of DNA helix are complementary • have one, can build other • have one, can rebuild the whole Matching halves?Why is this a good system?

  14. When does a cell copy DNA? • When in the life of a cell does DNA have to be copied? • cell reproduction • mitosis • gamete production • meiosis

  15. DNA replication “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” James Watson Francis Crick 1953

  16. 1953 | 1962 Watson and Crick … and others…

  17. 1953 | 1962 Maurice Wilkins… and…

  18. Rosalind Franklin (1920-1958)

  19. Interesting note… • Ratio of A-T::G-C affects stability of DNA molecule • 2 H bonds vs. 3 H bonds • biotech procedures • more G-C = need higher T° to separate strands • high T° organisms • many G-C • parasites • many A-T (don’t know why)

  20. Another interesting note… • ATPAdenosine triphosphate • modified nucleotide • adenine (AMP) + Pi + Pi + +

  21. Macromolecule Review

  22. Carbohydrates • Structure / monomer • monosaccharide • Function • energy • raw materials • energy storage • structural compounds • Examples • glucose, starch, cellulose, glycogen glycosidic bond

  23. Lipids • Structure / building block • glycerol, fatty acid, cholesterol, H-C chains • Function • energy storage • membranes • hormones • Examples • fat, phospholipids, steroids ester bond (in a fat)

  24. Proteins • Structure / monomer • amino acids • levels of structure • Function • enzymes u defense • transport u structure • signals u receptors • Examples • digestive enzymes, membrane channels, insulin hormone, actin peptide bond

  25. Nucleic acids • Structure / monomer • nucleotide • Function • information storage & transfer • Examples • DNA, RNA phosphodiester bond

  26. Let’s buildsome DNA, baby!

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