biochemistry chapter 2 1. atoms and their interactions 2
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Elements Substances that cannot be broken down into simpler chemical substances 92 naturally occurring 25 essential to life 3TRANSCRIPT
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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