Questions tagged [biophysics]

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

Filter by
Sorted by
Tagged with
1
vote
0answers
12 views

Can the eye determine which type of defocus is presented to it?

I have a question regarding myopic and hyperopic defocus. My question is, is the eye able to determine which type of defocus is presented to it and if so what mechanisms allow it to distinguish ...
1
vote
0answers
24 views

How would one model a Neutrophil Extracellular Trap with Hookean Springs?

This is a question based in biology but involves a good amount of physics. Given that a Neutrophil Extracellular Trap (N.E.T) behaves like an aggregate of DNA strands with citrullinated Histones and ...
0
votes
0answers
14 views

Mandibular angle steepness/curve — adjustment possibilities from a biological and physics/mechanical standpoint

Is there any known way by anyone on here who could postulate a method by which the steepness of the mandibular angle can be altered to a lower degree with the concepts of morphogenic, bioenergetic/...
0
votes
0answers
13 views

Can anyone explain in a simple manner what is Fourier shell correlation (FSC)? And how is the conversion from 1D to 3D FSC?

3D FSC curves are used to show directional isotropy and global resolutions in cryo-EM maps. I am having a difficulty to understand the graphs since I do not have absolute clear idea about 3D FSC and ...
0
votes
0answers
21 views

Does Morphogen acts on morphing surfaces?

I have read lot of examples where at early stages of the development, morphogen gradient gives positional information and causes cell differentiation. But I am wondering if there is a example where ...
1
vote
0answers
17 views

Biophysically, how to change from a tonically firing neuron to an occasionally firing one?

In terms of membrane properties, size and neuronal biophysics (assuming no change in incoming excitation), how can a tonically firing neuron become (say during development) an occasionally bursting ...
0
votes
0answers
21 views

Whole blood under very high pressure (10,000 atm)

Is there any experimental research regarding the viability of whole blood stored at high-pressures around 1 Gpa (or 10,000 atm)? Does it destroy the blood?
1
vote
1answer
20 views

Question about the Derivation of the cable equation for neurites

I read in Wikipedia how the cable equation was derived (here) and had a specific problem regarding one of its equation: At the start of the derivation it states that we first need to pretend that the ...
1
vote
1answer
29 views

Why the length constant of passive current flow isn't depend on the membrane capacitance?

I read that the equation for the length constant for passive conductance along a neuron depend on the resistance of the plasma membrane, the intracellular axoplasm and the extracellular medium. My ...
0
votes
0answers
16 views

Is there any problem using x ray crystallography on a complex of proteins?

for a lab quiz I have to determine the structure of a 30Kda protein and a 70Kda protein as well as a complex of the two. I was thinking that x-ray cystography would work for all three structures but a ...
0
votes
0answers
23 views

Does the zeta potential of a nanoparticle generally take into account ligand charge?

For example, if I had a quantum dot nanoparticle with conjugated linker peptides capped with polyarginine tracts. Would the localization of negative charge from arginine change the zeta potential ...
2
votes
0answers
49 views

Why does constant current in electrophoresis mean that the molecule moves at the same rate? [closed]

Two part question: Part 1: I have always learned that when running a SDS-PAGE current is what decideds how fast the macro molecules migrate. However, if the force excerted on a molecule is equal ...
2
votes
0answers
59 views

What is the charge of (bacterial) ribosome?

Ribosomes are negatively charged and thus electrostaticaly repelled from DNA. However, I could not find a good reference that would allow me to estimate the magnitude of negative charge on a ribosome. ...
3
votes
1answer
55 views

Ion-gated ion channels

Today I've heard for the first time of calcium-gated ion channels but find it hard to get an idea how they work, where they are located, and which role they play. I assume calcium-gated ion channels ...
1
vote
1answer
39 views

How do signalling molecules find their receptors at large distances?

I have been baffled with this question approx. for a dozen of years for now. There is a default "lock & key" mechanism of action assumed for the interaction between a signalling molecule and its ...
0
votes
1answer
55 views

How does energy conversion happen (chemical to mechanical?) in moving body muscles?

From my understanding, the brain sends electrical pulses through neurons to different part of the body to initiate a movement. My question is, how is the movement realized? For example, in a train, ...
0
votes
0answers
21 views

How to include multiple DNAs into a crystal structure

I have a crystal structure (PDB 3OS1)that shows the interaction of PFV intasome with a substate DNA. I would like to replace the existing DNA in the intasome as well in the substrate with a longer ...
1
vote
0answers
56 views

Can enzymes be modeled using classical mechanics?

When enzymes interact with substrates (i.e. a small ADP molecule and the much larger ATP synthase), does quantum mechanics play a significant role? Or can the interactions be relatively accurately be ...
2
votes
2answers
67 views

Which proteins are most sensitive to electric fields?

Many Proteins have ionic charges that can attract each other (e.g. Formation of salt bridges) or repel each other. On the other Hand, Proteins are mostly immersed in water that screens most of the ...
1
vote
2answers
89 views

Does the Rayleigh formula apply to electron microscopes or only light microscopes?

I am asked to determine the resolving power of both a TEM (transmission electron microscope) and a SEM (scanning electron microscope) and given the Rayleigh formula below. $$Resolution=\frac{0.61\...
1
vote
0answers
51 views

Bioenergetics book

I already asked this question on the physics SE but redirected here: In the field of biophysics, it seems there is a subfield called "bioenergetics" about the processes of generating energy by ...
14
votes
2answers
2k views

Can UV radiation be safe for the skin?

It is well known that UV radiation can damage the DNA and generally harm our skin. We also know that UV radiation helps on the production of melanin and Vitamin D. From what I could find, the DNA ...
0
votes
0answers
31 views

“Straight” or “linear” helix

If an alpha helix is discontinued for a short while and then continues in a different direction, I prefer to call in "kinked". If the helix is simply uniformly following one direction, I prefer to ...
1
vote
0answers
20 views

What is the native structure of amyloid-beta protein under physiological conditions?

The amyloid-beta protein forms cross-beta structured fibrils. But under normal physiological conditions what is their predominant secondary structure. Is it alpha-helix, random coil or beta-sheet?
3
votes
1answer
65 views

Why is wound contraction very slow?

I am working on mathematical model for healing of dermal wounds. For anyone who's a bit familiar with Physics and Math, for the model I use the Cauchy Momentum Equation as a basis, and from there I ...
5
votes
1answer
114 views

Where does this equation in the electrophysiology literature form come from?

In my studies I keep coming across the form of an equation that is used in many different mathematical models for voltage gated ion channels. The most general form I have found is in the 1977 paper ...
1
vote
0answers
33 views

How many frames per second do human eyes see? [duplicate]

I observed when a helicopter rotor or fan is spinning the blades blur making it impossible to count the blades, but after a certain speed the blades seem to become visible making it possible to count ...
2
votes
0answers
30 views

How does nitrogen gas partial pressure change when ascending during scuba dive?

Scuba divers suffer decompression illness in which during sudden ascension, gas bubbles form in blood vessels and do not get reabsorbed quickly, leading to various problems including a stroke. The ...
1
vote
1answer
39 views

Entropy during neuronal signaling

to begin with: I have some background in cognitive neuroscience, but have not intensely studied the biochemical background of neuronal signalling, so please correct me if my basic understanding is ...
3
votes
1answer
95 views

Is there any independent non-DNA based information system in the cell

The information in protein is not neccessarily independent of the genome as the information of amino-acid sequence comes directly from the genome. The process of post-translational modification may ...
8
votes
1answer
641 views

Difference between prions and amyloid proteins?

Amyloid and prions are misfolded proteins, but what, if any, is the difference between them? Is amyloid a type of prion with a fibrillar structure?
0
votes
0answers
47 views

How to derive the deactivation time constant in this model of Acetylcholine Receptor state kinetics?

I came across this simple analytical expression of time constant of deactivation in Elenes et al., 2006. How does one derive this expression $$\displaystyle\tau_\text{deactivation}\approx\frac{1}{D_+ ...
12
votes
2answers
237 views

How much energy does a small spider expend per day just waiting for its web to vibrate?

Roughly speaking, a small, complex electronic circuit or IC might sit in "sleep mode" using a current of roughly 1 µA (e.g. 1, 2), thereby using roughly $3\times 10^{-6}$ Watts, and that ...
1
vote
1answer
385 views

Why is there a layer of moist lining the inner walls of alveoli?

I'm taught that the walls of the alveoli are moist, so gaseous oxygen molecules can dissolve into this water. This then allows the dissolved oxygen (liquid state) to diffuse faster from the alveoli ...
3
votes
1answer
36 views

Why does the DSC peak have a bell shape?

I am studying Differential Scanning Calorimetry (DSC) and am not quite understanding why most proteins have a bell shape when the heat capacity is plotted against the temperature. Also, I would ...
-1
votes
2answers
95 views

Why biologic systems tends to become more complex?

From elements, chemical compounds, cells, multicellular organisms, society evolves and with each step possibilities increase and things get complex. We are builing structures like ribosome builds ...
-1
votes
2answers
151 views

Effects of horizontal vs. vertical motion on human body

I want to know if moving along a vertical plane in a circle differs in its effects on the human body from moving horizontally in a circle. Imagine a ferris wheel with a diameter of 50 metres. If a ...
2
votes
2answers
289 views

Why do neurons have long axons but short dendrites?

Cian O'Donnell, a British neuroscientist, originally asked this question on Twitter: https://twitter.com/cian_neuro/status/1075432086692089857. I am not a biophysicist by training but I wonder whether ...
6
votes
2answers
150 views

Can light function as a neurotransmitter?

Any animal with an eye has photoreceptors, which are essentially light-sensitive neurons. Green algae have channelrhodopsin, which are ion channels that open and close in response to light. Clearly, ...
2
votes
1answer
218 views

What is meant with “the chest wall and lungs are coupled together”?

Since the lung and chest are elastic, we can represent them with springs. Under normal conditions, they are coupled together: the “lung” springs are stretched and the “chest” springs are compressed. ...
1
vote
1answer
80 views

How are sound waves amplified while traveling within the cochlea?

How are sound waves amplified while traveling from the basal membrane to apical membrane within the cochlea? Are they amplified by the movement of the stapes?
0
votes
1answer
37 views

What is (are) the medium of conduction for an electrical current with an external source in the human body?

I am trying to get some background for some personal research I am doing into the effects of Electro Convulsive Therapy. I don't understand how electric current from an external household source, say, ...
1
vote
0answers
86 views

What waste products do cells secrete in culture, and at what rate?

I am designing microfluidic chips for mammalian cell culture. One aspect I am interested in modeling is the rate at which I must renew media to ensure that: Cells receive enough nutrients Cytotoxic ...
1
vote
1answer
553 views

Can multiple antibodies bind the same antigen?

Given the size difference between small molecule antigens and antibodies is it ever possible for multiple antibodies to bind to the same antigen if they recognize different domains on that antigen? ...
-1
votes
1answer
30 views

Square-cubed law and health

Does the square-cubed law lead to possible health detriments for taller people? I'm not sure what the optimum height is for humans (e.g. due to their cross-sectional bone density constraints), but ...
0
votes
1answer
27 views

Is it possible to induce protein activation via frequency-specific mechanical waves? [closed]

Would it be possible to induce shape changes in specific proteins by providing specific frequencies of mechanical waves in a thermostatically controlled environment such that those proteins may be ...
2
votes
0answers
74 views

How can diving with 100% oxygen not destroy your lungs? [closed]

It is possible this should be moved to physics, depending on the nature of the answer (i.e. if the reason is physical). But I suspect the explanation is biological, so I posted it here. Sometimes ...
2
votes
1answer
78 views

Fraction of channels open at equilibrium

I found the formula for the fraction of channels open at equilibrium for a three-state mechanism (Colquhoun's paper in the microelectrode book http://www.utdallas.edu/~tres/microelectrode/me.html) k1 ...
0
votes
2answers
113 views

Are resonances the reason receptors work?

From Visual phototransduction - Wikipedia: When struck by a photon, 11-cis retinal undergoes photoisomerization to all-trans retinal which changes the conformation of the opsin GPCR leading to ...
0
votes
1answer
45 views

Is summation linear in a passive membrane?

I am not too sure what it means for summation to be linear? I am running a simulation and as I decrease time for the second EPSP the amplitude decreases. Does summation being linear mean that there is ...

1
2 3 4 5 6