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 5membered ring
• Members include:
– Adenine (A)
– Guanine (G)
Purines
Nitrogenous Base
Functional 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 sugarphosphate 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.htm
l
• 2006 Miller & Levine Prentice Hall Biology
• 2005 Campbell & Reece Biology 7th ed