2CHEMISTRY OF LIFEElements: simplest form of a substance - cannot be broken down any further without changing what it isAtom: the actual basic unit - composed of protons, neutrons, and electrons
3THE ATOMJust like cells are the basic unit of life, the ATOM is the basic unit of matter.They are very small. If placed side by side one million would stretch a distance of 1cm.The atom is made up of 3 particles.ParticleChargePROTON+NEUTRONNEUTRALELECTRON-
4ATOMIC MASS = 4 (PROTONS & NEUTRONS) Electrons are not present within the atom, instead THEY REVOLVE AROUND THE NUCELUS OF THE ATOM & FORM THE ELECTRON CLOUDDraw a helium atom. Indicate where the protons, neutrons and electrons are.NEUTRONSPROTONS-ATOMIC # = 2 (PROTONS)ATOMIC MASS = 4 (PROTONS & NEUTRONS)++ELECTRONS-
5ISOTOPESatoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONSSome isotopes are radioactive. This means that their nuclei is unstable and will break down at a CONSTANT RATE over time.There are several practical uses for radioactive isotopes:CARBON DATINGTRACERSKILL BACTERIA / CANCER CELLS
6COMPOUNDSa substance formed by the chemical combination of 2 or more elements in definite proportionsEx: water, salt, glucose, carbon dioxideH20CO2NaCl
7The cell is a COMPLEX CHEMICAL FACTORY containing some of the same elements found in the nonliving environment.carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) are present in the greatest percentages
8Inorganic - usually "support" life - no specific ratio of C, H, and O TWO TYPES OF COMPOUNDSOrganic - Contain C, H, and O in some ratio (usually referred to as chemicals of life)Carbohydrates, Proteins, Lipids, Nucleic AcidsInorganic - usually "support" life - no specific ratio of C, H, and OWater (H2O), Carbon Dioxide (CO2)
9CHEMICAL BONDS Chemical bonds hold the atoms in a molecule together. There are 2 types of chemical bonds IONIC and COVALENT
10IONIC BONDSOccur when 1 or more electrons are TRANSFERRED from one atom to another.When an atom loses an electron it is a POSITIVE charge.When an atom gains an electron it is a NEGATIVE chargeThese newly charged atoms are now called IONSExample: NaCl (SALT)
12COVALENT BONDS Occur when electrons are SHARED by atoms. These new structures that result from covalent bonds are called MOLECULES** In general, the more chemical bonds a molecule has the more energy it containsSHARING IS CARING!
13MIXTURESWater is not always pure. It is often found as part of a mixture.A mixture is a material composed of TWO OR MORE ELEMENTS OR COMPOUNDS THAT ARE PHYSICALLY MIXEDEx: salt & pepper mixed, sugar and sand – can be easily separated
14SOLUTIONTwo parts:SOLUTE – SUBSTANCE THAT IS BEING DISSOLVED (SUGAR / SALT)SOLVENT - the substance in which the solute dissolvesMaterials that do not dissolve are known as SUSPENSIONS.Blood is the most common example of a suspension.Cells & other particles remain in suspension.
15FORMULAThe chemical symbols and numbers that compose a compound ("recipe")Structural Formula – Line drawings of the compound that shows the elements in proportion and how they are bondedMolecular Formula – the ACTUAL formula for a compoundC2H6O
16ACIDS & BASESAcids: always (almost) begin with "H" because of the excess of H+ ions (hydrogen)Ex: lemon juice (6), stomach acid (1.5), acid rain (4.5), normal rain (6)Facts about AcidsAcids turn litmus paper BLUE and usually taste SOUR.You eat acids daily (coffee, vinegar, soda, spicy foods, etc…)
17ACIDS & BASESBases: always (almost) end with -OH because of the excess of hydroxide ions (Oxygen & Hydrogen)EX: oven cleaner, bleach, ammonia, sea water, blood, pure waterFacts about BasesBases turn litmus BLUE.Bases usually feel SLIPPERY to touch and taste BITTER.
18Neutralization Reactions When an acid reacts with a base to produce a salt and water.
19pH SCALE measures degree of substance alkalinity or acidity Ranges from 0 to 140 – 5 strong acid6-7 neutral8-14 strong base
20The goal of the body is to maintain HOMEOSTASIS (neutrality) – to do this when pH is concerned, we add weak acids & bases to prevent sharp changes in pH.These are called BUFFERS
21And now for the Biochemistry portion of things….
23CARBOHYDRATESLiving things use carbohydrates as a key source of ENERGY!Plants use carbohydrates for structure (CELLULOSE)include sugars and complex carbohydrates (starches)contain the elements carbon, hydrogen, and oxygen (the hydrogen is in a 2:1 ratio to oxygen)
24Monosaccharides (simple sugars) all have the formula C6 H12 O6all have a single ring structure(glucose is an example)
25Disaccharides (double sugars) all have the formula C12 H22 O11sucrose (table sugar) is an example
26Polysaccharides Formed of three or more simple sugar units Glycogen - animal starch stored in liver & musclesCellulose - indigestible in humans - forms cell wallsStarches - used as energy storage
27How are complex carbohydrates formed and broken down?
28Dehydration Synthesis Combining simple molecules to form a more complex one with the removal of waterex. monosaccharide + monosaccharide ----> disaccharide + water(C6H12O6 + C6H12O6 ----> C12H22O11 + H2OPolysaccharides are formed from repeated dehydration syntheses of waterThey are the stored extra sugars known as starch
30HydrolysisAddition of WATER to a compound to SPLIT it into smaller subunits(also called chemical digestion)ex. disaccharide + H2O ---> monosaccharide + monosaccharideC12 H22 O11 + H2 O ---> C6 H12 O6 + C6 H12 O6
32Lipids (Fats) Fats, oils, waxes, steroids Chiefly function in energy storage, protection, and insulationContain carbon, hydrogen, and oxygen but the H:O is not in a 2:1 ratioTend to be large molecules -- an example of a neutral lipid is below
33Neutral lipids are formed from the union of one glycerol molecule and 3 fatty acids 3 fatty acids + glycerol ----> neutral fat (lipid)Fats -- found chiefly in animalsOils and waxes -- found chiefly in plantsOils are liquid at room temperature, waxes are solidsLipids along with proteins are key components of cell membranesSteroids are special lipids used to build many reproductive hormones and cholesterol
34PROTEINS contain the elements carbon, hydrogen, oxygen, and nitrogen composed of MANY amino acid subunitsIt is the arrangement of the amino acid that forms the primary structure of proteins.The basic amino acid form has a carboxyl group on one end, a methyl group that only has one hydrogen in the middle, and a amino group on the other end.Attached to the methyl group is a R group.
35AN R GROUP IS ANY GROUP OF ATOMS – THIS CHANGES THE PROPERTIES OF THE PROTEIN!
36FUNCTIONAL GROUPSThere are certain groups of atoms that are frequently attached to the organic molecules we will be studying, and these are called functional groups.These are things like hydroxyl groups which form alcohols, carbonyl groups which form aldehydes or ketones, carboxyl groups which form carboxylic acids, and amino groups which form amines.
38Major Protein Functions Growth and repairEnergyBuffer -- helps keep body pH constant
39Dipeptide formed from two amino acid subunits Formed by the process of Dehydration Synthesisamino acid + amino acid dipeptide + water
40Hydrolysis of a dipeptide Breaking down of a dipeptide into amino acidsdipeptide + H2O ---> aminoacid + amino acid
41Polypeptide (protein) composed of three or more amino acids linked by synthesis reactionsExamples of proteins include insulin, hemoglobin, and enzymes.** There are an extremely large number of different proteins.The bases for variability include differences in the number, kinds and sequences of amino acids in the proteins
42NUCLEIC ACIDS in all cells composed of NUCLEOTIDES store & transmit heredity/genetic informationNucleotides consist of 3 parts:1. 5-Carbon Sugar2. Phosphate Group3. Nitrogenous Base
44DNA (deoxyribonucleic acid) contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteinsfound in the chromosomes of the nucleus (and a few other organelles)
45RNA (ribonucleic acid) directs cellular protein synthesisfound in ribosomes & nucleoli
46CHEMICAL REACTIONSa process that changes one set of chemicals into another set of chemicalsREACTANTS – elements or compounds that enter into a chemical reactionPRODUCTS – elements or compounds that are produced in a chemical reactionChemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products.
47In a reaction, energy is either TAKEN IN (ENDOTHERMIC) or GIVEN OFF (EXOTHERMIC) Can you think of an everyday example of each type of reaction?
48Enzymes and Enzyme Action catalyst: inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itselfenzymes: organic catalysts made of proteinmost enzyme names end in -aseenzymes lower the energy needed to start a chemical reaction. (activation energy)begin to be destroyed above 45øC. (above this temperature all proteins begin to be destroyed)
49It is thought that, in order for an enzyme to affect the rate of a reaction, the following events must take place.The enzyme must form a temporary association with the substance or substances whose reaction rate it affects. These substances are known as substrates.The association between enzyme and substrate is thought to form a close physical association between the molecules and is called the enzyme-substrate complex.While the enzyme-substrate complex is formed, enzyme action takes place.Upon completion of the reaction, the enzyme and product(s) separate. The enzyme molecule is now available to form additional complexes.
50How do enzymes work? substrate: molecules upon which an enzyme acts the enzyme is shaped so that it can only lock up with a specific substrate moleculeenzymesubstrate > product
51"Lock and Key Theory"each enzyme is specific for one and ONLY one substrate (one lock - one key)this theory has many weaknesses, but it explains some basic things about enzyme function
52Factors Influencing Rate of Enzyme Action 1. pH - the optimum (best) in most living things is close to 7 (neutral)high or low pH levels usually slow enzyme activityA few enzymes (such as gastric protease) work best at a pH of about 2.0
532. Temperature - strongly influences enzyme activity optimum temperature for maximum enzyme function is usually about C.reactions proceed slowly below optimal temperaturesabove 45 C most enzymes are denatured (change in their shape so the enzyme active site no longer fits with the substrate and the enzyme can't function)