Unit A.2 The Chemical Basis for Life

BEWARE! 11 Slides Until You Know Why

SECTION 2-1: THE NATURE OF MATTER REMEMBER from a long, long time ago…REMEMBER from a long, long time ago… Atoms are made up of electrons (-), neutrons (neutral), and protons (+)Atoms are made up of electrons (-), neutrons (neutral), and protons (+) If the number of +s in the nucleus = the number of –s in the electron shells the atom is stable.If the number of +s in the nucleus = the number of –s in the electron shells the atom is stable. If not the atom wants to bond.If not the atom wants to bond.

Bonds Ionic bond – when electrons are transferred from one atom to anotherIonic bond – when electrons are transferred from one atom to another –Example NaCl Covalent bond – electrons are shared between atomsCovalent bond – electrons are shared between atoms –Example H 2 O

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.

BEWARE! 7 Slides Until You Know Why

SECTION 2-2: PROPERTIES OF WATER Polarity – uneven distribution of electrons between the hydrogen and oxygen atomsPolarity – uneven distribution of electrons between the hydrogen and oxygen atoms –Oxygen is bigger and attracts the electrons more than hydrogen Hydrogen bonds – slightly positive, polar H atoms are attracted to polar negative atoms like OHydrogen bonds – slightly positive, polar H atoms are attracted to polar negative atoms like O

Cohesion – attraction between molecules of same substanceCohesion – attraction between molecules of same substance –Water has high surface tension (allows some bugs to walk on water) Adhesion - attraction between molecules of different substancesAdhesion - attraction between molecules of different substances –Capillary action (water moves up a straw along the sides)

LIFE’S BACKBONE Most of the compounds that make up living things contain carbon.Most of the compounds that make up living things contain carbon. Carbon makes up the basic structure, or “backbone,” of these compounds.Carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms.Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms.

Carbon Backbone From this guy!!! And why is he called the cigarette snail?

SECTION 2-3: CARBON COMPOUNDS Organic compounds- chemical compounds that contain carbonOrganic compounds- chemical compounds that contain carbon Chemical Formulas - show how many and which types of atoms are in a compound (C 6 H 12 O 6 )Chemical Formulas - show how many and which types of atoms are in a compound (C 6 H 12 O 6 ) Structural Formulas - show the arrangement of the atoms in a compoundStructural Formulas - show the arrangement of the atoms in a compound

Isomers - compounds with the same chemical formula, but different structure (ex. propanol and isopropanol)Isomers - compounds with the same chemical formula, but different structure (ex. propanol and isopropanol)

COVALENT BOND #’S Atoms want to fill their electron shells. An atom wants to make just enough bonds to fill its shells.Atoms want to fill their electron shells. An atom wants to make just enough bonds to fill its 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 Molecules What are they?What are they? –Carbohydrates –Lipids –Proteins –Nucleic acids We’ll learn about them one at a time.We’ll learn about them one at a time.

CARBOHYDRATES Organic compounds composed of carbon, hydrogen and oxygen with a ratio of two hydrogen atoms to every one oxygen atomOrganic compounds composed of carbon, hydrogen and oxygen with a ratio of two hydrogen atoms to every one oxygen atom Building blocks are called “monosaccharides” aka simple sugarsBuilding blocks are called “monosaccharides” aka simple sugars

USE OF CARBOHYDRATES Source of energy for many living thingsSource of energy for many living things Also used to build body structuresAlso used to build body structures Examples: sugar and starch, cellulose, glycogen, and chitinExamples: sugar and starch, cellulose, glycogen, and chitin

Chitin!

3 TYPES OF CARBOHYDRATES MonosaccharidesMonosaccharides DisaccharidesDisaccharides PolysaccharidesPolysaccharides

MONOSACCHARIDES Only one sugar moleculeOnly one sugar molecule Examples -glucose, fructose, and galactoseExamples -glucose, fructose, and galactose All three are C 6 H 12 O 6, but they are isomersAll three are C 6 H 12 O 6, but they are isomers Draw GlucoseDraw Glucose

DISACCHARIDES Double sugars (two monosaccharides combined)Double sugars (two monosaccharides combined) Examples: sucrose, lactose, and maltoseExamples: sucrose, lactose, and maltose All are isomers with the chemical formula C 12 H 22 O 11All are isomers with the chemical formula C 12 H 22 O 11

POLYSACCHARIDES Long chains of monosaccharides joined togetherLong chains of monosaccharides joined together Examples: starch, glycogen, and celluloseExamples: starch, glycogen, and cellulose Plants store excess sugar as starch, and break it down for energyPlants store excess sugar as starch, and break it down for energy

Representation of a Polysaccharide

Humans store excess sugar as glycogen, & break it down for energyHumans store excess sugar as glycogen, & break it down for energy Cellulose used by plants for structural purposes.Cellulose used by plants for structural purposes.

DEHYDRATION SYNTHESIS Two molecules join together by losing a molecule of waterTwo molecules join together by losing a molecule of water

HYDROLYSIS REACTION Larger molecules broken down into smaller moleculesLarger molecules broken down into smaller molecules by the by the addition addition of water

Lipids

LIPIDS Include fats, oils, steroids & waxesInclude fats, oils, steroids & waxes Composed of carbon, hydrogen and oxygen, but the # of H atoms per molecule is much greater than the # of O atomsComposed of carbon, hydrogen and oxygen, but the # of H atoms per molecule is much greater than the # of O atoms An example, C 57 H 110 O 6An example, C 57 H 110 O 6

Other examples

USES OF LIPIDS Stored for energyStored for energy Form basic structure of cell membranesForm basic structure of cell membranes ProtectionProtection InsulationInsulation Waterproof coveringsWaterproof coverings

THE STRUCTURE OF SOME IMPORTANT FATS Built from 2 basic molecules:Built from 2 basic molecules: –Glycerol - an alcohol –Fatty Acids - a long carbon chain with a -COOH (carboxyl group) at one end

Triglyceride Structure

Phospholipid Structure

Different types of fatty acids:Different types of fatty acids: –Saturated - all single, covalent bonds in between carbons in chain –Unsaturated - one double bond between carbons in chain

–Polyunsaturated - many double bonds between carbons in chain Cholesterol - another lipid, made by animals, both helpful & harmfulCholesterol - another lipid, made by animals, both helpful & harmful

Proteins Yaw dis is aboout da Proteens !

PROTEIN Made up of amino acids linked togetherMade up of amino acids linked together Composed of C, H, & O as well as nitrogen, N, and possibly sulfur, S.Composed of C, H, & O as well as nitrogen, N, and possibly sulfur, S.

USES OF PROTEINS build living materials like musclebuild living materials like muscle act as enzymes to help carry out chemical reactionsact as enzymes to help carry out chemical reactions fight diseasefight disease transport particles into or out of cellstransport particles into or out of cells act as markers on cellsact as markers on cells

Alanine Serine General Structure

Each has same basic structure with the only difference being the “R” groupEach has same basic structure with the only difference being the “R” group Amino acids are linked by peptide bonds (formed by dehydration synthesis)Amino acids are linked by peptide bonds (formed by dehydration synthesis) Essential Amino Acids There are 20 main amino acids

Peptide bond is between two amino acidsPeptide bond is between two amino acids Polypeptide – (a protein) many amino acids joinedPolypeptide – (a protein) many amino acids joined

Amino acids

Nucleic Acids

Nucleic Acids are molecules that are used for the storage of energy or information.Nucleic Acids are molecules that are used for the storage of energy or information. Some examples of Nucleic Acids are DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and ATP (adenosine triphosphate)Some examples of Nucleic Acids are DNA (deoxyribonucleic acid), RNA (ribonucleic acid), and ATP (adenosine triphosphate) Nucleic Acids are made of monomers called NUCLEOTIDES.Nucleic Acids are made of monomers called NUCLEOTIDES.

Nucleotides

Nucleotides

DNA 3DDNA 3DDNA 3DDNA 3D

MATTER AND ENERGY

SECTION 2-4: CHEMICAL REACTIONS Chemical reactions always involve breaking bonds in reactants and making bonds in productsChemical reactions always involve breaking bonds in reactants and making bonds in products Some reactions release energy and therefore usually occur spontaneouslySome reactions release energy and therefore usually occur spontaneously Other reactions need energy to happenOther reactions need energy to happen

Activation energy – the minimum amount of energy needed to start a reactionActivation energy – the minimum amount of energy needed to start a reaction Enzymes are catalysts which speed up chemical reactionsEnzymes are catalysts which speed up chemical reactions Enzymes are proteins that lower activation energy and allow reactions to occur at normal temperaturesEnzymes are proteins that lower activation energy and allow reactions to occur at normal temperatures

Reaction pathway with enzyme Reaction pathway without enzyme Activation energy without enzyme Activation energy with enzyme

Each enzyme is specific and has a specific shapeEach enzyme is specific and has a specific shape Enzymes are not permanently changed and are not used up in the reactionEnzymes are not permanently changed and are not used up in the reaction

They are continuously recycled!They are continuously recycled! Most enzymes end in -aseMost enzymes end in -ase Reactants are called substratesReactants are called substrates

Enzymes The area where the enzyme interacts is called the active siteThe area where the enzyme interacts is called the active site Think of the substrate as a flexible key that must fit into the active siteThink of the substrate as a flexible key that must fit into the active site efurl= sPuPLl37wM:&tbnh=73&tbnw=110&prev=/images%3Fq%3Denzyme%2Bsubstrate%2Banimations%26svnum%3D10%26hl%3Den%2 6lr%3D%26safe%3Dactive

Enzyme Substrates Active site Products LAB/RESEARCH-1991-PRESENT/MATERIALS- SCIENCE/images/ lowres.jpeg

Enzyme Graphs