Organic Molecules

9/11/00

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Table of Contents Biological Molecules Can Have Complicated Structures How complicated are living things? 4 Kinds of Organic Molecules Properties of organic molecules: Organic molecules are built around carbon skeletons Functional Groups chemically active side branches Organic molecules are polymers Dehydration (Condensation) Synthesis - Polymer Elongation Hydrolysis - Polymer Disassembly Structures are built of large molecules which are built of small molecules Carbohydrates Sugars are characterized by size, the kinds of functional groups and their position Another example Linear carbon chains often become cyclic Synthesis and breakdown of carbohydrate polymers Disaccharides Polysaccharides Polysaccharides held together by weak bonds are used for energy storage (e.g., starch), whereas those held together by strong bonds are used or structural purposes (e.g., cellulose) Cellulose Lipids Fatty Acids A simple lipid - triglyceride Saturated fat Unsaturated fat other lipids: Phospholipid Phospholipids function in membranes Membranes - more than lipids membrane systems can be extensive Proteins Amino acids - 20 kinds Acidic and basic amino acids Non-polar amino acids Polar amino acids Peptide bond formation A short protein - 4 amino acids four levels of protein structure Secondary Structure and Hydrogen Bonds Quartenary Structure in Hemoglobin Hemoglobin and Sickle Cell Anemia: a single amino acid substitution can make a big difference Four levels of protein structure Proteins differ in their 3D shapes 3D shapes have specific cavities on their surface these cavities allow “lock and key” fits with other molecules with which the protein interact Enzymes Control Chemical Activity Molecules are modified in pathways, in numerous small controlled steps Biochemical Pathways Catalysts Control Chemical Activity What is the significance of complicated shapes? Numerous weak bonds among complementary complex surfaces allow molecular recognition and catalysis. Nucleic Acids: RNA & DNA Nucleotides have three subunits Four kinds of DNA nucleotides RNA is composed of a single polynucleotide strand DNA is double stranded DNA can replicate Replication DNA Synthesis - Replication RNA Synthesis - Transcription DNA structure is too monotonous to serve catalytic functions,but single stranded RNA can assume complicated shapes Protein, RNA and DNA Roles How does DNA store information for RNA and protein structure? Central Dogma of Biology

Author: Donald Buckley Email: don.buckley@quinnipiac.edu Home Page: http://faculty.quinnipiac.edu/health/biology/buckley/welcome.html Download presentation source