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1. Chapter 4
Nucleic Acids
“The Flow of Genetic
Information in the Cell”

2. Nucleic Acids
Polymers specialized for the storage,
transmission, and use of genetic
information.
DNA = deoxyribonucleic acid
RNA = ribonucleic acid
The monomeric units (building blocks
of nucleic acids) are nucleotides.

3. Nucleotides
Consist of a
pentose sugar, a
phosphate group,
and a nitrogen-
containing base.

4. Nitrogenous Bases
DNA bases: adenine (A),
cytosine (C), guanine (G),
and thymine (T)
Complementary base
pairing:
A–T(U)
C–G
Purines pair with
pyrimidines by hydrogen
bonding.
Instead of thymine, RNA
uses the base uracil (U).

5. Nucleic Acid Synthesis
The “backbone” of DNA
and RNA is a chain of
sugars and phosphate
groups, bonded by
phosphodiester linkages.

6. Nucleic Acid Synthesis
• The two strands of
DNA run in opposite
directions
(antiparallel).

7. RNA vs. DNA

8. DNA
The two strands of a DNA molecule
form a double helix. (anti-parallel)
All DNA molecules have the same
structure; diversity lies in the
sequence of base pairs.

9. RNA
Single Stranded
Less Stable then DNA
What clue does this
give us to its function
in comparison to
DNA?

10. “The Correct Flow of Genetic
Information in the Cell”
Central Dogma of Molecular Biology
The complete set of Not all the information
DNA in a living is needed at all times;
organism is called its sequences of DNA
genome. that encode specific
proteins are called
genes.