The Chemistry of Life

Chapter 2

Dr. Donna HowellBiology

Blacksburg High School

The Atom

•Everything in the universe is made of atoms.

•Three subatomic particles make up atoms:

– Protons (+)

– Neutrons (o)

– Electrons (-)

•Example: gold (Au), silver

(Ag), neon (Ne), etc.

Elements

•Atoms, or elements, can combine to form chemical compounds.•Example: water is made of two types of atoms: hydrogen (H) and oxygen (O).•The chemical formula for water is H2O.

Chemical Reactions

•There are many chemical reactions that occur in the body. •These chemical reactions involve changes in the chemical bonds that join atoms in compounds.•Ex:

– CO2 + H20 - H2CO3

– (carbon dioxide combines with water to

form carbonic acid, which is then carried to

the lungs.)

Chemical Reactions

•These chemical reactions can either release energy from the bonds, which happens spontaneously, or they require energy to proceed.•The energy required by some chemical reactions is called the activation energy.

Chemical Reactions

•Many chemical reactions in our bodies happen too slow to be of use to our bodies. •Some enzymes, or catalysts, in our bodies, speed up these reactions by lowering the activation energy.

Enzyme/Substrate Complex

•Each enzyme is specific for a substrate (what the enzyme acts on). •Example: sucrase is an enzyme that works only on sucrose, a sugar.•Fits like a lock and key model.

Enzyme/Substrate Complex

• Enzymes are affected by:– Temperature– pH

What is an organic compound?

An organic compound is a compound that contains the element carbon.– 90% of all

compounds in the world are organic

– Our bodies are made of organic compounds

Biological CompoundsThere are 4 major classes of organic compounds that are called “biological compounds” because they are found in all living things:•Proteins•Nucleic acids•Carbohydrates•Lipids

Monomer Polymer

ProteinsDefinition: large organic polymers formed from monomers of amino acids.Examples: used in the body to make up muscles, tendons, enzymes, hair, fingernails.Made of: carbon, hydrogen, oxygen, nitrogenFunction: form structure of our bodies

Nucleic AcidsDefinition: organic polymers made of monomers called nucleotidesExamples: DNA and RNAMade of: one nucleotide consists of a sugar, a phosphate group, and a nitrogen baseFunction: this is the hereditary information in each of our cells

CarbohydratesDefinition: the simple and complex sugars in our bodiesExamples: glucose, starchesMade of: carbon:hydrogen:oxygen in a 1:2:1 ratioFunction: serve as our body’s main short term energy source

Lipids Definition: commonly called fatsExamples: fat, butter, oils, cholesterolMade of: carbon, hydrogen, oxygen in different proportionsFunction: serve as our body’s main energy storage molecule

LipidsThere are 3 main classes

of lipids:

1. Fats – lipids made by animals. Usually are solid at room temperature, and are mostly saturated.

2. Oils – lipids made by plants. Usually liquid at room temperature, and are mostly unsaturated.

3. Cholesterol – lipid produced by animals for use in cell production.

The End!