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IB BIOLOGY: Biochemistry Review

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electronegativity
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attraction of an atom for the electrons of a covalent bond
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hydrogen bond
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forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative ion (occurs between water molecules)
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polar molecule
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the opposite ends of the molecule have opposite charges
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cohesion
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bydrogen bonds hold substances together; attraction between molecules of the same substance
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adhesion
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clinging of one substance to another substance
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surface tension
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a measure of how difficult it is to stretch or break the surface of a liquid
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calorie
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the amount of heat energy it takes to raise the temperature of 1g of water by 1*C
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specific heat
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the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1*C
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heat of vaporization
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quantity of heat a liquid must absorb for 1g of it to be converted from liquid to gaseous state
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evaporative cooling
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occurs because the hottest molecules leave as gas and take heat with them (sweating)
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solution
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homogeneous mixture of 2 or more substances
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solvent
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dissolving agent of a solution
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solute
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substance dissolved in a solvent
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aqueous solution
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solution in which water is the solvent
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hydrophilic
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affinity for water
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hydrophobic
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substances with an aversion to water
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hydrogen ion
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single proton with charge of +1 H+
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hydroxide ion
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a water molecule that lost a proton OH-
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Acids
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substances that increase the hydrogen ion concentration of a solution
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bases
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substances that reduce the hydrogen ion concentration of a solution
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ph
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the negative log of the hydrogen ion concentration. acids and bases are on this scale
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buffers
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substances that minimize changes in the concentration of H+ and OH- in a solution
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organic chemistry
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study of carbon compounds
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hydrocarbons
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organic molecules consisting of only carbon and hydrogen
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isomers
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compounds that have the same molecular formula but different structures and hence different properties
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structural isomers
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isomers that differ in the covalent arrangement of their atoms
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geometric isomers
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isomers that have the same covalent partnership, but they differ in spatial arrangements
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enantiomers
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molecules that are mirror images of eachother
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functional groups
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the components of organic molecules most commonly involved in chemical reactions
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hydroxyl group
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hydrogen atom bonded to an oxygen atom. -OH
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alcohols
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organic compounds containing hydroxyl groups; usually end in -ol
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carbonyl group
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carbon atom joined to an oxygen atom by a double bond. =CO includes aldehydes and ketones
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aldehyde
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if the carbonyl group is on the end of a carbon skeleton
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ketone
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carbonyl group not on the end of the carbon skeleton
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carboxyl group
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COOH; oxygen atom double bonded to a carbon atom thats also bonded to a hydroxyl group
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carboxylic acids
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compounds containing carboxyl groups
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amino group
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-NH2; nitrogen atom bonded to 2 hydrogen atoms and to the carbon skeleton
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amines
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organic compounds with amino groups
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sulfhydryl group
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-SH; sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape
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thiols
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organic compounds containing sulfhydryls
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phosphate group
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formed by the dissociation of an inorganic acid called phosphoric acid. transfers energy between organic molecules; in DNA
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OH
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hydroxyl
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CO
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carbonyl
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COOH
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carboxyl
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NH2
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amino
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SH
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sulfhydryl
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PO4
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phosphate
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macromolecules
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large molecules; includes proteins, lipids, carbohydrates, and nucleic acids
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polymer
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a long molecule consisting of many similar or identical building blocks linked by covalent bonds
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monomer
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repeating units that serve as the building blocks of a polymer. smaller molecules
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enzymes
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specialized macromolecules that speed up chemical reactions
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dehydration reaction
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2 molecules are covalently bonded with each other with the loss of a water molecule
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hydrolysis
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a process that is the revers of dehydration synthesis; polymers are disassembled by adding water molecules
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carbohydrates
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include both sugars and polymers of sugars
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monosaccharides
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carbohydrates. generally have formulas that are some unit of CH2O. simple sugars. includes glucose
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disaccharides
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2 monosaccharides joined by glycosidic linkage
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glycosidic linkage
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a covalent bond formed between 2 monosaccharides by a dehydration reaction
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maltose
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glucose+glucose; disaccharide
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sucrose
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glucose+fructose; disaccharide
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fructose
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monosaccharide: combines with glucose to make sucrose
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lactose
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glucose+galactose; disaccharide
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galactose
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monosaccharide: combines with glucose to make lactose
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polysaccharides
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macromolecules; polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages
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starch
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a polymer of glucose monomers; sugar storage for plants. comes in amylose and amylopectin
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glycogen
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the polysaccharide stored by animals; is more branched than amylopectin
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cellulose
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major component of cell walls in plants; structural polysaccharide; most abundant compound on earth; is a polymer of glucose but the glycosidic linkages differ
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chitin
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a structural polysaccharide used by arthropods to build exoskeletons
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lipids
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hydrophobic molecules consisting mostly of hydrocarbon regions. includes fats, phospholipids, and steroids
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fat
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a molecule assembled from glycerol and fatty acids
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fatty acid
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has a long carbon skeleton; the carbon at one end is part of a carboxyl group, the rest is a hydrocarbon chain
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triglyceride
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a fat composed of 3 fatty acids linked to one glycerol
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saturated fatty acid
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fatty acid with NO double bonds between carbon atoms in the chain
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unsaturated fatty acid
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fatty acid with 1 or more double bonds in the chain
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trans fats
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unsaturated fats w/ trans double bonds
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phospholipids
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make up cell membranes. hydrophilic head and hydrophobic tail
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steroids
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lipids characterized by a carbon skeleton consisting of 4 fused rings
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cholesterol
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a crucial molecule in animals; common in cell membranes and a precursor from which other steroids are synthesized
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catalysts
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chemical agents that selectively speed up chemical reactions without being consumed by the reaction
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polypeptides
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polymers of amino acids
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protein
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biologically functional molecule that consists of one or more polypeptides, each folded and coiled into a specific 3D structure. has lots of functions
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amino acid
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organic molecule possessing amino group and carboxyl group
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peptide bond
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covalent bond by dehydration synthesis of amino acids
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globular proteins
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roughly spherical proteins. i.e. hemoglobin
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fibrous proteins
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long rope-like proteins. i.e. collagen or keratin
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primary structure
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a linked series of amino acids with a unique sequence
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secondary structure
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regions stabilized by hydrogen bonds between atoms of the polypeptide backbone. level of protein structure. local folding
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alpha helix
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delicate coil held together by hydrogen bonding. in secondary structure
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beta pleated sheet
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2 or more strands of the polypeptide chain lying side by side are connected by hydrogen bonds between parts of the 2 parallel polypeptide backbones. in secondary structure
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tertiary structure
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3D shape of protein is stabilized by interactions between side chains; distant folding; disulfide bridges. level of protein structure
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hydrophobic interaction
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amino acids w/ hydrophobic side chains end up in clusters at the core of a protein (out of contact with water)
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disulfide bridges
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occur in tertiary protein structure; covalent bonds that form where 2 cysteine monomers w/ sulfhydryl groups are brought close together by protein folding. further reinforces the shape of a protein
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quaternary structure
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level of protein structure. association of multiple polypeptides forming a functional protein
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denaturation
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an alteration in pH, salt concentration, temperature, etc. that causes the chemical bonds and interactions within a protein to be destroyed causing the protein to change shape
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gene
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consists of DNA; a unit of inheritance that is programmed to make polypeptides
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nucleic acids
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polymers made up of monomers called nucleotides
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deoxyribonucleic acid
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DNA; uses deoxyribose sugar; double helix; contains instructions for synthesis of RNA and proteins
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ribonucleic acid
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RNA; single strand; mRNA and tRNA. has ribose sugar
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nucleotides
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monomers of polynucleotides
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polynucleotides
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nucleic acid polymers
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pyrimidines
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cytosine, thymine, uracil
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purines
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adenine, guanine
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double helix
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2 strands that spiral around eachother
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antiparallel
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the 2 sugar phosphate backbones in DNA run in opposite 5′-3′ directions from each other
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CHON
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4 most common chemical elements of life
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sulfur
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S; plays a role in amino acids. element common in living matter
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phosphorus
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common element in living matter. plays a part in DNA as phosphate