Enzymes

O Protein O Only act on certain substances called substrates

Functions O Increases the rate at which molecules in the body are built or broken down O They are catalysts; They speed up reactions

O Even though enzymes speed up reactions, they are NOT changed during the reaction O So enzymes are reusable

Functions O Play roles in other parts of the body O Myosin: important in muscle contraction

Enzymes at Work 1. An enzyme and a substrate are in the same area. 2. The enzyme grabs on to the substrate at a special area called the active site.

Enzymes at Work 3. A process called catalysis happens. Catalysis is when the substrate is changed. 4. The enzyme lets go, and returns to normal, ready to work on another molecule of substrate. The substrate is no longer the same. It is now called the product

Enzyme Video O hill.com/sites/ /student_view0 /chapter2/animation__how_enzymes_work. html hill.com/sites/ /student_view0 /chapter2/animation__how_enzymes_work. html

Factors that Affect Enzymes O Temperature- as temperature increases, enzyme activity increases O However extremely high temperatures cause enzyme activity to stop

Factors that affect Enzymes O pH-extremely high or low causes enzymes to stop working

Factors that affect Enzymes O Inhibition O Competitive: enzyme is inhibited by an inactive substrate, or competitor, so called because it competes with the real substrate for the active site O Feedback: an inhibitor binds to a different site of an enzyme, deactivating it

Inhibitors Feedback

Groups O The two main groups are: O Metabolic: all chemical reactions that take place in a living cell O Digestive: related to breaking down food for absorption

Digestive Enzymes O Lipase: breaks down fat O Protease: breaks down protein O Cellulase: breaks down fiber; herbivores have O Amylase: starts breaking down starches; starts chemical part of digestion

Digestive Enzymes O Lactase: breaks down dairy O Sucrase: breaks down sugar O Maltase: breaks down grain O All of these enzymes are secreted by mucosal cells that line your small intestine

Importance O Without enzymes our body would not function properly; there are several disorders related to lack of or improper enzymes

Importance-example O Disease called Phenylketonuria O Born with a mutation that leads to a mutation in the enzyme needed to break down the amino acid phenylalanine O If left untreated this could lead to mental retardation