1. Chemical composition of cells
Lab 3

2. Introduction Inorganic molecules nonliving things
Organic molecules living organisms

3. Salt molecules: NaCl (Sodium chloride Na+ Cl-) Sugar

4. Organic compounds in living thing
Proteins
Carbohydrates
Lipids
Nucleic acids

5. Concepts
A monomer is a molecule that may bind chemically to other molecules to form a polymer.
A polymer is a large molecule (macromolecule) composed of repeating structural units.
Proteins and some carbohydrates are polymers.
Dehydration reactions— smaller molecules bond as water is given off
Hydrolysis reactions— bonds are broken as water is added

6. Control
Positive control—goes through all the steps of the experiment and does contain the substance being tested (positive results are expected)
Negative control—goes through all the steps of the experiment except it does not contain the substance being tested (negative results are expected)
The control samples usually validate the experiment. If negative control samples give positive results, the experiment is invalid—the reagents may be contaminated or the procedure may need improvement.

7. Carbohydrate Carbohydrate— sugars and chains of sugars
Glucose— monomer – monosaccharide
Maltose— 2 sugar unit – disaccharide
Glycogen, Starch ect.—chains of glucose units—polysaccharides

10. Tests for carbohydrates
Test for starch (page29)
if starch is present Iodine— brown →blue;
if starch is absent Iodine— no color change
Which tube is the control?
Test for sugars (page31)
Benedict’s reagent reacts with small sugar molecules (glucose, maltose etc.) after heating — blue → green/yellow/red
!! Highly corrosive

11. Protein Amino acid (Aa) ~20 different common amino acids
＞10 Aa = polypeptide
＞50 Aa = protein
antibodies, transport proteins (hemoglobin, albumin), regulatory proteins (insulin); structural proteins (keratin— hair, myosin—muscle); enzyme (speed chemical reactions)
amino group (-H2N)
acidic group (-COOH)

13. Test for protein !! Highly corrosive
Biuret reagent (NaOH+CuSO4 ) page 33
Peptide bonds combine with the copper ions.
blue→ purple
!! Highly corrosive
Which tube is the control?

14. Lipids

15. Emulsification of Lipids
Emulsifier can cause a fat to disperse in water

16. Today’s tests Test for Fat Page 35 15 min
Chemical composition unknown A and B Page 38
Test for sugars Page min
Emulsification of Lipids Page min
Test for proteins Page 33
Test for starch Page 29
Microscopic observation* Page 30