Nucleic Acids
DNA & RNA
Nucleic Acid Characteristics
• Contain C, H, N , O, P (no sulfur)
• made of monomers called nucleotides (made
of a phosphate group, nitrogen base, and a 5carbon sugar)
• Monomers link by the process of dehydration
synthesis (remove water) to form the polymer
and break by the process of hydrolysis (add
water)
DNA
• DNA (Deoxyribonucleic Acid)
• Purpose →codes and stores all genetic
material of cell regarding replication and the
order in which amino acids should be joined
to form a protein.
• made of monomers called nucleotides (made
of a phosphate group, nitrogen base, and a 5carbon sugar (deoxyribose) )
• shape of a spiral helix or twisted ladder
(double helix)
Nucleotide Structure
Nitrogen base
5-carbon sugar
Purines vs. Pyrimidines
• The nitrogen bases can be distinguished by
separating them into 2 categories (purines and
pyrimidines)
• Purines- contain a double ring
•
ex. Adenine and Guanine
• Pyrimidines- contain a single ring
ex. Cytosine and Thymine
Look!! They contain the letter “Y”
just like the word pyrimidine
Purines vs. Pyrimidines
Purine
Pyrimidine
Complementary Base Pairing
• A purine (adenine or guanine) will always
bond with a pyrimidine (cytosine or thymine)
• So, adenine always pairs with thymine and
cytosine always pairs with guanine
• A-T
• C-G
Complementary Base Pairing
A purine & pyrimidine will always link by
weak Hydrogen bonds but in a specific
way…
*A-T contains 2 hydrogen bonds
*C-G contains 3 hydrogen bonds
Why is DNA said to be “anti-parallel”?
• The 2 sides of the ladder of DNA run antiparallel because they are organized from 5’
(prime) to 3’ (prime).
• If one strand runs from 5’ to 3’ then the
opposite side runs 3’ to 5’.
• The phosphate group always links to the 5’
end.
DNA nucleotides linked by dehydration synthesis
along the sides of the ladder (sugar to phosphate)
DNA Double Helix
RNA
• RNA (Ribonucleic Acid)-single stranded; types
are mRNA, tRNA, & rRNA
• involved with forming proteins
• made of monomers called nucleotides (made
of a phosphate group, nitrogen base, and a 5carbon sugar (ribose) )
• Contain a nitrogen base called Uracil and
DOES NOT CONTAIN Thymine:
• So, in RNA…
• A-U
• C-G
Deoxyribose vs. Ribose sugars
The nitrogen bases of DNA and RNA
RNA vs. DNA structure