Transcript Organic Compounds - Harford Community College

Organic Compounds
Lab 3
Carbohydrates
• Contain C, H, O atoms (1:2:1 ratio)
• # Carbon atoms = # Oxygen atoms
• Fx: 1. ENERGY STORAGE…WHY??
The C-H bonds store energy. When an
organism requires an energy source, C-H
bonds are the ones most often broken. This
results in the release of stored energy.
2. Structural Support!!!
• Comprise 1-2% of a cells mass
• 2 types: simple carbohydrates
complex carbohydrates
Simple Carbohydrates
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Monosaccharide
Simple sugar
Consists of one subunit; smallest
carbs
Ex. Glucose (C6H12O6)
Also, fructose, ribose, deoxyribose
Disaccharide
 Result of linkage of two
monosaccharides
 Ex. Sucrose, lactose, maltose
Complex Carbohydrates
Polysaccharides
• Long chain polymers of sugars
• Preferred form of energy storage
– Plants: starch = glucose
polysaccharide that plants use to
store energy
– Animals: glycogen = highly
insoluble macromolecule formed
of glucose and polysaccharides
that serves as stored energy
Lipids
• Contain C, H, and O
• Fx: 1. Sx makeup of membranes
2. Store energy, long term
3. Hormonal activities
• Hydrophobic (held together by non-polar covalent bonds)
• Contains MORE energy-rich C-H bonds than carbs
• Types include: neutral fats, phospholipids, steroids, carotenoids,
waxes
– Neutral fats:
most abundant type of lipid
3 Fatty Acids + glycerol
• Simplest lipid = fatty acid
Lipids
Triglycerides (Neutral Fat)
•Fats are synthesized from 2 components:
1. Fatty acid: long chain C and H atoms ending in a COOH group
2. Glycerol: a three C molecule; note, glycerol is an alcohol
•Glycerol forms a backbone to which 3 fatty acids are attached via a dehydration
reaction
fat molecule
•Provides long term energy storage, insulation
Protein
• Comprises 10-30% cell mass
• Contains C, H, O, N, S (sometimes)
• Fx: 1. enzymes
2. structural roles (collagen, keratin)
• All proteins are a long polymer chain of amino acid subunits
– small molecules, 20 total
– all 20 have a basic structure of a central carbon
atom to which the 4 following are attached:
hydrogen atom
amino group (-NH2)
carboxyl group (-COOH)
an “R” group
How to make a protein
• Link specific amino acids
together at functional
groups
– Functional group = the
portion of a molecule
that takes part in a
chemical reaction
– Peptide bond = covalent
bond that links 2 amino
acids together
– Polypeptides = long
chains of amino acids
liked by peptide bonds
Nucleic Acids
 DNA and RNA
 DNA (deoxyribonucleic acid)
 Possible nucleotides: Adenine, Guanine, Cytosine, THYMINE
 Structure: 2 nucleotide strands = double helix
 RNA (ribonucleic acid)
 Possible nucleotides: Adenine, Guanine, Cytosine, URACIL
 Long, single strand
Nucleotides
Part A: Testing for Carbohydrates:
Reducing Sugars
• Benedict’s Reagent: tests for reducing sugars present in
carbohydrates
• Reducing sugar = any sugar that when in solution forms
an aldehyde or ketone, i.e. monosaccharides (nonlocked)
• How?? Benedict’s Reagent contains blue copper (II) ions
(Cu2+) that are reduced to copper (I) ions (Cu+). The Cu+
ions are precipitated in water as red copper (I) oxide.
Glucose
Gluconic Acid
Part A: Reducing Sugars
• Test glucose, sucrose and starch solutions in
the presence of Benedict’s reagent to detect
presence of reducing sugars
Glucose
Sucrose
Starch
Part B: Testing for Carbohydrates:
Starch
• Iodine reacts with starch producing a
dark blue, black color
• How?? Starch is a coiled
polysaccharide. When iodine is
introduced, it forms a linear molecule
and inserts into the starch coil thus
resulting in a color change
• Test starch presence in glucose,
sucrose and starch solutions as well
as potato slices
Starch
Cellulose
Part C: Testing for proteins, Biuret Test
• Biuret test detects protein by copper sulfate
reacting with peptide bonds producing a violet
color
Part C: Testing for proteins, Biuret Test
• Test for protein in honey solution, corn oil and
egg white solution
Part D: Testing for Nucleic Acids,
Dische Diphenylamine Test
• Diphenylamine Reagent reacts with the
deoxyribose sugar in DNA producing a blue
color when heated
Part E: Testing for Lipids, Sudan III Test
• Takes advantage of the fact that lipids are
NONPOLAR compounds
– They DO NOT dissolve in water. Why?
– They DO dissolve in ether, a nonpolar solvent
• Sudan III dye is made with ether as is its solvent
• Note: nonlipid substances will NOT dissolve in
Sudan III, rather, they will form two distinct layers
in a test tube
• Test honey, corn oil and egg white for the
presence of lipids
• DO NOT POUR SUDAN III DOWN THE DRAIN!!!