Transcript Carbohydrates (cont.)

3-2: MOLECULES OF LIFE

There are 4 classes of organic compounds
essential to life:
 Carbohydrates
 Proteins
 Lipids
 Nucleic Acids
 Each
of these compounds are made up of C, H,
+ O atoms; but occur in different ratios
Carbohydrates
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
Organic compounds composed of C, H, + O
Found in ratios of 2H:1O; the # of C varies
Carbohydrates (cont.)
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Monosaccharides
Monomer – a simple sugar (1C:2H:1O ratio)
 Formula = (CH2O)n ; where n = 3-8
 Common types:
 Glucose - - used in cells
 Fructose - - found in fruits
 Galactose - - found in milk
 All have same formula = C6H12O6
 Isomers = same formula, different structures

Examples
Carbohydrates (cont.)
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Disaccharide – “double sugar” – combination of
2 monosaccharides from a condensation rxn
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Ex. Sucrose
Carbohydrates (cont.)
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Polysaccharide – complex molecules composed
of 3 or more monosaccharides
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In animals, glucose is stored as glycogen
Found in branched chains
 Stored in liver + muscles
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Carbohydrates (cont.)
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In plants, glucose is stored as starch or
cellulose
Starch – found as branched or unbranched chains
 Cellulose – gives strength + rigidity to plant cell
walls
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Proteins

Organic compounds composed mainly of C, H,
O, + N
Formed from monomers
 Found in skin, hair, nails + muscles
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Proteins (cont.)
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Amino Acids (AA)
Building blocks of proteins – monomer
 20 different AA in living things
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Difference = functional groups attached to C
R. Groups can be simple or complex
 Can take on a variety of shapes, thus carrying out different
activities in living things
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Proteins (cont.)
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Dipeptide – the bonding of 2 AAs

Forms a peptide bond
Proteins (cont.)
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Polypeptide – a long chain of AA’s
Chain folds or bends based on certain conditions
( i.e. Temperature increase/decrease) – ex. egg
 When polypeptide folds, takes on a globular shape


Enzymes
Proteins (cont.)
RNA or protein molecules that act as biological
catalysts
 Work by a “lock-and-key” method with its
substrate – the reactant being catalyzed
 Substrate will only “fit” if shape of active site is a
match
 Once enzyme is done, it releases the product(s) and
can be used over + over again
 Mail fail to work if environment changes (temp or
pH)

How an enzyme works…
Lipids

Large, nonpolar organic molecules that do not
dissolve in water
Higher ratio of C + H atoms to O atoms
 C-H bonding (stores more nrg)
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Lipids (cont.)
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Fatty acids – monomer of a lipid – unbranched
chains
 Contain a carboxyl group, -COOH, at one end
 Hydrophilic
 Hydrocarbon
end – attracted to water (polar)
at other end
 Hydrophobic
end – “afraid” of water (nonpolar)
Saturated vs. Unsaturated
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Saturated – all C atoms are “full”
Unsaturated – has double bond(s) between C
atoms
Lipids (cont.)

Triglyceride – 3 fatty acid molecules + glycerol
 Functions:
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NRG, insulation + protection, nutrition
(vitamins ares stored in fats in body)
Types:

Saturated
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High melting point, solid @ room temp.
 Examples: shortening (Crisco), animal fats
Unsaturated
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Low melting point, liquid @ room temp.
 Examples: plant seed oils, fruits
Lipids (cont.)
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Phospholipids – 2 fatty acid molecules +
glycerol
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Forms lipid bilayer for cell membranes
Lipids (cont.)
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Wax – long fatty acid chain + long chain of
alcohol
Highly waterproof
 Used as a protective coating
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Lipids (cont.)
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Steroids – molecules of 4 fused C-rings with
different functional groups
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Common types:
Hormones – testosterone
 Cholesterol – needed by nerves + cells
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Nucleic Acids
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Very large, complex organic molecules that store
important information in cells
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Two types:
DNA – deoxyribonucleic acid – determines characteristics
of organism and directs cells activities
 RNA – ribonucleic acid
 Stores + transfers info. essential to make proteins
 Can also act as an enzyme
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Nucleotides – monomers of Nucleic Acid
5-C sugar
 Phosphate group
 Nitrogen-base
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What a nucleotide looks like…
DNA vs. RNA