Day Date Subject To be read prior to this class period: M 1/14 no class - Snow Day! W 1/16 Evolution: Unity and Diversity Chapter 1 M 1/21 no class – Rev. Martin Luther King, Jr. Day W 1/23 Water and the Chemical Environment Chapter 2 (except pp30-35) M 1/28 Quiz #1 on Ch. 1 and parts of Ch. 2 and related lectures/handouts (no make ups for missed quiz) Cell Membranes Chapter 6 W 1/30 Macromolecules Chapter 3 (except pp63-69) M 2/4 Macromolecules W 2/6 Quiz #2 on Ch. 3 and 6 and related lectures/handouts The Cell Chapter 7 M 2/11 Bioenergetics W 2/13 Cell Respiration Chapter 9 M 2/18 no class - Winter Break W 2/20 no class - Winter Break M 2/25 EXAM I Chapters 1, 6,7, parts of 2, 3

Aquaporin protein makes a water channel through the cell (plasma) membrane.

Chapter 3 is about protein structure. The example will we use is the protein Aquaporin. In Chapter 3, the material on pages 63 -69 is not really covered until after the first test. That means you need to read it now but you don’t need to study it until after the first test. Also, I will talk about this material in class but not until after the first test. Aquaporin is a protein that floats in the cell membrane. The function of aquaporin is to form a channel (hole, pore) through the membrane that allows water to passively diffuse across the cell membrane. In other words, aquaporin’s job is to allow the rate of osmosis to increase.

Aquaporin is a very selective filter for water and it is also very fast. A membrane 4” x 4” with embedded aquaporins could filter 1 gallon of pure water in just 30 seconds.

Aquaporin creates a channel through the cell membrane that only lets H O through. 2

Major Sites of Expression and Function of Human Aquaporin Aquaporin-0 Eye: lens fiber cells Fluid balance within the lens Aquaporin-1 Red blood cells Osmotic protection Kidney: proximal tubule Concentration of urine Eye: ciliary epithelium Production of aqueous humor Brain: choriod plexus Production of cerebrospinal fluid Lung: alveolar epithelial cells Alveolar hydration state Aquaporin-2 Kidney: collecting ducts Mediates antidiuretic hormone activity Aquaporin-3 Kidney: collecting ducts Reabsorbtion of water into blood Trachea: epithelial cells Secretion of water into trachea Aquaporin-4 Kidney: collecting ducts Reabsorbtion of water Brain: ependymal cells CSF fluid balance Brain: hypothalamus Osmosensing function? Lung: bronchial epithelium Bronchial fluid secretion Aquaporin-5 Salivary glands Production of saliva Lacrimal glands Production of tears Aquaporin-6 Kidney Very low water permiability; function? Aquaporin-7 Testis and sperm Aquaporin-8 Testis, pancreas, liver, others Aquaporin-9 Leukocytes

Aquaporin protein makes a water channel through the cell (plasma) membrane.