INTRODUCTION TO BIOLOGY – PART 2

THE MOLECULES OF LIFE (PP. 44-47)

I. Importance of Carbon Test: 9/13

Although a cell is composed of 70 - 95% water, most of the rest is carbon – based compounds.

A. Structure of carbon

1. Atom # 6: 6 protons & 6 electrons: 2 in the first shell & 4 in

the second.

2. Has 4 valence electrons – so it can make

four covalent bonds

3. Usually bonds with: hydrogen, oxygen,

phosphorus, sulfur, and nitrogen

4. Can also bond w/other carbon atoms

5. Compounds with carbon-carbon bonds

called organic

B. Macromolecules – macro = large, so these are very large molecules

1. Polymers a. Poly = many b. These are large

molecules made up of similar or identical building blocks

2. Monomers a. Mono = one b. Are the building

blocks or subunit of polymers

3. Classes of macromolecules are also called

Biomolecules

a. Carbohydrates b. Lipids c. Nucleic acids d. Proteins

II. Carbohydrates

A. Elements: C, H, O, always a 1:2:1 ratio of H atoms to

O atoms (2H:1O)

B. Monomer: monosaccharide

C. Function: immediate and stored energy; building

material

D. Where found in body: bloodstream, liver; cell walls

of plants

E. Food source:

sugar and starches

F. Examples:

1. Monosaccharides: (simple sugar)

a. Glucose (C6H12O6) – preferred energy

molecule for most organisms;

including humans

b. Galactose – one component of milk

c. Fructose – found in some fruits

2. Disaccharides: 2 monosaccharides

bonded together

a. Sucrose – table sugar: glucose +

fructose

b. Lactose – milk sugar: glucose +

galactose

3. Polysaccharides: more than 2 monosaccharides

bonded together; two groups

a. Storage Polysaccharides: long polymers of glucose;

broken down for needed energy Glycogen

Storage of glucose in animals

Stored in livers and muscles Starch

Storage of glucose in plants

Humans can break down glucose for

energy

b. Structural Polysaccharides: used for building materials Cellulose

Component of plant cell walls

Humans unable to break down

Important source of fiber in our food

Chitin

Component of fungi cell walls

Component of insect and other arthropod exoskeleton

III. Lipids: (waxy, fatty or oily) compounds A. Elements: C, H, O, many more H than in carbs. B. Monomer: glycerol & fatty acids C. Function: energy storage; insulation; cushioning D. Where found in body: cell membrane, innermost

layer of skin, surrounding some organs E. Food Source: olive oil, corn oil, sesame oil, peanut oil,

canola oil F. Example:

1. Fats and Oils a. All have 3 fatty acids b. Fats are solid at room temperature c. Oils are liquid at room temperature d. Saturated fats – no carbon – carbon double

bond e. Unsaturated fats – at least one carbon –

carbon double bond

f. Saturated fats linked to heart disease

2. Phospholipids

a. Unique lipid

b. Found in every

living cell membrane

3. Steroids

a. Used for hormone

production

b. Used for animal

cell structure

c. Example:

cholesterol,

testosterone

IV. Proteins

A. Elements: C, H, O, P, N

B. Monomer: amino acids, only 20 different amino acids

combine in different numbers, patterns & arrangement

C. Function: support, structure, protection, movement, metabolism

D. Where found in body: muscle,

hair, skin, enzyme

E. Food Source: meat, beans, eggs,

dairy products

F. Examples:

1. Enzymes

a. Biological catalyst

b. Trigger chemical reactions

c. Could not maintain

homeostasis without them

V. Nucleic Acids A. Elements: C, H, O, P B. Monomer: nucleotides C. Function: genetic instructions &

usable energy D. Where found in body: nucleus of

cells E. Food Source: none F. Examples:

1. DNA a. Deoxyribonucleic acid b. Contains the genetic

instructions for the cell2. RNA a. Ribonucleic acid b. Carries out the instructions in DNA3. ATP a. Adenosine triphosphate b. Produces useable energy for the cell