Enzymes

Metabolism The sum of all the chemical reactions in your body What does it mean if you have a high metabolism? Low? Does your metabolism change? Why?

Chemical Reactions Review: A + B CAnabolic Reactants Product OR A B + CCatabolic Reactant Products

Types of Reaction Anabolic reactions: add things together e.g. 2 glucose to maltose Catabolic reactions: cut things apart e.g. maltose split into 2 glucose

Reversible Reactions

Metabolic Pathways A B C D E A series of reactions in which the product of one reaction becomes the reactant of the next.

Metabolic Pathways Very complex, lots of reactions

Thyroxin protein hormone produced by the thyroid gland thyroid gland accumulates iodine to produce it Increases cell metabolism by binding to receptor sites, increases oxygen use

Cell Metabolism

Metabolism Hyperthyroidism: too much thyroxin. Symptoms? Hypothyroidism: not enough thyroxin. Symptoms?

Energy and Reactions Exothermic reactions: reactions that release more energy than they require Endothermic reactions: reactions that require more energy than they release Energy can be in the form of heat or ATP.

Energy and Reactions Activation energy: the energy required for a chemical reaction to take place.

Energy Think of all the reactions in metabolism… Where can we get all that energy?

Enzymes Biological catalysts: speed up reactions Lower activation energy

Structure and Function Enzymes are PROTEINS Need to remember protein structure

Enzymes Proteins with tertiary or quaternary structure Have a unique 3-D shape

Chemical Reactions Enzyme reactions A + B C Substrates Product OR A B + C Substrate Products

Enzymes SUBSTRATESPRODUCTS Enzymes bind to substrate(s) at active site Enzyme-Substrate Complex (E-S Complex)

Lock and Key Unique fit – one substrate per enzyme

Induced fit hypothesis As the E-S complex forms, stress is put on chemical bonds Can be anabolic or catabolic or both for some enzymes

Cofactors and Coenzymes Co-factors: inorganic. Stabilize enzymes. E.g. Zn 2+, Mg 2+ Co-enzymes: organic. Assist in enzyme reactions. e.g. NAD brings H + ions

Factors that affect enzymes 1)Temperature 2)pH 3)Heavy metal ions 4)Inhibitors 5)Substrate & enzyme concentration

Temperature Enzymes function at an optimum temperature High temperatures denature enzymes Low temperature reduces particle energy

Denatured Protein H-bonds that hold tertiary shape break Loses specific 3-D shape, not reversible

pH Enzymes function at an optimum pH Conditions outside of that pH denature enzymes

Heavy Metal Ions Have strong positive charges Disrupt the electron configuration of enzymes Too many ions can denature enzymes

Inhibitors Competitive: bind at active site and prevent substrate from binding Non-competitive: bind at another site and alter enzyme shape preventing substrate from binding

Concentration Increasing substrate concentration increases reaction rate to a point Same for enzymes

Vitamins & Minerals Why do you need them?

Digestive Enzymes Enzymes found in your digestive system that act in catabolic reactions Turn macromolecules (starch, protein, lipids) into monomers (glucose, amino acids, fatty acids and glycerol). Optimum temperature = 37 o C Optimum pH = varies

Mouth salivary glands produce enzyme salivary amylase pH

Stomach gastric cells produce gastric juice contains inactive pepsinogen, HCl HCl kills bacteria, activates pepsinogen by turning it into enzyme pepsin pH ~2.5

Small Intestine pancreas produces pancreatic juice contains bicarbonate ions, and the enzymes: trypsin, pancreatic amylase, nuclease, lipase bicarbonate ions (HCO3-) lower pH by “over- neutralizing” the acid pH ~8.4

Small Intestine duodenum produces intestinal juice contains enzymes peptidases (carboxypeptidase, aminopeptidase, dipeptidase) nucleosidases and phospatases, disaccharidases (maltase, lactase, sucrase )

Carbohydrates Mouth starch  maltose salivary amylase Small intestine starch  maltose pancreatic amylase disaccharides  monosaccharides disaccharidases

Proteins Stomach proteins  polypeptides pepsin Small intestine polypeptides  peptides trypsin peptides  amino acids peptidases

Nucleic Acids Small Intestine nucleic acids  nucleotides nucleases nucleotides  sugar, phosphate, bases nucleosidases, phosphatases

Lipids Small Intestine lipids  fatty acids and glycerol lipases