Water, pH, and Macromolecules Unit 2, Part 1 Water, pH, and Macromolecules

Properties of Water Polar - due to the unequal sharing of electrons Hydrogen Bonds - because of partial positive and negative charges, polar molecules, such as water, can attract each other Adhesion - stickiness-attraction between molecules of a different substance Cohesion - stickiness-attraction between molecules of the same substance

Where is water? What does it do? 2/3 of the cell is made of water Most biochemical processes of life occur in water solutions Water is able to dissolve many substances due to polarity Water carries nutrients into the cell and waste away from the cell

Mixtures, Solutions and Suspensions Two or more elements or compounds that are physically mixed together, but not chemically combined Mixtures have the same properties as their components There is no fixed proportion between the components The components can be separated from the mixture Examples sugar and salt air with nitrogen, oxygen

Solution The components in a solution may not be separated from the solution by leaving it to stand, or by filtration If a material dissolves in a liquid the material is said to be soluble. A solution is saturated if no more solute can be dissolved with temperature remaining constant.  Examples salt in sea water Table salt placed in water dissolves forming a solution. The salt will settle out Water = solvent Salt = solute

Suspension A suspension is a mixture of liquids with particles of a solid which may not dissolve in the liquid. The solid may be separated from the liquid by leaving it to stand, or by filtration Some materials do not dissolve, but separate into small particles. The movement of the solute keeps them suspended. They will not settle out. Examples sand in water

pH Scale Acid Base (Alkaline) Acids, Bases, pH Concentration of H+ in solution Figure 2-10, page 43 Acid Contains more H+ than pure water, pH value below 7 Base (Alkaline) Contains more OH- than pure water, pH value above 7 Acids, Bases, pH H2O <=> H+ + OH- water hydrogen hydroxide ion ion

pH Scale

Buffer Weak acid or base that can react with strong acid or base used to prevent sharp, sudden changes in pH.

Macromolecules Four groups of organic compounds in living things “giant” molecules Made by polymerization Made from monomers and polymers Four groups of organic compounds in living things Carbohydrates Lipids Nucleic Acids Proteins

Carbohydrates Made of carbon, hydrogen, oxygen in a 1:2:1 ratio Main energy source for living things Structural for some plants Monosaccharides - single, simple sugar Polysaccharides – large, complex sugars

Lipids Made mostly of carbon and hydrogen Fats, oils, waxes, steroids Used to store energy Membranes and waterproof coverings Glycerol plus fatty acids Saturated and polyunsaturated

Nucleic Acids Made up of carbon, hydrogen, oxygen, nitrogen, and phosphorous Polymers assembled from monomers called nucleotides Nucleotides consist of three parts; a five carbon sugar, a phosphate group and a nitrogenous base They store and transmit hereditary or genetic information Examples; DNA & RNA

Proteins Made up of carbon, hydrogen, oxygen, and nitrogen Polymers of molecules called amino acids Some control the rate of reactions and regulate cell processes Some form bone and muscle Others transport substances into and out of cells and fight disease

Macromolecules