Nucleic Acids and Biological Macromolecules Study Guide PDF

Nucleic Acids and Biological Macromolecules Study Guide 1. Nucleic Acids Structure and Components Nucleic acids encode biological information in sequences of nucleotide monomers Each nucleotide has three structural components: 1. Five-carbon sugar (deoxyribose or ribose) 2. Pho...

Nucleic Acids and Biological Macromolecules Study Guide 1. Nucleic Acids Structure and Components Nucleic acids encode biological information in sequences of nucleotide monomers Each nucleotide has three structural components: 1. Five-carbon sugar (deoxyribose or ribose) 2. Phosphate group 3. Nitrogenous base (adenine, thymine, guanine, cytosine, or uracil) DNA and RNA have different structures and functions DNA vs RNA Structural differences: 1. DNA contains deoxyribose; RNA contains ribose 2. DNA uses thymine; RNA uses uracil 3. DNA is usually double-stranded; RNA is usually single-stranded 4. DNA strands are antiparallel Both DNA and RNA have a 5’ to 3’ orientation Base Pairing Adenine pairs with thymine (DNA) or uracil (RNA) Cytosine pairs with guanine In DNA, base pairs are held together by hydrogen bonds (A-T: 2 bonds, C-G: 3 bonds) Directionality and Synthesis Nucleic acids have 5’ and 3’ ends During synthesis, nucleotides are added to the 3’ end of the growing strand 2. Proteins Amino Acids Building blocks of proteins Have an amino (NH2) terminus and a carboxyl (COOH) terminus 20 different amino acids, differentiated by their R groups (side chains) R groups can be hydrophobic, hydrophilic, or ionic Protein Structure 1. Primary structure: Sequence of amino acids 1  2. Secondary structure: Local folding (alpha-helices and beta-pleated sheets) 3. Tertiary structure: Overall 3D shape due to R group interactions 4. Quaternary structure: Interactions between multiple polypeptide units Protein Synthesis Amino acids are joined by dehydration synthesis, forming peptide bonds Synthesis occurs from the amino to the carboxyl terminus Protein Denaturation Loss of native conformation due to changes in pH, temperature, or other factors Denatured proteins are biologically inactive 3. Carbohydrates Types and Functions Include simple sugars (monosaccharides) and polymers (polysaccharides) Functions: Fuel, building material, storage, structure Structure Monosaccharides: Basic units (e.g., glucose, fructose) Disaccharides: Two monosaccharides joined (e.g., sucrose) Polysaccharides: Many monosaccharides joined (e.g., starch, cellulose, glycogen) Synthesis and Breakdown Joined by dehydration synthesis (condensation reaction) Broken down by hydrolysis 4. Lipids Characteristics Do not form polymers Hydrophobic due to hydrocarbon components Main types: Fats, phospholipids, steroids Fats (Triglycerides) Composed of glycerol and three fatty acids Saturated fats: No double bonds, solid at room temperature Unsaturated fats: Have double bonds, liquid at room temperature 2 Phospholipids Have polar (hydrophilic) heads and nonpolar (hydrophobic) tails Form bilayers in cell membranes Steroids Four fused carbon rings Examples: Cholesterol, sex hormones 5. Elements of Life Carbon Forms the backbone of biological molecules Can form four covalent bonds, allowing for diverse molecule formation Other Important Elements Nitrogen: Used in proteins and nucleic acids Phosphorus: Used in nucleic acids and some lipids 6. Water and Its Properties Structure Composed of two hydrogen atoms and one oxygen atom Polar molecule due to unequal electron sharing Hydrogen Bonding Occurs between water molecules Responsible for many of water’s unique properties Important Properties 1. Cohesion: Attraction between water molecules 2. Adhesion: Attraction between water and other substances 3. Surface tension: Resistance of water’s surface to rupture 4. High specific heat: Ability to absorb or release heat with minimal temper- ature change 5. Lower density as a solid: Ice floats on liquid water 6. Universal solvent: Can dissolve many polar and ionic substances Hydrophilic vs Hydrophobic Hydrophilic: Has an affinity for water Hydrophobic: Does not have an affinity for water 3 7. Synthesis and Breakdown of Polymers Dehydration Synthesis (Condensation Reaction) Joins monomers to form polymers Removes a water molecule in the process Hydrolysis Breaks down polymers into monomers Adds a water molecule in the process 4