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9

The mechanism of aconitase classifies it as a lyase, even if (under most physiological conditions), the relative concentrations of substrates results in it catalysing the conversion of citrate to isocitrate. In short, it is not an isomerase because the substrate is released after each step. As the mechanism of aconitase shows, it catalyses the conversion ...


6

These terms are completely unrelated. Alpha-subunit is an arbitrary name for a protein subunit in a multi-subunit protein complex (one having a quaternary structure like haemoglobin or G-protein etc). Alpha-helix is a type of secondary structure. Addition by David: For those who may be unfamiliar with this, alpha, beta, gamma etc. are Greek letters of ...


5

Yes, tRNA can form dimers. For example it was shown that E. Coli tRNA GCC forms homodimers, i.e. two identical molecules interact with each other. In this case the dimerization occurs between the anti-codon loops (what was probably meant with UUU and AAA). References: Sequence and structure of naturally-occurring tRNA transcripts and site-directed ...


5

Basal tears are always in our eyes to serve the purpose of lubricating, nourishing, and protecting the eyes. Reflex tears protect the eyes from irritants, including wind, smoke, or onions. Tears produced by emotion Although these tears contain higher levels of stress, such as ACTH and enkephalin, and endorphin and natural pain killer, ...


5

Short answer The distinction between Gram positive (Gram+) and negative bacteria (Gram-) has absolutely nothing to do with membrane potentials; it is all about the Gram staining procedure. Background The Gram staining was named after the Danish bacteriologist Hans Christian Gram, who originally devised it in 1882 (Gram, 1884). Gram staining is a common ...


3

In most cases, it's not a good idea to replace glucose with glycerol in animal cell media. Animals do possess the ability to metabolize glycerol, via a pathway starting with the enzyme glycerol kinase. However, glycerol kinase is only expressed in certain cell types, such as liver cells and kidney cells. References: ...


3

I answered this implicitly in a comment to my answer to: Light and Dark Reaction of photosynthesis?. Anyway: There is no such thing as NADPH2. There is only NADP+ and NADPH. Consult Wikipedia or a reputable text such as Berg. The nicotinamide portion of NADP that undergoes oxidation and reduction is exactly the same as in NAD. The changes undergone are: ...


2

It is a misconception that cats cannot synthesize taurine. Cats can synthesize taurine, just like other mammals, but not enough of it to make up for an entirely taurine-deficient diet. Cats (and other mammalian carnivores) would have consumed a taurine-rich diet in the ancestral environment. It is only when they are fed vegetable/fruit/grain-derived foods ...


2

This is coenzyme A (CoA). As you can see, it has an -SH group at its end. So when it interacts with other reagents, it forms thiolesters. CoA is just shorter.


1

Not sure if there is a definite answer. However, from structural studies, its proposed that essentially the Chlorophyll a and pheophytin(Pheo) are positioned ~10A away, and the transfer of a radical electron from the P680 center to Pheophytin does occur. The exact mechanism is possibly mediated by a tyrosine Durant J.R et al (1995). Proceedings of the ...


1

Since the ability to utilize glucose for energy is necessary for life (look at the effect of hypoglycemia on brain function, for example), it makes sense that the regulation of serum glucose concentration would have a number of pathways, that is, redundancy helps to ensure continued proper function should one of the regulatory mechanisms fail. Glucagon is ...


1

I took a 30 second look at the book you mentioned. The authors just made this up, just like 95% of the book. The authors are not wrong, they didn't want to write something useful and made a mistake, they're just bullshitting: They're making stuff up, letting it sound a tiny bit scientific and try to sell a lot of books. If you want to know more about ...


1

I am not too sure but this is my logic: There would be in total of 18 molecules of Acetyl-CoA which means 18 TCA cycles. Propionyl-CoA gets converted to Succinyl-CoA which is a TCA intermediate (at about half of the cycle). If you do consider this, the 3 molecules of propionyl-CoA would only give you 3 partial rounds (or lets assume 1.5 rounds) of TCA ...


1

I am putting here the main points from the link given by @WYSIWYG (i.e. this): High glucose levels reduce the levels of the powerful vasodilator nitric oxide in blood vessels, a shortfall that increases the risk of high blood pressure and eventually narrows down the vessels...increased modification of proteins by a glucose-derived molecule is a player in ...


1

The following is not an answer to the original question: "Are Gram negative bacteria classified as such because of their negative membrane potential?" but to the questions later in the text. Usually the membrane potential is given for the inner cytosolic part and the extracellular space, for E. Coli it is around -120 mV; see also this article. Due to the ...



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