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Chapter 2 Mystery • THE GHOSTLY FISH • Page 33… – How do these animals manage to survive without red blood cells? What’s the matter? • What states of matter exist? • Is all matter visible? • Does all matter take up space? Chapter 2 Chemistry of Life Section 2.1 The Nature of Matter Objectives • What 3 subatomic particles make up atoms? • How are all of the isotopes of an element similar? • In what ways do compounds differ from their component elements? • What are the main types of chemical bonds? What 3 subatomic particles make up atoms? • Atoms – basic unit of matter – 100 million atoms side by side = 1 cm long • Subatomic particles = protons, neutrons, and electrons Protons and Neutrons • Protons and neutrons = same size • Protons = + charge • Neutrons = 0 charge • Nucleus – formed by protons and neutrons bound by strong forces at the center of an atom Electrons • Electron - - charge; • 1/1840 mass of a proton – In constant motion in space around nucleus Atomic charge • In all atoms: #protons = #electrons – + and – charges balance out – Electrically neutral Atomic Number •Atomic number = # protons •Element – pure substance – consists of entirely one type of atom •Each element has its own unique atomic number •Each element represented by unique 1 or 2 letter symbols Isotopes • Isotope – atoms of the same element that differ in number of neutrons – Mass number – number of protons and neutrons in nucleus of an atom – Atomic mass – weighted average of masses of an element’s isotopes • b/c they have same # of electrons, all isotopes of an element have the same chemical properties In what ways to compounds differ from their component elements? • Compound – substance formed by chemical combination of 2 or more elements in definite proportions • Chemical formula – shows composition – Physical and chemical properties of a compound are usually very different from those of the elements from which it is formed • Example – H & O = gases at room temp; combine = liquid water What are the main types of chemical bonds? • Involves electrons that surround each nucleus • Valence electrons - Electrons that are available to form bonds Ionic Bond • Formed when one or more electrons are transferred from one atom to another • Atom that loses electrons - positively charged • Atom that gains electrons - negatively charged • Ions – positively and negatively charged atoms • Example - NaCl Covalent Bonds • Electrons are shared between 2 atoms • The moving electrons travel about the nuclei of both atoms = covalent bond – Single covalent – when atoms share 2 electrons – Double bond – atoms share 4 electrons – Triple bond – atoms share 6 electrons • Molecule – structure that results when atoms are joined by covalent bonds; smallest unit of most compounds • Example – oxygen molecule, water molecule Radioactive Isotopes • Radioactive – nuclei are unstable and break down at a constant rate over time – Radiation given off can be dangerous – Have scientific & practical uses: • • • • determine ages of rocks and fossils detect and treat cancer kill bacteria labels “tracers” to follow movements of substances w/in organisms Van der Waals Forces – Atoms have different abilities of attraction to electrons so sharing is not always equal between 2 atoms – Even when sharing is equal, rapid movement of electrons can create regions w/ tiny + or – charge • Van der waals forces – slight attraction b/w oppositely charged regions of nearby molecules – Not as strong as ionic or covalent bonds – Can hold molecules together (especially large molecules) Mystery Clue • Page 37….. – Fish do not break water molecules into their component atoms to obtain oxygen. – Rather, they use oxygen gas dissolved in the water. – How are the atoms in an oxygen molecule joined together? Atom Activity • • Intro to atoms discussion Choose an element from the periodic table 1. Using the beads, construct a 3D diagram of an atom & show me for 1 grade – – – Red = protons Blue = neutrons Pencil marks = electrons 2. Choose a partner (or 2 if needed) with an atom that your atom can bond with 3. Identify the type of bond (ionic or covalent) 4. Answer the questions that follow on a separate sheet of paper for a second grade Atoms lab follow up questions • 1. 2. 3. 4. 5. 6. Due on next lab day Name of your atom Diagram of your atom Which atom(s) did you bond with? Diagram of bond Was the bond covalent or ionic? Explain how you knew if it was covalent or ionic. - use valence electrons; tranferred or shared in your explanation Section 2.2 Properties of Water • How much water is on Earth? (gallons) • How much water is drinkable? (gallons) • If all the water on Earth was contained in __________, how much would represent the drinkable amount? _____________ • Demonstration!! Objectives • How does the structure of water contribute to its unique properties? • How does water’s polarity influence its properties as a solvent? • Why is it important for cells to buffer oslutions agains rapid changes in pH? How does the structure of water contribute to its unique properties? • Water = H2O • Neutral (10 protons; 10 electrons) • Liquid state over most of Earth’s surface Polarity • Greater probability of finding the shared electrons in water close to O than H – Angles of chemical bonds cause O and H to be on opposite ends of molecule • O = slight – charge & H = slight + charge • Polar – charges are unevenly distributed Hydrogen Bonding • Partial + & - charges attract other H2O molecules • Hydrogen bond – attraction b/w H on one H2O molecule and O of another • Not as strong as covalent or ionic • H2O – able to form multiple H-bonds Cohesion • Cohesion – attraction b/w molecules of same substance • 1 H2O molecule can be involved in 4 H-bonds at the same time • H2O molecules drawn together drops of water form beads on smooth surface – Cohesion produces surface tension • Allows some animals to walk on surface of water Adhesion • Adhesion – attraction b/w molecules of different substances – Capillary action – attractions b/w water & another substance which causes water to rise in narrow tube against force of gravity • Draws water out of roots of plant up to stem & leaves Heat Capacity • Heat capacity – amount of heat energy required to increase its temperature – A lot of energy to cause water molecules to move faster – B/c multiple H-bonds b/w water molecules • Organisms protected from drastic changes in temp b/c large amt. of heat w/ small change in temp (ocean/lake) • Water absorbs heat produced by cell processes regulates temp of cell helps w/ homeostasis Mystery Clue • Page 42….. • The solubility of gases increases as temperatures decrease. Think about when a can of warm soda is opened – the carbon dioxide dissolved in it fizzes out more rapidly because the gas is less soluble at warm temperatures. • How might the temperature of antarctic waters affect the amount of dissolved oxygen available for ice fish? How does water’s polarity influence its properties as a solvent? • Mixture – material composed of 2 or more elements or compounds physically mixed together but not chemically combined • Salt + pepper • Sugar + sand • 2 types w/ water: – Solutions – Suspensions Solutions • Solution – all components are evenly distributed – Solute – substance dissolved – Solvent – substance in which solute dissolves • Example: salt + water – Saturated – given amount of water has dissolved all of the solute it can Suspensions • Suspensions – water and nondissolved material – Some materials separate into pieces so small that they do not settle out – Movement of water molecules keeps the small particles suspended • Example: blood = mostly water – Cells/undissolved particles remain in suspension pH scale • pH scale – measurement system devised to indicate the concentration of H+ ions in solution – Water = neutral = 7 on pH scale – <7 = acidic = have more H+ ions – >7 = basic = have more OH- ions Quick Lab • P. 43 • Acidic and Basic foods Acids • Acid – any compound that forms H+ ions in solution – HCl – produced by stomach – helps digest food Bases • Base – compound that produces OH- ions in solution – Lye (NaOH) – used in soap making – strong base Buffers – Human cells must stay b/w 6.5 & 7.5 pH • Will effect chemical reactions • Important to maintain homeostasis • Buffers – dissolved compounds – weak acids or bases that can react w/ strong acids or bases to prevent sharp, sudden changes in pH Section 2.3 Carbon Compounds Objectives • What elements does carbon bond with to make up life’s molecules? • What are the functions of each of the four groups of macromolecules? Chemistry of Carbon • Carbon atoms have 4 valence electrons allowing them to form strong covalent bonds with many other atoms – Form chains, rings, multiple bonds, complex structures • H, O, P, S, N bonds = molecules of life Macromolecules • Macromolecules – “giant molecules” – polymerization – small compounds join to form larger compound • Monomers – smaller units joined together • Polymers – final product of monomer joining – Monomers may be identical (metal watch band) or may be different (beads on multicolored necklace) Polymer Carbohydrates • Carbohyrates – made of C, H, and O atoms (usually 1:2:1 ratio) – Breakdown of sugars (glucose) provide immediate energy for cellular activities – Many organisms store extra sugar as complex carbohydrate= starches Simple Sugars • Single sugar molecules = monosaccharides • • • • Glucose Galactose (milk) Fructose (fruits) Sucrose (table sugar) = glucose + fructose disaccharide (compound made by joining 2 simple sugars Complex Carbohydrates • Polysaccharide – marcromolecules formed from combinations of monosaccharides – Many animals store excess sugar in polysaccharide called glycogen in muscles (animal starch) • When glucose levels in blood runs low glycogen is broken down into glucose glucose released into blood • Supplies energy for muscle contraction (movement) Complex Carbohydrates – Plants use starch to store excess sugar – Plants also use cellulose to give strength and rigidity • Wood/paper Lipids • Lipids – made mostly from C and H atoms • Not soluble in water • Fats, oils, waxes – Store energy – Form membranes / waterproof coverings – Make steroids in the body • Ex: hormones – chemical messengers **Formed when glycerol molecule combines w/ fatty acids Lipids • Saturated – each C atom in a lipid’s fatty acid chain is joined to another C atom by a single bond – Fatty acid contains max possible # of H atoms • Polyunsaturated – at least one C-C double bond in a fatty acid • Liquid at room temp • Olive oil, corn oil, sesame oil, canola oil, peanut oil Nucleic Acids • Nucleic Acids – macromolecules containing H, O, N, C, and P – Store and transmit hereditary (genetic) information • RNA – ribonucleic acid (ribose = sugar) • DNA – deoxyribonucleic acid (deoxyribose = sugar) • Nucleotides – Polymers assembled from individual monomers – 3 parts: 5-carbon sugar, phosphate group (PO4), and nitrogen base – Can be joined by covalent bonds to form polynucleotide or nucleic acid Protein • Protein – macromolecules that contain N, C, H, and O – Made of polymers of molecules called amino acids – Protein is functional molecule built from one or more polypeptides • Amino Acids – compounds w/ an amino group (NH2) on one end and carboxyl group (COOH) on the other – Peptide bonds – covalent bonds that link amino acids together to form polypeptide Functions of Proteins • Some proteins control rate of reactions and regulate cell processes • Others form cell structures • Others transport substances into or out of cells • Help fight disease Structure and Function • All amino acids are identical in regions where may be joined together by covalent bonds – Allows any amino acid to be joined to any other amino acid (amino or carboxyl group) • Amino acids differ from each other b/c each has a different side chain (R group) – Some acidic & some basic – Some polar & some nonpolar – Some contain large ring structures Levels of Organization • Amino acids assembled into polypeptide chains according to instructions coded in DNA • 4 levels of structure in proteins: – Primary structure – sequence of its amino acids – Secondary – folding or coiling of polypeptide chain – Tertiary – complete, 3-dimensional arrangement of polypeptide chain – 4th level – have more than one chain – describes the way different polypeptides are arranged w/ respect to each other • Shape of protein is maintained by variety of forces: ionic, covalent, van der Walls forces, hydrogen bonds Section 2.4 Chemical Reactions and Enzymes Objectives • What happens to chemical bonds during chemical reactions? • How do energy changes affect whether a chemical reaction will occur? • What role do enzymes play in living things and what affects their function? Chemical Reactions • Chemical Reaction – process that changes, or transforms, one set of chemicals into another • Vary in speed – Reactants - Elements/compounds that enter into a chemical reaction – Products – elements/compounds produced by a chemical reaction • Chemical reactions change chemical bonds that join atoms Energy in Reactions • Energy can be released or absorbed whenever chemical bonds are formed or broken in chemical reactions Sodium added to water releases a great amount of energy. Reaction of sulfuric acid and sugar creates a mound of black carbon and steam. Energy Changes • Chemical reactions that release energy often occur spontaneously • Ex: burning H gas (H reacts w/ O to produce water vapor) • Energy released in form of heat • Chemical reactions that absorb energy will not occur without a source of energy – Ex: water changed into H and O • Absorbs so much energy that doesn’t occur by itself Energy Sources • Every organism needs energy to carry out chemical reactions – Plants get energy by trapping and storing energy from sunlight in energy-rich compounds – Animals get energy when they consume plant or animals – Humans release energy through chemical reactions when we metabolize (break down) digested food Activation Energy • Activation Energy – energy needed to get a reaction started – Example: lighting a match to start fire gets reaction started Enzymes • Catalyst – substance that speeds up the rate of a chemical reaction – Lowers a reaction’s activation energy for reactions that are too slow to be practical for living tissue Nature’s Catalysts • Enzymes – proteins that act as biological catalysts – Enzymes speed up chemical reactions in cells – Lower activation energies • Ex: carbonic anhydrase speeds up reaction by 10 million times than natural removal of carbon dioxide from blood Enzyme-Substrate Complex – For chemical reaction to occur, reactants must collide w/ enough energy so existing bonds will be broken and new bonds will be formed • Substrates – reactants of enzyme-catalyzed reactions • Active Site – site on enzyme where substrates bind – Active site and substrates have complementary shapes – so precisely fit – like lock and key Regulation of Enzyme Activity • Enzymes: control chemical pathways, make materials cells need, release energy, transfer information • Temperature, pH, and regulatory molecules can affect activity of enzymes • Many affected by temp (37oC in human body) • Work best at certain ionic conditions and pH values – Ex: stomach enzyme (pepsin) – begins protein digestion – works best under acidic conditions • Regulated by molecules that carry chemical signals w/in cells (switch on or off as needed) Mystery Clue • P. 53…. – The chemical reactions of living things, including those that require oxygen, occur more slowly at low temperatures. – How would frigid antarctic waters affect the ice fish’s need for oxygen? Solve the Mystery • Ice fish produce antifreeze proteins to keep their blood from freezing; their body temperature stays below 0oC. How does low body temperature affect the blood’s ability to carry dissolved oxygen? • People living at high altitudes generally have more hemoglobin in their blood than people living at sea level. Why do you think this is so? • If the antarctic oceans were to warm up, how might this affect ice fish? • The chemical reactions in all living things slow down at low temperatures. Since some of the most important reactions in our body require oxygen, how would low temperatures affect the ice fish’s need for oxygen?