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Unit 2 The Chemistry of Life How can this plant digest a frog? Like other carnivores, the Venus flytrap eats animals to get nutrients that it needs to make molecules such as proteins and nucleic acids. Other chemical compounds made by plant’s cells enable the Venus flytrap to digest the animals that it eats. These chemicals are similar to the chemicals that allow you to digest the food that you eat. ???????? If plants can make their own food through photosynthesis, why would a plant species evolve a mechanism to capture and eat animals? The animal must be supplying nutrients that the plant cannot get from other sources. Venus fly traps grow in swampy areas that have nitrogen poor soil. These plants get the nitrogen they need for survival by trapping and digesting animals. Video http://www.youtube.com/watch?v=ymnLpQNyI6g What does your backpack, shoes, and ipod all have in common? They are all made up of ATOMS-> Smallest basic unit of matter. Atoms are made up of: Protons-> positively charged particles and dense Neutrons-> neutral charge / no charge Electrons-> negatively charged particles and small Protons and neutrons live in the nucleus (center of the cell) Electrons are in the outer levels= electron cloud Draw and label the atom Element A type of atom that cannot be broken down into simpler substances. Can also be a group of atoms of the same type. Ex-> gases such as hydrogen and oxygen. Metals= aluminum and gold. Atoms are made up of the same types of particles, so what makes one element different from another? Different elements differ in the number of protons they have. Atomic number= number of protons Atomic Mass How many protons does hydrogen have? Oxygen? Hydrogen= 1 Oxygen= 8 Energy levels Different energy levels can hold a different number of electrons. 1st energy level= hold 2 electrons 2nd level= hold 8 electrons Stable atoms have a full outermost energy level 91 elements 4 that make up 96 % of your body= carbon, oxygen, nitrogen, and hydrogen The other 4% are called trace elements because they are found in little amounts but we need them to survive-> like calcium, iron, potassium Compounds Atoms of elements found in organisms are usually linked or bonded to other atoms= compound. Common compounds= water (H2O), carbon dioxide (CO2) Ion Atom that has gained or lost one or more electrons. Forms because an atom is more stable when its outermost energy level is full. The gain or lose results in a full outer level. Either positive or negative Atoms with few electrons= lose electrons and becomes more positive Gains electrons= more negative. NaCl Transfers electron from sodium atom to chlorine atom When sodium loses electron it becomes positive-> full charged because it has a filled outermost energy level. The electron lost goes to the chlorine ion, causing the chlorine to become more negative and have a full energy level. End product is an ionic bond-> bond that forms when two oppositely charged particles exchange electrical forces. Opposites attract (+ / -) What determines whether an atom becomes a positive ion or a negative ion? Atoms with few outer electrons tend to lose electrons and form positive ions; atoms with almost full outer energy levels tend to gain electrons and form negative ions. Covalent Bonds Form when atoms share a pair of electrons. Need 4 electrons to fill its outermost energy level CO2= Carbon Dioxide O C O An oxygen atom needs 2 electrons to fill its outer energy level. In Carbon dioxide, carbon makes a double bond, or shares two pairs of electrons with each oxygen atom. Molecule Two or more atoms held together by covalent bonds. Properties of Water!!!!! Waters unique properties allow life to exist on Earth. Polar vs. Nonpolar Polar: Water and some gases Uneven distribution of electrons Nonpolar= liquids, CO2, Oxygen, oils, fats electrons are distributed more evenly around the outer shell. They both tend to remain separate that is why they say “oil and water don’t mix.” Life depends on hydrogen bonds Water is polar-> act the same way as the magnetic poles. Have regions with a slight positive and slight negative charge. Waters oxygen atoms are slightly negative and hydrogen is slightly positive= HYDROGEN BOND Where else can we find hydrogen bonds? DNA Proteins Properties of Hydrogen Bonds Weakest of the bonds High specific heat= water resists changes in temperature, therefore water must absorb more heat energy to increase temperature. Very important with cells because our cells release a lot of heat and water absorbs that heat which allows us to regulate cell temperatures. Properties Continue Cohesion-> attraction among molecules of a substance. Makes water molecules stick together. Ex- beads on a car when it is washed Spider walking on top of the water. Properties Cont. Adhesion-> attraction among molecules of different substances. Water molecules stick to other things. Ex- upward curve of the surface of the water-> graduated cylinder Ex- plants transport water up their roots to their leaves. Examples http://www.youtube.com/watch?v=OuD P9-TA7dg http://www.youtube.com/watch?v=tv4J rc06yLA&feature=related http://www.youtube.com/watch?v=45y abrnryXk Many compounds dissolve in water Molecules and ions can’t take part in chemical processes inside cells unless they dissolve in water. Materials such as sugar and oxygen cannot be transported from one part of an organism to another unless they are dissolved in blood, plant sap, or water based fluids. Solution= mixture of substances that is the same throughout= homogeneous mixture Solvent-> substance Solute-> substance that is present in the that dissolves. greatest amount, Example= kool aid and is the substance powder that dissolves solutes. Example= Water Example / Scenario Your plasma (liquid Why do the solutes such as proteins and sugars part of your blood) is 95% water. Which dissolve in the water of blood plasma? is the solvent and Answer-> polar= because solute? the attraction between the Solvent= water; water molecules and the Solute is the other solute molecules is 5% which is made greater than the attraction up of proteins, among the molecules of sugars. the solutes. 1. What is the most comment solvent in everyday life? 1. 2. 3. 4. A. carbon containing chemicals B. ethanol C. water D. All of the above 3. What is solubility? a. The ability of a given substance(solute) to dissolve into a solvent. b. The ability of a given substance(solvent) to dissolve into a solute. 2. In a solution (which is a mixture of a solute and a solvent) which do you typically have more of? a. Solute b. Solvent c. Same amount of both 4. How does temperature affect solubility? a. Solubility is not affected by temperature. b. Solubility decreases with an increase in temperature. c. Solubility increases with an increase in temperature. 5. How does a solute dissolve into a solvent? a. Polar solvent molecules separate the molecules of other polar substances. b. Polar solvent molecules separate the molecules of other non-polar substances. c. Non-polar solvent molecules separate the molecules of other non-polar substances. 6. What are the main factors that affect solubility? a. Temperature b. Pressure c. Nature of solute and solvent d. All of the above Answers 1. C- Water 2. B 3. A 4. C 5. A 6. D Acids and Bases Acids Releases a hydrogen ion (H+) when it dissolves in water. 0 to 7= acids Strong Acid Bases Removes H+ ions from a solution 7-14= basic Weak base Weak Acid Strong Base Ph of 7=Neutral-> neither acidic or basic Ph Scale (Potential Hydrogen) How is Ph regulated in our bodies? Through buffers-> compounds that can bind to H+ ion when the H+ concentration increases and can release an H+ ion when the H+ ion decreases. Buffer “locks up or stops” the H+ ions in order for our bodies to maintain homeostasis. Example-> normal Ph of blood is 7.35-7.45 (slightly basic), therefore a small change in this could really disrupt your cells and can be fatal. Carbon Based Molecules Carbons unique bonding properties Building blocks of life because they are the basis of most molecules that make up living things. Keep organisms alive! Yay :) Unique atomic structure because it has four unpaired electrons on the outer energy level and can form covalent bonds with up to four other atoms!!!!!! Three types of molecular structures Straight Chain Branched Chain Ring Monomer / Polymer Polymer= molecule that contains many Monomers bonded together. Monomer= small molecular subunit How many monomers are above? Four Carbon Based Molecules in Living Things / Macromolecules 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids Carbohydrates Fruits, grains, sugars, starches Made up of carbon, oxygen, and hydrogen when broken down they provide a source of usable chemical energy for cells Major part of plant cell structure too!!! Most basic= simple sugars or monosaccharides Six carbon sugar in fruits= fructose Six carbon sugar= glucose two sugars bonded= table sugar Many glucose molecules bonded together form polysaccharides which are polymers of monosaccharides Polysaccharides What are they? Polymers-> cellulose and starches Lipids Nonpolar molecules such as fats, oils, and cholesterol Carbon chains bonded to oxygen and hydrogen Some are broken down for cell use and others are parts of cell structures. Olive oil, meat, butter-> have a molecule called glycerol which are bonded to molecules called fatty acids. Two types of fatty acids-> saturated and unsaturated Lipids cont. Many contain three fatty acids bonded to glycerol= triglycerides Saturated fats= maximum number of hydrogen atoms possible. Unsaturated fats= fatty acids are not saturated with hydrogen atoms. Cell membrane-> made up of a phospholipid bilayer with polar heads and nonpolar tails. Head is made up of glycerol, two fatty acids, and a phosphate group (hydrophilic= water loving). Tail= fatty acids (hydrophobic= water fearing). Proteins Most varied- apart of everything from moving your leg to digesting your pizza. Protein is the polymer made up of monomers called amino acids. Amino acids are referred to as the “building blocks” of proteins. We use 20 different amino acids to build proteins in our bodies. Your body makes 12 and the others need to be ingested through meat, beans, and nuts. All have similar structures: hydrogen atom, an amino group (NH2), and a carboxyl group (COOH). Proteins Cont. Covalent bonds called peptide bonds. Peptide bond Polypeptide is a chain of precisely ordered amino acids linked by peptide Bonds. A protein is made up of one or more polypeptides. Nucleic Acids Detailed instructions that build proteins and are stored in extremely long carbon based molecules. Nucleic acid = polymer Nucleotides = monomer Nucleotides are made up of: sugar, phosphate group, and a nitrogen base. Two types= DNA and RNA ONE FUNCTION!!!!!-> DNA and RNA work together to make proteins. DNA stores information for putting amino acids together to make proteins, and RNA helps to build proteins. DNA is the basis of genes and heredity. Chemical Reactions When substances are changed into different substances by breaking and forming chemical bonds. What do your cells need to breathe? How do they get it? Cellular Respiration Reactants vs. Products Reactants Products What causes bonds in oxygen and glucose molecules to break? Energy is added that causes the bonds to break into oxygen and glucose. Each bond requires a different amount of energy= Bond Energy What happens when new bonds form in carbon dioxide and water? When new bonds form, energy is released and this energy that is released is equal to the amount of energy that breaks the same bond. Sometimes bonds can form a chemical equilibrium, meaning they are reversible and the same on both sides of the equation. Example of Equilibrium Blood cells and plasma transport materials throughout the body. Carbonic acid dissolves in the blood so that carbon dioxide can be transported to the lungs. Chemical reactions release or absorb energy Energy added = breaks chemical bonds Energy released= new bonds form Energy is released or absorbed and in different amounts. Activation energy Amount of energy that needs to be absorbed for a chemical reaction to start. Ex.- the energy you would need to push a rock up a hill. Exothermic Releases more energy than it absorbs Excess energy is typically given off in heat or light Reactants have more energy than products Ex- firefly squid, fireflies, cellular respiration (releases usable energy as well as keep your body warm). Endothermic Absorbs more energy than it releases Products have more energy than reactants Example- photosynthesis-> plants absorb energy from the sun and use that energy to make simple and complex carbs. Enzymes How did the Venus Flytrap digest the frog? Enzymes-> type of protein that help to start and run chemical reactions in living things. Break down food into smaller molecules that the body can use. What is activation energy? The energy needed to get things started Most of the time the activation energy for a chemical reaction comes from an increase in temperature-> sometimes the process is very slow. In order to speed the process up substances called catalysts decrease the activation energy needed to start the chemical reaction -> in the end increases the chemical reaction. When a catalyst (ex- enzymes) is present less energy is needed and products form a lot faster. What are two functions of catalysts in chemical reactions? 1. Decrease activation energy 2. Increase reaction time. Enzymes Definition= catalysts for chemical reactions in living things Reactants are usually found at very low concentrations in the body, but really need to occur quickly. Almost all are proteins= long chains of amino acids Each one depends on its structure to function Temperature and ph can affect the shape, function, and activity of the enzyme. Work best at normal body temperature If temperature is a little elevated then the hydrogen bonds will fall apart, enzymes structure will change, and its ability to function will be lost. This is the reason why a high temperature / fever is very dangerous to a person. Examples of enzymes in action Amylase is an enzyme in saliva that breaks down starches into simpler sugars. Without amylase it would take a million times slower. Blood cell engulfing a pathogen The structure is so important because each enzyme’s shape is specific to a certain reactant= allows them to fit perfectly together just like a key fits into a lock Specific reactant an enzyme acts on are called substrates The sites where substrates bind to enzymes are called active sites. Enzymes bring substrate molecules close together, then they decrease activation energy, substrates attach together and their bonds are weakened, and then the catalyzed reaction forms a product that is released from the enzyme. Reflection On a sheet of paper, review the three parts of the lock and key model and write a paragraph (3-5 sentences) describing the analogy. Consider why the model is described as a lock and key. Also identify the different parts and what happens to each part after the reaction is complete. You may use your notes