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7

Pure nicotine is a yellow colored liquid (although some sources say it's a clear liquid.) "Tar" is a complex sludge that is also yellow-brown. So it's difficult to distinguish 'nicotine stain' from a 'tar stain' based on visual inspection. Let's go to other considerations. The concept of a 'stain' implies that simple hand washing doesn't remove the ...


6

Homeothermic multicellular organisms have special tissues that burn resources to warm up (usually this involves breaking the electron-transporting chain at the final stages of respiration to transform all chemical energy into thermal energy). And they have special tissues (fat) and enough body mass (this is more about the volume/area ratio) to keep this ...


5

Short answer Tar deposition is the cause of the yellow cigarette stains. Background Both tar and nicotine cause yellow to brown staining. Although nicotine itself is colorless/white, it turns yellow upon exposure to air. In a study on cigarette stains, the author speaks of tobacco-tar stains, implicitly acknowledging it is tar and not nicotine (John et ...


5

In my experience, half an hour at room temperature will make absolutely no difference. Boehringer Mannheim (now part of Roche), who at one time supplied the best NADPH, used to recommend storage at 4o C. By A340 callibration, NAD(P)H is typically about 85% 'pure' based on dry weight measurements, and Sigma will try to tell you that the remainder is mainly ...


4

This is difficult to answer exactly since the thermodynamics of cellular metabolism are not well understood. These are spontaneous reactions, so there is certainly a loss of Gibbs' energy $\Delta G < 0$; this energy corresponds to your "energy" term on the product side of the reactions. For the anaerobic case (glycolysis) a balanced reaction formula is ...


4

You could measure OD at 340nm. If OD340 is much lower than expected, NADPH is oxidized and does not have much biochemical activity. http://www.bmglabtech.com/media/35216/1043734.pdf


3

In the context of this book, dAT joining is a method used in molecular cloning to join two DNA molecules. Basically, terminal transferase is used to add polyA or polyT to the 3' ends of each DNA molecule. This creates cohesive ends which can anneal and then be ligated together, giving a covalently closed circular DNA molecule. Image from: Jackson DA, ...


3

I think when they sent it to you without dry ice, it is probably OK to store it at room temperature. Sigma seems to advise on their NADPH to store dehydrated NADPH at room temperature, while they advise to store the hydrated forms at -20oC. Likely the presence or absence of molecular water in the material is crucial for its storage. disclaimer: I am not ...


3

From the derivation of Michaelis-Menten kinetics you can see that: $$K_m=\frac{k_f + k_{cat}}{k_r}$$ Where $k_f$ and $k_r$ are binding and unbinding rate constants (for Enzyme-Substrate binding), respectively, and $k_{cat}$ is the turnover number. This is for the Quasi-Steady-State approximation (QSSA). For the equilibrium approximation: ...


2

Basically, they engineered a vector which, when transfected to E. coli, produces transcripts of -and thus proteins to- a fusion gene which produces these transmembrane α helices conjugated to the staphylococcal nuclease. In other words, the E. coli are just factories for producing proteins: Expression, Extraction, and Purification of SN/GpA - For high ...


1

Take a look on reaction catalyzed by dihydrolipoyl dehydrogenase. It acts upon $NAD^+$ according to following equation: $NAD^+ + FADH_2\rightarrow NADH+H^++FAD$ Same way you can write other reactions, e.g. by pyruvate dehydrogenase: $Pyruvate+TDP\rightarrow CO_2+TDP-Hydroxyethyl$


1

Texts usually have a verbal explanation of these kind of diagrams, so look in the text where it references Figure 17.5 and read the section before and section after. That being said, if you start at the top with pyruvate, it enters the cycle where the curved circles touch on pyruvate dehydrogenase, which catalyzes its decarboxylation. That product then ...


1

It was a simple search. You could have easily searched for glucose oxidase in KEGG, and you would have got this reaction. In fact if you had clicked the link for glucunolactone's compound page, you would have got a list of many different reactions that convert glucose to glucunolactone. You can even click the arrow which opens the KEGG-ORTHOLOGY page. You ...


1

The short answer is NO. A shadow is strictly due to the blocking of sunlight, so the shadow of 2 equally non-transparent (i.e., same density of leaves, both have similar trunk diameter, etc.) trees on the same hillside in the same weather conditions would not have different temperature shadows. A plant's metabolism can and will affect the temperature ...


1

Someone has thought this was a very good question and performed an MD simulation on spontaneous bilayer assembly. There, lipids start in random orientations. The ordered bilayers we know and love spontaneously assemble in under 100ns. So if the lipids were jumbled up (or even reversed), the would probably reform fairly quickly. I wouldn't imagine that it ...



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