*Biological Macromolecules *Enzymes *Digestive System: Organ Structure and Function Large molecules that are necessary for life Most biological macromolecules are polymers. Polymers are large molecules that are formed from chains of smaller molecules (monomers) linked together. Monomers can be bonded together in many different combinations to produce complex biological polymers. Carbohydrates provide energy to all living organisms. Particularly through glucose, which is the simple sugar (monosaccharide) that autotrophs create by photosynthesis. Monomers are called monosaccharides (simple sugars) E.g. Glucose, fructose Two monomers linked = disaccharides Polymers are called polysaccharides (complex sugars) E.g. Cellulose, Glycogen, Starch Glucose is broken down during a process called cellular respiration, producing useable energy in the form of ATP (adenosine triphosphate). ATP is the energy currency of the cell. NOT polymers because they are not built from monomers. Lipids are predominantly nonpolar/hydrophobic No areas of charge caused by uneven sharing of electrons. Lipids have many different types and functions. 1.Fats/Oils = trigylcerides (3 fatty acids chains) Function as long term storage of fatty acids; sources of energy. 2.Phospholipids (2 fatty acid tails and a phosphate head) Major component of plasma (cell) membranes. Amphipathic. 3.Steroids (generally have a ring structure, sometimes with tail) Function in reproduction, absorption, metabolism, and brain activity Proteins are involved in every cell, tissue, organ, and organ system in all living things. Cell structure, chemical signaling, and transport of materials Synthesizing and repairing DNA Catalyzing chemical reactions (enzymes) Monomers are called amino acids Polymers are called polypeptides The shape (form) of a protein determines its function Slight changes to the shape can cause it to be dysfunctional The two main types of Nucleic Acids are DNA and RNA. DNA is the genetic material found in all living organisms. RNA is mostly involved in protein synthesis. Monomers are called nucleotides: Nitrogenous base (A, T, C, or G) 5 carbon sugar (ribose) Phosphate group The sequence of bases determines genetic traits of organism. Macromolecular biological catalysts Enzymes are biological molecules; usually proteins Enzymes significantly speed up the rate of all chemical reactions that take place within living organisms. Reactions occur a million times faster in presence of an enzyme! Each enzyme has a specific shape that matches a specific set of reactants, called substrates (like a lock and key) The substrates bind to the enzyme on a region called the active site. Digestive Enzymes These enzymes help break large molecules into smaller pieces that are more easily absorbed by the body. Other enzymes help bind two molecules together to produce a new molecule (biosynthesis). Enzymes catalyze (speed up) chemical reactions by lowering the activation energy. Activation energy= energy level required for reaction to proceed. Enzymes are not used up in the reaction; they are unchanged and free to bind with more substrate. Digesting food as sources of energy Mouth (teeth and tongue) Esophagus Stomach Small intestine Large Intestine Rectum & Anus Salivary Glands Liver & Gall Bladder Pancreas Mouth: The entrance (first opening) to the digestive tract. Teeth: calcified structures in the mouth that aid in mechanical digestion by tearing, ripping, and chewing food. Tongue: muscular organ in the mouth, used for swallowing Esophagus: The muscular tube that pushes food from the mouth to the stomach by peristalsis. Peristalsis- wave-like contraction of smooth muscle that moves food through organs of digestive tract. Stomach: Muscular organ that is a major site of digestion. Mechanical digestion by the contractions of muscular walls lined with rugae which grinds and churns food into chyme. Chemical digestion by the action of HCl (hydrochloric acid) and protease enzymes that breakdown protein polymers into amino acid monomers. Sphincters: cylindrical muscles that can constrict to open/close the tract. Small Intestine: The major site of chemical digestion and absorption of nutrients into the bloodstream. Maximizing surface area is key!!! Large Intestine (Colon): Site where water is reabsorbed into the body. Rectum & Anus: Where fecal waste is expelled from the digestive tract. Salivary Glands: Produce salivary enzymes in the mouth. Epiglottis: Cartilage that blocks the trachea when you swallow. Liver: Produces bile, a fat emulsifier. Gall Bladder: Stores bile. Pancreas: Produces and secretes most digestive enzymes.