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Chemical Bonds Bonding is FUN! Remember: Compounds form when elements are chemically combined. Chemical bond- the force that joins the atoms of a compound; bonds contain energy. Atoms need to have their outer energy level filled to be stable. In order to do this, they bond with other atoms. (1st level: 2 electrons, 2nd level: 8 electrons, 3rd level: 8 electrons) 3 types of Bonds 1. Covalent Bond- two atoms share electrons so that both atoms have full outer energy levels. Write in the side column: Strongest type of bond A molecule is a group of atoms held together by covalent bonds. A) Carbon- can form 4 covalent bonds Methane molecule CH4 Why does Carbon form 4 covalent bonds? B) Water Oxygen can form 2 covalent bonds H2O 2. Ionic Bonds Electrons are transferred from one atom to another so that both atoms have full outer energy levels. Ion- a charged atom Write in the side column: One atom loses electrons and becomes positively (+) charged. The other atom gains electrons and becomes negatively (-) charged. Ionic bonds break apart in water. Example: NaCl Na transfers one electron to Cl, making Cl attracted to Na. Na has 11p+ 11n and 11e- Cl has 17p+ 17n and 17e- Safari Video WOOHOO!! Remember: so far we have talked about 2 types of chemical bonds Covalent bonds – electrons are shared Ionic bonds – electrons are transferred Hydrogen Bond Links 2 polar molecules together (NOT atoms!!) Hydrogen bonds are very weak. Hydrogen bonds only form when molecules are very close together. Hydrogen bonds determine shapes of proteins and DNA. Polar Molecule A molecule with unequal areas of charge. Non-Polar Molecule A molecule with equal areas of charge. Example In water, electrons are shared unevenly, so different parts of the molecule have different charges. Oxygen pulls harder on the electrons than hydrogen. The electrons spend more time with the oxygen, making that area negative and the hydrogen area positive. Water Molecules form hydrogen bonds between each other. Cohesion Attraction between water molecules. (creates surface tension) Example: surface tension Example: water forms drops Adhesion Attraction of water molecules to another polar molecule. Example: water sticks to glass Example: capillary action Water is called the universal solvent Many things dissolve in water because it is a polar molecule. Solvent= a substance in which something can be dissolved. Water dissolves ionic compounds like salt (NaCl) Water is unique because its solid form (ice) is less dense than the liquid form. Question: Why is this property of water important to aquatic plant an animal life? Specific Heat Water has a high specific heat. It takes more energy to heat water than other liquids, and also to cool water down. Water acts as an insulator and helps maintain homeostasis in plants during extreme heat and cold. Why is water so important to biology? NFL Body Building Macromolecule Large molecule. There are 4 main groups of biological macromolecules (biomolecules) Macromolecules are made by linking smaller molecules called monomers. Since macromolecules are made of many monomers, they are called polymers. Monomers are joined together through a process called dehydration synthesis. (synthesis=to make) ** Can also be called condensation** A-H + B-OH --> A-B + H2O Polymers can be broken down into their component parts through a process called hydrolysis. (lysis= to break) A-B + H2O --> A-H + B-OH Carbohydrate Structure Atoms in a carbohydrate: carbon, hydrogen, and oxygen. Monomer: monosaccharide; they can be joined together to form complex carbohydrates called polysaccharides. (complex sugar) The elements in a carbohydrate are combined in a ratio of 1:2:1 (C:H:O) Example: a carbohydrate with 6 carbons has the formula: C6H12O6 What would the formula be for a carbohydrate with 5 carbons? C5H10O5 Functions of Carbohydrates Carbohydrates, especially glucose, are the main energy source used in the body. (monosaccharide) 2 rings= disaccharide In animals, excess sugar (glucose) is stored as glycogen. (polysaccharide) Plants store sugar in the form of starch. ( glycogen and starch are polysaccharides) Plants use the carbohydrate cellulose to strengthen their cell walls. What do humans use cellulose for? Humans can’t digest it, so it passes through the digestive system as fiber. Structure of Proteins Atoms in a protein: carbon, oxygen, hydrogen, and nitrogen. Monomer: amino acids Amino acids join to make long chains that are folded into 3-D structures. The shape of the protein determines its function. Function of Proteins Proteins form bone and muscle. Antibodies help fight off disease and are made of proteins. Proteins called enzymes speed up chemical reactions in the body. (catalyst) Hemoglobin is a protein that helps red blood cells carry oxygen. When you eat meat, beans, eggs, and rice you get protein from these foods. video clip Gatorade/H2O In the movie “The Water Boy”, Adam Sandler is told that Gatorade is better than water. After reading the information with your group, do you agree or disagree? Share with your group, and then your group should be ready to share with the class. Structure of Lipids Lipids are not soluble in water. This is because water is polar and most lipids are nonpolar. Lipids are made mostly from carbon and hydrogen atoms. There are 3 categories of lipids: fats, oils, and waxes. Fats and oils are made of smaller units (monomers) call triglycerides. Function of Lipids Lipids can be used to store energy. Lipids are important parts of biological membranes and waterproof coverings. Lipids also form steroids which serve as chemical messengers in the body. Structure of Nucleic Acids Nucleic Acids are made of carbon, hydrogen, oxygen, nitrogen, and phosphorous. Nucleic Acids are polymers made from monomers called nucleotides. Function of Nucleotides Nucleic Acids store and transmit hereditary or genetic information. There are 2 kinds of nucleic acids: Ribonucleic acid (RNA) and Deoxribonucleic acid (DNA) Energy in Living Things ATP and Metabolism What is energy? The ability to do work (measured in joules or calories) Why do cells need energy? To move, digest, make proteins, get rid of waste Law of Conservation of Energy Energy cannot be created or destroyed. How do consumers obtain energy? By eating other things All molecules store energy in bonds between atoms. The energy in molecules is released by breaking the bonds between atoms. When bonds are created between atoms, energy is stored. The major energy source for all cells is a carbohydrate called amylose starch. To do work, cells must convert starch into glucose. How do producers obtain useable energy? They produce “food” through photosynthesis with energy from the sun. Why do lipids have more energy per gram than carbohydrates? Lipids have higher energy bonds and more bonds. More bonds = more energy stored. ATP – Adenosine Triphosphate – the primary source of energy used by cells. 3 PHOSPHATES ADENOSINE When the last phosphate is removed, energy is released. +℗ ATP ADP + Phosphate Where does the energy in ATP come from? Energy from food/light is stored in chemical bonds in ATP. ADP + ℗ ATP Enzymes Objectives 6-8 Enzymes - A protein that acts as a catalyst (speeds up chemical reactions) Why are enzymes needed? So reactions happen fast enough to sustain life functions How do enzymes work? Enzymes lower the activation energy of a chemical reaction. Activation Energy is the energy needed to ______ start a chemical reaction. No enzyme With enzyme Finish shape based on how Each enzyme has a specific ________ the ________ protein is folded. Substrate – Substance that the enzyme acts on Each enzyme binds only to certain substrates. In order for the substrate to bind to the enzyme it must shape be the right ________. The place where the substrate binds to the enzyme is called the active _______ site ______ Once the enzyme and substrate bind, a reaction occurs. Draw a picture explaining how an enzyme works in the space below. Active site -substrate products ENZYME Example: The reaction shown below helps convert CO2 into a form that is more easily carried through the bloodstream. Without enzymes this reaction wouldn’t happen fast enough and dangerous levels of CO2 would build up in the bloodstream. The enzyme carbonic anhydrase allows this reaction to happen 10 million times faster. CO2 + H2O ENZYME H2CO3 Video Controlling Enzymes Enzymes don’t always need to be “ON.” There are 2 ways to turn an enzyme “OFF.” Competitive Inhibition – Inhibitor A substance other than the substrate blocks the active site Substrate Non- Competitive Inhibition – A molecule binds to a location other than the active site and changes the shape of the enzyme Substrate Inhibitor V ideo