320 likes | 626 Views
Building Blocks of Life . An Introduction. Carbon is unparalleled in its ability to form large, complex, and diverse molecules Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds. Carbon—The Backbone of Biological Molecules.
E N D
Building Blocks of Life An Introduction
Carbon is unparalleled in its ability to form large, complex, and diverse molecules • Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds Carbon—The Backbone of Biological Molecules
Electron configuration determines the kinds and number of bonds an atom will form with other atoms • With four valence electrons, carbon can form four covalent bonds with a variety of atoms • makes large, complex molecules possible Carbon atoms can form diverse molecules by bonding to four other atoms
The valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen) are the “building code” that governs the architecture of living molecules
Within cells, small organic molecules are joined together to form larger molecules • Macromolecules are large molecules composed of thousands of covalently connected atoms Macromolecules
Monomers build polymers linked together by covalent bonds • Three of the four classes of life’s organic molecules are polymers: • Carbohydrates • Proteins • Nucleic acids • Lipids polymers built from monomers
Monomers form larger molecules by condensation reactions called dehydration reactions • Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction The Synthesis and Breakdown of Polymers
Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Longer polymer Dehydration reaction in the synthesis of a polymer Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer
Sugars and sugar polymers • Monosaccharides • Simple sugars • glucose Carbonyl group Hydroxyl group Carbohydrates
Disaccharides • 2 or more monosaccharides joined by glycosidic linkage, covalent bond by dehydration reaction • Glucose + fructose sucrose Carbohydrates
Storage • Plant starch • Stored energy can be broken down by hydrolysis into glucose • Animal polysaccharide • Glycogen • Stored in liver and muscles • Used for short term energy Carbohydrates
Structure • Cellulose: cell walls • Requires an enzyme for animals to break it down • Chitin: exoskeleton of arthropods and fungi Carbohydrates
Fats, oils, waxes • Mix poorly with water • Fats • Large molecules of glycerol and fatty acid chains connected by dehydration Lipids
Cell Membranes • Phospholipid bi-layer Lipids
Polymer of amino acids called polypeptides • Functions • Enzymes • Storage of amino acids • Hormones • Motor • Defense • Transport • Receptors for chemical stimuli • structure Proteins
Amino acids • 20 amino acids from 1000’s of proteins • Side chains “R” determines the properties • Hydrophillic:polar • Hydrophobic: non polar • Hydrophillic: electric charge Proteins
Structure • 1° • Linear chain Proteins
2° • Alpha helix: hair • β pleated sheets: spider web • Held together by hydrogen bonds between amino groups Proteins
3° • Interactions between side chains “R” • Hydrogen bonds • Ionic bonds • Disulfide bonds • Van der Waals Proteins
4° • Aggregation of polypeptide subunits • Collagen • hemoglobin Proteins
Denaturation • Weak chemical bonds and interactions can be destroyed • Heat • pH Proteins
Polymer of nucleotides • DNA and RNA Nucleic Acids