Download Nucleic Acids Powerpoint

Nucleic Acids
• Nucleic acids are large biomolecules (polymers) –
essential for all known forms of life
• Include DNA and RNA
• Made from long strands of nucleotides
(monomers)
– A nucleotide contains a 5-carbon sugar, a phosphate
group, and a nitrogenous base
– The nitrogeneous bases are connected by the sugar
and the phosphate group (rungs of the ladder)
DNA vs. RNA
• If the sugar molecule is Deoxyribose, the
nucleic acid is DNA
• If the sugar molecule is Ribose, the nucleic
acid is RNA
• RNA – mRNA, tRNA, rRNA
Purines vs Pyrimidines
Purines have a 2-Carbon nitrogen ring base
Adenine
Guanine
Pyrimidines have a 1-carbon nitrogen ring base
Thymine
Cytosine
Nitrogeneous Bases
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Adenine
Thymine (DNA only)
Cytosine
Guanine
Uracil (RNA only)
Chargaff’s Rule
• Chargaff's rules states that DNA from any cell
of all organisms should have a 1:1 ratio (base
Pair Rule) of pyrimidine and purine bases and,
more specifically, that the amount of guanine
is equal to cytosine and the amount of
adenine is equal to thymine.
Base Pairing
• The rules of base pairing (or nucleotide
pairing) are: A with T: the purine adenine (A)
always pairs with the pyrimidine thymine (T)
• C with G: the pyrimidine cytosine (C) always
pairs with the purine guanine (G)
• The bases are paired with hydrogen bonds – 2
between A and T and 3 between C and G