Unit A.2 The Chemical Basis for Life. BEWARE! 11 Slides Until You Know Why.
-
Upload
kory-watson -
Category
Documents
-
view
214 -
download
1
Transcript of Unit A.2 The Chemical Basis for Life. BEWARE! 11 Slides Until You Know Why.
SECTION 2-1: THE NATURE OF SECTION 2-1: THE NATURE OF MATTERMATTER• REMEMBER from a long, long REMEMBER from a long, long
time ago…time ago…• Atoms are made up of electrons Atoms are made up of electrons
(-), neutrons (neutral), and (-), neutrons (neutral), and protons (+)protons (+)
• If the number of +s in the If the number of +s in the nucleus = the number of –s in nucleus = the number of –s in the electron shells the atom is the electron shells the atom is stable.stable.
• If not the atom wants to bond.If not the atom wants to bond.
BondsBonds
• Ionic bondIonic bond – when electrons – when electrons are transferred from one are transferred from one atom to anotheratom to another– Example NaClExample NaCl
• Covalent bondCovalent bond – electrons – electrons are shared between atomsare shared between atoms
– Example HExample H22OO
Bonds• All of what we do in this unit will
focus on different types of COVALENT BONDS
• Now let’s look at the difference between Polar and NON-Polar Covalent bonds.
SECTION 2-2: PROPERTIES OF SECTION 2-2: PROPERTIES OF WATERWATER• PolarityPolarity – uneven distribution of – uneven distribution of
electrons between the electrons between the hydrogen and oxygen atoms hydrogen and oxygen atoms – Oxygen is bigger and Oxygen is bigger and
attracts the electrons more attracts the electrons more than hydrogenthan hydrogen
• Hydrogen bondsHydrogen bonds – slightly – slightly positive, polar H atoms are positive, polar H atoms are attracted to polar negative attracted to polar negative atoms like Oatoms like O
• CohesionCohesion – attraction between – attraction between molecules of same substancemolecules of same substance– Water has high surface Water has high surface
tension (allows some bugs tension (allows some bugs to walk on water)to walk on water)
• AdhesionAdhesion - attraction between - attraction between molecules of different molecules of different substancessubstances– Capillary action (water Capillary action (water
moves up a straw along the moves up a straw along the sides)sides)
http://www.epa.gov/acidrain/education/site_students/phscale.html
LIFE’S BACKBONELIFE’S BACKBONE
• Most of the compounds that Most of the compounds that make up living things contain make up living things contain carboncarbon. .
• Carbon makes up the basic Carbon makes up the basic structure, or “backbone,” of structure, or “backbone,” of these compounds. these compounds.
• Each atom of carbon has four Each atom of carbon has four electrons in its outer energy electrons in its outer energy level, which makes it possible for level, which makes it possible for each carbon atom to form each carbon atom to form four four bonds bonds with other atoms. with other atoms.
SECTION 2-3: CARBON SECTION 2-3: CARBON COMPOUNDSCOMPOUNDS• Organic compoundsOrganic compounds- chemical - chemical
compounds that contain carbon compounds that contain carbon • Chemical FormulasChemical Formulas - show how - show how
many and which types of atoms many and which types of atoms are in a compound are in a compound (C(C66HH1212OO66))
• Structural FormulasStructural Formulas - show the - show the arrangement of the atoms in a arrangement of the atoms in a compoundcompound
• IsomersIsomers - compounds with - compounds with the same chemical formula, the same chemical formula, but different structure (ex. but different structure (ex. propanol and isopropanol)propanol and isopropanol)
COVALENT BOND #’SCOVALENT BOND #’S
•Atoms want to fill their Atoms want to fill their electron shells. An atom electron shells. An atom wants to make just wants to make just enough bonds to fill its enough bonds to fill its shells.shells.
•H (white) makes one bondH (white) makes one bond•O (red) makes two bondsO (red) makes two bonds•C (black) makes four bondsC (black) makes four bonds
The Big 4 Biological MoleculesThe Big 4 Biological Molecules
•What are they?What are they?–Carbohydrates Carbohydrates –LLipidsipids–Proteins Proteins –Nucleic acidsNucleic acids
• We’ll learn about them one at a time.We’ll learn about them one at a time.
CARBOHYDRATESCARBOHYDRATES
•Organic Organic compounds compounds composed of composed of carboncarbon, , hydrogenhydrogen and and oxygenoxygen with a with a ratio of two hydrogen atoms ratio of two hydrogen atoms to every one oxygen atomto every one oxygen atom
• Building blocks are called Building blocks are called ““monosaccharidesmonosaccharides” aka ” aka simple sugarssimple sugars
USE OF CARBOHYDRATESUSE OF CARBOHYDRATES
• Source of energy for Source of energy for many living things many living things
• Also used to build body Also used to build body structuresstructures
• Examples: Examples: sugarsugar and and starchstarch, , cellulosecellulose, , glycogenglycogen, and , and chitinchitin
3 TYPES OF CARBOHYDRATES3 TYPES OF CARBOHYDRATES
• MonosaccharidesMonosaccharides
• DisaccharidesDisaccharides
• PolysaccharidesPolysaccharides
MONOSACCHARIDESMONOSACCHARIDES
• Only one sugar moleculeOnly one sugar molecule
• Examples -Examples -glucoseglucose, fructose, , fructose, andand galactose galactose
• All three are All three are CC66HH1212OO66, but , but
they are isomersthey are isomers
• Draw GlucoseDraw Glucose
DISACCHARIDESDISACCHARIDES
• Double sugars (two Double sugars (two monosaccharides combined) monosaccharides combined)
• Examples: sucrose, lactose, and Examples: sucrose, lactose, and maltose maltose
• All are isomers with the chemical All are isomers with the chemical formula formula CC1212HH2222OO1111
POLYSACCHARIDESPOLYSACCHARIDES• Long chains of Long chains of
monosaccharides joined monosaccharides joined together together
• Examples: Examples: starchstarch, , glycogenglycogen, , and and cellulosecellulose
• PlantsPlants store excess sugar store excess sugar as as starchstarch, and break it down , and break it down for energyfor energy
Representation of a Polysaccharide
• HumansHumans store excess store excess sugar as sugar as glycogenglycogen, & , & break it down for energy break it down for energy
• CelluloseCellulose used by used by plants plants for structural purposes.for structural purposes.
DEHYDRATION SYNTHESISDEHYDRATION SYNTHESIS
• Two molecules join together Two molecules join together by losing a molecule of by losing a molecule of water water
HYDROLYSIS REACTIONHYDROLYSIS REACTION
• Larger molecules broken Larger molecules broken down into smaller down into smaller moleculesmolecules
by theby the
addition addition
of water of water
LIPIDSLIPIDS
• Include Include fatsfats, , oilsoils, , steroidssteroids & & waxeswaxes
• Composed of carbon, Composed of carbon, hydrogen and oxygen, but hydrogen and oxygen, but the # of H atoms per the # of H atoms per molecule is much greater molecule is much greater than the # of O atoms than the # of O atoms
• An example, An example, CC5757HH110110OO66
USES OF LIPIDSUSES OF LIPIDS• Stored for energy Stored for energy • Form basic structure of cell Form basic structure of cell
membranesmembranes• Protection Protection • Insulation Insulation • Waterproof coveringsWaterproof coverings
THE STRUCTURE OF SOME IMPORTANT THE STRUCTURE OF SOME IMPORTANT FATSFATS
• Built from 2 basic molecules: Built from 2 basic molecules:
–GlycerolGlycerol - an alcohol - an alcohol –Fatty AcidsFatty Acids - a long carbon - a long carbon
chain with a -COOH chain with a -COOH (carboxyl group) at one end(carboxyl group) at one end
Phospholipid StructurePhospholipid Structure•
http://library.tedankara.k12.tr/chemistry/vol5/polarity%20and%20activity/z247.htm
• Different types of fatty acids: Different types of fatty acids: –SaturatedSaturated - all single, covalent - all single, covalent
bonds in between carbons in bonds in between carbons in chain chain
–UnsaturatedUnsaturated - one double bond - one double bond between carbons in chainbetween carbons in chain
–PolyunsaturatedPolyunsaturated - many - many double bonds between double bonds between carbons in chaincarbons in chain
• CholesterolCholesterol - another lipid, - another lipid, made by animals, both made by animals, both helpful & harmful helpful & harmful
PROTEINPROTEIN
• Made up of Made up of amino acids amino acids linked togetherlinked together
• Composed of Composed of CC, , HH, & , & OO as as well as nitrogen, well as nitrogen, NN, and , and possibly sulfur, possibly sulfur, SS..
USES OF PROTEINSUSES OF PROTEINS
• buildbuild living materials like living materials like musclemuscle
• act as act as enzymesenzymes to help carry to help carry out chemical reactionsout chemical reactions
• fightfight disease disease• transporttransport particles into or out particles into or out
of cellsof cells• act as act as markersmarkers on cells on cells
• Each has same basic structure Each has same basic structure with the only difference being with the only difference being the “R” group the “R” group
• Amino acids are linked by Amino acids are linked by peptide bonds (formed by peptide bonds (formed by dehydration synthesis) dehydration synthesis)
Essential Amino Acids
There are 20 main amino acids
• Peptide bondPeptide bond is between two is between two amino acids amino acids
• PolypeptidePolypeptide – (a protein) – (a protein) many amino acids joined many amino acids joined
Nucleic AcidsNucleic Acids• Nucleic Acids are molecules that Nucleic Acids are molecules that
are used for the storage of energy are used for the storage of energy or information.or information.
• Some examples of Nucleic Acids Some examples of Nucleic Acids are DNA (deoxyribonucleic acid), are DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and ATP RNA (ribonucleic acid), and ATP (adenosine triphosphate)(adenosine triphosphate)
• Nucleic Acids are made of Nucleic Acids are made of monomers called NUCLEOTIDES.monomers called NUCLEOTIDES.
SECTION 2-4: CHEMICAL REACTIONSSECTION 2-4: CHEMICAL REACTIONS
• Chemical reactions always Chemical reactions always involve breaking bonds in involve breaking bonds in reactantsreactants and making bonds in and making bonds in productsproducts
• Some reactions release energySome reactions release energy and therefore usually occur and therefore usually occur spontaneouslyspontaneously
• Other reactions need energy to Other reactions need energy to happenhappen
• Activation energyActivation energy – the – the minimum amount of energy minimum amount of energy needed to start a reactionneeded to start a reaction
• Enzymes Enzymes are catalysts which are catalysts which speed up chemical reactionsspeed up chemical reactions
• EnzymesEnzymes are are proteinsproteins that that lowerlower activation energyactivation energy and and allow reactions to occur at allow reactions to occur at normal temperatures normal temperatures
Reaction pathwaywith enzyme
Reaction pathwaywithout enzyme
Activation energywithout enzyme
Activation energywith enzyme
• Each enzyme is specific and Each enzyme is specific and has a specific shape has a specific shape
• Enzymes are not Enzymes are not permanently changed and permanently changed and are not used up in the are not used up in the reactionreaction
• They are continuously They are continuously recycled! recycled!
• Most enzymes end in Most enzymes end in --asease
• Reactants are called Reactants are called substratessubstrates
EnzymesEnzymes
•The area where the enzyme The area where the enzyme interacts is called the interacts is called the active siteactive site•Think of the substrate as a flexible Think of the substrate as a flexible key that must fit into the active sitekey that must fit into the active site
http://images.google.com/imgres?imgurl=http://www.phschool.com/science/biology_place/labbench/lab2/images/indfit.gif&imgrefurl=http://phschool.com/science/biology_place/labbench/lab2/induced.html&h=160&w=240&sz=39&hl=en&start=5&tbnid=t6KasPuPLl37wM:&tbnh=73&tbnw=110&prev=/images%3Fq%3Denzyme%2Bsubstrate%2Banimations%26svnum%3D10%26hl%3Den%26lr%3D%26safe%3Dactive
Enzyme
Substrates
Active site
Products
http://imglib.lbl.gov/ImgLib/COLLECTIONS/BERKELEY-LAB/RESEARCH-1991-PRESENT/MATERIALS-SCIENCE/images/96703439.lowres.jpeg