BIOLOGY NOTES BIOLOGY NOTES CHAPTER 2CHAPTER 2

“THE CHEMISTRY OF LIFE”

I. pH ScaleI. pH ScaleA. Measures how acidic or

basic a solution is.B. Scale ranges from

0 – 141. below 7 acid2. above 7 base3. at 7 neutral

C. Many chemical processes in living organisms require a certain pH level to function.

Ex: hydrochloric acid in stomach used in the process of digestion has a pH of about 2.

II. Compounds of LifeII. Compounds of LifeA. Inorganic Compounds – do not contain carbon. Come

from nonliving sources.

ex: water – a polar molecule with a +(positive) charge on one end and a – (negative) charge on the other.

B. Water is POLAR! (has a + end and a – end) Which causes it to have unique properties:

adhesion, cohesion, surface tension, capillary action

1. Cohesion-water attracting to water

2. Adhesion – water attracting to other substancescauses a meniscus in a graduated cylinder

3. Surface Tension – allows the surface of water to resist an external force

4. Capillary Action – water is able to creep up thin tubes due to adhesion

C. Organic Compounds – contain carbon and come from living things.

1. most organic molecules are polymers, which are large molecules made from small individual molecules called monomers.

D. There are 4 major organic compounds (macromolecules)

1. Carbohydrates – include sugars and starches.

Elements of carbon, hydrogen, and oxygen. (1:2:1 ratio) Source of energy.

Made of monomers called monosacharides. (simple sugars)

C6H12O6 chemical formula for the simple

sugar glucose made by plants.

2. Lipids – waxy, fatty, or oily compounds.

Store and release energy in the cell.

Many lipids are made by combining the

monomers fatty acids and glycerol.

Phospholipids – make up cell membranes.

3. Proteins – functions include growth, repair, moving substances across cell

membrane, and regulating chemical reactions. EX: hemoglobin, enzymes

Made of monomers called amino acids

4. Nucleic acids – store genetic information and involved in making proteins.

Made of units called nucleotides.

DNA and RNA are the two nucleic acids.

III. Chemical Reactions and III. Chemical Reactions and EnzymesEnzymes

A. Chemical reaction is a process that changes one set of substances into a new set of substances.

B. Enzymes – special proteins that act as a catalyst, which is a substance that speeds up a chemical reaction without being used up in the reaction.

Without enzymes, most reactions in organisms would occur too slowly to work.

1. Substrate –the substance that is being acted upon and that binds to the enzyme.

2. Active site – region on the enzyme where the substrate fits. Each enzyme only fits a certain substrate.