Module 7 Intro

Module 7—The Digestive and Respiratory Systems

Lesson Summary

 

In this lesson the following questions were examined:

• What are the chemical characteristics of carbohydrates, lipids, and proteins and their corresponding enzymes?

• How are digestive enzyme functions controlled by the internal environment?

Carbohydrates, lipids, proteins, and nucleic acids are macromolecules and all have distinct characteristics. Carbohydrates can be simple sugars or polysaccarides. Their purpose is to store energy. Lipids are insoluble in water, store energy, and form the hormones of estrogen and testosterone. Lipids comprise membranes because of their insoluble nature. The bond structure of lipids causes them to be saturated or unsaturated.

 

Proteins are the most functionally diverse macromolecule. Hair, bones, muscles, nuclei, and nails all contain very different proteins. Proteins are made up of chains of amino acids. An amino group is connected to a carbon molecule, which is bonded to an acid group. There are 20 different amino acids that can bond together in different combinations to give different proteins. The physical structure of proteins determines whether they will be water soluble (enzymes) or insoluble (fingernails).

 

Enzymes are designed to bind to substrate molecules (which are any macromolecules). Each enzyme has a specifically shaped binding, or activation, site. Enzymes exist to speed up reactions in building or breaking down molecules. If people’s bodies lacked enzymes, they could not quickly access the stored energy of glucose from a polysaccaride chain. As a result, they could die.

 

Enzymes also require optimal conditions to work. As seen in the virtual lab, there was an optimal pH range at which enzymes were the most productive. In your textbook, “Figure 6.11” on page 215 showed that the optimal temperature for enzyme action was around 37oC or body temperature. If internal conditions become too basic or acidic or too hot or cold, enzyme function can be inhibited. Enzyme function can also be controlled by negative feedback loops.

 

Lesson Glossary

 

anabolic: the metabolic process that builds larger molecules from smaller molecules

 

catabolic: the metabolic process in which materials are broken down

 

catalyze: to increase the rate of reaction

 

dehydration synthesis: an enzyme-controlled composition reaction in which compounds are formed by the removal of water

 

feedback inhibition: the process by which the accumulated end product of a biochemical pathway stops the synthesis of that product

 

hydrolysis: the decomposition of a compound in a reaction by using water

 

substrate molecule: a molecule that an enzyme interacts with chemically

 

For example, the enzyme sucrase only binds to the substrate molecule of sucrose.

 

Biology 20 © 2008 Alberta Education