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Published byChristiana Wheeler Modified over 9 years ago
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1 The Chemical Building Blocks of Life Chapter 3
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2 Outline Biological Molecules – Macromolecules Proteins Structure and Denaturation Nucleic Acids DNA and RNA Lipids Fats and Phospholipids Carbohydrates Transport and Storage
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3 Biological Molecules The framework of biological molecules consists of carbon bonded to other carbon molecules, or other types of atoms. – Hydrocarbons consist of carbon and hydrogen. Covalent bonds store considerable energy.
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4 Biological Molecules Macromolecules – proteins – nucleic acids – lipids – carbohydrates Functional groups – specific groups of atoms attached to carbon backbones retain definite chemical properties Link: Functional groups
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5 Building Macromolecules Macromolecules are often polymers. – long molecule built by linking together small, similar subunits Dehydration synthesis removes OH and H during synthesis of a new molecule. Hydrolysis breaks a covalent bond by adding OH and H.
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6 The Many Functions of Proteins – enzyme catalysis – defense – transport – support – motion – regulation – storage
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7 Amino Acid Structure contain an amino group (-NH 2 ), a carboxyl group (-COOH) and a hydrogen atom, all bonded to a central carbon atom – twenty common amino acids grouped into five classes based on side groups nonpolar amino acids polar uncharged amino acids charged amino acids aromatic amino acids special-function amino acids
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8 Amino Acids Peptide bond links two amino acids. – A protein is composed of one or more long chains of amino acids linked by peptide bonds (polypeptides).
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9 Protein Structure Protein function is determined by its shape. – Protein structure primary - specific amino acid sequence secondary - folding of amino acid chains tertiary - final folded shape of globular protein quaternary - forms when two or more polypeptide chains associate to form a functional protein
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10 Chaperone Proteins Chaperone proteins are special proteins which help new proteins fold correctly. – Chaperone deficiencies may play a role in facilitating certain diseases.
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11 Unfolding Proteins Denaturation refers to the process of changing a protein’s shape. – usually rendered biologically inactive salt-curing and pickling used to preserve food
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12 Nucleic Acids Deoxyribonucleic Acid (DNA) – Encodes information used to assemble proteins. Ribonucleic Acid (RNA) – Reads DNA-encoded information to direct protein synthesis. Nucleic acids are composed of long polymers of repeating subunits, nucleotides. – five-carbon sugar – phosphate – nitrogenous base purines adenine and guanine pyrimidines cytosine, thymine, and uracil
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13 Nucleic Acid Structure DNA exists as double- stranded molecules. – double helix – complementary base pairing hydrogen bonding RNA exists as a single stand. – contains ribose instead of deoxyribose – contains uracil in place of thymine
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14 Lipids Lipids are loosely defined as groups of molecules that are insoluble in water. – fats and oils Phospholipids form the core of all biological membranes. – composed of three subunits glycerol fatty acid phosphate group
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15 Fats and Other Lipids Fats consist a of glycerol molecule with three attached fatty acids (triglyceride / triglycerol). – Saturated fats - all internal carbon atoms are bonded to at least two hydrogen atoms – Unsaturated fats - at least one double bond between successive carbon atoms Polyunsaturated - contains more than one double bond usually liquid at room temperature
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16 Fats as Energy Storage Molecules Fats, on average, yield about 9 kcal per gram versus 4 kcal per gram for carbohydrates. – Animal fats are saturated while most plant fats are unsaturated. Consumption of excess carbohydrates leads to converted into starch, glycogen, or fats for future use.
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17 Carbohydrates Carbohydrates are loosely defined as molecules that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio. – monosaccharides - simple sugars – disaccharides - two monosaccharides joined by a covalent bond – polysaccharides - macromolecules made of monosaccharide subunits isomers - alternative forms of the same substance
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18 Carbohydrate Transport and Storage Transport disaccharides – Humans transport glucose as a simple monosaccharide. – Plants transform glucose into a disaccharide transport form. Storage polysaccharides – plant polysaccharides formed from glucose - starches most is amylopectin Cellulose - plants – alpha form or beta form of ring Chitin - arthropods and fungi – modified form of cellulose
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