Water is a charged or polar molecule (H+ - O- - H+) that is always
moving across cell membranes. Scientists theorize that this is
possible because it is such a small molecule or because there are
special gap or pores that allow water movement through the cell
membrane. The predominant direction of water flow is determined by the
concentration of the solutes (non-water molecules) inside and outside
of the cell. Water molecules will show a new movement from an area of
higher water concentration (& lower in solutes) to an area of lower
water concentration (& higher in solutes). In other words the net
water flow tends to dilute an area of higher solute concentration.
When water moves by diffusion through a semi-permeable membrane it is
called osmosis. This is a type of passive transport because no
cellular energy (ATP) is involved in the movement of water.
For convenience we will use tonicity & osmolarity as interchangeable
terms. In fact, there are exceptions when these terms do not have
identical meaning.
An extracellular solution is isotonic ["iso" = same, tonicity = tone
or tension] or iso-osmotic to a cell if the cell has no net gain or
loss of water. This is a dynamic equilibrium. The cell & the
extracellular solution have the same concentration of water & the same
concentration of solutes. Our extracellular fluids need to stay
isotonic in order for cells to survive. If cells are place in a
solution that contains a higher concentration of solutes than the
cell, cells suffer a net loss of water and appear crenated ["cren" =
notched] or wrinkled. These cells are in a hypertonic or hyperosmotic
solution. Cells in a highly hypertonic solution may die. A solution
that has a lower solute concentration than is present in cells is said
to be a hypotonic or hypo-osmotic solution. In this case, excess water
flows into the cells and the cells swell. These cells may eventually
rupture or burst open. This process is called lysis.
Although we simplify osmolarity problems by using the % of a solute to
That familiar fizzing you hear when you drop an Alka Seltzer tablet into a glass of water is the result of a chemical reaction, and chemical reactions are extremely prevalent when it comes to what living things do to carry out life processes. In addition, environmental conditions can alter the results of chemical reactions, and in this lab, we will be answering the
To identify an unknown microorganism by performing a series of biochemical tests on a pure bacterial culture.
perform a lot of procedures in order to obtain an anhydrous alum at the end. What we first wanted to obtain was a hydrated alum crystal. To achieve this, we broken down aluminum foil into pieces and let it reacts with 25mL of 3M KOH. Next, we filtered it to get rid of any undissolved particles. Furthermore, we heated the solution and let it rest until crystals were formed, and then cooled it once again to get the hydrated alum crystals. Then, we washed/filtered the crystals by wetting them with a non-soluble solution and let the crystals dry. After that, we took 2g of the alum crystals and burned them on a crucible, taking its mass beforehand. Lastly, we heated the solution for five more minutes and let it cool to room temperature.
The unknown bacterium that was handed out by the professor labeled “E19” was an irregular and raised shaped bacteria with a smooth texture and it had a white creamy color. The slant growth pattern was filiform and there was a turbid growth in the broth. After all the tests were complete and the results were compared the unknown bacterium was defined as Shigella sonnei. The results that narrowed it down the most were the gram stain, the lactose fermentation test, the citrate utilization test and the indole test. The results for each of the tests performed are listed in Table 1.1 below.
The goal of the project was to characterize an "unknown" organic acid in order to make a proper identification of the acid, while learning proper techniques for scientific measurement and analysis of error.
Using your finger, gently tap the tubes to mix the Luria broth with the cell suspension. The test tubes will need to rest for approximately five to fifteen minutes in a room temperature environment.
Before any chemical reactions occurred, there was 0.46 grams of elemental copper metal. After the copper was added to the 250 milliliter beaker containing the 5.0 milliliters of nitric acid, nitrogen dioxide gas came out. The gas color was a light brown color, and the clear nitric acid within the beaker became a green-brown color. Once the chemical reaction concluded and nitrogen dioxide gas stopped releasing from the beaker, 20 milliliters of distilled water was added to the solution, and the color within the beaker turned to a neon blue. This was the chemical equation for the first chemical reaction, 4 HNO3 (aq) + Cu (s) → Cu(NO3)2 (aq) + H2O (l) + 2 NO2 (g).
The purpose of this lab was to determine the density of water and an unknown liquid, along with a rectangular solid and an irregular shaped solid. In this lab, the relative density was calculated and then used to make an educated guess on the substance. Density is the relationship between the mass of a substance and the amount of space taken up. This measurement is influenced by the mass of atoms, the size, and how they are arranged. The density of the four objects was determined by using the mass (g) and volume (mL or c3). Mass is the property of matter that measures its resistance to acceleration. In addition, volume is the amount of space that a substance or object occupies. Finally, the mass (g) was divided by the volume (mL or c3) to find the final density (g/mL or c3).
The experiment is aimed at giving a better understatement of osmosis process and the different conditions in which osmosis occurs.
For the first trial, 2 dry evaporating dishes were weighed on the balance, and their masses were recorded. The first dish was 71.74 grams by mass, while the second dish was 52.03 grams by mass. We added 2 grams of unknown mixture to the first evaporating dish, and we weighted it on the balance and recorded its mass. The mass of this dish was 74.74g. Then, the first evaporating dish was put on the clay triangle using crucible tongs on the Bunsen burner in the hood area. The mixture was heated, and there was a gas that was produced which was NH4CL. After the NH4CL was removed, we took the evaporating dish using tongs and it was left to allow it to cool. After the dish was cooled down, the dish was placed on the balance and weighted again after heating (McHugh 46).
The presence of coliforms in a water supply can mean there is fecal contamination circulating in that water, which we tested for in this experiment. It is hypothesized that all of the water supplies will exhibit the presence of fecal coliforms, because they are all outside sources of water that have road runoff, sewage waste and animals defecating in them. We gathered several water samples and inoculated lactose broth with these water samples which tested for fermentation and helped determine if coliforms were present. Then if there was possible coliforms present, we placed them on either an Endo agar
The propensity of these hydrophobic tails to self-associate to exclude interactions with water, via the energy provided by Van der Waals forces and preferential hydrogen bonding between hydrophobic tails, and the propensity of the hydrophilic heads to interact with the aqueous environment are the basis for the thermodynamic stability and self-assembly of the bilayers of biological membranes. However, many of these bilayers are asymmetrical in nature, with the inner leaflet having fewer amphipathic molecules or a different lipid composition than the outer leaflet, attributing the circular curvature of most biological membranes. For the lipid component of these membranes, phospholipids, with varying head groups such as phosphatidylcholine and phosphatidylserine, are the primary component of these bilayers, with sphingolipids, such as sphingomyelin, and sterols, such as cholesterol, typically found in lesser concentrations, but both still play an integral role in biological membranes (Nicolson, 2014). Small gaseous molecules, like O2, hydrophobic molecules, like benzene, and small polar but uncharged molecules, like ethanol, are essentially able to dissolve in the phospholipid bilayer and thus cross the diffuse across the cell
In our Biology Lab we did a laboratory experiment on fermentation, alcohol fermentation to be exact. Alcohol fermentation is a type of fermentation that produces the alcohol ethanol and CO2. In the experiment we estimated the rate of alcohol fermentation by measuring the rate of CO2 production. Both glycolysis and fermentation consist of a series of chemical reactions, each of which is catalyzed by a specific enzyme. Two of the tables substituted some of the solution glucose for two different types of solutions. They are as followed, Table #5 substituted glucose for sucrose and Table #6 substituted the glucose for pH4. The equation for alcohol fermentation consists of 6 Carbons 12 Hydrogens 6 Oxygen to produce 2 pyruvates plus 2 ATP then finally the final reaction will be 2 CO2 plus Ethanol. In the class our controlled numbers were at Table #1; their table had 15 mL Glucose, 10 mL RO water, and 10 mL of yeast which then they placed in an incubator at 37 degrees Celsius. We each then measured our own table’s fermentation flasks every 15 mins for an hour to compare to Table #1’s controlled numbers. At
Enzymes are proteins that consist of a long chain of different amino acids that increase the rate of chemical reactions by lowering activation energy. (Bbc, 2016) Activation energy is the minimum amount of energy required to activate molecules to undergo a chemical reaction, so lowering the activation energy enhances the chemical reaction, allowing it to occur faster and more often. (Encyclopedia Britannica, 2016) Chemical reactions happen within cells, with molecules called substrates. (Live Science, 2016) Two molecules must collide at the same time, with the right orientation and sufficient energy in order for the chemical reaction to occur. (Rsc, 2016) Once together the enzyme and substrates bind at the active site and the chemical reaction
The actual, theoretical, and percent yield of sodium chloride was found. Sodium Carbonate was mixed with hydrochloric acid and the liquid was boiled until there was nothing left. The result was the production of salt, or sodium chloride.