Biochemistry of Digestion BIG IDEAS Biochemistry of Digestion

Element vs. Compound Pure substance All elements are organized on the Periodic Table Represented by a Chemical Symbol Cl – Chlorine I – Iodine O2 – oxygen gas 2 or more different elements chemically combined Represented by a Chemical Formula NaCl – table salt H2O – water CO2 – carbon dioxide

Organic vs. Inorganic RARELY contains the element carbon (C) Examples: NaCl H2O Never living Contains the element carbon (C) Often includes other elements such as hydrogen (H), oxygen (O), phosphorus (P), nitrogen (N), sulfur (S) Examples: C6H12O6 (glucose) CH4 (methane gas) C3H6O3 (lactic acid) Is or once living Carbohydrates - energy: bread, fruit, vegetables Proteins - structure: meat Lipids – energy storage, cell membrane: fats, oils Nucleic Acid: DNA

So why should I care about organic compounds? Organic compounds are broken apart and recycled by the body to function and grow

Physical vs. Chemical Digestion SAME substance Change in appearance or location AKA Mechanical digestion Examples: Crushing, grinding, tearing food with teeth Swallowing food Peristalsis: pushing or squeezing of food Bile breaks fat into tiny fat droplets NEW substance Change in properties Examples: Enzymes, saliva, and stomach acid help to break bond of compounds to form simpler substances Saliva in mouth breaking down carbohydrates Pepsin breaks down protein in the stomach Energy transformation and absorption by the villi in the small intestines

LARGE MOLECULES  small molecules Carbohydrates are large molecules Complex carbohydrates are also called starches Chemical digestion or carbohydrates begins in the mouth Sugar is a smaller molecule

LARGE MOLECULES  small molecules Large molecules (carbohydrates)are like a long train of multiple box cars (smaller molecules, sugar) linked together Digestion breaks the bonds between compounds

Energy Transformations in organisms Radiant energy  Chemical energy (photosynthesis) Food people eat has stored chemical energy Chemical energy  Thermal energy (digestion) Chemical energy  Heat energy (digestion) Chemical energy  Mechanical energy (moving) Mechanical energy  Heat/Thermal energy

Law of Conservation of … ENERGY cannot be created or destroyed, only rearranged Organisms must eat to obtain energy MATTER cannot be created or destroyed, only rearranged Organisms recycle or chemically change food (matter) for their needs