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SAT II Biology – Biochemistry

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Atom
Atom
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Consists of: Protons (positively charged) and Neutrons (no charge) in the nucleus, electrons (negatively charged) outside the nucleus.
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ground state
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electrons in the lowest available energy level
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isotopes
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Atoms of one element that vary in the number of neutrons. Example: Carbon-12 and Carbon-14 are isotopes
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radioisotopes
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radioactive isotopes
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half-life
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the rate at which radioisotopes decay
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ionic bonds
ionic bonds
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bonds that form when electrons are transferred.
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anion
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an atom that gains electrons
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cation
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an atom that loses electrons
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molecule
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a group of two or more atoms held together by chemical bonds.
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covalent bond
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bonds that form when electrons are shared
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polarity
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the unequal distribution of charges on a molecule
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nonpolar covalent bonds
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Bonds where electrons are shared equally. They are formed between any two atoms that are alike.
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polar covalent bonds
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Bonds where electrons are shared unequally. They are formed between any two atoms that are unalike.
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hydrogen bonds
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Weak bondsbetween the negative side of the water molecule oxygen and the positive side that the hydrogens create; bonds that hold water molecules together and result in high specific heat; good solvent properties and cohesion that results in surface tension. Keeps strands of DNA bonded together forming the double helix
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Nonpolar molecules
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weak attractions such as Van der Waals. Carbon Dioxide is a nonpolar molecule
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hydrophobic
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“water hating” Nonpolar molecules are hydrophobic and do not dissolve in water.
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hydrophilic
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“water loving” polar molecules are hydrophilic and dissolve in water.
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Characteristics of Water
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1. Water has a high specific heat 2. water has a high heat of vaporization 3. water has high adhesion properties 4. Water is the universal solvent 5. Water has strong cohesion tension (transpirational pull) 6. Ice floats because it is less dense than water
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adhesion
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the clinging of one substance to another
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cohesion tension
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molecules of water tend to stick to each other
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capillary action
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the force of water rising in a thin tube due to cohesion and adhesion
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mixture
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a material that is composed of two or more substances that are physically combined
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heterogeneous mixture
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the different substances can be seen and separated out
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homogenous mixture
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the different substances are evenly mixed and cannot be separated easily
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solution
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is a homogenous mixture that appears to be a single substance but is composed of particles of two or more substances that are distributed evenly amongst each other.
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solute
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the substance that is dissolved
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solvent
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the substance in which the solute is dissolved
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pH
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a measure of acidity and alkalinity (basic) of a solution
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buffers
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substances that resist change in pH
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acidic
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a solution that has a greater amount of H+ than OH- ions
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basic
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a solution that has a greater amount of OH- than H+
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macromolecules
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Four main classes of large biological molecules (carbohydrates, lipids, proteins, nucleic acids) made up of many smaller molecules and atoms.
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monomers
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small chemical units that can join together with other small units to form larger units called polymers
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polymers
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Large compounds formed from combinations of many monomers.
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organic compounds
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Compounds that contain carbon atoms and are found in living things.
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inorganic compounds
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Compounds that do not contain carbon; many are also essential to life.
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isomers
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compounds with the same molecular formula, but with different structures. Example: glucose, galactose, fructose
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monosaccharides
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monomer of carbohydrates Have chemical formula of C6H12O6. Examples: glucose, galactose, fructose.
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disaccharides
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All have the chemical forumla C12H22O11. They consist of 2 monosaccharides joined by a process known as the Dehydration synthesis
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maltose
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Glucose + Glucose
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lactose
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Glucose + Galactose
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sucrose
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Glucose + Fructose
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hydrolysis
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opposite of dehydration synthesis, the breakdown of a compound with the addition of water
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polysaccharides
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polymers of carbohydrates Examples: cellulose, chitin, starch, glycogen
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cellulose
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polysaccharide that makes up plant cell walls
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starch
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the way plants store carbohydrates
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chitin
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polysaccharide that makes the exoskeleton in arthropods and the cell walls of mushrooms
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glycogen
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the way animals store starch. Stored in humans in the liver and skeletal muscle.
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lipids
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class of organic compounds that include fats, oils, and waxes. usually made up of one glycerol and three fatty acids
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saturated fatty acids
saturated fatty acids
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Contain only single bonds between carbon atoms. Come from animals, solid at room temperature, linked to heart disease.
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unsaturated fatty acids
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Have at least one double bond between carbon atoms and the hydrocarbon chain. Are extracted from plants, are liquid at room temperature.
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Lipid Functions
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1. energy storage 2. phospholipids make up cell membrane 3. some lipids are endocrine hormones
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Steroids
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Fashioned on a backbone of four linked carbon rings and include cholesterol and hormones (testosterone, estrogen).
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proteins
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macromolecules containing carbon, hydrogen, oxygen and nitrogen; proteins are considered the building blocks of tissue
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amino acids
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building blocks (monomers) of proteins; twenty kinds
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Amino group
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-NH2
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Carboxyl group
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-COOH
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R-group
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used to represent one of 20 possible side chains found in amino acids of living systems, “variable group”
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polypeptides
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repeating units of amino acids
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peptide bonds
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bonds between amino acids, form polypeptides
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dipeptide
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two amino acids combined
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Primary structure proteins
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the order of amino acids in a protein
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Secondary structure proteins
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the three dimensional shape that results from the hydrogen bonding between the amino and carboxyl groups of adjacent amino acids
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tertiary structure proteins
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additional three dimensional shaping of a protein that dominates the structure of globular proteins
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Quaternary structure proteins
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The particular shape of a complex protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide.
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enzymes
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a chemical that speeds up chemical reactions within a living cell
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coenzyme
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a small molecule (not a protein but sometimes a vitamin) essential for the activity of some enzymes
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cofactor
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Any organic or inorganic substance that is needed for the operation of an enzyme.
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energy of activation
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the amount of energy needed to begin a reaction
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substrate
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the chemical that an enzyme works on
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induced-fit model
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describes how enzymes work, As the substrate enters the active site, it induces the enzyme to alter its shape slightly so the substrate fits better
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denaturation
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when proteins lose their natural shape due to change in temperature or pH
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prions
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A misfolded, infectious protein that are normally found in the brains of mammals and cause several brain diseases. (Mad Cow)
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nucleic acids
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macromolecules containing hydrogen, oxygen, nitrogen, carbon and phosphorus and are associated with organism’s genetic code
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nucleotides
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building blocks (monomers) of nucleic acids
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DNA
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Deoxyribonucleic Acid. Double stranded chain. Deoxygenated (deoxyribose) 5 carbon sugar.
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RNA
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Ribonucleic Acid. Single stranded chain. Oxygenated (ribose), 5 carbon sugar.
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biochemistry
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Chemistry of life, the study of chemical substances and reactions within living organisms.
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alpha helix
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A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure.
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beta sheet
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secondary structure of proteins with a pleated, ribbonlike shape