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the study of the molecules that compose living organisms
– Carbohydrates
– Fats
– Proteins
– Nucleic acids |
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| simplest form of matter to have unique chemical properties |
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| of an element - number of protons in its nucleus |
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| – 24 elements have biological role |
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• 6 elements = 98.5% of body weight
– oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus
• trace elements in minute amounts |
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--Inorganic elements like Ca, P, Cl, Mg, K, Na, I, Fe, Zn, Cu, and S
– constitute about 4% of body weight
– structure (teeth, bones, etc)
– enzymes |
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| needed for nerve and muscle function are mineral salts |
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| of an element is equal to its total number of protons and neutrons |
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| clouds that surround the nucleus |
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in the outermost shell
• determine chemical bonding properties of an atom |
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varieties of an element that differ only in the number of neutrons
– same chemical behavior, differ in physical behavior
– breakdown (decay) to more stable isotope by giving off radiation |
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| unstable isotopes that give off radiation |
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| radioisotopes decay to stable isotopes releasing radiation |
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| transfer of electrons from one atom to another |
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| --Salts that ionize in water and form solutions capable of conducting an electric current |
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| Electrolytes important in |
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– chemical reactivity
– osmotic effects (influence water movement)
– electrical effects on nerve and muscle tissue
– Imbalances have ranging effects from muscle cramps, brittle bones, to coma and cardiac arrest |
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| – chemical particles composed of two or more atoms united in a chemical bond |
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| – molecules composed of two or more different elements |
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| molecules with identical molecular formulae but different arrangement of their atoms |
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| bonds – forces that hold molecules together, or attract one molecule to another |
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• The attraction of a positive ion(cation) to a negative ion.(anion)
• electron donated by one and received by the other
• Relatively weak attraction that is easily disrupted in water, dissolves |
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| One pair of electrons are shared |
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• shared electrons spend approximately equal time around each nucleus
• strongest of all bonds |
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| • if shared electrons spend more time orbiting one nucleus than they do the other, they lend their negative charge to the area they spend most time |
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a weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another.
• Water molecules are weakly attracted to each other by hydrogen bonds |
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consists of substances physically blended, but not chemically combined
• body fluids are complex mixtures of chemicals
– each substance maintains its own chemical properties
– Most mixtures in our bodies consist of chemicals dissolved or suspended in water
• Water 50-75% of body weight
– depends on age, sex, fat content, etc. |
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| • Water’s polar covalent bonds and its V-shaped molecule |
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| gives water a set of properties that account for its ability to support life. |
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ability to dissolve other chemicals
• water is called the Universal Solvent |
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– substances that dissolve in water
• molecules must be polarized or charged |
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substances that do not dissolve in water
• molecules are non-polar or neutral (fat)
• Virtually all metabolic reactions depend on the solvency of water |
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• Polar water molecules overpower the ionic bond in Na+ Cl-
– forming hydration spheres around each ion
– water molecules: negative pole faces Na+, positive pole faces Cl- |
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| – tendency of one substance to cling to another |
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tendency of like molecules to cling to each other
– water is very cohesive due to its hydrogen bonds |
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| on surface of water is due to molecules being held together by a force called surface tension |
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into H+ and OH-
– water ionizes other chemicals (acids and salts)
– water involved in hydrolysis and dehydration synthesis reactions
– Thermal Stability of Water |
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| the amount of heat required to raise the temperature of 1 g of a substance by 1 degree C. |
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the amount of heat that raises the temperature of 1 g of water 1 degree C.
• hydrogen bonds inhibit temperature increases by inhibiting molecular motion
• water absorbs heat without changing temperature very much |
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| 1 ml of perspiration removes 500 calories |
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| consists of particles of matter called the solute mixed with a more abundant substance (usually water) called the solvent |
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can be gas, solid or liquid
– solute particles do not scatter light
– will not separate on standing |
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• Most common colloids in the body are mixtures of protein and water
• Many can change from liquid to gel state within and between cells
– scatter light and are usually cloudy
– particles remain permanently mixed with the solvent when mixture stands |
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– defined by the following physical properties
• cloudy or opaque in appearance
• separates on standing |
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– suspension of one liquid in another
• fat in breast milk |
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| is proton donor (releases H+ ions in water) |
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is proton acceptor (accepts H+ ions)
– releases OH- ions in water |
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a measure derived from the molarity of H+
– a pH of 7.0 is neutral pH (H+ = OH-)
– a pH of less than 7 is acidic solution (H+ > OH-)
– a pH of greater than 7 is basic solution (OH- > H+ |
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on the pH scale represents a 10 fold change in H+ concentration
– a solution with pH of 4.0 is 10 times as acidic as one with pH of 5.0 |
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to resist changes in pH
– slight pH disturbances can disrupt physiological functions and alter drug actions
– pH of blood ranges from 7.35 to 7.45
– deviations from this range cause tremors, paralysis or even death
– pH Scale |
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capacity to do work
– to do work means to move something
– all body activities are a form of work |
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| energy contained in an object because of its position or internal state |
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| potential energy stored in the bonds of molecules |
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- energy of motion; energy that is actively doing work
– moving water flowing through a dam |
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| kinetic energy of molecular motion |
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| a process in which a covalent or ionic bond is formed or broken |
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symbolizes the course of a chemical reaction
– reactants (on left) ® products (on right) |
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| – classes of chemical reactions |
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– decomposition reactions
– synthesis reactions
– exchange reactions |
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| • Decomposition Reactions |
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• Large molecule breaks down into two or more smaller ones
• AB ® A + B |
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| • Two or more small molecules combine to form a larger one • A + B ® AB |
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• Two molecules exchange atoms or group of atoms
• AB+CD ® ABCD ® AC + BD |
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| reactions occur when molecules collide with enough force and the correct orientation |
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| • Reaction Rates affected by: |
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– concentration
• reaction rates increase when the reactants are more concentrated
– temperature
• reaction rates increase when the temperature rises |
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–substances that temporarily bond to reactants, hold them in favorable position to react with each other, and may change the shapes of reactants in ways that make them more likely to react.
• speed up reactions without permanent change to itself
• holds reactant molecules in correct orientation
• catalyst not permanently consumed or changed by the reaction |
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| most important biological catalysts |
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| All the chemical reactions of the body |
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– any chemical reaction in which a molecule gives up electrons and releases energy
– molecule oxidized in this process
– electron acceptor molecule is the oxidizing agent
• oxygen is often involved as the electron acceptor |
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– any chemical reaction in which a molecule gains electrons and energy
– molecule is reduced when it accepts electrons
– molecule that donates electrons is the reducing agent |
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| oxidation-reduction (redox) reactions |
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– oxidation of one molecule is always accompanied by the reduction of another
– Electrons are often transferred as hydrogen atoms |
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| • 4 categories of carbon compounds |
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– carbohydrates
– lipids
– proteins
– nucleotides and nucleic acids |
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| – binds with other atoms that can provide it with four more electrons to fill its valence shell |
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| – carbon atoms bind readily with each other – carbon backbones |
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– forms long chains, branched molecules and rings
– forms covalent bonds with hydrogen, oxygen, nitrogen, sulfur, and other elements |
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| carries a variety of functional groups |
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small clusters of atoms attached to carbon backbone
• determines many of the properties of organic molecules |
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very large organic molecules
– very high molecular weights
• proteins, DNA |
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| molecules made of a repetitive series of identical or similar subunits (monomers) |
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| an identical or similar subunits |
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| joining monomers to form a polymer |
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• Monomers covalently bond together to form a polymer with the removal of a water molecule
– A hydroxyl group is removed from one monomer and a hydrogen from the next |
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| • Hydrolysis--Splitting a polymer |
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(lysis) by the addition of a water molecule (hydro)
– a covalent bond is broken
– All digestion reactions consists of hydrolysis reactions |
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Carbohydrates
• hydrophilic organic molecule
• general formula
– (CH2O)n n = number of carbon atoms
– for glucose, n = 6, so formula is C6H12O6
– 2:1 ratio of hydrogen to oxygen |
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| • names of carbohydrates often built from |
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– word root ‘sacchar-’
– the suffix ’-ose’
– both mean ‘sugar’ or ‘sweet’
• monosaccharide or glucose
– Monosaccharides |
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– simple sugars
– 3 important monosaccharides
– glucose, galactose and fructose
– same molecular formula - C6H12O6
• isomers
– produced by digestion of complex carbohydrates
• glucose is blood sugar
• Disaccharides
• Sugar molecule composed of 2 monosaccharides |
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| • 3 important disaccharides |
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– sucrose - table sugar
• glucose + fructose
– lactose - sugar in milk
• glucose + galactose
– maltose - grain products
• glucose + glucose |
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| • 3 polysaccharides of interest in humans |
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– Glycogen: energy storage polysaccharide in animals
– Starch: energy storage polysaccharide in plants
• only significant digestible polysaccharide in the human diet
– Cellulose: structural molecule of plant cell walls
• fiber in our diet
• Glycogen |
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• quickly mobilized source of energy
– all digested carbohydrates converted to glucose
– oxidized to make ATP |
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| • • hydrophobic organic molecule |
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– composed of carbon, hydrogen and oxygen
– with high ratio of hydrogen to oxygen
– Less oxidized than carbohydrates, and thus has more calories/gram |
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| • Five primary types in humans (lipids) |
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– fatty acids
– triglycerides
– phospholipids
– eicosanoids
– steroids |
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| on one end, methyl group on the other and hydrogen bonded along the sides |
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| carbon atoms saturated with hydrogen |
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| contains C=C bonds without hydrogen |
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| – obtained from diet, body can not synthesize |
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| liquid at room temperature• often polyunsaturated fats from plants |
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solid at room temp.
saturated fat came from animals |
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| storage, insulation and shock absorption (adipose tissue) |
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• similar to neutral fat except that one fatty acid replaced by a phosphate group
• structural foundation
of cell membrane |
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– fatty acid “tails” are hydrophobic
– phosphate “head” is hydrophilic |
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| – role in inflammation, blood clotting, hormone action, labor contractions, blood vessel diameter |
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| a lipid with 17 of its carbon atoms in four rings |
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the ‘parent’ steroid from which the other steroids are synthesized
– cortisol, progesterone, estrogens, testosterone and bile acids
• Cholesterol
– synthesized only by animals
• especially liver cells
• 15% from diet, 85% internally synthesized
– important component of cell membranes
– required for proper nervous system function |
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high-density lipoprotein – “good” cholesterol
– lower ratio of lipid to protein
– may help to prevent cardiovascular disease |
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low-density lipoprotein – “bad” cholesterol
– high ratio of lipid to protein
– contributes to cardiovascular disease |
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| • Organic Molecules: Proteins |
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• Representative Amino Acids
• Note: they differ only in the R group
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| – any molecule composed of two or more amino acids joined by peptide bonds |
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joins the amino group of one amino acid to the carboxyl group of the next
– formed by dehydration synthesis
– Dipeptide Synthesis |
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| • (protein) Primary structure |
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| – protein’s sequence amino acid which is encoded in the genes |
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| (Protein)• Secondary structure |
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– coiled or folded shape held together by hydrogen bonds
– hydrogen bonds between slightly negative C=O and slightly positive N-H groups
– most common secondary structure are:
• alpha helix – springlike shape
• beta helix – pleated, ribbonlike shape |
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| – further bending and folding of proteins into globular and fibrous shapes |
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| compact tertiary structure well suited for proteins embedded in cell membrane and proteins that must move about freely in body fluid |
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| slender filaments better suited for roles as in muscle contraction and strengthening the skin |
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– associations of two or more separate polypeptide chains
– functional conformation – three dimensional shape |
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unique three dimensional shape of protein crucial to function
– ability to reversibly change their conformation
• enzyme function
• muscle contraction
• opening and closing of cell membrane pores |
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– extreme conformational change that destroys function
• extreme heat or pH
• Primary Structure of Insulin |
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tough structural protein
• gives strength to hair, nails, and skin surface |
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| durable protein contained in deeper layers of skin, bones, cartilage, and teeth |
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– some hormones and other cell-to-cell signals
– receptors to which signal molecules bind |
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| any hormone or molecule that reversibly binds to a protein |
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– channels in cell membranes that governs what passes through
– carrier proteins – transports solute particles to other side of membrane
– turn nerve and muscle activity on and off |
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| – Recognition and Protection |
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– immune recognition
– antibodies
– clotting proteins |
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| molecules with the ability to change shape repeatedly |
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– proteins bind cells together
– immune cells to bind to cancer cells
– keeps tissues from falling apart |
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proteins that function as biological catalysts
– permit reactions to occur rapidly at normal body temperature
– Substrate - substance an enzyme acts upon |
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– named for substrate with -ase as the suffix
• amylase enzyme digests starch (amylose) |
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| • Lowers activation energy |
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energy needed to get reaction started
– enzymes facilitate molecular interaction |
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| • Substrate binds to active site forming enzyme-substrate complex |
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| – highly specific fit –’lock and key’ |
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| one enzyme molecule can consume millions of substrate molecules per minute |
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| – Factors that change enzyme shape |
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– pH and temperature
– alters or destroys the ability of the enzyme to bind to substrate
– enzymes vary in optimum pH
• salivary amylase works best at pH 7.0
• pepsin works best at pH 2.0
– temperature optimum for human enzymes – body temperature (37 degrees C) |
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inorganic partners (iron, copper, zinc, magnesium and calcium ions)
– some bind to enzyme and induces a change in its shape, which activates the active site |
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– organic cofactors derived from water-soluble vitamins (niacin, riboflavin)
– they accept electrons from an enzyme in one metabolic pathway and transfer them to an enzyme in another |
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| single or double carbon-nitrogen ring) |
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| • Adenosine Triphosphate (ATP) |
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• body’s most important energy-transfer molecule
• briefly stores energy gained from exergonic reactions
• holds energy in covalent bonds
– 2nd and 3rd phosphate groups have high energy bonds ~
– most energy transfers to and from ATP involve adding or removing the 3rd phosphate |
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| – Adenosine triphosphatases (ATPases) |
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Definition
hydrolyze the 3rd high energy phosphate bond
– separates into ADP + Pi + energy
– Phosphorylation
– addition of free phosphate group to another molecule
– carried out by enzymes called kinases (phosphokinases)
• Sources and Uses of ATP |
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| • Overview of ATP Production |
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• ATP consumed within 60 seconds of formation
• entire amount of ATP in the body would support live for less
than 1 minute if it were not continually replenished
• cyanide halts ATP synthesis |
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| • Guanosine triphosphate (GTP) |
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Definition
– involved in energy transfer
– donates phosphate group to other molecules |
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| – Cyclic adenosine monophosphate (cAMP) |
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– cAMP becomes “second messenger” within cell
– activates metabolic effects inside cell |
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| • DNA (deoxyribonucleic acid) |
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• – constitutes genes instructions for synthesizing all of the body’s proteins
• transfers hereditary information from cell to cell and generation to generation |
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| • RNA (ribonucleic acid) – 3 types |
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– messenger RNA, ribosomal RNA, transfer RNA
– carries out genetic instruction for synthesizing proteins
– assembles amino acids in the right order to produce proteins |
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