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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Why are odd numbers of chromosomes (triploidy, pentaploidy) less common than even ones (tetraploidy, hexaploidy)?

Perhaps there is an obvious reason, and I know that most organisms that are either exclusively sexual or at least capable of sexual reproduction are diploid, but.... Is there a specific reason ...
Kurt Hikes's user avatar
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Lipid Bilayer composition

I am currently taking a course on introduction to biomolecules and the other day our professor showed us a photo describing the composition of lipid bilayers of various organelles in a eukaryotic cell....
Preetham Karki's user avatar
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Recycling of nitrogen in hibernating mammals

Hibernating mammals are required to undergo profound changes in metabolism. In addition to the more studied requirement of providing energy, there are problems in relation to nitrogen metabolism ...
Aseku Vena's user avatar
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Can you perform D-glucose assimilation test for a bacterial strain without API kit?

Background facts: Glucose assimilation test is based on the ability of a bacterial species to utilize glucose as a sole carbon source. The test is designed to determine whether the organism can use ...
Freezing Soul's user avatar
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Cellular respiration and membrane surface protons

The final product of cellular respiration is the proton motive force, formed by protons pumped out of the membrane and by the voltage due to all charges. While Mitchell’s original theory considered ...
scrx2's user avatar
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Where can I find the standard curves for Bovine Serum Albumin (BSA) and ovalbumin as determined through the Bradford Assay?

I was wondering if anyone would please be able to point me in the direction of a database or something similar which contains standard curves/absorbance levels for BSA and ovalbumin, as measured using ...
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Different enzymes catalyzing the same reaction but in opposite directions

Nelson, D. L., & Cox, M. M. (2017). Principles of Biochemistry 7e. W. H. Freeman. 13.3: Phosphoryl Group Transfers and ATP: Inorganic Polyphosphate Is a Potential Phosphoryl Group Donor. (This ...
Sadegh Rizi's user avatar
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Why does an Enzyme-Substrate Complex have slightly less energy than the substrate alone?

In some books the graph of the change in free energy during an enzyme-catalysed reaction is depicted as shown below, where S = substrate, E = enzyme, P = product, and T* represents the transition ...
STEM769's user avatar
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How Difficult is Artificial ATP Synthesis?

One way of making ATP requires: A membrane (would probably have to be a phospholipid bilayer) A difference in H+ chemical potential across the membrane ATP synthase anchored to the low-potential side ...
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D-Galactose effects on primates?

A lot of studies are made using D-Galactose as a accelerated aging model in rats and mice, but why not in non human primates? How much relevant is the galactose rat model for human health perpective? (...
Luiz Henrique Carareto's user avatar
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The springlike behavior of titin problem

I am currently reading a textbook (Molecular Biology of the Cell, 6th ed), and this problem on p. 170 is driving me crazy. I read through the solution given in this book but I couldn’t understand it ...
Son of Sevenless's user avatar
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Is Chemiosmosis a hypothesis or a theory?

I was trying to find out whether chemiosmosis is a hypothesis or a theory. Naturally, I first searched on Wikipedia, but the article on chemiosmosis uses both the words, which is confusing. The ...
Aditya Kumar Panda's user avatar
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Antibody structural determinants of epitope size

I am curious whether there are structural correlates in antibodies that relate not to epitope sequence but to epitope size. Specifically, I imagine that the antibody-epitope interface size is ...
Maximilian Press's user avatar
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What keeps pyridoxamine phosphate inside the aminotransferase enzyme active site?

In the function of an aminotransferase enzyme after the first substrate (amino acid) has been deaminated there seem to be nothing binding the resulting pyridoxamine phosfate to the rest of the enzyme (...
AlexanderCar's user avatar
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Can Iron(III) accept electrons from NADH without the other enzymes?

During the electron transfer chain in cellular respiration, the NADH turns into NAD+ while donating an electron. Those electrons pass through many enzymes and chemical reactions. One such chemical ...
Aakarsh Tathachar's user avatar
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Why can't other electron acceptors produce as much ATP as oxygen?

I have been wondering about life using a different "Final" electron acceptor(replacing oxygen), but every thing I can find in my research say that oxygen produces more ATP because of its ...
KaffeeByte's user avatar
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Why is iodine added to salt? As opposed to fluor or fats/oils like iron and vitamin A?

Is there a particular reason why certain foods are enriched or fortified with certain nutrients? Such as salt with iodine? Or did we just get used to doing things a certain way since we started ...
Kurt Hikes's user avatar
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Primary charge separation in Photosystem II

I was reading through an article about primary charge separation in Photosystem II when I came across the following graphic: I assumed that the axis is measured with respect to the unexcited system, ...
slithy-tove's user avatar
3 votes
2 answers
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Is it possible to change an amino acid within a protein but not affecting that protein's functions?

In the answer(source - Campbell Essential Biology with Physiology, self-quiz question), it's given that "if the change doesn't affect the protein's shape in any way then it's possible to do so&...
anonymous's user avatar
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[IAL Biology]: Struggling to understand how pH and temperature affect haemoglobins affinity for oxygen

As seen in the graph above, why do we say that increasing pH increases haemoglobins affinity for O2, but decreasing pH reduces its affinity? If the pH increases above or decreases below haemoglobins ...
Nawaz_04's user avatar
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1 answer
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In drug discovery, what is an undruggable target? [closed]

The term "undruggable" is often use in drug discovery. As far as I understand it, it means "for which no inhibitor has been found so far". It's a fuzzy, non-satisfying, definition. ...
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Calvin cycle question [duplicate]

Why does the 6-carbon molecule produced when Rubisco attaches a Co2 onto RUBP split into 2, 3 carbon molecules? Is it because its unstable or is there another reason?
confused's user avatar
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Advantages of NADP+ dependent Isocitrate Dehydrogenase

I came across a question (Q-5b) that asks: Isocitrate Dehydrogenase in the [human] TCA cycle is associated with NAD+. Why does it make good metabolic sense that it should use NADP+? Explain and show ...
AvadaMouse's user avatar
5 votes
0 answers
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How does labelled N from tyrosine appear in phenylalanine if the latter is an essential amino acid?

A certain question (not my course or instructor or even university) goes: Exposed to regular metabolic activity in a rat liver, a 13C label in tyrosine will not appear as a 13C label in phenylalanine....
AvadaMouse's user avatar
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1 answer
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The nitrogen cycle

As I understand it, bacteria absorb nitrogen from the air, and deposit nitrates in the soil. These are absorbed by plants which use them to build complex molecules such as proteins. This enters the ...
Pete's user avatar
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Why is hydrogen to oxygen ratio used to compare energy storage efficiency?

I came across an article that says that lipids are more efficient energy storage molecules compared to starch because lipids have higher “hydrogen to oxygen ratio”. I do not understand how “hydrogen ...
green onion's user avatar
19 votes
3 answers
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Is atmospheric nitrogen chemically necessary for life?

It is my (very basic) understanding that neither plants nor animals utilize the nitrogen in the atmosphere. Humans do not make use of atmospheric nitrogen through respiration and plants do not ...
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Does the body make alterations to fatty acids before their storage?

I was wondering if you would be at all able to help me with some questions I can’t find the answers to. I’m a first-year uni student doing some research for the fun of it but I’m really struggling to ...
Mason's user avatar
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Could abiogenesis still be ocurring? [duplicate]

From my understanding, most biologists believe that under certain conditions life can form from inert chemicals. If the conditions for this to happen still apply, is it possible that in bodies of ...
The_Wandering_Ishmaelite's user avatar
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What are the main challenges for developing imaging techniques for cellular-scale structures?

Small disclaimer: I'm not a biologist, so I'll try my best to write a high-quality, objective question, but please forgive me if it doesn't turn out as expected. Imaging technologies such as MRI and ...
MaiaVictor's user avatar
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Why do catabolic reactions release heat despite that breaking bonds absorbs heat?

According to Campbell, the definition of a catabolic reaction is: Some metabolic pathways release energy by breaking down complex molecules to simpler compounds. these degradative processes are ...
Bakr Alrawe's user avatar
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What were fed to the rodents in Calhoun's experiments?

From, (https://en.wikipedia.org/wiki/Behavioral_sink) (https://en.wikipedia.org/wiki/John_B._Calhoun) (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1644264/)(https://www.gwern.net/docs/sociology/1962-...
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Biological investigations or Biochemical investigations

I am working on phytochemicals and their antimicrobial and antioxidant activities. Are these activities investigations called Biological investigations or Biochemical investigations? What is the ...
Saif Ali's user avatar
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1 answer
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How does red light change the cellular mechanism in cells?

As winter approaches and the amount of sunlight decreases in the northern hemisphere, I have been reading about red light therapy and its supposed beneficial clinical effects. Yet there is no much ...
Evamentality's user avatar
1 vote
1 answer
624 views

Are DNA molecules negatively charged at low pH values?

We know, that for each monomer of DNA, phosphate groups are having -1 charge because one of the oxygen is negatively charged (2nd oxygen participates in the phosphodiester covalent bond), but isn't it ...
Lasha Bukhnikashvili's user avatar
4 votes
1 answer
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Do lipids have a monomer or not?

My biology class and I have been on the topic of macromolecules for quite some time now. Chapter 2.3 of the Foundations to Biology Textbook says that lipids are not polymers, so they do not have ...
Honey Boochie Bun's user avatar
5 votes
1 answer
466 views

Why does low redox potential mean less oxygen?

I often see statements about adding reducing agents like cysteine to anaerobic medium to decrease the amount of the dissolved oxygen. However, I am not sure why. I am wondering if it is because under ...
Beginner's user avatar
4 votes
1 answer
124 views

Do cancer cells use as much NADH as normal cells?

Recent literature shows that cancer cells have a different electron transport chain mechanism from normal cells and both of cancer cells and normal cells use NADH as electron donors. So, is there a ...
Kevin's user avatar
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2 votes
1 answer
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Why aren't complex-stabilizing proteins like transcription factors considered catalysts/enzymes?

I'm not asking the question on a superficial level. Obviously, (most) transcription factors are not acting directly on a substrate to produce a chemical change. I pose the above question as more of a ...
curious_catalyst's user avatar
3 votes
1 answer
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Does nature have a mechanism to turn charcoal back to usable carbon?

I have in past asked this about ash, but apart from ash most fires - whether natural or fires in stoves - leave a bunch of charcoal as well. When I was sifting old compost last year, I could identify ...
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Comparison of different glassy matrices for protein immobilization at room temperature

I am completely new to protein biology experiments. I care about experiments where proteins are immobilized near a surface with the help of a glassy matrix or similar materials. I am looking for a ...
Ben's user avatar
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If guanosine transfer reaction in the RNA capping is reversible, should intermediate reactions be reversible as well?

Guanosine transfer is the second step of RNA capping. The enzyme (GTase) first displaces a pyrophosphate of a GTP molecule, forming an unstable covalent enzyme-GMP intermediate (E + Gppp ⇌ E-pG + PPi)....
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Does ellagic acid dissolved in DMSO react with Brain Heart Infusion media?

I dissolved 2mg of Ellagic acid in 500 microliter of DMSO. I used 100 microliters of this solution to test for antimicrobial susceptibility against E.faecalis by adding it to 100 microliters of BHI ...
Shreesha Padyana's user avatar
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What specific molecules cause the difference in spectral sensitivity in the cones?

What causes the difference in their spectral sensitivity of the S, M and L cones. I'm guessing that the opsin or photopigments are different, but haven't been able figure out conclusively from my web ...
vxs's user avatar
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PEGylation safety and hybridomas

PEGylation is the covalent attachment of PEG (PolyEthylene Glycol) to molecules (e.g. proteins). It states in wikipedia ("PEGylation"): The covalent attachment of PEG to a drug or ...
Ynk's user avatar
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What is mechanism of action of ellagic acid as an antimicrobial compound?

Ellagic acid (a polyphenol) works as an antimicrobial compound. But what is its mechanism of action? I found these 2 research papers related to this, however the mechanism of action is not clearly ...
Shreesha Padyana's user avatar
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What is the conjugation capacity of the liver?

Our liver conjugates 250-300 mg bilirubin per day under normal circumstances but it is capable of conjugating much more. What is the upper end per day after which it won’t be able to conjugate leading ...
Aman Karimi's user avatar
4 votes
1 answer
348 views

How does one derive a KD from an equilibrium titration experiment?

If I have an antibody A and a target B, and experimentally titrate the antibody against a single concentration of B, and then measure the % of B that is bound after the solutions reach equilibrium, I ...
Justin's user avatar
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4 votes
1 answer
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Why does the luminal test need hydrogen peroxide?

In the chemiluminescent reaction of Luminol in an aqueous solution, the luminol needs to react with molecular oxygen to produce a photon of blue light. In the technique, the hemoglobin of blood ...
Evamentality's user avatar
10 votes
1 answer
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Source for "The human body recycles its body weight of ATP each day"?

I have read in many biology textbooks and scientific journals that "you create your own bodyweight in ATP each day", but they are all just stated as facts. I have yet to see a study or ...
Matt Henning's user avatar

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