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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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24 views

How can we explain that glucose at its concentration less than a Km for the transporter enters the peripheral circulation?

I'm studying biochemistry from Kaplan's book. In it, I found the following paragraph in the topic on glucose metabolism: "GLUT 2, a low-affinity transporter, is in hepatocytes. After a meal, ...
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1answer
32 views

Identifying substance in body fluid (serum, urine)

I have a large number of serum and 24 hour urine samples from a collection of individuals on many consecutive days. Some of the samples contain a 'large' amount of a substance that has a brown color. ...
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1answer
66 views

Why does the time to reach equilibrium across a membrane decrease with concentration?

We're learning about flux and Fick's law and there's one point I'm having trouble understanding. Assuming we have a higher concentration of a species on one side of a membrane, I understand that ...
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Is brown or black eumelanin more photoprotective?

Is black or brown eumelanin better at protecting against the sun's harmful ultraviolet radiation? I searched on the web for answers with no luck. I do know that pheomelanin is phototoxic and eumelanin ...
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1answer
84 views

How to measure the pH of a bacterial species?

I would like to calculate the pH of a certain bacteria species before after an experiment. I was reading about the pH cell of bacteria and I found out about Bacterial Intracellular pH which I ...
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Why do bile salts have non-polar binding to polar bits?

My textbook has this image of the mechnaism of bile salts. It states that bile salts are amphipathic. Thus, their hydrophilic end will face the water and their hydrophobic end will face inside. ...
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33 views

Where does the hydroxyl group on DNA/RNA phosphate group preceding phosphodiester linkage come from?

I have a curiously simple question that I have been struggling to find an answer to online. When I look at a standard diagram of a solitary nucleotide, the phosphate group contains two oxygens with a ...
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63 views

What is the point of lipoproteins if albumine exists?

Why do Lipoproteins (Apo B 48/100 , Chylomicrones, etc.) exist if Albumine is capable of transporting fatty acids? Why doesn't the body just transport everything via albumine?
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89 views

Why is there no wavelength change in the hyperchromic shift in DNA?

From Wikipedia article on hyperchromicity (emphasis my own): "When the bases become unstacked, the wavelength of maximum absorbance does not change, but the amount absorbed increases by 37%.&...
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Is lignification within plants a reversible process? If so which factors can reverse lignification?

Lignification is an important process in plants such as trees to allow for structural rigidity. Is this process reversible by the plant and if so which factors influence this reversibility?
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71 views

Why does Diphenylamine only react with the deoxyribose of purines?

The deoxyribose in DNA in the presence of acid forms β-hydroxylevulinaldehyde which reacts with diphenylamine to give a blue color with a sharp absorption maximum at 595nm. In DNA, only the ...
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1answer
34 views

Does nacre/mother-of-pearl have a greater compressive strength than human bone?

Exactly what it says on the tin: as measured in mPa, does nacre/mother-of-pearl have a greater compressive strength (i.e. it can take getting squeezed more before breaking) than human bone? I ...
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40 views

What is the density of nacre?

What is the physical density of nacre/mother-of-pearl? I can't find an authoritative figure for it.
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22 views

Do any animals mix porphyrins and carotenoids in their pigmentation?

Many animals (particularly birds) use carotenoids or porphyrins in their diet to contribute to the brilliance of their skin/fur/feather coloration. A few even mix melanin in with carotenoids to get ...
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81 views

Do quantum mechanical effects such as uncertainty, tunnelling and entanglement play role in the electron transport system of respiration?

The electron transport system of aerobic respiration involves an extensive pathway of electron and proton transfer from one centre to another. Now, since they are quantum mechanical particles, shouldn'...
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1answer
137 views

How does the hydrophobic amino acid fuse the corona virus with the host cell membrane?

I am reading the article How the coronavirus infects cells — and why Delta is so dangerous. It describes the fusion process of the virus into the host cell as follows right above an animation ...
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How does medicine work? [closed]

Take aromatase inhibitors for example. In order for a molecule to stop the enzyme aromatase from converting androgens into estrogens, it must meet 6 criteria: Not get broken down by the acidity or ...
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3answers
284 views

What does it mean to quantitatively describe a cell?

To begin this question, I will quote Molecular Biology of the Cell (page 38): ... Biological systems are, ..., full of feedback loops, and the behavior of even the simplest of systems with feedback ...
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1answer
49 views

difference between biotic and living? [closed]

how can we differentiate between biotic and living things,is there any difference? and same for abiotic and non-living? I think it is that biotic is like biomass and living should carry out life ...
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1answer
118 views

Should fat calories' numerical values be increased to better reflect the new scientific findings?

According to a study discussed on this website, people lose more weight on a calorie restricted fat reduced diet than on a similar calorie restricted carb reduced diet. Is this study a fair dinkum, ...
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1answer
85 views

What's happening in the "C" and "T" stripes of a covid test kit?

I have a COVID home test kit which produces C and T (control and test) stripes when the solution is applied to the strip. Something similar happens in pregnancy test kits. I understand the purpose of ...
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1answer
43 views

How easy is it for quantum dots to enter the intracellular portions of cells?

As quantum dots have better quantum yield than organic dyes, many are being developed as a substitute for them. Nonetheless, could these substitutes be small enough to enter inside cells as current ...
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46 views

Do some flowers excrete urea or uric acid?

Sometimes when I sniff a flower up close, I can't but help smelling a faint urine like odor. From my layperson's understanding, uric acid and urea both are responsible for giving urine its ...
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1answer
64 views

Is there a term that distinguishes extracellular "transport" proteins from membrane-bound "transport" proteins?

I've been researching genetics and biochemistry in my free time and I've noticed that proteins such as albumin and apolipoproteins that facilitate extracellular transport and proteins such as GLUT1 ...
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1answer
87 views

Thermodynamically, how did the first cell arise?

Living cells are biochemical systems that constantly perform chemical reactions. One of the important consequences of these chemical reactions is the capacity of a living cell to replicate itself. The ...
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1answer
147 views

What's the difference between Kd and IC50?

What's the difference between the equilibrium binding constant ($K_d$) and Inhibitory Concentration 50 $IC_{50}$? They both seem to mark halfway points. Is the only difference that $K_d$ refers to any ...
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Why/How can Hydrophobic things pass the lipid bilayer? [duplicate]

I’m just looking for a simple answer for this question. I’m in Bio 10, and don’t know the in depth stuff. So the lipid bilayer is hydrophilic and the ends, but hydrophobic in the middle; so how can ...
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1answer
142 views

Besides fats, proteins, and carbs, what compounds can the body use for energy?

What kinds of chemical species that do not belong to the category of fats, carbohydrates or proteins can the body metabolise? Clarifications: By metabolise, I mean extract energy from (e.g. as ATP). ...
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53 views

What is the effect of an acidic solution on hydrolytic enzymes?

I'm working on a school research project and my research question is "What is the effect of increasing concentrations of Acid X on hydrolytic enzymes, measured through the loss of mass of leaf ...
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28 views

Why are symptoms like headache and coma common in patients of metabolic acidosis?

Metabolic acidosis is a systemic electrolyte disorder in humans. Headache is a common symptom of metabolic acidosis. Is the headache due to excess amount of acid and coma when the brain becomes too ...
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1answer
28 views

Can Ni-NTA-Atto Conjugates bind to single His-tag

Can I label a protein with a single His-tag with Ni-NTA-Atto conjugates? Papers generally use this technique to label 6His-tag.
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How do transmembrane proteins bind to specific locations on the membrane?

Taking a specific case, how do some GPCRs only bind to dendrites and others only to the axon terminals (reuptake receptors)?
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Why does activated charcoal prevent tetracycline activity in E. coli culture?

My lab just found that using activated charcoal in an E. coli culture prevents tetracycline function. What kind of reaction could be causing this effect? Thanks!
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61 views

Numbering of C atoms of pyrimidine rings in nucleosides

For a presentation of my work I wanted to show a structural representation for dihydrouridine with numbering of the C atoms of the pyrimidine ring, according to this numbering convention. Then I found ...
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Are all organelle lumens a reducing environment like the cytosol, or nonreducing like the extracellular space and the ER lumen?

I am interested to know if cysteine can form disulphide bridges in proteins within organelles. Typically cysteine will not form disulphide bonds in the reducing environment of the cytosol, but will in ...
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2answers
29 views

Detecting multiple compounds on a lateral flow immunoassay – is this a case of monoclonal vs polyclonal antibodies?

I am working on developing lateral flow immunoassays for drugs of abuse and needed some advice on detecting multiple drug compounds in one immunoassay. As an example, an existing LFIA on the market ...
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1answer
55 views

What is the point of calculating extinction coefficients of a protein without Cys residues?

ProtParam computes various physico-chemical properties that can be deduced from a protein sequence. One of these parameters are "Extinction coefficients". They provide two values. One value ...
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33 views

Why does warfarin decrease biological activity of protein C?

Warfarin inhibits VKOR. Hence it disrupts vitamin K dependent $\gamma$-carboxylation of Fc- II, VII, IX, X. But what exactly it does to Protein C and Protein S? How does it also affect anticoagulant ...
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1answer
153 views

What is the minimum number of chemical elements required for life on earth? Does it vary between kingdoms?

As a non-biologist, I assume that there are certain elements that occur in all life forms as we know them. Examples might be carbon, hydrogen, oxygen and so forth. There are also elements that are ...
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1answer
148 views

Different flowers have same colour

I notice that certain (wild) flowers have the same colour, although they are not closely related. For example, the yellows of the dandelion (Taraxacum) and the buttercup (Ranunculus) are, at least to ...
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1answer
102 views

Is there an 'opposite' neurotransmitter to dopamine?

Dopamine is a neurotransmitter (i.e. chemical) in the brain that gives us great feeling. From here: Dopamine plays a role in how we feel pleasure. It's a big part of our unique human ability to ...
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1answer
39 views

Can a constitutively active kinase be highly regulated?

I am studying the protein kinase GSK3 and I am learning about the regulation of its activity. Many journal papers that I have read have stated that GSK3 is unique because it is a constitutively active ...
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43 views

Conservation Law in Gene Regulatory Network modelling

I was going through the GRN modelling from Chemical and enzyme kinetics by D. Gonze & M. Kaufman (PDF). The gene has 2 sites for activator/repressor. It say the DNA $D_0$ combines with activator/...
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1answer
64 views

Can any gas other than nitrogen cause decompression sickness (the bends)?

I know that our bodies use most of the oxygen we breathe in during a dive but, wouldn't our tissues, under pressure, absorb more oxygen than we need? For instance, in normal circumstances, we don't ...
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1answer
56 views

Is chloride necessary for animals?

Of the twelve well-known atomic constituents of our body eleven elements have specific properties obviously relevant to their rôle, making them indispensable. Oxygen (electronegativity and valence), ...
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1answer
150 views

Do people need nitrogen from air for health?

Can people breath totally nitrogen-free atmosphere for a long time? I know, nitrogen is essential for life, and in big quantities, but maybe people can take it entirely from food, from proteins, etc?
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112 views

Types of structures formed by various types of lipid molecules

Since Phosphatidylcholine (PC) and phosphatidylserine (PS) are roughly cylindrical in shape , they tend to form flat bilayers. Phosphatidylethanolamine (PE) on the other hand is conical in shape which ...
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71 views

How can I clone a gene into a plasmid vector with an N-terminal his tag and TEV cleavage site between the tag and the start of the sequence?

I'm a scientist who has significant experience in chemistry but am relatively new to molecular biology and biochemical techniques. I'm trying to make an isolated domain of a protein (166 residues, 19....
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1answer
146 views

Pyruvate dehydrogenase: Apparently anomalous NAD/FAD redox reaction

Below is the mechanism for the reactions of the pyruvate dehydrogen complex, which oxidatively decarboxylates pyruvate and transfers the acetyl group to coenyzme A for further metabolism in the Krebs ...
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Do different acids have different effects on the enamel of our teeth?

Do different acids or acidic solutions corrode the enamel of our teeth at different rates or in different ways? Are these effects present even when controlling for pH?

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