Presentation on theme: "Chapter 2: Biochemistry"— Presentation transcript:
1 Chapter 2: Biochemistry Section 2: Water and Solutions
2 Storage of EnergyMany organisms release excess heat through water evaporation.
3 Storage of EnergyIn organisms, this ability to control temperature enables cells to maintain a constant internal temperature when the external temperature changes.In this way, water helps cells maintain homeostasis.
4 Cohesion and AdhesionCohesion is attraction between substances of the same kind.Because of cohesion, water and other liquids form thin films and drops.
5 Cohesion and AdhesionMolecules at the surface of water are linked together by hydrogen bonds like a crowd of people linked by holding hands.This attraction between water molecules causes a condition known as surface tension.
6 Cohesion and AdhesionAdhesion is an attraction between different substances.Adhesion powers a process, called capillary action, in which water molecules move upward through a narrow tube, such as the stem of a plant.
7 Aqueous SolutionsA solution is a mixture in which one or more substances are evenly distributed in another substances.=
8 Aqueous SolutionMany important substances in the body have been dissolved in blood or other aqueous fluids.Because these substances can dissolve in water, they can more easily move within and between.
9 PolarityThe polarity of water enables many substances to dissolve in water.When ionic compounds are dissolved in water, the ions become surrounded by polar water molecules.
10 PolarityThe resulting solution is a mixture of water molecules and ions.When sodium chloride, NaCl, is dissolved in water, sodium ions, Na+, and chloride ions, Cl-, become surrounded by water molecules, H2O.
11 NonpolarNonpolar molecules do not dissolve well in water.
12 Non-polarThe inability of non-polar molecules to dissolve in polar molecules is important to organisms.For example, the shape and function of cell membranes depend on the interaction of polar water with non-polar membrane molecules.
13 Acid and BasesCompounds that form hydrogen ions when dissolved in water are called acids.When an acid is added to water, the concentration of hydrogen ions in the solution is increased above that of pure water.
14 Acid and BasesCompounds that reduce the concentration of hydrogen ions in a solution are called bases.Many bases form hydroxide ions when dissolved in water.
15 pH ScaleThe pH scale measures the concentration of hydrogen ions in a solution.NeutralAcidBase