Transcript Introductory Chemistry, 2nd Edition Nivaldo Tro

Unit 12
Biochemistry
Carbohydrates
Carbohydrates
• carbon, hydrogen & oxygen
• also known as sugars, starches, cellulose,
dextrins & gums
• Produced through photosynthesis by plants
• Identified by the number of carbon atoms
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Lipids
Lipids
• chemicals of the cell that are insoluble in water,
but soluble in nonpolar solvents
• fatty acids, fats, oils, phospholipids, glycolipids,
some vitamins, steroids and waxes
• structural components of cell membrane
 because they don’t dissolve in water
• long-term energy storage
• insulation
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Fatty Acids
• carboxylic acid (head) with a very long
hydrocarbon side-chain (tail)
• saturated fatty acids contain no C=C double bonds
in the hydrocarbon side-chain
• unsaturated fatty acids have C=C double bonds
 monounsaturated have 1 C=C
 polyunsaturated have more than 1 C=C
Head
Tail
CH3
CH2
CH2
CH2
CH2
CH2
CH2
O
CH2
CH2
CH2
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CH2
CH2
CH2
C OH
6
Fats & Oils: Triglycerides
• fats are solid at room temperature,
oils are liquids
• trigylcerides are triesters of
glycerol with fatty acids
 the bonds that join glycerol to the
fatty acids are called ester linkages
• triglycerides differ in
 Length of the fatty acid side-chains
(12 to 20 C)
O
ester linkage
CH2
OH
CH2
O
C
O
CH2CH2CH2CH2CH2CH2CH2 CH2CH2CH2CH2 CH2 CH3
CH2
OH
CH2
O
C
O
CH2CH2CH2CH2CH2CH2CH2CH2 CH2CH2CH2CH2CH3
CH2
OH
Glycerol
CH2
O
C
CH2CH2CH2CH2CH2CH2CH2 CH2CH2CH2CH2 CH2 CH3
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Steroids
• characterized by 4 linked carbon
rings
• mostly hydrocarbon-like
dissolve in animal fat
• mostly have hormonal effects
• serum cholesterol levels linked to
heart disease and stroke
levels depend on diet, exercise,
emotional stress, genetics, etc.
• cholesterol synthesized in the liver
from saturated fats
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Proteins
Amino Acids
• main difference between amino acids is the side
chain
R group
•
•
•
•
•
some R groups are polar, others are nonpolar
some polar R groups are acidic, others are basic
some R groups contain O, others N and others S
some R groups are rings, other are chains
the differences in the R groups give the amino
acids their different properties
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Types of Proteins
• tertiary structure determines the type of protein
• globular
 folds into a fairly compact, spherical shape
 water soluble
 mobile
• fibrous
 long coils aligned in stacks like pipes
 water insoluble
 provide strength to tissues
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Common Functions of Proteins
• Structure – bone, skin, cartilage, tendons,
nails, hair
• Movement – muscles
• Protection – antibodies, blood clotting
• Catalysis – emzymes
• Transport – oxygen (hemoglobin)
• Energy – extract energy from food
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Nucleic Acids
Nucleic Acids
• carry genetic information
• Every cell has a complete copy
• RNA molar mass = 20K to 40K amu
 i.e BIG polymers
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DNA
• deoxyribonucleic acid
• sugar is deoxyribose
• one of the following amine
bases
 adenine (A)
 guanine (G)
 cytosine (C)
 thymine (T)
• 2 DNA strands wound together
in double helix
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