Section 2.3 Biomolecules

What are the four types of biomolecules?

Today you will:

• Learn about each type of biomolecule• Learn how to test for the presence of each

biomolecule in different food substances.

Questions to discuss

• In this lab you will put different food sources in a test tube to test for the presence of various macromolecules. Why will one of your test tubes be filled with distilled water?

• What is the dependent variable? What is the independent variable?

Biomolecules

• Molecules are either inorganic compounds or organic compounds– Organic-has carbon– Inorganic-no carbon

• Why is carbon so special?– It can form 4 bonds with other atoms. It loves

to COVALENTLY BOND!– It can form single, double, and triple bonds.

Biomolecules• There are 4 types of

biomolecules in our bodies– Carbohydrates– Lipids (fats)– Proteins– Nucleic acid (DNA)

• These are large molecules (polymer) that are made up of smaller building blocks (monomers)

• Polymers are made of monomers.

• http://www.phschool.com/science/biology_place/biocoach/bioprop/monomers.html

Proteins

• Elements: C, H, O, N, or S (sulfur)• Structure: look for N or S• What do they do-THEY DO A LOT!

– Hemoglobin in your blood that carries oxygen– Muscles, tendons, hair– Defend body from microorganisms– Control chemical reactions-enzymes– Carry out almost all of the body’s everyday functions

• Building block-amino acids

Testing for proteins

• You will use a biuret reagent

• It will turn a blue violet color in the presence of a protein.

• You will add each substance to a test tube and then add a few drops of biuret reagent.

Carbohydrates• Elements-C, H, O• Function: Main source of

energy, gives plants tough structure

• Examples: sugars and starches, glycogen, sucrose, glucose, cellulose (END IN ose)

• Shape-rings connected• Building Block-

monosaccharide or simple sugars (glucose)

Different types of carbohydrates

• Based on size– Monosaccharide-one sugar

• MONO MEANS ONE– Disaccharide-two sugars

• DI MEANS TWO– Polysaccharide-many

sugars (2 OR MORE)• Cellulose-makes plants

have a rigid structure• Glycogen-animal starch

Two carbohydrate tests-starch and simple sugars

• Starch– Iodine will turn black or purple

in the presence of starch• Benedict’s solution

– Add substances to tube with benedict’s solution

– Heat for 3 to 5 minutes to look for color change

– The redder the more simple sugar (glucose) present

– Will form a percipitate

Lipids (Fats)• Not a polymer

– Why? Does not have the same unit repeating over and over

• Elements-C, H, O• Has the most energy but we

can’t consume tons of fat; part of membranes; insulation

• Structure-long chain of carbons attached

• Examples: cholesterol, wax, steroids, oils

• Building Block-fatty acids and glycerol

Saturated vs. Unsaturated• Saturated-bad for you;

causes cholesterol problems, clogged arteries; solid at room temperature; lard

• Unsaturated-liquid at room temperature; not as bad for you; olive oil, canola oil, peanut oil

• Trans fat-type of unsaturated; causes coronary heart disease

2 ways to test for lipids

• Brown paper bag– Substance will

leave an oil spot if present

• Sudan 4 test– Substance will turn

red

Nucleic Acids• Tell your cells how to

function• Contains the genetic

information• DNA (deoxyribose

sugar) and RNA (ribose sugar)

• Elements: C, H, O, N, P• We talk about these a TON

second semester! So you only need to know these points.