THE CHEMICALS OF LIFE

Biomolecules:StructureFunction

Four major types of biomolecules:

Most of the molecules in your body are one of four things:- carbohydrates- lipids- proteins- nucleic acids

a

d

b

c

Carbohydrates

General formula is (CH2O)n Classified as Simple or Complex

Simple = one carbohydrate unit (glucose) = monosaccharide

Complex = many carbohydrate units (starch) = polysaccharide

Provide major source of easilyaccessible energy

Water soluble

Carbohydrate Examples Glucose is the monosaccharide most

readily used by cells, and the only source of energy for the brain

Starch is a polysaccharide stored in roots and seeds for future energy needs

Cellulose is indigestible in humans and is used by plants to provide rigidity

Glycogen is how animals store carbohydrates for future needs

Sources of Carbohydrates

Cereal grains such as wheat and rice contain many complex carbohydrates

Root crops such as potatoes and carrots contain large quantities of carbohydrates

Fruits contain many sugars (monosaccharides and disaccharides)

Candy, soda, and other sweets are very high in monosaccharides

Lipids

A lipid is the technical name for a triglyceride (fat) or steroid (cholesterol)

Triglycerides are a glycerol attached to 3 fatty acids

The fatty acids are non-polar, long hydrocarbon chains A chain with all single bonds is saturated A chain with one or more double bonds is unsaturated.

Saturated Fats

Saturated fats have the maximum number of hydrogen atoms on them

Saturated fats tend to be solids at room temperature

Unsaturated Fats

Unsaturated fats, with their double bonds, can hold more hydrogen atoms

Unsaturated fats tend to be liquids at room temperature

Proteins

Very large molecules Fundamental to structure and function of all

organisms Often consist of 2 or more subunits held in

place by covalent bonds Each subunit is made of a very long chain

of amino acids which folds up on itself Bond joining amino acids is called a

peptide bond

Proteins (continued)

Basic structure of an amino acid:

NH2

O

OH

R

H

Acid group

Functional Group

Amine Group

Amino Acid Structure

The amino acid is determined by the “R” group, shown here in blue. Note that small differences in the “R” structure result in a totally different amino acid.

Protein Structure

The structure of a protein is determined by the order of the amino acids and their respective polarities Non-polar functional groups attract non-

polar functional groups Polar functional groups attract polar

functional groups The protein folds as the different

functional groups are attracted to each other and the protein takes its shape in this manner

Sources of Protein Meats, eggs, seafood are all

excellent sources of protein but contain significant amounts of fat

Dairy products are also good sources of protein but contain sugar (lactose) and fat

Legumes, including beans and lentils, are excellent sources of protein

Soy products such as tofu are excellent sources of protein

Egg whites are pure protein; all the fat in an egg is in the yolk

Protein Function Proteins have many functions

Provide structure (hair, nails, muscle) Enzymes = catalyze chemical reactions Hormones = signaling between tissues Antibodies = recognizing pathogens (germs) Storage and Transport

Across cell membrane Hemoglobin

Check your comprehension…

With your seat partner:

1. Without looking at your notes, name 3 different foods that contain each of the 3 biomolecules we’ve discussed so far?

2. Why do you think it is important for our bodies to get a balanced diet of all of these foods?

Nucleic Acids

Nucleic acids are found in the nucleus Contain information that is passed from

generation to generation – genetic material

Two forms Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)

DNA vs. RNA

DNA stays in nucleus

Double helix EXTREMELY large Nitrogenous bases

Adenine Guanine Cytosine Thymine

RNA leaves nucleus Single strand Large, but not very Nitrogenous bases:

Adenine Guanine Cytosine Uracil

DNA vs. RNA - molecular level

Review Questions 1. What are the 4 macromolecules most common in

living organisms?

2. Which macromolecule includes starches and sugars?

3. What is the difference between saturated and unsaturated fats?

4. What are the building blocks of proteins called?

5. What are 3 things our body uses proteins for?

6. Which type of nucleic acid uses deoxyribose sugar?