Nucleic Acids & Proteins Chapter 3 Biochemistry

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

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

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

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)

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

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

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)

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)

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

20 Amino Acids

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

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

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)

Structure Animation http://www.youtube.com/watch?v=lijQ3a8yUYQ

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.