BiochemistryChapter 2

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Atoms and their interactions

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Elements Substances that cannot be broken down into simpler chemical substances92 naturally occurring 25 essential to life

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Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) 96% of human bodyTrace elements present in small amounts Iron, magnesium, iodine

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Atoms Smallest particle of an element that has the characteristics of that elementNucleus central portion Protons positive charge Neutrons no charge

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Atoms cont.Electron cloud surrounds the nucleus Negative charge Travel in energy levels 1st level 2e- 2nd level 8e- 3rd level 8e- (18e- total)Most atoms have equal numbers of protons and electrons no net charge

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Isotopes Atoms of the same element containing different numbers of neutronsEffects mass only (not charge)Some are unstable radioactive

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Carbon 12 6p and 6nCarbon 14 6 p and 8n

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Compounds and bonding

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CompoundComposed of atoms of 2 or more different elements that are chemically combinedWater H2OBonding occurs between atoms to reach stabilityStability = outermost energy level is full

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Covalent bonding sharing e-

H2O: O 6e- in 2nd level H 1e- in 1st levelMost compounds in living organisms have covalent bonds strong

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Hydrogen gas covalent bond

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Ionic bonding gaining or losing e-

Produces ions charged particlesNaCl: Na 1e- in 3rd level Cl 7e- in 3rd level

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How an ionic bond forms

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Chemical reactionsBreaking and forming bondsAtoms are rearranged to form new substancesMetabolism all the chemical reactions in an organism

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Chemical reactions cont.Represented by chemical equations2H2 + O2 2H2O2H2 + O2 are the reactants2H2O is the productThe numbers of each atom must be = on each side of the equation

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Mixtures and solutions

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Mixture Combination of substances that each retain their own propertiesCan easily be separatedSalt and iron

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Solution 1 or more substances (solutes) are distributed equally in another (solvent)Cannot easily be separatedKool-Aid sugar dissolved in water

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Acids and basesThe pH scale

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Water and diffusion

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The importance of waterEssential for most life processesUniversal solventMeans of transport

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Polarity unequal distribution of charge

e- not shared equally positive and negative ends to a moleculePolar molecules attract other polar molecules and ions (opposites attract)

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Polarity continued Form weak hydrogen bonds

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Cohesion water molecules stick together

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Surface Tension

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Adhesion water sticks to other molecules

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Capillary action water creeps up thin tubes

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Water resists temperature changes

Requires a lot of heat to increase water temperatureInsulator helps maintain homeostasisExpands when freezes ice is less dense than water and floats

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Diffusion Movement of particles from an area of high concentration to an area of lower concentration

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Diffusion continuedDue to random movement of all molecules slowContinues until equilibrium is reached equal concentration on each side

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Diffusion cont.Concentration gradient difference in concentration No energy required to move with the

gradient

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Rate is affected by

Concentration higher concentration of molecules = faster diffusion

Temperature higher temperatures = faster diffusion

Pressure higher pressure = faster diffusion

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Life substances

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Role of carbon organic compounds (C-H bonds)

Can form 4 different bonds versatile Straight chains, branched chains,

rings Any number of C atoms infinite

number of structures

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Isomersame formula, different structures

C6H12O6

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Role of carbon cont.Polymers long chains of repeating units

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Polymer productionMade from smaller molecules bonded together by the removal of water dehydration synthesis

Hydrolysis breaking apart polymers by adding water

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Opposite ReactionsDehydration Synthesis Hydrolysis

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Carbohydrates C:H:O in a 1:2:1 ratio

Used to store and release energyMonosaccharides simple sugars Building blocks of carbs Glucose C6H12O6

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Forms of glucoseLinear (dry) form Ring (dissolved) form

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Disaccharides 2 monosaccharides linked together Glucose + glucose maltose

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Carbs cont.Polysaccharides polymers of monosaccharides Used for food storage Starch (plants), glycogen (animals),

and cellulose

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Lipids CHOLess O than carbsUsed for energy storage, insulation, protection, cell membrane components

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Nonpolar insoluble in waterBuilding blocks 3 fatty acids and 1 glycerol moleculeFats, oils, and waxes

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Lipids cont.Saturated fats C-C bonds are single Maximum amount of H Solid at room temperature Increase cholesterol levels

cardiovascular disease

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A saturated fat no C=C in tails

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Unsaturated fats some C-C double bonds Liquid at room temperature Plant products Hydrogenation converting

unsaturated to saturated by adding hydrogen

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An unsaturated fat at least 1 C=C in tails

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Proteins CHONUsed for tissue structure and cell metabolismBuilding blocks amino acids Humans need 20 different amino

acids Held together by peptide bonds

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Proteins cont.Number and order of amino acids determines the protein Each protein has a specific 3-D shape Shape determines function Denaturation changing the shape of

a protein impairs it’s function

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Proteins cont.Enzymes protein catalysts that change the rates of chemical reactions, but are not changed themselves

Most reactions will occur without enzymes, but at a slower rate

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Highly specific 1 enzyme per substrate

Lock and key model enzyme and substrate fit together precisely to form an enzyme-substrate complex

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Factors affecting enzyme action:

Concentrations of enzyme and substrateTemperature 37oC (human body temp.)pH of environmentHomeostasis must be maintained in order for enzymes to function

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Nucleic acids DNA and RNA

Store cellular information in code formBuilding blocks nucleotides 5-C sugar Nitrogenous base Phosphate group

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DNA deoxyribonucleic acid

Double helix structure Watson and CrickSugar is deoxyriboseBases: cytosine, guanine, adenine, thymine

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RNA ribonucleic acid

Single strandSugar is riboseBases: cytosine, guanine, adenine, uracil

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The End!!

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