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Questions tagged [biochemistry]

The study of chemistry within the scope of biology: the compounds that occur and the reactions involving them in living organisms.

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Does eating food with MSG make you thirsty?

My grandma alleges that she's thirsty after a meal that doesn't taste salty, if and only if the food contains MSG (monosodium glutamate). Is she correct? She doesn't believe the answers in this ...
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15 views

Valence electrons in DNA nucleotide addition [on hold]

Can anyone explain the movement of valence electrons during the nucleophilic attack that occurs during DNA synthesis? The 3' oxygen starts with two lone pairs of electrons but what happens during the ...
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19 views

Depolarisation of post synaptic neuron

When the post synaptic neuron begins to depolarise as positive sodium ions move into it and it reaches threshold- does the inside of the neuron actually switch to being more positive than the outside? ...
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18 views

Calculate dissolved methane concentration from concentration in headspace [closed]

I am going to run an experiment with chemostats that will continuously be supplied with air that contains 10% methane. I would like to know what the resulting methane concentration in the water of the ...
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Some religeous people say that piercing of ears controls blood circulation of veins…How is piercing of ears related with blood circulation? [closed]

This is the picture of a program organised by a science organisation. I am standing on left side with my friend. I am very curious about knowing something new in science
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2answers
654 views

Where does the proton come in the reduction of NAD?

In our curriculum biology textbook the reduction of NAD+ is depicted as follows: NAD+ + 2 H+ → NADH + H+ If this proton in the products was not present in the reactants, then where does it come ...
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1answer
69 views

How is bad garlic breath eliminated by swalllowing a bit of raw garlic?

Please bear with me, as I am just a poor physicist. I have learned how to make traditional pastourma from a recipe given by my late aunt Dora, which is like pastrami except with a very strong garlic ...
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2answers
107 views

How can dehydrogenation steps in some biochemical pathways produce ATP?

Dehydrogenation reaction of alkanes is inherently endothermic as one removes two thermodynamically more stable C-H bonds and replaces it with one less stable C=C. Although the product is conjugated ...
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1answer
88 views

What is the difference between a signal peptide and a transit peptide?

From what I know, the two names are used interchangeably and I haven't found any resource which says otherwise either. Is there at all any difference, is there a transit peptide that is not a signal ...
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Is the chemical composition of urine detrimental or beneficial for a tree?

Seeing as a lot of people around the world urinate against trees it came to mind that I never thought about how the tree responds to this. Is it detrimental for a tree if people urinate against them? ...
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20 views

Will inhibiting an enzyme be rendered ineffective if another enzyme metabolizes the same drug? [closed]

I have heard the LSD is metabolized by the enzymes CYP3A4 and CYP2D6. After hundreds of LSD trips, a patient is unable to gain substantial effects, even after a 5-year detox from SSRIs, and trips up ...
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Is there an endothermic reaction with glucose without needing to be activated? [on hold]

Is there an endothermic reaction with D-glucose as substrate that does not require the glucose to be activated?
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2k views

What inactivates pepsin in infants?

In infants, rennin helps in digestion of milk. Pepsin is also present in their stomach. Why do infants need rennin for milk digestion, at the first place? Why does pepsin not act on the milk ...
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8k views

Why do some vegetables taste bitter?

Bitter gourd, cucumber, etc. are bitter to taste. Which chemical causes bitterness in them? I found these when I searched online: this says that it is because of calcium, while this and this talk ...
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1answer
95 views

Where would vegetarians/vegans get a substitute of hemo/myoglobin from?

As far as I understand, there is a difference in the iron absorbed from meat than from other sources like grains and vegetables. If this is the case, is it possible that not ingesting the hemoglobin ...
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3answers
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Why do Type II Restriction Endonucleases cleave at palindromic sequences?

Type II Restriction enzymes usually cut only at palindromic sequences. Is there any specific reason for that? Is there any advantage for bacteria if they cleave phage DNA at this type of sequence?
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2answers
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Why isn't acetyl-coA an entry point for gluconeogenesis?

The process of gluconeogenesis starts from various possible precursors - plausible entry points like, Pyruvate, OAA, Fumarate, Propionate (as succinate) and alpha-KG. It is important to note that, ...
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Evolutionary basis for medicine

As a complete non-expert, It seems extraordinary to me that minute amounts of chemicals, taken orally or in other ways can affect the regulation of body processes. Is there an evolutionary point of ...
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1answer
30 views

Where do the lysines come from during ubiquitination?

I know that Ub forms an isopeptide bond with lysine, but where do the lysine come from? Are they just always available for the Ub to find to during the ubiquitination process? Is there a free lysine ...
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58 views

What happens to drug metabolism when CYP450 enzymes are presented with two substrates

What happens when two substances, both substrates for Cytochrome P450 metabolism, are both present in the bloodstream? For example, with sertraline and cannabidiol (CBD), if someone took a sertraline ...
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11 views

What proteins are assisted by chaperone folding?

I've been looking into a lot of papers, and most say that chaperones assisted in the folding of misfolded proteins, or Ubiquitin markers aggregates for degradation by the proteasome. Or it will say ...
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What is the fastest way to crystallise lysozyme (for student course)?

High school sudents are going to visit my university and I plan to demonstrate crystallisation of lysozyme. I ordered pure lysozyme from VWR. I can easily crystallise this within 15 min in batch (4% w/...
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Cadmium Poisoning and Toxicity Mechanisms

Is anyone aware of the toxic mechanisms of specific instances in which cadmium ions can interfere with cellular functions resulting in acute cadmium poisoning?
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1answer
5k views

How do bile salts affect lipase activity?

BACKGROUND: It is well known that bile salts are needed for emulsification of fats. It is then said that this increases the surface area for activity of pancreatic lipase, implying that bile salts ...
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1answer
105 views

Difference between prions and amyloid proteins?

Amyloid and prions are misfolded proteins, but what, if any, is the difference between them? Is amyloid a type of prion with a fibrillar structure?
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3answers
120 views

What happens to Km when enzyme concentration is *very* high?

Let Km be an empirical measurement of a certain enzyme with concentration [E]. Theoretically, this value is constant and shouldn't vary when [E] goes up or down. Now let [E']=10*Km. Under this ...
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Toxic Metals and Oxidative Phosphorylation

I was reviewing the toxicity of certain toxic metals, specifically cadmium and their effect on Oxidative Phosphorylation and Cellular Respiration, I have found that metals such as cadmium inhibit ...
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3answers
110 views

Is oxygen's paramagnetism biologically relevant?

It seems our most common everyday O2 molecule happens to be a paramagnetic one (see https://en.wikipedia.org/wiki/Oxygen). But, does this have a biological relevance as well? In other words, Do any ...
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1answer
72 views

Why can't diamine oxidase be supplemented?

I've read from an academic article that diamine oxidase cannot be supplemented but it had no explanation as for why. I am curious as to why this? Food rich in histamine or red wine may cause ...
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1answer
188 views

Do chaperone proteins misfold?

If molecular chaperone proteins assist in the folding process of other proteins and misfolded proteins, can chaperone themselves misfold since they are also proteins? What would happen if chaperones ...
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1answer
27 views

How can sodium and potassium from burned organic matter (ashes) reenter the ecosystem?

If you thoroughly burn something you end up with bunch of oxides and hydroxides, as far as I know. Sodium and potassium hydroxides are plentiful in ashes, which is why lye was created by soaking ...
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1answer
16 views

Can someone help me interpret these charts on fluorescent polarization?

I have to present an article about binding designed proteins to fentanyl for my biochem class; I understand everything except how to interpret these charts on fluorescence at the very top of Figure 2a:...
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1answer
78 views

HELP! How will pH 14 affect enzyme structure? [closed]

If a substance is very alkaline/ basic, e.g. a pH of 14, does this mean that there are near to zero H+ ions (or it is possible to have such a situation where there are zero H+ ions and it is still ...
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3answers
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How, on a physical level, does ATP confer energy?

When ATP is used as the energy currency to make, say, reaction X + Y → Z happen, is what happens on a physical level down at the molecular scale that during the reaction ATP + H2O → ADP + Pi  &...
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1answer
68 views

What is the importance of alkaline condition in biuret test?

Biuret test aims to quantify the amount of protein in a given unknown sample. Biuret agent contains copper sulphate, sodium potassium tartrate and Sodium hydroxide. Coppper ions form the complex of ...
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Chemical composition of human nucleoplasm?

I'm working on a computer visualisation of the inside of a human cell nucleus (embryonic stem cell for now if it makes a difference) and want a good approximation of the chemical composition of the ...
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1answer
42 views

How can P450 distinguish between foreign and native compounds?

It is my understanding that P450 enzymes are capable of selectively degrading compounds that enter the cell from the outside (e.g. synthetic drugs) without damaging compounds that are metabolic ...
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Biological Nitrogen Fixation

I just studied Biological Nitrogen Fixation and saw it's reaction but i do not understand why there is 8 electrons and 8 protons are involved and Hydrogen molecule is formed side by side along with ...
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2answers
999 views

What is the source of the electrons generated in the Krebs cycle?

In the Krebs cycle, where do the hydrogens and electrons that NAD+ and FAD accept come from? It seems that citric acid only loses two hydrogens because it starts out with eight hydrogens and then ...
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1answer
132 views

Book-recommendation: Biochemistry

I need to have a book which covers following topics two may also be fine: (a) Structure and role of carbohydrates, fats, fatty acids and cholesterol, proteins and amino-acids, nucleic acids. ...
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27 views

Why does carbon dioxide diffuse easier through the bilipid layer than oxygen?

When gas exchange occurs during respiration, the pressure of oxygen in alveoli is around 105 mmHg, whereas in the blood vessels in close contact with alveoli is 40 mmHg. For carbon dioxide the values ...
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Naming of Secondary Structure Elements

I have 2 questions regarding the naming of secondary structure elements ($\alpha$-helix and $\beta$-sheets), like helix C or sheet 2, which are often used in publications. Example protein: CYP1A2 ...
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Conversion of 2E trans-2-enoyl CoA to 3E trans-2-enoyl CoA

I am working on a project that aims to synthesize a particular molecule from a purely synthetic route, in doing so I am attempting to create a strain of e.coli which would be able to use its trans ...
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1answer
36 views

can magnesium bicarbonate be absorbed in the mouth?

Can Magnesium Bicarbonate be absorbed in the mouth?" Magnesium Bicarbonate occurs naturally in some mineral waters.
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plant uptake of large molecules

I have read several studies concluding that plants can indeed take up molecules with a molecular weight largar than 390 g/mol. Does this mean plants do also take up large molecules like hormones if ...
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27 views

PBS or TBS, where cannot use each buffers?

As you know, Tris buffered saline and Phosphate buffered saline is multipurpose. For finding each buffer's use, there's so many use experiment for PBS and TBS. TBS uses for western blotting, and PBS ...
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Is there a software simulator for monomeric formation, a la Miller-Urey?

At the moment, does any widely-available software exist for small-scale, programmable simulation of monomeric formation in specific conditions? Could one, for instance, recreate the Miller-Urey ...
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What happens to Bacterial Cells stored at 4 degrees?

4C is when water is most dense and is not so low as to cause ice crystal formation. For short term storage bacterial cultures are often simply kept in a fridge at 4C. I guess that this significantly ...
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Why does hydroxylation of fatty acids occur in the middle of the acyl chain and increase fluidity?

I wanted to check and see why a) hydroxylation of fatty acids is most likely to occur in the middle of the acyl chain and b) why that increases fluidity. If our goal is to increase fluidity, then by ...
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Can one talk about deacetylation of a promoter rather than associated histone?

I am confused on a detail in a paper I am reading and am not sure whether I am misunderstanding the wording or misunderstanding the concept. I am including the whole abstract of this paper for ...