*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 it’s 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.