Download Organic Compounds

Organic Compounds
Lab 3
Carbohydrates
• Contain C, H, O atoms (1:2:1 ratio), (CH2O)n
• # 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




Monosaccharide
Simple sugar
Consists of one subunit; smallest
carbs
Ex. Glucose (C6H12O6)
Also, fructose, ribose, deoxyribose
Disaccharide
 Result of linkage of two
monosaccharides, glycosidic
linkage
 Ex. Sucrose, lactose, maltose
Figure 5.5
1–4
glycosidic
1 linkage 4
Glucose
Glucose
Maltose
(a) Dehydration reaction in the synthesis of maltose
1–2
glycosidic
1 linkage 2
Glucose
Fructose
(b) Dehydration reaction in the synthesis of sucrose
Sucrose
Complex Carbohydrates
Polysaccharides
• Long chain polymers of sugars
• Plant structural polysaccharide:
Cellulose, form the plant cell wall and
give support and shape.
• 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
Figure 5.6
Chloroplast
Starch granules
Amylopectin
Amylose
(a) Starch:
1 m
a plant polysaccharide
Mitochondria
Glycogen granules
Glycogen
(b) Glycogen:
0.5 m
an animal polysaccharide
(C) Cellulose: Structural polysaccharide
Figure 5.8
Cellulose
microfibrils in a
plant cell wall
Cell wall
Microfibril
10 m
0.5 m
Cellulose
molecules
 Glucose
monomer
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
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 (non-locked). Any
sugar that contains free aldehyde or ketone group(s).
• 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 (brick red ppt).
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
The color: green or yellow (+), orange (++), brick red (+++), brown (++++)
The change in color indicates more concentration of monosaccharides
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
Solubility test of fats using ether
solvent
Translucent oil spot appear
Hold the paper toward the light to see the spot
Testing for Lipids, Sudan III or IV 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!!!
Sudan IV is a reddish liquid dissolves in lipids