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Properties of Water
Water is a key inorganic molecule, involved in biological processes for several reasons:
1. Water is a good solvent.
- Water dissolves polar molecules and ions.
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Properties of Water
2. Water organizes nonpolar molecules.- hydrophilic: “water-loving”-hydrophobic: “water-fearing”- Water causes hydrophobic molecules to aggregate or assume specific shapes.
3. Water can form ions.
H2O OH-1 + H+1
hydroxide ion hydrogen ion
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Biological Molecules
Biological molecules consist primarily of-carbon bonded to carbon, or-carbon bonded to other molecules.
Carbon can form up to 4 covalent bonds.
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Isomers: molecules with same chem. formula.
but a different arrangement(Shape)
Biological molecules are typically large molecules constructed from smaller subunits.
Monomer: single subunit
Polymer: many units
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dehydration synthesis: formation of large molecules by the removal of water
-monomers polymers
hydrolysis: breakdown of large molecules by the addition of water
-polymers monomers
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Carbohydrates
Molecules with a 1:2:1 ratio of C, H, O
-empirical formula: (CH2O)n
-examples: sugars, starch, glucose
C – H covalent bonds hold much energy
Carbohydrates are good energy storage molecules.
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Carbohydrates
Glucose
-a monosaccharide – single sugar
-contains 6 carbons
-very important in energy storage
-fructose & galactose are isomers
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Carbohydrates
Disaccharides
-2 monosaccharides linked together by dehydration synthesis
-used for sugar transport or energy storage
-examples: sucrose, lactose, maltose
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Carbohydrates
Polysaccharides
-long chains of sugars
-used for energy storage
(plants use starch; animals use glycogen)
-used for structural support
(plants use cellulose; animals use chitin)
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Nucleic Acids
Two types: DNA and RNA
Functions: specialized for the storage, transmission, and use of genetic information
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Nucleic acids are polymers of nucleotides.-nucleotide: (Monomer) sugar + phosphate + nitrogenous
base
Nucleotide
DNAmolecule
-Nitrogenous bases include-purines: adenine and guanine-pyrimidines: thymine, cytosine, uracil
• A pairs with T (or U in RNA)
• C pairs with G
• Order of the bases determines genetics
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Nucleic Acids
RNA
-contains ribose instead of deoxyribose
-contains uracil instead of thymine
-single polynucleotide strand
-functions:
-read the genetic information in DNA
-direct the synthesis of proteins
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Proteins
Protein functions include:1. enzyme catalysts2. defense3. transport4. support5. motion6. regulation7. storage
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Proteins
Monomer: Amino acid
-central carbon atom surrounded by
-amino group
-carboxyl group
-single hydrogen
-variable R group (dictates the chemical properties of the amino acid)
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ProteinsThe structure of a protein determines its
function
1) order of amino acids
2) folding and final shape
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Proteins
Denaturation is a change in the shape of a protein, usually causing loss of function.
-can be caused by changes in:
-pH
-temperature
-salt concentration
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LipidsLipids are a group of molecules that are
insoluble in water (hydrophobic)
Two main categories:
-fats (triglycerides)
-phospholipids
Monomers: Fatty acids hydrocarbon chains containing a carboxyl group (COOH)
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Lipids
Triglycerides
-composed of 1 glycerol + 3 fatty acids
-store twice as much energy as carbohydrates
-saturated fats (animals) solid at room T
-unsaturated fats (plant oils) liquid at room T
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Lipids
Phospholipids -composed of:
-1 glycerol
-2 fatty acids
-a phosphate group
Phospholipids contain polar “heads” and nonpolar “tails”.
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Lipids
Phospholipids spontaneously form micelles or lipid bilayers cell membranes!
hydrophobic regions toward the inside and leave the hydrophilic regions exposed to the water environment.