Tagged Questions

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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1answer
30 views

Is the sense for salt depending on the electrolyte level in our body?

I often noticed, after (heavy) physical activity like cycling, running, swimming or working an isotonic drink (to recover the electrolyte level) tastes less "salty" compared to when drinking it before ...
5
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1answer
147 views

Equation for accurate prediction of PCR yield

It is a cliche of freshman biology labs to point out that "every cycle of PCR doubles the DNA, so the yield will be $2^{cycles}$ times the template amount". However, if this were true, 1 ng of ...
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0answers
34 views

What causes the odor when a container is sealed with moisture inside?

I'm not sure if this is a biology or chemistry question since I don't know the cause of it (though I think it is bacteria or fungal related). I'm just wondering what creates that awful odor when a ...
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2answers
91 views

alpha tubulin molecular weight problem

Is there any academic reference that shows α-tubulin is around 50-55 kDa? The only thing I found is some data sheets from companies. I need the real reference.
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2answers
85 views

How does guanidium denature DNA?

Guanidium salts like (G-isothiocyanate) disrupt the hydrophobic interactions inside a protein or nucleic acid and denature it. What happens when hydrophobic interactions in DNA are broken? (I don't ...
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1answer
87 views

How do a particular arrangement of atoms become self aware? [closed]

At the simplest level, we're all just atoms, animals, plants and humans alike. But what I don't understand, is how a particular arrangement of atoms such as us can become self aware, and be able to ...
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2answers
56 views

What are the ecological effects of moderately high and prolonged concentrations of nitrogen deposition on an ecosystem?

There are many sources of nitrogen which eventually get deposited out of the atmosphere and onto the land/surface. Typically higher levels of nitrogen compounds are emitted near urban and roadway ...
2
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1answer
98 views

Anaerobic respiration choice in E. coli

Under anaerobic conditions E. coli has two options to generate ATP: fermentation (substrate-level phosphorylation), and respiration (proton gradient, chemisomotic phosphorylation). Which is favored? ...
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2answers
187 views

How much vanilla will kill a person?

I received a gift that is a jug of Pure Mexican Vanilla. Having never dealt with large quantities of vanilla, it made me curious as to what would happen if a person had too much vanilla. I understand ...
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1answer
171 views

Drinkable liquids that dont contain water [closed]

Are there any drinkable liquids that don't contain water? By drinkable I mean it would not harm me by just drinking it, like water.
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2answers
483 views

Diffusion of Hypotonic solution into solution with glucose and starch

Cell walls are selectively permeable to ions and organic molecules. Sometimes the selectivity is passive and a reflection of the physical laws governing diffusion. We can do simple experiments that ...
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1answer
32 views

Feedback affecting myocyte metabolism in humans

I understand that there are several reserves available to muscle that can be tapped for ATP, and that each reserve is being used to some degree at all times. Are these reaction rates purely due to ...
2
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1answer
41 views

What is inside IDL (intermediate density lipoproteïn)?

I am studying about the endogene lipidcycle in the human body and I know that VLDL (very low density lipoproteïn) is made in the liver and that it contains triglycerides and cholesterol from your food ...
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1answer
64 views

Fatty Acid Synthesis

I have a problem in my reasoning on the fatty acid synthesis in the human body. In the synthesis process you have this homodimer. So the synthesis starts with the transfer of a acetyl group from ...
2
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1answer
35 views

Trimming of tRNA precursors

From Molecular Biology of the Cell (4th edition) by Bruce Alberts et al. (Chp 6, Pg 338) : Both bacterial and eucaryotic tRNAs are typically synthesized as larger precursor tRNAs, and these are ...
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1answer
134 views

Is fluoride toxic, and how worried should I be about it?

A recent flurry of "fluoride is bad!" posts are appearing on my social network news feeds. Usually I can simply ignore them after a brief look, but this one, stemming from a recent article in The ...
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0answers
29 views

Few innervations to blood sugar regulation

Assume you have a case of young female where the intake of 75 grams of pure sugar leads to a rapid peak of blood glucose level (within seconds) plateau phase with very steady blood glucose level ...
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0answers
39 views

Vitamin D oral intake, transportation and absorption

Several factors affecting vitamin D and its active form absorption and storage acidity of stomach (not significant effect) cytopathic effects of viruses cytopathic effects of bacteria where the ...
2
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1answer
44 views

H O N C alternatives for organic life?

Most organic structures built from hydrogen, oxygen, nitrogen and carbon. They are represent 1-,2-,3-,4- bond relations (chemical valence) which allow to build variety of chain structures. Are there ...
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1answer
98 views

Transverse diffusion of lipids in red blood cells

The membrane of a human erythrocyte has polarity: Phosphatidylethanolamine and phosphatidylserine are predominantly on the inner side. Phosphatidylcholine and sphingomyelin are predominantly on the ...
5
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2answers
279 views

Signaling through G protein Coupled Receptors?

There are two different cell lines but we do not know that these cell lines have Gs or Gi proteins, associated with their G-protein coupled receptors. If we wants to know about this. Can we design a ...
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0answers
50 views

Early versions of the biochemical pathways wall chart. Where have they gone?

A lot of them in the bin as new versions were released, I imagine. I have been looking for early versions of the wall chart, but I've largely come up empty handed. I did find that besides the ...
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0answers
22 views

Is life in a supercritical fluid possible?

Someone claimed that the dinosaurs could only live because back then athmospheric density was around 650 kg/m³, providing some buyoncy, this claim is checked on Skeptics SE. The claim itself is beside ...
3
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1answer
49 views

Why is brown fat brown?

I read in Tortora and Derrickson Anatomy and Physiology that : Another type, called brown adipose tissue obtains its darker color from a very rich blood supply , along with numerous pigmented ...
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2answers
154 views

What are the functions of disulphide bonds?

What are the functions of disulphide bonds between amino acids in proteins or peptides?
3
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1answer
66 views

Dimerization of Immunoglobulin G

I would like to know the specific determinants for formation of IgG dimers. My understanding is the stem of the antibody is a homodimer of two heavy chains, covalently bonded through two disulfide ...
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2answers
118 views

What is most simple eukaryotic genome?

Expressed in number of Base Pairs or Bytes, about how large is the simplest eukaryotic genome? How much of this is 'junk-DNA' (non-coding)?
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1answer
371 views

What is the difference between vegetable and animal fats?

I often hear from many people saying to waiters - "Please, don't put oil to salad". They probably believe the fat from vegetables has the same impact on the weight as an "animal" fat (meat, eggs, ...
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1answer
105 views

Topology of closed circular DNA

Why are covalently closed circular plasmid DNAs naturally found in an underwound state ? Is it because this makes it easier for the DNA replication machinery to access and unwind DNA ? Or is it ...
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2answers
71 views

How are atoms created? [closed]

From small baby to the old age, we will be grown. We are composed of bunch of atoms, multitude of atoms. When you are grown from baby to the teen age, everyone will say "he has grown!" What do you ...
2
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1answer
115 views

What is optical density in Lowry's protein estimation method?

I have a few questions: What is an OD value? Why do we use blank solution in Lowry's protein estimation method? If The OD of a protein is 0.01, what does it mean? Thanks in advance.
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0answers
14 views

To increase the stretchability of the ascending aortic arch

The thread about To decrease the amount of proteins in the lymphatic drainage for short term here raised this question. This paper discusses the stretch and Cauchy-stress properties of the heart. So ...
3
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1answer
62 views

Amino acid profile of GPCRs

You are studying cellular signalling through a newly identified GPCR. Specifically you’re working on a pair of newly identified GPCRs, GPCR-A and GPCR-B. Each binds the same small ligand, but ...
1
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1answer
45 views

Measurement of glucose concentration in the human brain

If I want to measure the exact glucose concentration in a human brain then how can I proceed to do that? Is there any technique or assay to do that?
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1answer
25 views

fibrinogens and fibrins - are they the same molecule?

Some proteins are "activated", like fibrinogens; they are turned into fibrins by thrombins, and then the fibrins can aid in blood clotting. Are fibrinogens and fibrins the same molecule, just in ...
3
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2answers
76 views

How to determine whether the energy of a stem-loop fold is significant or not?

If I have a predicted RNA stem-loop of energy -0.30 kcal/mol, and another of -4.9 kcal/mol, how do I tell whether such a structure is a significantly stable structure or not? Our two competing ...
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1answer
50 views

What is the film that covers the tongue?

What is the film that covers the tongue in the mornings, even after brushing the teeth and tongue the night before and why does it have color variations? Do the different colors mean anything?
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1answer
80 views

What is reductive deamination?

This presentation on anaerobic digestion mentions (pg. 19) two major pathways for the digestion of amino acids: Stickland reaction and reductive deamination. While I find some info on the former, what ...
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1answer
37 views

Why doesn't the avocado turn brown when it is kept with its seed?

Why doesn't the avocado turn brown when its kept with its seed? What does the seed release that slows down the oxidation process?
2
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1answer
26 views

Roles of creatine and bilirubin in foetus circulation

I think they are not inputs from maternal placenta. I think they are the results of foetus metabolism. However, I do not understand it how and where exactly. What are the roles of creatine and ...
6
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1answer
153 views

What exactly makes bananas go brown?

I know that often oxidation processes are mentioned when referring to the color change from yellow to brown in bananas (specifically: those that you get everywhere in supermarkets, with no seeds). ...
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2answers
170 views

Why isn't the phosphoglycerate kinase reaction of the glycolysis pathway irreversible?

Step 7 of the glycolysis pathway is the conversion of 1,3-bisphosphoglycerate into 3-phosphoglycerate by the action of the enzyme phosphoglycerate kinase, resulting in the production of 2 ATP ...
5
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2answers
188 views

What is an irreversible reaction?

There are reactions with large Delta G negative values. Why these reactions are irreversible? As in: out of 10 steps of Glycolysis, 3 are irreversible steps. I need an explanation for why they are ...
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2answers
90 views

Can excessive carbonated drink consumption lead to elevated red blood cell levels?

I've recently had a blood test and the results displayed elevated levels of erythrocytes as well as hemoglobin. (As a result my hematocrit levels were also above average) At my workplace there is a ...
2
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1answer
68 views

Substitute 25mM dNTPs mix with 10mM dNTPs

I need to make a solution of multiple compounds, one of them is dNTPs. The recipe calls for 20 μl 25 mM dNTPs in a 1250 μL master mix. Unfortunately I do not have it available at that concentration, ...
3
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1answer
50 views

Significance of lipids in biological membranes…?

Membranes are specifically designed by lipids to maintain internal hydrophilic environment in narrow range.There are hydrophobic amino acids among naturally occurring 20 amino acids and as well as ...
1
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1answer
35 views

Cells created using differently aligned proteins

I remember reading that scientist were making cells (I assume bacteria), that used differently oriented proteins to create a whole new class of life. Because apparently right and left aligned proteins ...
3
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1answer
49 views

Function of heparin and dextran sulfate for removing proteins

From this article : The reaction was terminated and the histones, and most nonhistones, were removed by adding the nuclease-treated chromosomes to a solution containing dextran sulfate (2 ...
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1answer
56 views

Missing 4$H_2O$s (per glucose) in Cellular Respiration… Where can they be?

I having trouble understanding the equation of the cellular respiration. The thing that bothers me is the number of $H_2O$ molecules. Generally, cellular respiration is written thus : $C_6H_{12}O_6 + ...
2
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1answer
223 views

What can cause the bloating in high protein diet of Whey proteins?

I am thinking what can cause the swelling of gastrointestinal system i.e. bloating after high protein diet of Whey proteins. Liver does breaks those proteins to branched chain amino acids (BCAA), ...