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Molecules of Life
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Molecules of Life Carbohydrates monosaccharides energy supply Proteins
amino acids structural components Lipids fatty acids structural components, energy, hormones Nucleic acids nucleotides DNA-genetic material
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Composition Most-carbon based organic compounds
unique to living systems with exception of CO2 & carbides carbon is necessary for life electroneutral never loses or gains electrons always shares or forms covalent bonds
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H | H--C--H | H Covalent Bonding carbon can form 4 covalent bonds with other elements or with itself has 4 electrons in outermost shell makes each carbon atom a connecting point from which another molecule can branch in four directions
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Covalent Bonding since carbon can bind to itself
has capacity to construct endless numbers of carbon skeletons varying in size & branching patterns
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Organic Compounds chain of carbons-carbon skeleton
branched or unbranched double or single bonds straight or arranged in ring form each has a unique 3-D shape properties depend on carbon skeleton & atoms attached to skeleton groups of atoms participating in chemical reactions are functional groups H | C ||| C | H
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Functional Groups OH- (hydroxyl) C=O (carbonyl) COOH (carboxyl)
NH2 (amino) SH-sulfhydryl group PO3 (phosphate) Phosphate group
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Classes of Molecules Related to Functional Groups
COOH & NH2- amino acids hydroxyl groups-alcohols carboxyl groups-carboxylic acids-acetic acid sugars contain both-carbonyl group & several hydroxyl groups phosphate groups-nucleic acids
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Macromolecules 4 main classes
consist of many identical or similar molecular units strung together monomers cells link monomers in anabolic reactions by dehydration synthesis chemical reaction which removes water broken down into monomers by adding water catabolic reactions-hydrolysis
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Carbohydrates composed of C, H & O 1:2:1 ratio
Formula: (CH2O)n gives formula for any carbohydrate may contain nitrogen, phosphate and/or sulfur Monomers-monosaccharides simple sugars building blocks for all other carbohydrates 2-10 monosaccharides form oligosaccharide hundreds- polysaccharide. hydrophilic water loving larger molecules are less soluble in water Glucose
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Monosaccharides simple sugars single chain or ring of 3-7 carbons
named for number of carbons they contain 5 carbons-pentoses 6 carbons-hexoses glucose contains 6 carbons-hexose formula-C6H1206 most important metabolic fuel in body broken downATP + CO2 fructose-6 carbon monosaccharide same formula as glucose fructose & glucose are isomers chemical compounds with same molecular formula but with elements arranged in different configurations Galactose-isomer of glucose & fructose Glucose Galactose Fructose
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Disaccharides double sugars
covalent bond- between hydroxyl groups of two simple sugars physiologically important disaccharides Sucrose sugar cane & sugar beets Glucose + fructosesucrose + H2O Lactose-found in milk of mammals disaccharide of galactose & glucose Maltose major degradation product of starch composed of 2 glucose monomers Disaccharides-too large to pass through cell membranes must be broken down into constituent parts by hydrolysis Sucrose + H20 glucose + fructose.
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Polysaccharides complex carbohydrates
dehydration synthesis reactions add more monosaccharides polysaccharides most carbohydrates in nature are in this form fairly insoluble make perfect storage molecules Glycogen major stored carbohydrate in animal liver & muscle cells highly branched at about every 8-10 residues Starch major form of stored carbohydrate in plants Structure-identical to glycogen-less branching at every residues Cellulose found in plants most abundant compound on earth cannot be digested by humans
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Lipids contain mostly C & H 1:2 ratio
also contain oxygen (less than carbohydrates) often have N, S & phosphorous hydrophobic do not dissolve in water neutral fats, phospholipids & steroids
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Lipid Functions structural components of biological membranes
cholesterol, phospholipids & glycolipids form & maintain intracellular structures energy reserves provide 2X as much energy as carbohydrates hormones & vitamins-steroids lipophilic bile acids important for lipid solubilization
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Lipids fatty acids-long-chain hydrocarbon molecules
composed of fatty acids & glycerol (an alcohol) fatty acids-long-chain hydrocarbon molecules hydrocarbon chains make lipids nonpolar and therefore insoluble in water fat synthesis involves attaching 3 fatty acid chains to one glycerol by dehydration synthesis-producing triglycerides glycerol is always the same; fatty acid composition varies length of neutral fat’s fatty acid chains & degree of saturation determine how solid a fat is at room temperature saturated fatty acids with no carbon to carbon double bonds unsaturated have double bonds monounsaturated fats have one unsaturated bond polyunsaturated fats have multiple unsaturated bonds double bonds make for lower melting points presence of unsaturated fatty acids makes fat liquid at room temperature
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Hydrolysis of Triglycerides
Hydrolysis breaks triglycerides fatty acid + glycerol
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Steroids large lipid molecules with carbon skeleton bent into 4 rings
most important one-cholesterol obtained by absorption from animal products in diet meat, cream & egg yolks can also be made by the body absolutely essential for life component of cell membranes raw material for Vitamin D, steroid hormones & bile salt synthesis needed to make steroid hormones such as estrogen & testosterone corticosteroids-essential for life
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Proteins C, H, O, N & small amounts of S & sometimes phosphorous
monomer-amino acids 1-7 amino acids-peptide up to 100-polypeptide more than 100- protein
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Proteins most abundant organic compound in human body
provide support for cells, tissues & organs and create a 3-D framework for body contractile proteins allow for movement via muscle contractions transport proteins carry insoluble lipids, respiratory gases & minerals in blood serve as buffers; help to prevent dangerous pH changes enzymes are proteins important in metabolic regulation speed rate of chemical reactions protein hormones coordinate, control & influence metabolic activities of nearly every cell important for defense skin, hair, & nails protect underlying tissues from environment antibodies protect from disease clotting proteins protect from from bleeding out
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Amino Acids 20 amino acids
(excluding proline) contain carboxylic acid-COOH & amino-NH2 or amine group functional groups are attached to same carbon atom R group attaches to same carbon amino acid is distinguished by its particular R-group 2 broad classes based upon whether R-groups-hydrophobic or hydrophilic hydrophobic repel aqueous environments reside predominantly in interior of proteins hydrophilic amino acids interact with aqueous environments & often form H-bonds found predominantly on exterior of proteins
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Protein Structure each protein contains unique sequence of amino acids
four levels of protein structure Primary Secondary Tertiary Quaternary
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Structure & Function structure determines function
shape of protein allows it to carry out specific duties protein whose job is to fill in a space (active site) on another molecule-globular in shape those that make up muscles or tendons-fibrous shapes depend on environmental characteristics ionic composition, pH & temperature non homeostatic change in any of these will denature protein denaturation causes protein to lose shape loss of shapecannot function properly
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Nucleic Acids largest, organic molecules in body
C, H, O, N, & phosphorous long stretches of nucleotides monomer for nucleic acids provide directions for building proteins RNA translates DNA code DNA contains genetic information that is inherited from our parents
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Nucleic Acids RNA DNA single polynucleotide chain double helix form
two polynucleotide chains wrapped around one another
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Nucleic Acids exist in mono-, di-, & tri-phosphorylated forms
often abbreviated to AMP Mono, Di- & tri-phosphorylated forms of adenosine are abbreviated AMP, ADP & ATP phosphate bonds are high energy bonds bonds contain energy broken-yield 7kcals ATP ADP + Pi + energy ATP is energy currency of all cells
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