Chem of Life
Macromolecules:Nucleic Acids
Nucleic Acids
• Biomolecules• Store and Transmit Hereditary Information
Examples (Types) of Nucleic Acids
• Deoxyribonucleic Acid (DNA)• Ribonucleic Acid (RNA)
DNA Functions
• Provides directions for its own replication• Direct RNA synthesis• & through RNA controls protein synthesis
Genes
• Consist of DNA (a nucleic acid polymer)• Molecules that enable living organisms to
reproduce their complex components from one generation to the next.
DNA
• Inherited from parents• Each chromosome contains one long DNA
molecule with several hundred to more than a thousand genes)
• Copied before cell division to be passed onto next generation.
Molecular Structure:
• Monomer: nucleotide• Each nucleotide monomer consists of:– A phosphate group– Pentose sugar– Nitrogenous base
RNA Structure
• Polynucleotide:– Pentose Sugar = Ribose– Nitrogenous base (a purine or a pyrimidine)– Phosphate group
• Simple polynucleotide (single strand)
RNA
DNA Structure
• Polynucleotide:– Pentose Sugar = deoxyribose– Nitrogenous base (a purine or a pyrimidine)– Phosphate group
• Double Stranded
DNA
Ribose vs. Deoxyribose
• Deoxyribose lacks an Oxygen atom on the second C in the ring
FYI
• Numbered Carbons have a prime (‘) after them, note the 5’ C end is the one that sticks out from the ring.
• The phosphate group attached to the 5’ C of the ring
Recap
• Nucleic Acid Polymer = polynucleotides– Examples: DNA & RNA
• Nucleic Acid Monomer = nucleotide– Nucleoside (nitrogenous base & pentose)– Phosphate group
Nitrogenous Bases
• Two families:– Pyrimidine– Purine
Pyrimidine:
• 6-membered ring & N atoms– N atoms take up the H+ from solution (base)
• Members include:– Cytosine (C)– Thymine (T)• (found only in DNA)
– Uracil (U) • (found only in RNA)
Pyrimidine:
Purines
• Larger 6-membered ring fused to a 5-membered ring
• Members include:– Adenine (A)– Guanine (G)
Purines
Nitrogenous BaseFunctional Groups
• Vary • Attached to the rings
(Handout)
Polymerization
• Adjacent nucleotides are joined by covalent bonds (phosphodiester linkages)
• Involves the –OH group on 3’ C of one nucleotide to the phosphate group on the 5’ C of another nucleotide
Polymerization
• Result = backbone with repeating sugar-phosphate with a distinct 3’ and 5’ ends– DNA (The 2 sugar phosphate strands run in
opposite directions = antiparallel) • The nitrogenous bases stick out like
appendages and are complementary in DNA.
Biological Staining:
• Acridine orange (AO) is a nucleic acid selective fluorescent cationic dye useful for cell cycle determination. It is cell-permeable, and interacts with DNA and RNA by intercalation or electrostatic attractions. When bound to DNA, it is very similar spectrally to fluorescein. Like fluorescein, it is also useful as a non-specific stain for backlighting conventionally stained cells on the surface of a solid sample of tissue (fluorescence backlighted staining[4]).
Wells J. (1988) A Technique for Staining the Superficial Cells of Plucked Hair Follicles and Other Solid Tissues, Stain Technology, Vol 63, No3.
Resources:
• http://www.millerandlevine.com/chapter/12/bases.html
• http://www.biologycorner.com/bio1/DNA.html
• 2006 Miller & Levine Prentice Hall Biology• 2005 Campbell & Reece Biology 7th ed