1. Nucleic Acids & Proteins
Chapter 3
Biochemistry

2. What you need to know!
How to recognize nucleic acids and proteins by their structural formulas
The cellular functions of nucleic acids and proteins
The 4 levels of protein structure
The denaturing impact that heat, pH, and other variables can have on protein structure

3. Nucleic Acids Consists of C, H, N, O, P
3 types: DNA – Deoxyribonucleic Acid
RNA – Ribonucleic Acid
ATP – Adenosine Triphosphate
Different functions
DNA: hereditary information
RNA: production of proteins
ATP: energy molecule
Monomer = Nucleotide

4. Nucleotide Three parts: Phosphate group
Sugar (Deoxyribose in DNA, Ribose in RNA & ATP)
Nitrogenous base: (Adenine, Guanine, Cytosine, Thymine, Uracil)

5. Nitrogenous Bases Come in 2 groups: Purines fit with Pyrimidines
Pyrimidines (single ring):
Thymine (T), Cytosine (C), Uracil (U)
Purines (double ring):
Adenine (A),
Guanine (G)
Purines fit with Pyrimidines
A pairs with T (2 Hydrogen Bonds)
G pairs with C (3 Hydrogen Bonds)
RNA replaces all T’s with Uracil (U)

6. Polynucleotides DNA double helix RNA single helix
Nucleotide monomers can form Phosphodiester bonds
Phosphate-Sugar backbone of DNA and RNA
DNA double helix
RNA single helix

7. ATP Single nucleotide with 3 Phosphate groups (P) instead of 1
It can lose P to release energy
ATP  ADP + Energy
ADP  AMP + Energy

8. Proteins Contain C, H, O, N, S
Millions of functions some of which include:
Enzymatic proteins regulate chemical Rxs
Structural proteins support (ex. Muscles, cartilage)
Storage proteins store amino acids
Transport proteins move substances
Hormonal proteins coordinate multicellular organisms
Receptor proteins respond to environmental stimuli
Contractile and motor proteins allow for movement
Defensive proteins protect against disease (antibodies)

9. Proteins Monomers: 20 different amino acids (AA) Polymer = polypeptide
Small protein = ~100 AA
Large protein = 1000’s of AA (Titin)
Proteins are sensitive to
temperature pH
Imbalanced solutions
all cause denaturizing (loss of accurate 3D structure)

10. Amino Acids
Zwitterions: molecules that have both an amino group (NH3) and carboxyl group (COO or COOH)
20 different AA
All have the same central carbon, amino group, and carboxyl group
Different functional groups (R – side chain)
R can be:
Polar, non-polar, charged, uncharged, hydrophilic, hydrophobic

11. 20 Amino Acids

12. Polypeptides Connecting multiple AAs
Condensation Reaction forms peptide bond
Repetitive peptide backbone
(NCC-NCC-NCC-NCC)

13. Protein structure (4 stages)
Structure and function determined by # and sequence of AA
Primary structure (AA sequence)
Secondary structure (Hydrogen to Oxygen)
Primary polypeptide coil and fold
Due to hydrogen bonds between adjacent peptide bonds O   H (NOT r-side chains)
Special: alpha-helix, beta-pleated sheet

14. Protein Structure Tertiary Structure (R-side interactions)
Further coiling of secondary polypeptide due to R interactions
Hydrophobic vs. Hydrophilic
Polar Molecules
Formation of disulfide-bridge S-S
Hydrogen bonds
Van der Waals
Quaternary structure
Some proteins will associate with other tertiary proteins to form quaternary proteins
Several tertiary polypeptides connect together; usually held together by R-side chain interactions (hemoglobin)

15. Structure Animation

16. Mutations  Abnormal Proteins
Gene mutations can lead to the exchange of one or more AAs. This sometimes leads to a non-functional quaternary structure (Structure  Function)
Example: Sicle-Cell Anemia, 1 AA is exchanged in the hemoglobin primary structure, resulting in abnormal folding.