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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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Effect of the Marcus Theory on Photosynthesis

As far as I know, the Marcus Theory explains the rates of electron transfers in reactions as a function of differences in free energy between the product/reactant's potential well. Furthermore, there ...
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43 views

Why can polar molecules like water pass aquaporin better than unpolar like H2 or CO2

We learned in our lecutre, that aquaporin lets Water pass, but blocks Ions like H+ and unpolar molecules like CO2 and H2. The reasons for the Ion blocking are comprehensible, but I dont get, why less-...
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1answer
189 views

Why add hydrogens in molecular dynamics simulations?

In my molecular dynamics lecture, our prof said, that we always have to add hydrogen atoms to titratable groups, before we start the force field simulations, and that it is especially important for ...
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1answer
40 views

Where is cleavage site located? [closed]

I feel a bit confused about cleaving! Is cleavage site always located on the substrate or on the enzyme?
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2answers
65 views

Using evolutionary algorithms in molecular biology? [closed]

I am currently an MSc student studying molecular biology (on paper I'm a chemist) and soon I have to talk to my supervisor about my future, PhD research topic. Besides molecular biology I'm also ...
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2answers
109 views

Can the human body utilize electricity? [closed]

In any way could the body store electricity supplied externally?
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37 views

What happens to the brain during meditation?

I've read several experiments on the internet according to which it is possible to reach a psychedelic state without taking any psychedelic drugs like DMT, LSD and other tryptamine derivatives. It ...
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1answer
53 views

Is it possible to cure dandruff? [closed]

If dandruff is caused due to oleic acid released by fungi malassezia then is it possible to control it by applying any base in our scalp ? Since base nullify the effect of oleic acid or base cause any ...
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1answer
48 views

Could Cannabidiol steady a hand? [closed]

Can Cannabidiol be used to steady shaky or nervous hand for precision work like surgery? I have used it for shooting pool/billiards and I'm not sure if it is a placebo or it is helping? but I am ...
3
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1answer
154 views

How does BH2 reduction to BH4 need only one NADPH molecule?

Dihydrofolate reductase (DHFR) reduces dihydrobiopterin (BH2) to tetrahydrobiopterin (BH4). Someone told me that this reaction needs only one NADPH molecule (I am not sure if this is correct), namely, ...
3
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1answer
201 views

Parallel DNA double-helices with Watson–Crick base-pairing: Why do they not occur? [duplicate]

I know that parallel DNA helices exist and are governed by Hoogsten base pairing, but why can’t they be possible with Watson-Crick pairing? In the diagram below, if we were to flip one of the strands ...
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1answer
65 views

Why is suicide inhibition considered a catalytic reaction when the catalyst is irreversibly modified because of the reaction? [closed]

I understand that this might be meaningless semantics, but I'm confused and would appreciate clarification. I've always been taught that, a catalyst is, by definition, a substance that is increases ...
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67 views

how does environment affect methylation status in dna

There are many examples where environmental stress can induce changes in gene activation and deactivation. I find in many examples that the DNA methylation status of cytosine is changed to on or off ...
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237 views

Passive diffusion of non-polar molecules across plasma membrane

I understand that small, nonpolar molecules that can dissolve in the hydrophobic (nonpolar) part of the plasma membrane are able to cross it and passively diffuse into or out of the cell. But doesn'...
3
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2answers
98 views

Using nanodrop for analysing biological samples other than nucleotides

I am a 3rd timer postdoctoral fellow with some experience in molecular biology and biochemistry, but major skills in Zoology and Natural History. I am studying some natural extracts, and isolating ...
1
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1answer
27 views

What does ensemble-based model of enzyme mean?

I am reading Pan et al. (2000), a paper about dihydrofolate reductase (DHFR). They claim using a ensemble-based model of DHFR. What is a ensemble-based model?
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1answer
142 views

What determines the reversibility of cell of G0 phase in cell cycle?

From Weinberg's The Biology of Cancer: A cell that has been recently formed by mitosis must decide whether it will once again initiate a new round of active growth and division or retreat into non-...
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0answers
113 views

Question about Racemic Mixtures in Miller-Urey Experiment

I'm studying the Miller-Urey Experiment for my Biology class, and a significant point made by my professor was that Miller made a 50/50 racemic mixture of chiral monomers. However, life is homochiral....
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95 views

Why doesn’t a basic side chain (R group) of an amino acid form a peptide bond in protein biosynthesis? [closed]

Why doesn’t a basic side chain (R group) of an amino acid form a peptide bond in protein biosynthesis? Consider lysine, for example, why can’t its side-chain amino group, –(CH2)4–NH2, form a peptide ...
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54 views

CRISPR/Cas9 in E Coli: whole gene insertion

This is a long shot, but can someone explain/refer me to a good explanation about how to design plasmids for whole gene insertion using CRISPR/Cas9 in E. coli? I've looked all over Addgene and read a ...
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0answers
12 views

Is it possible to reprogram osteoblasts and osteoclasts to change the angle and shape of the mandible?

Surgery is too expensive. I have just heard of a thing called DNA reprogramming, and there are lots of articles that are reputable and back this scientifically. The idea is that cells/DNA can change ...
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1answer
1k views

Can I kill bacteria with distilled water?

Given that bacteria are hypertonic (contain more salts) compared to distilled water, and that they rely on ion concentration differences across the plasma membrane to survive, can I kill a bacterial ...
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0answers
54 views

Direction of ATP synthase C ring under different circumstances

In a mitochondrial intermembrane space, the concentration of protons is much greater than in the mitochondrial matrix. In this condition, ATP synthase rotates in a counterclockwise (ccw) manner. In a ...
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1answer
112 views

Why does enteral carbohydrate yield higher energy than parenteral?

The following is written in a well-known textbook of surgery: Each gram of enteric carbohydrate provides 4.0 kilocalories (kcal) of energy. Parenterally administered carbohydrates (eg, ...
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33 views

Methylation of DNA

How does the addition of methyl groups to DNA prevent the attack of endonucleases present in the cell? I have searched a lot on this topic but have not found the exact chemistry behind it.
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3answers
159 views

Why doesn't surgical steel cause inflammation?

It seems some very specific alloys like implant surgical steel and titanium don't cause inflammation in the human body, but when I asked my doctor about it, they simply said "it just has some chemical ...
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1answer
1k views

Purpose of the conversion of 3-PGA to G3P in the calvin cycle?

3-PGA ($\ce{C_6H_7O_7P}$) is converted to G3P ($\ce{C_6H_7O_6P}$) before it is able to be made into glucose, with an expansion of 6 ATP and 6 NADPH. My question is why this process is needed and why ...
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17 views

Drying and re-wetting soil

When conducting drying and re-wetting experiments of soil in the lab, under aerobic conditions, most studies I have seen incubate the soil in the darkness even though it is dried. But comparing this ...
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11 views

Methane and wetlands

Some papers I have read show carbon accumulation (peat) in wetlands is reduced because of low methane emissions. Why is this the case? Why does low methane emission reduce carbon accumulation in ...
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1answer
73 views

Dopamine involvement in pleasure

There are some psychologists who believe that dopamine is not released during pleasurable activities but before them; my understanding is that a little dopamine is released pre-reward in order to ...
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0answers
20 views

How to convert a test tube assay to microplate assay?

I am trying to measure Ascorbic acid levels in tissue using Omaye et al protocol (Methods in Enzymology, Volume 62, 1979, Pages 3-11). This method is based on reduction of ferric chloride and ...
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1answer
585 views

During non-cyclic photophosphorylation, how does NADP+ become NADPH?

I know that NADP+ gets reduced to form NADPH, but what exactly is being donated? Is it two individual electrons (from photolysis or the chlorophyll molecules) and a hydrogen ion (proton)? If this is ...
4
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1answer
87 views

How did shellfish and coral survive acidic oceans in earlier eras?

Throughout most of Earth's history, the planet has had more CO2 in its atmosphere, correct? Therefore th pH of the oceans was even lower, right? So how did CaCO3-using animals create their shells ...
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21 views

biodegradable environment in desert

If all the biodegradable material is put into the desert then is there any chances that it would act as fertilizer and make the deserted land fertile.
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2answers
47 views

What directs macromolecules to their cellular locations

For example I know that after transcription a mature mRNA is sent outside of the nucleus through the nuclear pore and then it goes to ribosome. But as for the free floating ribosomes that are out ...
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1answer
2k views

Why can't amylase break down glycogen?

Amylase is an enzyme that breaks down starch in the form of amylopectin and amylose. Both amylose and amylopectin are formed by alpha glucose joined together by (1-4) and (1-6) glycosidic bonds. ...
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1answer
103 views

Organism with the greatest amount of gold as percentage of body mass

I've read that the human body contains trace amounts of gold: http://www.tellmehowmuch.net/how-much-gold-is-found-in-the-human-body.html http://web2.airmail.net/uthman/elements_of_body.html Are ...
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1answer
42 views

What is the active site (not metal binding site) of tyrosinase and other monooxygenase/oxidoreductases?

On https://www.uniprot.org/uniprot/P07524, tyrosinase is shown as a monophenol monooxygenase. However, the UniProt database only shows a metal (copper) binding site, when there is presumed to be an ...
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21 views

Lipase digesting lipids leads to a basic solution

I saw a video where lipase was mixed with homogenized milk and water and then phenolphthalein was added. The solution turned dark pink. The video didn't explained why. Could someone explain this to ...
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1answer
23 views

How to identify Ag nanoparticles in a solution?

Doing an experiment involving the production of Silver nanoparticles using bacterial extracts. The issue is proving that they've been formed. AgNO3 is added to the solution, and the reduction ...
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1answer
1k views

What is the difference between gene expression and protein synthesis? [closed]

I have no idea what I'm supposed to do. Can someone please help me? What is the difference between gene expression and protein synthesis?
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0answers
99 views

Why do plants produce and store both amylose and amylopectin?

Since both forms of starch has its primary purpose of storing glucose and hence releasing energy, why are there 2 variations of this sugar? Is it possible for an organism to contain/depend only on 1 ...
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2answers
327 views

Intermediate of Krebs cycle that can form Chlorophyll?

This was a question in a test in my school today. Q) Which intermediate of Krebs cycle further can form chlorophyll? A) Oxaloacetic acid B) Citric acid C) Succinyl CoA D) Fumarate Given answer was ...
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1answer
164 views

Why would I see no bands in DNA gel electrophoresis of red blood cells?

For forensic inspection, you only obtained red blood cells from an individual and amplified for the D1S80 locus in chromosome 1. Twenty nine different alleles of D1S80 have been identified, and 435 ...
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2answers
307 views

Potato Power. Self sustaining medium using a living potato plant possible?

The second picture are potatoes wired in parallel. I understand that the potato is the medium for a chemical reaction between the copper and zinc. That aside, would wired and in soil potato plant ...
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1answer
104 views

How do alcohols and aldehydes destroy the plasma membranes of bacteria?

I am interested in knowing why a 60-80% solution of alcohol (usually ethanol or 2-propanol) can effectively kill vegetative bacteria and fungi. I know that it can coagulate essential proteins like ...
3
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1answer
52 views

Is Ellman's reagent specific for low molecular weight proteins and thiols?

Is it still possible to quantify cystein rich low molecular weight proteins such as Metallothionein in a given sample using Ellman's reagent if the sample is contaminated with some high molecular ...
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1answer
46 views

Required energy to metabolize fat

Tl;dr: What is the net joule value of fat if used for energy provision, compared to e.g. carbohydrates. So does 1 Joule Fat intake result in 1 - X Joule energy provided to the cell, or does it work in ...
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1answer
92 views

Does severing the Corpus callosum, effect the brain's communicating ability?

With serious epileptic seizures, a treatment is to sever the corpus callosum, which stops the seizures. However, does this affect the communicating ability between the two hemispheres? Or how does ...
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54 views

What medium is the bacteria used to synthesize B12 sourced from?

Would that be from water, soil, plants, funguses,...? I asked the question in Quora but that, at the time of posting in this forum, haven't been very helpful. I also have searched for the ...