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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Examples of mechanisms of metabolic trapping inside cells that create concentration gradient
I am looking for examples in biology in which a metabolite that can diffuse freely across a cell membrane (through passive diffusion), once inside, gets modified to a form that cannot diffuse back ...
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Effects of oxygenated water on bacteria
I was curious if any of you would happen to have any experience with this but any hypotheses regarding how this would turn out would be much appreciated.
I’m wondering if water fully aerated with ...
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According to an online course, ribose and adenine can bond to make ATP. Is this true?
I recently came across this question in the MIT Open Learning Library Pre-7.01 Biology Course. It is question 2d in Problem Set 1 (archived link).
The question, as well as the correct answers and ...
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Bi-phenyl degradation pathway in lignin
I am studying lignin - and really like the bi-phenyl degradation pathway of DDVA by SYK-6, as shown below
But I can't find any literature on whether this pathway transfers from the dimer to the ...
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How does a product form from a transition state in an enzyme despite the weak interactions being at its optimal
In the book Lehninger Principles of Biochemistry, there is a metal stick analogy to explain why an enzyme being compliment to its substrate would actually make a terrible enzyme.
If the enzyme is ...
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How to convert Kilo Units (KU) to mg? [duplicate]
Im searching for AChE (Acetylcholinesterase) and on sigma-aldrich it is showing 2 KU or 2000U/mg of protein and on MedChemExpress it is showing 50mg then how can we calcute how much will be the drug ...
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How can saliva neutralise acids produced by bacterial cells in our mouth if it is itself acidic in nature?
My school textbook makes the following claim:
This means that saliva must be basic. However, I learnt that the pH value of saliva is about 6.8, which would surely make it acidic. How can the above ...
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Question on protonation/deprotonation of amino acid side chains
I understand that actual pKa of amino acid side chains is greatly influenced by the surrounding environment. I am trying to deeply understand the equilibrium between protonated and deprotonated form ...
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How does $\ce{H2CO3}$ form in the blood with a ratio of 1:20 with $\ce{HCO3-}$ if there are not enough $\ce{H+}$ ions
I have recently been studying about the bicarbonate buffer in the blood and have a doubt regarding the concentration of carbonic acid in the blood plasma.
My understanding of the buffer system is that ...
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What's the grade of D-glucose that can be used in glucose assimilation test in bacteriology?
Background information
Carbon assimilation test is based on the ability of a bacterial species to utilize an organic compound (e.g. D-glucose) as a sole carbon source.
This means that for carbon ...
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Minimum growing conditions of a given plant
Micro-algae are organisms that can grow in aquatic environments and use light and carbon dioxide (CO2) to create biomass. Researches showed that Micro-algae biomass can be used as bio-fertilizer.
My ...
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Is Eugene Koonin's probabilistic argument for the necessity of a multiverse to explain the origin of life sound?
About Eugene Koonin
Eugene Koonin, Ph.D.
NIH Distinguished Investigator
Evolutionary Genomics Research Group
NLM/NCBI
Dr. Koonin graduated from Moscow State University, Moscow, Russia and received ...
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Compute a melting temperature in viennaRNA?
Posting here to get views, but may be more appropriate for bioinformatics or chemistry SE.
There are a variety of utilities such as biopython or primer3 that compute melting temperatures.
However, ...
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Allowed Deviations in fixed bond length and bond angles in peptides from the typical values
I am using frag builder python module to generate peptide structures to compute the interaction energy for ensemble of peptides of a given sequence for a fixed bond lengths and bong angles. However, ...
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What are major obstacles that OOL research still has to overcome in order to come to a full understanding of how life could have arisen from non-life? [closed]
Dr. James Tour recently uploaded a video titled Dr. James Tour vs Dave Farina | Are we clueless about the origin of life? #abiogenesis.
The description in the video says:
Join us for an exciting ...
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How is bio electricity modulated experimentally? [closed]
In the research performed by Micheal Levin et al, the morphological changes induced by changes in bio electricity are well demonstrated, most strikingly in his experiments in planarian worms.
Yet ...
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Aerobic respiration takes place in the mitochondria; anaerobic respiration takes place in the cytoplasm. Is there a biochemical reason for this?
According to hyperphysics.edu, and my general knowledge, anaerobic respiration occurs in the cytoplasm. ("Anaerobic respiration (both glycolysis and fermentation) takes place in the fluid portion ...
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Pathway where carbon dioxide captured by phosphoenolpyruvate is not re-released?
I have been reading about C4 carbon fixation in which CO2 is captured by phosphoenolpyruvate (PEP) to make oxaloacetate.
Are there known pathways in plants that use substantial amounts of this ...
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What is the energy of activation of uncatalyzed ATP hydrolysis reaction? Say in aquous solvent?
By ATP hydrolysis, I mean the chemical reaction: ATP + Water -> ADP + Pi. Focusing only on the reaction, this is a nucleophillic substitution reaction, most likely occuring in SN2 mechanism. But so ...
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Resazurin not turning pink
I want to add resazurin to my media as an anaerobic indicator.
To my understanding, the resazurin is blue when first added to the media, then turns pink after autoclaving, and finally it turns ...
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Why doesn't the cell just use one messenger?
I recently learned the second messenger model, where adrenaline activates adenyl cyclase, which converts ATP into cAMP. Then cAMP acts as a second messenger which activates portein kinase enzymes. The ...
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Why is iron transported across membranes in the ferrous form?
Iron in the diet of animals is predominantly in the ferric form, but it must be reduced to the ferric form by a specific ferrireductase before it can be transported across the cell membrane into the ...
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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 ...
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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....
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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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How to prepare the standard curve solution for Proline estimation
My aim is to estimate proline content from plant tissues using Ninhydrin method with a spectrophotometer(colorimetric method). Briefly, Proline when in contact with Ninhydrin yield a colured solution ...
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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? (...
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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 ...
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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 ...
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What types of fat are made when you eat carbohydrates?
There are many types of fat and each type can have different influences on your health, like saturated/unsaturated, omega-3 or omega-6, trans or cis etc.
When you ingest excess carbohydrates, some of ...
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Why is DNA not single stranded? [duplicate]
From what I have researched DNA is not single stranded, because if it was single stranded, nitrogenous bases (the 'information' of the DNA) would be exposed to the cellular environment (although, I ...
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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 ...
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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 (...
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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 ...
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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 ...
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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 ...
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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, ...
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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&...
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Xenobiotic metabolism: phase 1 reduction enzyme
Phase biotransformation reactions can be oxidations, reductions or hydrolysis of the xenobiota molecule.
Phase 1 oxidations are catalyzed by the cytocrome P450 enzyme, abbreviated with the CYP acronym:...
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Are all factors (hormonal) necessarily peptides? [duplicate]
While studying the endocrine system I came across the following terms:
Atrial natriuretic factor
Sperm Maturation factor
Growth factor
Are all factors necessarily peptides or can they have other ...
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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 ...
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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?
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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 ...
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