The use of methods from the physical sciences to aid in the study of biological systems.

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1answer
61 views

What is membrane-partitioning free energy? Can it be simulated?

Firstly, is there a strict definition of the "membrane-partitioning free energy"? It is banded around in membrane biology, but I have never seen it strictly defined. The only non-scholarly site that ...
3
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1answer
43 views

Why is statistical mechanics relevant to RNA and protein folding?

This is a very naive question. As far as I understand the folding of a molecule is governed by the electromagnetic forces between its atoms and also between its atoms and the atoms in the surrounding ...
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1answer
17 views

Why is nitrogen isotopic labelling required for protein NMR?

Why is labelling required for Nitrogen (by 15N) for studying structure of a protein using NMR?
3
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1answer
35 views

Why does migration distance depend on log of molecular weight in SDS-PAGE?

I really want to know why in the result of SDS PAGE, log of molecular weight(MW) and migration distance (distance from the loading well) have a linear relationship. Why is it log(MW) instead of MW? ...
2
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1answer
79 views

Why don't membrane proteins move?

I understand that based on their tertiary structure, intrinsic proteins have hydrophobic non-polar R-groups on their surface and that they 'interact with the hydrophobic core of the cell membrane to ...
3
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0answers
19 views

Phase Transitions of Purified Proteins

Why do solutions of purified protein condense into droplet phases? I'm trying to understand the protein phase transitions. Here is the article http://www.cell.com/cell/fulltext/S0092-8674(12)00634-4#...
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1answer
1k views

Why doesn't the cell membrane just…break apart?

Forgive me if this is a silly question. I can't understand the basics. Why doesn't the cell membrane just break apart? What's keeping the layers in the phospholipid bilayer together? I know that the ...
0
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1answer
23 views

Enzymes and Reversibility of Reactions

Richard Feynman mentions in the third chapter of The Feynman Lectures: So the real system is in the GDP-GTP transformation; in the dark the GTP which has been stored up during the day is used to ...
2
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2answers
43 views

Diffusion coefficient of cells in blood?

What's the diffusion coefficient of white cells in blood? Is it well defined, or are cells too large and few as to be treated as particles in this context? P.S. I have tried to look this up, but what ...
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0answers
28 views

What is the sedimentation coefficient of Mycoplasma?

I have attempted to find the sedimentation coefficient of a number of bacterial species, namely E. coli and a number of Mycoplasma species, but they seemed to be rather elusive in the literature. If ...
16
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1answer
593 views

How fast can a human run?

I'm a runner (cross country) and I'm always amazed at how fast Olympic sprinters are. There's a lot of hype about those in the 100-meter dash being the fastest in the world, and we're constantly ...
2
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0answers
40 views

Do trees have genes for stopping the grow?

Do trees have genetically encoded to stop growing at some height, to keep dividing the cells only to a certain amount, or to pump nutritions only till it's advantageous because they've already ...
4
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3answers
67 views

Is Einstein's mass energy equivalence ($E=mc^2$) relevant to biological systems?

I'm more than 100% sure that the kilograms I eat don't get directly converted to feces and urine. I'm sure some of it goes to regenerating tissue that is constantly being disposed as well, and maybe ...
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0answers
8 views

How does a higher channel density increase speed of propagation of an Action Potential?

If there is a higher density of sodium channels then there will more Na+ flux in the cell. So it's like trying to pass more material through a pipe and therefore the speed of action potential (AP) ...
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0answers
22 views

What exactly is the time constant of an ion channel gating?

Let's take a channel that does not get inactivated, but is only in open and closed states. I understand what m (activation variable) represents. It's the fraction of the gates open. But what does t(...
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0answers
30 views

Why do the vines change their spinning direction?

Look at the vines holding onto the lattice. The "vine springs" change their spinning direction in the middle. Why? And how do they achieve this? (By the way, what's the name for this plant? Is is ...
11
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1answer
359 views

What is the transmembrane 'Positive-Inside Rule' nowadays? Has the definition changed over time?

First definition. Two publications by von Heijne in 1989 and 1992 coined the 'Positive-Inside rule' and showed it's practical value in topology prediction of transmembrane helices. It was clearly ...
8
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1answer
514 views

What is the difference between organelle membranes?

Cells and organelles are contained in lipid bilayers. I'm particularly interested in eukaryotic organelle bilayers and the biophysicochemical differences between them. Many papers assume a ...
0
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1answer
29 views

Enzyme kinetics: recommended literature to grasp the concepts better

I have had a few biochemistry courses, but I still feel confused and a bit scared each time they try to explain and apply enzyme kinetics or even chemometrics in different situation during class. On ...
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1answer
31 views

Difference between pulse coupling and diffusive coupling In biological oscillators

What are the differences between pulse coupling found among neuron cells and diffusive coupling found in cells that exhibit calcium waves? Moreover, in both methods, is it a strict requirement that ...
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0answers
10 views

Detecting brainwaves with no direct contact and no electrodes

Brainwaves are low frequency waves which is hard to detect and can be interfered with radio waves.i heard that it is possible to detect it with radio telescope and can be analysed with computers and ...
2
votes
1answer
54 views

Optimizing Gel Electrophoresis: Ampere, Volts and Buffer concentrations

I am a master student in biochemistry, and I have used gel electrophoresis many times before. What I want to know is how one should adjust the mA (mAmpere) compared to the voltage and the buffer one ...
1
vote
1answer
36 views

Question about radiation and how it affects biological systems

I'm doing research on the effects of radiation, and specifically UV, X-Ray and Gamma radiation, on biological systems at the cellular level and beyond. I understand that radiation types can be ...
9
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2answers
344 views

How do diving marine mammals avoid decompression sickness?

How do marine mammals, whose very survival depends on regular diving, manage to avoid decompression sickness or "the bends?" Do they, indeed, avoid it?
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0answers
15 views

Killing water-born pathogens with vacuum

Can water-born pathogens be killed by applying a vacuum to a body of water, causing it to boil at room temperature? Do most pathogens contain enough gaseous molecules that the expansion of the gas due ...
6
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1answer
103 views

Software recommendation for protein in electric field modeling? [closed]

I'd appreciate a suggestion for software to compare models of two proteins in an alternating electric field. The more detail, or perhaps direction towards an existing and similar paper, the better. ...
4
votes
1answer
159 views

How's the membrane potential restored to resting state after hyper polarisation?

I have known for so long that Na+/ K+ pump restores the membrane potential. But as it pumps in 2 K+ for every 3+ Na+ moving out how can it make the membrane potential less negative when the net result ...
7
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1answer
299 views

What keeps the resting potential of neurons constant at -70 mV?

I know the sodium-potassium pump pumps out 3 Na+ ions and pumps in 2 K+ ions per reaction so the negative charge in the axon increases. However, once the voltage (difference of charge inside and ...
4
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1answer
51 views

How can space-time affect ageing? [closed]

I recently watched the movie -"interstellar" and I came through the question that how can ageing be affected by space-time? Wherever I look, I get it as a fact that it's kind of ageing slows down in ...
3
votes
1answer
70 views

How does heat generated by metabolism differ compared with heat generated through exercise?

I am from a mathematical background so I don't have much knowledge on biology. I'm building a mathematical model to predict heat generation with parameters of metabolic heat generation and exercise ...
3
votes
1answer
2k views

What is the difference between rheobase and threshold?

Neuronal tissues can be excited by electrical stimulation. Two commonly encountered characteristics for electrically stimulating nerve cells is the threshold and the rheobase. My question is what the ...
5
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1answer
111 views

Criteria for compound action potential thresholds

As opposed to action potential thresholds (which are binary yes/no events), electrophysiological thresholds of compound action potentials are arbitrary. Mostly a certain noise level is picked and when ...
2
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1answer
161 views

What are wave frequencies in the EEG?

Here is a typical EEG reading: I understand that each row corresponds to the signal read between two sensors on a standard 10-20 (or 10-5) distribution setup (e.g. ...
2
votes
2answers
69 views

What are some useful physical information of a protein?

Beside energy and heat, I don't know any useful physical information of a protein. Can you help me list some of it. Somethings like Fourier-transform infrared spectroscopy to provide protein structure ...
3
votes
2answers
314 views

Confusion about resting membrane potential and the Na/K pump [duplicate]

To this day, very few people and sources have been able to clear up my confusion about resting membrane potential and how it is maintained. It seems like this is one of those topics that few people ...
3
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2answers
1k views

How does Bernoulli’s Principle apply to the cardiovascular system?

Below are graphs which illustrate the cross-sectional area, velocity, and fluid pressure through each vascular segment of the cardiovascular system. It makes sense that velocity and cross-sectional ...
3
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2answers
57 views

Is there a way to know how many sodium channels are active (conducting) at a given time in the brain?

I was doing some reading about anti-epileptic sodium channel blockers, then wondered how many sodium channels are actually conducting (actively passing ions) at any given time, that is, in an "average,...
4
votes
1answer
34 views

How is green fluorescent protein distributed while inside an organism?

I would like to know a relatively simple thing, but something I wasn't finding the answer to. When fluorescent protein is used in a relatively large, non-transparent animal, like a mouse, or ...
4
votes
1answer
80 views

What causes the opaque green colour in Lepidoptera?

Link here to what I mean by 'opaque' colouration on the insect, the colour intensity remains constant despite changes in light intensity and angle (not shown by the picture but the moth exhibits this ...
6
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2answers
394 views

How efficient is the human body at metabolizing food?

My friend and I were having a discussion over how "efficient" human digestion is. If a human ate a 1000 calorie hamburger, how many of those calories (how much energy) does the body process into ...
2
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1answer
59 views

Why is stimulation of nerve tissue with a negative pulse called “cathodic” stimulation?

By definition, the cathode is defined as the terminal through which current exits a polarized device. But in the context of neuromodulation, such as spinal cord stimulation, deep brain stimulation, ...
9
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2answers
7k views

Why is saltatory conduction faster than continuous conduction?

How does spacing apart sodium and potassium channels allow the action potential to travel faster down the axon? This is the reason always cited for saltatory conduction and myelination, but my mental ...
3
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2answers
81 views

How can neuronal signals faithfully be reproduced by scalp electrodes?

There is a skull barrier (and possibly other layers too) between the brain and the scalp. I have seen people trying to extract EEG signals from the scalp by connecting electrodes and interface it to ...
5
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2answers
116 views

Role of microvilli in cell volume regulation

Does the presence of microvilli on a cell's surface ensure that it's more resistant to cell swelling or lysis in a hypotonic solution, as compared to a normal cell?
7
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2answers
101 views

Permeability of Plasma Membrane

I’m having trouble grasping why small polar molecules can cross the hydrophobic region of the membrane and not ions. Won’t the polar molecules be attracted to the watery extracellular medium and not ...
3
votes
1answer
468 views

Relationship between turgor pressure and osmotic pressure?

I would like to know if there is a relationship between osmotic pressure (inside and outside of a cell) and turgor pressure. If so, is there a way to formalize it mathematically? Thank you in advance,...
8
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1answer
68 views

How does membrane potential vary between intraceullar membranes and the cellular membrane?

Question Does each type of membrane have a different membrane potential? I'm especially interested in answers that can cite academic papers that have attempted to measure membrane potentials. ...
8
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2answers
431 views

Can a living organism run on electricity?

Each time I'm too lazy too cook I think it'd be cool to be able to just plug myselt into an outlet. Yet I know it is not possible - I need amino acids and a lot of other stuff that electricity can't ...