Unit 2: The Chemical Basis of Life Waters unique properties support life High specific heat: Specific heat is the amount of energy required to change the temperature of a substance. Because water has a high specific heat, it can absorb large amounts of heat energy before it begins to get hot. It also means that water releases heat energy slowly when situations cause it to cool. Water's high specific heat allows for the moderation of the Earth's climate and helps organisms regulate their body temperature more effectively. Cohesion: The intermolecular attraction between like molecules. Surface tension results from cohesion of water. Adhesion: The intermolecular attraction between unlike molecules. Capillary action results from the adhesive properties of water and the molecules that make up plant cells.

Unit 2: The Chemical Basis of Life Water expands and floats as it freezes. Ice is less dense than water so it floats in water. Ice can insulate large bodies of water and prevent it from freezing. It is a universal solvent: It is able to dissolve a large number of different chemical compounds. This feature also enables water to carry solvent nutrients in runoff, infiltration, groundwater flow, and living organisms. This is because water is polar and can dissolve other polar molecules. Polar: one side is negative, the other side is positive. Opposite charges will attract other molecules in a weak hydrogen bond. Water is attracted to water.

Unit 2: The Chemical Basis of Life Water is responsible for the pH scale. pH is a measure of the H+ or OH- in water. 1-6 is acidic Acids increase the H+ concentration and lower the pH 8-14 is basic Bases decrease the H+ concentration and raise the pH 7 is neutral

Unit 2: The Chemical Basis of Life Carbon is uniquely suited to form biological macromolecules (large molecules) It forms covalent bonds with other carbon: Because carbon has 4 electrons it can form 4 covalent bonds with other atoms. This makes it the only atom that can be used to build the variety of molecules needed for complex life. Carbon can be used to build large molecules (polymers, macromolecules) like carbohydrates (sugars), lipids (fats), proteins (including enzymes) and nucleic acids (DNA, RNA). Carbon can come in chains of all lengths. Even branched chains. Carbon can form rings. It can form double bonds

Unit 2: The Chemical Basis of Life Biological macromolecules form from monomers Monomer: A molecule of any compound that can react with other molecules of the same or different compound to form a polymer. Each biological macromolecule has characteristic monomers. Macromolecules: A polymer with a high molecular mass. Within organisms there are four main groups: carbohydrates, lipids, proteins, and nucleic acids. Synthesis: the formation of molecules

Unit 2: The Chemical Basis of Life Structure and function of carbohydrates, lipids, proteins, and nucleic acids Carbohydrate: A macromolecule that contains atoms of carbon, hydrogen, and oxygen in a 1:2:1 ratio and serves as a major source of energy for living organisms (e.g., sugars, starches, and cellulose). Lipids: A group of organic compounds composed mostly of carbon and hydrogen including a proportionately smaller amount of oxygen; are insoluble in water, serve as a source of stored energy, and are a component of cell membranes. Proteins: A macromolecule that contains the principal components of organisms: carbon, hydrogen, oxygen, and nitrogen; performs a variety of structural and regulatory functions for cells. Nucleic Acids: A biological macromolecule (DNA or RNA) composed of the elements C, H, N, O, and P that carries genetic information.

Unit 2: The Chemical Basis of Life The role of an enzyme as a catalyst Catalyst: A substance that enables a chemical reaction to proceed at a usually faster rate or under different conditions (e.g., lower temperature) than otherwise possible without being changed by the reaction. They can speed up the reaction without being consumed (used up). The shape of enzymes is very important. Substrates and enzymes fit together very precisely, so any shape change will affect this.

Unit 2: The Chemical Basis of Life pH, temperature, and concentration levels can affect enzyme function All enzymes have an optimal temperature and pH that they work best at. For example: your enzymes in your stomach work best at 98.6⁰F (your normal body temperature) and at an acidic pH (since your stomach has Hydrochloric acid). Changing pH can cause enzymes to change shape (denaturing) Temperature changes can affect enzymes. Too hot or too cold and it will slow down. Way too hot and it can change the shape (denaturing). Concentration levels can change the speed. Too little and it will slow down. If there is more substrate or enzymes the faster it will work.

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