Physiological and chemical concepts

1. Physiological and chemical concepts Lab session # 1 Physiol. 102 Dr. Isam Abu-Amarah

2. Solutions In chemistry, a solution is a homogeneous mixture of one or more substances. The substances that are dissolved are named solutes.[1] The substance the solutes are dissolved in is named a solvent. An example from everyday experience is a solid (like salt or sugar) dissolved in a liquid (like water). Gases can dissolve in liquids. An example is carbon dioxide or oxygen in water. Liquids may dissolve in other liquids and gases in other gases. Examples of solid solutions are alloys and some minerals.

3. Concentrations • Molarity, Molality, and Normality Molarity = Moles of solute(g)/Liters of Solution, abb (M) Molality = Moles of solute (g) /Kg of Solvent, abb (m) Normality = equivalent solute (g/L)/Liters of Solution abb (N) The weight of a molecule is the sum of the weights of the atoms of which it is made. Avogadro's Number How many molecules are there in a mole? The number is approximately 6 x 1023. This number is called Avogadro's number after the chemist who first attempted to determine it. Avogadro's number applies to a mole of any substance: molecule or ion. Thus we can properly refer to a mole of hydrogen ions (1 g).

4. Molecular Mass Calculations Calculate the Molecular Mass (MM) of the compound carbon monoxide, CO The formula for carbon monoxide is composed of one atom of carbon and one atom of oxygen Atomic mass carbon = 12.01 (from the Periodic Table) Atomic mass of oxygen = 16.00 (from the Periodic Table) Molecular Mass (MM) for cabon monoxide     = atomic mass carbon + atomic mass oxygen Molecular mass (MM) = 12.01 + 16.00     = 28.01 g/mole Calculate the Molecular Mass (MM) of the compound carbon dioxide, CO2 The formula for carbon dioxide is composed of one atom of carbon and two atoms of oxygen Atomic mass carbon = 12.01 (from the Periodic Table) Atomic mass of oxygen = 16.00 (from the Periodic Table) Molecular Mass (MM) for carbon dioxide     = atomic mass carbon + (2 x atomic mass oxygen) Molecular Mass (MM) = 12.01 + (2 x 16.00)     = 12.01 + 32.00     = 44.01g/mole Molecular Mass (MM) = 40.08 + [2 x (16.00 + 1.008)]     = 40.08 + [2 x 17.008]     = 40.08 + 34.016     = 74.096g/mole

5. How to Calculate the molecular weight (mass) Calculate the Molecular Mass (MM) of the compound water, H2O The formula for water is composed of two hydrogen atoms and one oxygen atom Atomic mass hydrogen = 1.008 (from the Periodic Table) Atomic mass of oxygen = 16.00 (from the Periodic Table) Molecular Mass (MM) for water     = (2 x atomic mass hydrogen) + atomic mass oxygen Molecular Mass (MM) = (2 x 1.008) + 16.00     = 2.016 + 16.00     = 18.016g/mole

6. Example Calculate the Molecular Mass (MM) of the compound calcium hydroxide, Ca(OH)2 The formula for calcium hydroxide is composed of one calcium "atom" (actually an ion) and two hydroxide ions. Each hydroxide ion is composed of one hydrogen "atom" (actually an ion) and one oxygen "atom" (also an ion) Atomic mass calcium = 40.08 (from the Periodic Table) Atomic mass hydrogen = 1.008 (from the Periodic Table) Atomic mass of oxygen = 16.00 (from the Periodic Table) Molecular Mass (MM) for calcium hydroxide     = atomic mass calcium + (2 x atomic mass oxygen) + (2 x atomic mass hydrogen) Molecular Mass (MM) = 40.08 + (2 x 16.00) + (2 x 1.008)     = 40.08 + 32.00 + 2.016     = 74.096g/mole Alternatively, Moelcular Mass = atomic mass of calcium + (2 x molecular mass of hydroxide ions)

7. How to: • 1- Prepare 0.154M NaCl solution Note: Molecular weight (mass) for Na+ = 23 and for Cl- = 35.5 • 2- Prepare 154mM NaCl solution

8. Try to find the answers: Knowing that MW for C= 12 H= 1 O= 16 Na= 23 1.  How many moles of ethyl alcohol, C2H5OH, are present in 65 ml of a 1.5M solution? (0.098 mol alcohol) 2- How many grams do you need to prepare 6.0M of NaOH?

9. Functioning Proteins Lab session # 2 Phsiol. 102 Dr. Isam Abu-Amarah

10. Relating transport to physiology • Our bodies exchange material with the environments • Some exchange is by simple diffusion • Breathing; O2 and CO2 • Other exchanges involve transport proteins • Nutrient uptake from our gut • Glucose release/uptake from bloodstream

11. Concepts • Steady-state is not at equilibrium • Gradients are a form of energy • Energy can change form • The differences and similarities of channels and pumps • Structural elements involved in ion transport across membranes

12. Diverse transport processes maintain the cell in a steady state that is not in equilibrium.

13. Proteins and glycoproteins in the cytoplasmic membrane are quite diverse and function as: a. channel proteins to form pores for the free transport of small molecules and ions across the membrane b. carrier proteins for facilitated diffusion and active transport of molecules and ions across the membrane c. cell recognition proteins that identifies a particular cell d. receptor proteins that bind specific molecules such as hormones and cytokines e. enzymatic proteins that catalyze specific chemical reactions. substances may cross the cytoplasmic membrane of eukaryotic cells by simple diffusion, osmosis, passive transport, active transport, endocytosis and exocytosis. We will now review each of these methods of transport. 1. Passive Diffusion Passive diffusion is the net movement of gases or small uncharged polar molecules across a phospholipidbilayer membrane from an area of higher concentration to an area of lower concentration (see Fig) . Examples of gases that cross membranes by passive diffusion include O2, and CO2; examples of small polar molecules include ethanol, H2O, and urea.

14. Osmosis is the diffusion of water across a membrane from an area of higher water concentration (lower solute concentration) to lower water concentration (higher solute concentration).Osmosis is powered by the potential energy of a concentration gradient and does not require the expenditure of metabolic energy. A cell can find itself in one of three environments: isotonic, hypertonic, or hypotonic. (The prefixes iso-, hyper-, and hypo- refer to the solute concentration). · 1- In an isotonic environment, both the water and solute concentration are the same inside and outside the cell and water goes into and out of the cell at an equal rate. ·   2- If the environment is hypertonic, the water concentration is greater inside the cell while the solute concentration is higher outside (the interior of the cell is hypotonic to the surrounding hypertonic environment). Water goes out of the cell. ·   3- In an environment that is hypotonic, the water concentration is greater outside the cell and the solute concentration is higher inside (the interior of the cell is hypertonic to the hypotonic surroundings). Water goes into the cell.

15. Even water need help! Osmosis is the diffusion of water from high concentrations to low concentrations

16. Osmotic pressure affects cell shape and life

17. 2. Transport of Substances Across the Membrane by Transport (Carrier) Proteins. For the majority of substances a cell needs for metabolism to cross the cytoplasmic membrane, specific transport proteins (carrier proteins) are required. Transport proteins allow cells to accumulate nutrients from even a sparce environment. Examples of transport proteins include channel proteins, uniporters, symporters, antiporters, and the ATP- powered pumps. These proteins transport specific molecules, related groups of molecules, or ions across membranes through either facilitated diffusion or active transport. a. Facilitated Diffusion Facilitated diffusion is the transport of substances across a membrane by transport proteins, such as uniporters and channel proteins, along a concentration gradient from an area of higher concentration to lower concentration. Facilitated diffusion is powered by the potential energy of a concentration gradient and does not require the expenditure of metabolic energy. 1. Uniporter: Uniporters are transport proteins that transport a substance from one side of the membrane to the. Amino acids, sugars, nucleosides, and other small molecules can be transported through eukaryotic membranes by different uniporters. 2. Channel proteinstransport water or certain ions down either a concentration gradient, in the case of water, or an electric potential gradient in the case of certain ions, from an area of higher concentration to lower concentration. While water molecules can directly cross the membrane by passive diffusion, as mentioned above, their transport can be enhanced by channel proteins called aquaporins.

18. b. Active Transport whereby the cell uses both transport proteins and metabolic energy to transport substances across the membrane against the concentration gradient. (WHY?) The energy is provided by either proton motive force, the hydrolysis of ATP, or by the electric potential (voltage) difference across the membrane. Proton motive force is an energy gradient resulting from hydrogen ions (protons) moving across the membrane from greater to lesser hydrogen ion concentration. ATP is the form of energy cells most commonly use to do cellular work. Electric potential is the difference in voltage across the cytoplasmic membrane as a result of ion concentration gradients and the selective movement of ions across membranes by ion pumps or through ion channels. 1. Antiporter: Antiporters are transport proteins that transport one substance across the membrane in one direction while simultaneously transporting a second substance across the membrane in the opposite direction (see Fig). Antiporters use the potential energy of electrochemical gradients from Na+ or H+ to transport ions, glucose, and amino acids against their concentration gradient

19. 2. Symporter: are transport proteins that simultaneously transport two substances across the membrane in the same direction (see Fig). Like antiporters, symporters use the potential energy of electrochemical gradients from Na+ or H+ to transport ions, glucose, and amino acids against their concentration gradient. 3. ATP-Powered Pumps: couple the energy released from the hydrolysis of ATP with the transport of substances across the cytoplasmic membrane. ATP- powered pumps are used to transport ions such as Na+, Ca2+, K+, and H+ across membranes against their concentration gradient.

20. 4- Endocytosisis a form of active transport in which a cell takes in solutes or particles by enclosing them in vesicles or vacuoles pinched off from its cytoplasmic membrane. There are three forms of endocytosis: phagocytosis, pinocytosis, and receptor-mediated endocytosis