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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.