Yggdrasil

The problem can be attributed to both patients and doctors. Patients will often quit taking antibiotics after the symptoms of their infection have gone away. While this will still allow them to recover alright, it leaves a small population of bacteria which are more resistant to the antibiotic. Had the patient taken the full course of antibiotics, the entire population of bacteria would have likely been eliminated, preventing the more resistant bacteria from propagating their resistance genes. Doctors make the problem worse because they often prescribe antibiotics when they're not needed. Hospitals teach doctors to prescribe antibiotics even for viral infections just so that the patient thinks the doctor did something to help him/her and they don't walk away empty-handed. Worse, some patients will demand antibiotics as a treatment for their cold and the doctor will prescribe them so that their patient doesn't go elsewhere. Generation times. Some bacteria reproduce every 20 minutes. Most humans wait until they are around 20-30 years old before they begin to reproduce. By the time one human generation passes, a huge number of generations of bacteria will have passed. More generations amounts to a greater chance that a random mutation will benefit the organism and it also gives the gene time to propagate throughout the population.

Yes, the rubbing alcohol sold in drug stores is a solution of isopropyl alcohol.

Make flash cards of important reactions. On one side write the starting material and reagent, so that you need to guess the product. On the other side, write the starting material and product, but leave the reagents blank so you have to guess at them. Reviewing these periodically will help you remember the reactions.

Natural gas itself doesn't have a smell, but manufacturers put in an additive to make it smell so leaks can be more easily detected.

Google is great for finding out basic info, though my first search is usually in wikipedia, since it will generally provide good links and you don't need to sift through irrelevant links. However, for more advanced topics and info on more current research, I rarely use google. For those, I rely on Crossfire, SciFinder, and PubMed.

Do a google search for resources on bioinformatics. Computational biology and structural biology are other branches of biochemistry which rely on computational methods as well.

True. Or, react isoamyl alcohol with acetyl chloride or acetic anhydride in the presence of an organic base. However, acyl chlorides and acyl anhydrides probably aren't available to most DIY chemists.

React isoamyl alcohol (a.k.a. isopentyl alcohol or 3-methylbutan-1-ol) with acetic acid (a.k.a ethanoic acid).

Both terms are just names of reaction mechanisms: A saponification is the base-catalyzed hydrolysis of an ester, forming a carboxylate (deprotonated carboxylic acid) and an alcohol. A Fischer esterification is the acid-catalyzed condensation reaction between a carboxylic acid and an alcohol which produces an ester. Here's a list of some different esters and their smells: Isoamyl acetate - banana oil Ethyl butyrate - pineapple Isobutyl propionate - rum Octyl acetate - orange Methyl anthranilate - grape Isopentenyl acetate - "Juicy Fruit" benzyl acetate - peach n-propyl acetate - pear methyl butyrate - apple ethly phenylacetate - honey methyl salicylate - oil of wintergreen 2-phenyl ethyl propionate - lily flower Note that isoamyl acetate (IUPAC: 3-methylbutyl ethanoate) is also the alarm pheromone for honey bees.

Synthesis of Methyl salicylate (oil of wintergreen) from aspirin and methanol: Step 1: Saponification of acetylsalicylic acid Extract acetylsalicylic acid from a ground up aspirin tablet using acetone. Prepare a strong solution of NaOH and disolve the acetylsalicylic acid in it. Heat to a boil for about 2 minutes, then cool to room temperature. This will saponify the acetylsalicylic acid (an ester itself) to produce salicylate and acetate. Add an ice-cold solution of dilute HCl to protonate the salicylate and precipitate it from solution. Collect the solid (salicylic acid) and dry well. Step 2: Fischer esterification of salicylic acid and methanol Disolve the salicylic acid from part 1 in methanol, then add a catalytic amount of conc. sulfuric acid. Heat to produce methyl salicylate. If you want to isolate the methyl salicylate, remove the salicylic acid by extracting with cold aqueous base (so the base does not promote hydrolysis of the ester), dry with a drying agent, then distill off the methanol (bp =64.6C) from the methyl salicylate (bp = 220 - 224C). What remains should be colorless, yellowish or reddish oily liquid.

Most plant biologists use a plant called Arabidopsis thaliana (thale crest) as their model organism. It is a small weed from the mustard family. The advantages of studying Arabidopsis are its small size, relatively short generation time, large number of seeds, and small genome. It is especially useful for genetic experiments as the Arabidopsis genome has been sequenced and there are many resources available for studying the Arabidopsis genome.

The following reactions occur when glucose is in water. The cyclic hemiacetal forms (on the left and right) are favored over the straight-chain form (in the center).

Along the same lines, molecules with 4n electrons in a cyclic conjugated pi system are anti-aromatic.

Yes. The fatty acids from triacylglycerides (fats) and the amino acids from proteins can be broken down to TCA cycle intermediates (such as oxaloacetate). The enzyme phosphoenolpyruvate carboxylase converts oxaloacetate to phosphoenolpyruvate, which can be made back into glucose through a process known as gluconeogenesis (essentially the reverse of glycolysis).

Yes. Here are some example calculations: For a solution at pH = 2.0 [H+] = 1.00x10-2M [OH-] = Kw/[H+] = 10-14/10-2 = 1.00x10-12M For a solution at pH = 10 [H+] = 1.00x10-10M [OH-] = Kw/[H+] = 10-14/10-10 = 1.00x10-4M When [H+] is high, [OH-] is low and vice versa.

I think higher pressure decreases evaporation rates. For example, water boils at a lower temperature at higher altitudes, meaning that it's easier for the water molecules to evaporate because of the lower pressures at high altitudes. Similarly, instead of using heat to promote evaporation (which can sometimes lead to decomposition of your product), chemists sometimes use low pressure to evaporate volitile compounds in a process called vacuum distilation. I believe this is an effect of Le Chatalier's principle. At high pressure, the system will prefer the more dense form (i.e. liquid). This principle also explains why ice melts when pressure is applied; the more dense form of water (liquid) is favored over the less dense form (ice). Similarly for sublimation, high pressures will favor the more dense form (solid) and low pressures will favor the less dense form (gas). Unfortunately, I know no equations for the rates of evaporation and sublimation.

To explain why cyclobutadiene is not aromatic requires one to talk about molecular orbitals, unfortunately, since resonance, conjugation and aromaticity are based on molecular orbital theory. Basically, the four p-orbitals on each of the four carbon atoms will form four Pi orbitals, a bonding orbital, two non-bonding orbitals, and an antibonding orbital. Since each p-orbital contributes one electron to the Pi system, there will be four electrons: the first two fill the bonding orbital, so the other two go into the non-bonding orbital. However, since the two non-bonding electrons will go into opposite orbitals, this makes cyclobutadiene a highly-unstable diradical species (hence, cyclobutadiene is known as an anti-aromatic molecule, a molecule which becomes highly unstable when it forms a cyclic conjugated Pi system). Since the formation of this conjugated Pi system is so unfavorable, cyclobutadiene will adopt a conformation which prevents the two adjacenct pi bonds from becomming conjugated. Since conjugation is essentially resonance, cyclobutadiene will not have a resonance form.

Yes, sulfates can and do act as Bronstead bases.

albertlee, remember the autodisociation of water: H2O <--> H+ + OH- Has the equilibrium constant, Kw = [H+][OH-] ~ 10-14. Therefore, you can use [OH-] to calculate [H+]. [Edit: Kw ~10-14, not 1014] Also, pKa = pH + ([A-]/[HA]) is incorrect. The correct equation is called the Henderson-Hasselbach equation and takes the form: pKa = pH + log([HA]/[A-]) It's derrivation is as follows: Ka = [H+][A-]/[HA] (definition of Ka) Now, take the -log of both sides: -log(Ka) = -log([H+][A-]/[HA]) -log(Ka) = -log([H+]) - log([A-]/[HA]) Since pKa = -log(Ka) and pH = -log([H+]), pKa = pH - log([A-]/[HA]), or equivalently pKa = pH + log([HA]/[A-])

Muscles get tired mainly because of the buildup of lactic acid from anaerobic metabolism. My guess is that since the lungs and heart are so close to the sites of gas exchange and since they work at such a regular rate, the constant supply of oxygen to the heart and lungs is enough to power their aerobic metabolism and they do not need to switch to anaerobic metabolism in order to provide the necessary energy to perform their work.

Einstein's equation turns 100 From Wikinews, the free news source you can write! September 27, 2005 The man behind E=mc2, Albert Einstein.Albert Einstein's best known equation, and probably the best known aspect of all physics, E=mc2, turns one hundred today. September 27, 1905 is generally considered the birthday of the equation because that is the day that Einstein's paper outlining the significance of the equation arrived in the offices of the German journal Annalen der Physik. In the equation, 'E' stands for Energy, 'm' stands for mass, and 'c' stands for the speed of light. The equation shows that matter and energy are, essentially, two aspects of the same thing, and that a small amount of matter can be converted into an enormous amount of energy. Nuclear reactions, including fusion in the sun and in nuclear weapons, are examples of large amounts of energy released from the conversion of comparatively small quantities of mass. The United Nations declared 2005 the International Year of Physics in recognition of Albert Einstein's work in 1905. In addition to discovering his famous equation, over the course of 5 months in 1905 Einstein developed the theory of Special Relativity (which led him to the equation E=mc2), proved the existence of atoms and molecules, and showed that light is made of photons. 1905 is often called Einstein's annus mirabilis, or miracle year. The 100th anniversary of Einstein's miracle year is being celebrated in many countries around the world as the World Year of Physics. In the UK, it is called the Einstein Year. Link

Cytotoxic T-cells will generally kill cells exhibiting uncontrolled growth. However, most cancer cells in a tumor have mutations which make them invulnerable, or at least more resistant, to cytotoxic T-cells.

Antibodies can only recognize antigens on the surface of cells. Since telomerase is in the nucleus of cells, which is inaccessible to antibodies, anti-telomerase antibodies could not be used to target cancer cells. However, cancer cells do display some unique antigens on their surface which can allow the immune system to target cancerous cells. However, researchers are still trying to identify and study there antigens and develop treatments based on this principle (immunotherapy).

IIRC, one can write the equation for the first law of thermodynamics as: [math]\Delta E_{sys} = -\Delta E_{sur}[/math] Which means that energy is conserved; if the system gains energy, it comes at the expense of the surroundings, and if the system loses energy, the surroundings take up the lost energy.

See post #4.