Cornell notes pg 17 in your INB
Chemistry of Life
The Essential Ingredients for
Ingredients for Life
Properties of water
organisms are made mostly of
Adhesive (adhere to other surfaces)
Cohesive (adhere to each other)
The universal solvent
does water have these special
…because water is POLAR!
molecules have an
(make sure to illustrate and label figures)
short term energy
Simple sugar (monosaccharide) –
sugar (polysaccharide) -
insoluble (do not dissolve) in water
“stores the most energy”
Ex: 1. Fats
Some functions of lipids:
1. Long term energy storage
3. Major component of membranes
acids (20 different kinds)
Amino Acids bonded together form a chain
called a polypeptide chain.
A polypeptide chain folds into a protein.
functions of proteins:
Transport: hemoglobin in red blood cells
Structural: membranes, hair, nails
Enzymes: cellular reactions
a. DNA (deoxyribonucleic acid)genetic material
b. RNA (ribonucleic acid)-copy of
Nucleic acids are composed of long
chains of nucleotides
do you know if a food contains protein?
do you know if a food contains starch?
is the difference between starch and
should you be careful of biuret solution?
What should you do if you spill some on
The most common organic compounds found in living
organisms are lipids, carbohydrates, proteins, and
Common foods, which often consist of plant materials
or substances derived from animals, are also
combinations these organic compounds. Substances
called indicators can be used to test for the presence
of organic compounds. An indicator is a substance
that changes color in the presence of a particular
compound. In this investigation, you will use several
indicators to test for the presence of lipids,
carbohydrates and proteins in various foods.
Repeated # of trials:
The effect of _______ on _____.
Using the indicators (listed below)
which test for specific compounds.
Which of the 4 major types of
organic compounds are found in
change color if
present in a
the rest of your
Lab-write up on your own.
indicators added to
color change of the
color of the samples
before adding indicator
for each indicator
compound test you need:
5 drops egg white
5 drops apple juice
5 drops corn oil
5 drops fish
5 drops of distilled water
5 drops butter
5 drops of potato
5 drops of spinach
Starch test: Iodine
Sugar test: Benedicts
Protein: Biuret solution
1. Divide a piece of brown paper towel into 8 equal
sections. In each section, write the name of one test
substances, as shown.
2. In each section, place a small drop of the identified
food onto the brown paper towel. With another paper
towel, wipe off any excess pieces of food that may stick to
the paper. Set aside for 10-15 minutes
3. Hold paper to light or window. If food sample
produces a translucent or see-through spot, there is a
presence of a LIPID.
Carbohydrate Test - Starch
Label test tubes: distilled water, egg, oil,
butter, apple juice, potato, spinach, fish
2. Add 5 drops of each food sample to its proper
3.Add 2-3 drops of iodine solution to each test
tube and shake.
*Iodine will change color from yellow brown
→blue black in presence of STARCH.
4. Record data on table.
5. Wash test tubes thoroughly!
Carbohydrate Test - Sugar
Set up hot water bath: Fill half the beaker with
tap water and heat to a gentle boil.
2. While water bath is heating, fill each cleaned test
tube with 5 full drops of the appropriate food sample.
3. Add 2-3 drops of Benedicts solution and shake.
4. Place test tubes in hot water bath and heat for 3-5
5. Caution: Remove test tubes from water bath with
test tube holder!
*When heated, Benedicts solution will change color
from blue → green, yellow, orange, or red in the
presence of SUGAR.
6. Record any color changes on data table.
7. Wash test tubes thoroughly!
Put 5 drops of appropriate food samples in each
labeled test tube.
2. Add 2-3 drops of Biuret solution to each test tube
and gently shake.
Caution: Biuret contains NaOH, a strong base. If
you splash any on yourself, wash with water and
notify your teacher immediately!
*Biuret changes color from light blue→blue-violet
in the presence of PROTEIN.
3. Record any color change on data table.
4. Wash test tubes thoroughly!
POST LAB QUESTIONS
foods come from plants? What
biomolecule is most common in these foods?
foods come from animals? What
biomolecule is most common in these foods?
water contain any of the
macromolecules that you tested for? Explain
why water is used as a control.
FILL OUT THE FOLLOWING TABLE BY
LISTING THE FOODS THAT YOU TESTED.
High in Protein
High in Lipids