BIO 151 Study Guide
Topic Three: Biochemical Compounds
The Central Role of Carbon (C)
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Carbon can form four bonds
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Hydrocarbons: chains in which C's bond only to other C's or to H's.
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Functional groups can be added to hydrocarbons (e.g., hydroxyl group, carboxyl
gp., amino gp., phosphate gp.)
Four major classes of Biochemical Compounds
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Carbohydrates
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very important for nutrition and structural support
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Basic Formula 1:2:1 ratio of C:H:O (CH2O)n
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monomers: Monosaccharides (= "simple sugars")
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polymers: Polysaccharides (= "complex carbohydrates")
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Storage polysaccharides (e.g, starch, glycogen)
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Structural polysaccharides (e.g., cellulose, chiten)
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Lipids
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Long hydrocarbon chains result in hydrophobic properties
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Fats--used primarily for energy storage
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More efficient energy storage than carbohydrates
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Glycerol + 3 Fatty Acids = Trigylceride
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saturated vs. unsaturated fats
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most animals fats are solid at room temperature
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most plant fats are liquid at room temperature (called "oils")
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Phospholipids
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Glycerol + 1 phosphate gp + 2 Fatty Acids
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fatty acid "tails" are hydrophobic
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glycerol-phosphate "head" region is hydrophilic
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"phospholipid bilayers" form the basic framework of membranes
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Steroids
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Basic hydrocarbon skeleton of 4 rings, differing by functional gps.
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examples: cholesterol, sex hormones
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Waxes and Wax-like substances (incl. cutin and suberin)
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very, very long hydrocarbon chains
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much harder and more water resistant than fats
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important in water regulation in plants
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Chlorophylls--photosynthetic pigments
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porphyrin ring "head"
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hydrocarbon "tail"
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embedded within the membranes of chloroplasts
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Proteins
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many functions within the cell, organism
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monomers: Amino acids
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polymers: Polypeptides
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polypeptides not considered "proteins" unless functional
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protein function related to shape or conformation--4 levels of structure
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Primary--amino acid sequence
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Secondary--the regular 3-D shape
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a helices, b pleated sheets
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due to H bonds between amino acids
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Tertiary--the irregular 3-D shape
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due to interactions among R groups
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"globular" proteins
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Quaternary--interactions between polypeptide chains
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Enzymes--an example of the importance of proteins
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enzymes are proteins that catalyze biochemical reactions (lower EA)
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active site is substrate specific
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enzyme activity depends on 3-dimensional shape of the protein
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effect of temperature and pH on enzyme activity
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cofactors (inorganic and organic)
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inhibitors (competitive and non-competitive)
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regulation of enzymes
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Nucleic acids
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monomers: Nucleotides, each with three components
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phosphate group
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5 carbon sugar
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ribose (in RNA)
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deoxyribose (in DNA)
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nitrogenous base
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adenine, guanine, cytosine, uracil (in RNA)
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adenine, guanine, cytosine, thymine (in DNA)
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nucleotides linked together to form a sugar-phosphate backbone
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RNA can form a single strand; DNA forms a double-stranded "helix"
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seq. of nulceotides in nucleic acids determines seq. of amino acids in
proteins