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Lab: Using indicator dyes to examine macromolecules in food.
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Chemistry deals with the study of matter.
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Matter: Anything that takes up space and has mass (rock, bug, human).
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Atoms are the fundamental units of matter.
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Atoms combine via bonding to make molecules.
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Molecules found in living organisms can be classified as organic (carboncontaining + H) or inorganic (non-carbon + Hydrogen containing)
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Compounds – 2 or more different elements combine to form a molecule of a
compound. A molecule of a compound is the smallest particle that has the
specific properties of the compound CH4 (methane).
Chemical reactions used to build molecules and break down foods.
Chemical reactions involve the formation or
breaking of chemical bonds
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Reactants: what is put into reaction
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Products: end result of reaction
Synthesis: formation of bonds, requires energy input
A+B
Reactants

C+D
Product
Decomposition reaction: breaking of bonds, releases
energy
AB  A + B
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Biochemistry: Study of matter in living organisms
Two different types of compounds are found in living organisms: inorganic
and organic molecules.
Inorganic molecules:
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Electrolytes, minerals, and compounds that do not contain carbon
with hydrogen.
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Ex: oxygen (O2), carbon dioxide (CO2), water (H2), inorganic
acids (H+) and bases (OH-), salts (NaCl, KCl)
Organic molecules:
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Always contain carbon with hydrogen, and sometimes oxygen
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Often soluble in water
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Covalently bonded
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4 Major macromolecules found in food:
1.
Carbohydrates
2.
Fats
3.
Proteins
4.
Nucleic Acids
Elements in Human Body by dry
weight %
Carbon... 61.7
Nitrogen.. 11.0
Oxygen.. 9.3
Hydrogen... 5.7
Calcium.. 5.0
Phosphorus..3.3
Potassium.. 1.3
Sulfur.. 1.0
Chlorine.. 0.7
Sodium.. 0.7
Magnesium..0.3
Trace amounts of B, F Si, V, Cr,
Mn, Fe, Co, Cu, Zn, Se, Mo,
Sn, I.
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Solutions
A solution is a uniform mixture of two or more substances
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It consists of a solvent, or medium, in which atoms, ions, or molecules of
another substance, called a solute, are individually dispersed
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Solutions are often defined by the concentration of a solute e.g. a teaspoon
of sugar dissolved in 1 liter of water.
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Concentration can be expressed as # of solute molecules in a specific
volume of solvent (most often water).
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Concentration of H+ ions in solution:
pH = -log [H+]
Ex:
pH 1 = 10 -1 = .01 moles of [H+] /liter
pH 7 = 10 -7 = .0000001 (neutral in
water)
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Acids
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Solute that dissociates and releases hydrogen ions
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Often referred to as proton donors
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After losing an electron, a hydrogen ion consists solely as a proton
Strong acids dissociate completely
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Example: hydrochloric acid (HCl)
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HCl  H+ + Cl–
• pH below 7
Hydrochloric acid (HCl), a strong acid because it releases hydrogen ions
Bases
•Solute that removes hydrogen ions from solution
•Proton acceptor
•Strong bases dissociate completely
•Example: sodium hydroxide (NaOH)
•NaOH  Na+ + OH–
•pH above 7
Sodium hydroxide (NaOH), a strong base because it releases hydroxide
ions that remove hydrogen ions from solution
What is an indicator?
Indicators are chemical compounds used to detect the presence of other
compounds. They change shape in the presence of certain
compounds as a result of chemical reactions.
Standards: “Known” substance used for comparison in experiment with “unknown”
INDICATOR
MACROMOLECULE
NEGATIVE
TEST (color)
POSITIVE
TEST (color)
Benedict’s
solution
simple
carbohydrate
blue
orange
Iodine solution
complex
carbohydrate
dark red
black
Biuret solution
protein
blue
violet, black
Sudan IV
lipid
dark red
reddishorange
Test for Simple Carbohydrates: Benedict’s
Benedict's solution is a chemical indicator for
simple sugars such as glucose: C6H12O6.
Unlike some other indicators, Benedict’s
solution does not work at room temperature
- it must be heated first
Details:
Benedict’s reagent changes color when exposed to a reducing agent. A
reducing agent is a term for electron gain
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A molecule that gains an electron is thus……“reduced”
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A molecule that donates electrons is called a……“reducing
agent”
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A sugar that donates electrons is called a … “reducing
sugar”. The electron is donated by the carbonyl group in
the sugar.
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All monosaccharides are reducing sugars
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Some disaccharides that have free carbonyl’s are also
reducing sugars (maltose)
Test for Complex Carbohydrates: Iodine Solution
Iodine is an indicator for complex carbohydrates.
Starch is a ploymer made up of hundreds of
simple sugar molecules (e.g. glucose).
Iodine solution  color change = blue to black
Test for Protein (amino acids): Biuret solution
Proteins are polymers of amino acids. Biuret solution is an indicator of amino acids
 dark violet blue to pinkish purple
Test for Fats (lipids): Sudan IV
Sudan IV is a test for lipids. If lipids are present the Sudan IV will stain
them reddish-orange (positive test).
Structure: Glycerol + fatty acids
4 Types:
Triglycerides – neutral fats (solid) and oils
(liquid)
Phospholipids
Steroids (testosterone)
Eicosanoids (prostaglandin)
No Tests Today: Nucleic acids (DNA and RNA) made of nucleotides
• 5 carbon sugar (Deoxyribose – DNA, ribose – RNA)
• Phosphate group
• Nitrogenous base