1. Reminder-we recognize four classes of large biomolecules
Carbohydrates/polysaccharides
Lipids
Proteins/polypeptides
Nucleic acids/polynucleotides-information storage, hard drives for living systems

2. Two Types Nucleic Acid DNA and RNA
Function:
Information
Storage
And
Control
DNA 1
Synthesis of mRNA
Two Types Nucleic Acid DNA and RNA
mRNA
NUCLEUS
CYTOPLASM
mRNA 2
Movement of mRNA into cytoplasm
Ribosome
Figure 5.25 DNA → RNA → protein. 3
Synthesis of protein
Amino acids
Polypeptide

3. Components of nucleic acids
Nucleic acids are polymers
Nucleotides are the monomers
Each nucleotide consists of a base, a sugar and a phosphate
But the base plus the sugar without the phosphate is called a nucleoside
Bases are purines (Pu) or pyrimidines (Pyr)
Sugars are either ribose or 2-deoxyribose

4. Phosphodiester Bond Links nucleotides together
Sugar and phosphate involved
This example is a 3’-5’ bond
Gives two distinct ends

5. Figure 5.26 Components of nucleic acids.
Sugar-phosphate backbone
5 end
Nitrogenous bases
Pyrimidines
5C
3C
Nucleoside
Nitrogenous base
Cytosine (C)
Thymine (T, in DNA)
Uracil (U, in RNA)
Purines
5C
1C
Phosphate group
3C
5C
Sugar (pentose)
Adenine (A)
Guanine (G)
3C
(b) Nucleotide
Figure 5.26 Components of nucleic acids.
Sugars
3 end
(a) Polynucleotide, or nucleic acid
Deoxyribose (in DNA)
Ribose (in RNA)
(c) Nucleoside components

6. RNA Structure Individual chains in cells Aka “single-stranded”: ssRNA
Chains generally from nucleotides
Distributed throughout the cell

7. RNA molecules fold up on themselves
Secondary structure refers to folding pattern
Confers unique shape
Primary structure is the 5’ to 3’ sequence of bases 5’ 3’

8. DNA structure-different from RNA
Two molecules interact to form double strand

9. Important features of the double helix
Antiparallel strands
Bases on the inside
Chain held together by hydrogen bonds
Watson-Crick base pairs
AT and GC are the Watson-Crick
base pairs
Complementary

10. DNA Structure Almost always double helix Aka “double-stranded”: dsDNA
Not as flexible as RNA
Chains can be very long 120,000,000 nucleotides
Not Distributed throughout the cell
Sequestered
DNA Structure

11. Individual nucleotides
Mononucleotides
Have different functions
Energy carriers
Help with enzyme reactions as cofactors
Signalling