TOPIC 3.2
Carbohydrates, Lipids and Proteins
3.2.1
Organic and Inorganic
• Organic Compounds
– Produced by living things
– All C containing compounds found in living things
except hydrogencarbonates (HCO3-), carbonates
(CO32-) and oxides of carbon (CO and CO2)
• Inorganic Compounds
– All other compounds
Important Organic Compounds in
Living Things (biochemicals)
Molecule
Subcomponents
(precursors or subunits)
Example Molecules
carbohydrates
monosaccharides
monosaccharides: glucose, galactose,
fructose
disaccharides: maltose, lactose, sucrose
polysaccharide: starch, glycogen, cellulose
proteins
amino acids
enzymes, antibodies
lipids
glycerol and fatty acids
triglyceride, phospholipid
nucleic acids
nucleotides
DNA, RNA
3.2.2
Identify Glucose & Ribose from Diagrams
• Carbohydrates contain C, H and O in
approximately a 1:2:1 ratio
• Building blocks = monosaccharides or simple
sugars
– Types of carbohydrates:
• Monosaccharides (one simple sugar molecule)
• Disaccharides (two simple sugar molecules covalently
bonded together)
• Polysaccharides (many simple sugar molecules covalently
bonded together
Glucose – a monosaccharide
C6H12O6
Hexagon shape with
6 carbon atoms
Ribose – a monosaccharide (pentose
sugar = 5 carbon atoms)
• C5H10O4
Deoxyribose is the sugar
component of DNA
• C5H10O5
Ribose is the sugar
component of RNA
3.2.3 Monosaccharide, Disaccharide and
Polysaccharide (3 examples of each)
• Monosaccharides = glucose, fructose and
galactose (all C6H12O6)
– Isomers = same chemical formula, but different
structural formula
• Disaccharides = maltose, sucrose and lactose
– Isomers (all C12H22O11)
• Polysaccharides = starch, glycogen and cellulose
– Plants store glucose as the polysaccharide starch
– Animals store glucose as the polysaccharide glycogen
3.2.4 Functions of Carbohydrates in
Animals and Plants
• Animals:
– Glucose = source of E ; glucose is broken down to
produce ATP in cellular respiration
– Lactose = sugar found in milk of mammals; source of E
– Glycogen = used for short term E storage in the liver and
muscles
• Plants:
– Fructose = very sweet; good source of E (found in fruits)
– Sucrose = used to transport and store E
– Cellulose = one of the primary components of cell walls
3.2.5
Condensation Reaction (dehydration synthesis)
• Two molecules of glucose form maltose plus water
C6H12O6 + C6H12O6
C12H22O11 + H2O
condensation reaction=
a water molecule is
removed as two glucose
combine to form
maltose (also called
dehydration synthesis)
•
Condensation and Hydrolysis Reactions (cont.)
• glucose + glucose
maltose + water
• glucose + fructose
sucrose + water
• glucose + galactose
lactose + water
• this direction (
• this direction (
) indicates condensation
) indicates hydrolysis
(hydro = water; lysis = splitting)
3.2.2
Identify Fatty Acids from Diagrams
• the building blocks of lipids
• lipids include triglycerides (glycerol plus three fatty
acids), phospholipids and steroids (ex. cholesterol)
• triglyceride structure:
condensation reaction
unsaturated fatty acid
saturated
fatty acids
Lipids
• contain C, H and O atoms, but not in a 1:2:1 ratio
like carbohydrates…lipids contain very few O
atoms
• fats and oils are lipids
– fats generally come from animals; they are solid at
room T°; contain single bonds and are saturated
– oils generally come from plants; they are liquid at
room T°; contain 1 or more double bonded carbon
atoms and are unsaturated
• lipids store twice the energy of carbohydrates
• important for insulation and membrane structure
3.2.2
Identify Amino Acids from Diagrams
• polypeptides are long chains of amino acids
• amino acids are the building blocks of proteins
• 20 different amino acids all have similar
structure:
– central C atom has four groups attached to it:
•
•
•
•
amine group - NH2
carboxyl group - COOH
a hydrogen atom - H
the “R” group which is different in different amino acids
Generalized Amino Acid Structure
Amino Acids Form Chains
Condensation Reactions
water molecule removed
polypeptide chains are formed through condensation
reactions (dehydration synthesis) at ribosomes