Questions tagged [cell-membrane]

A selectively-permeable biological membrane that separates the interior of all cells from the outside environment.

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How does a protein molecule enter a cell through the cell membrane? [closed]

I can't find a good explanation as to how a whole protein molecule enters a cell membrane. Is it through endocytotic vesicles, with the help of ATP? How does this occur? Thanks for the help!
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How is Facilitated Diffusion saturable but simple diffusion not?

In some cases it is pretty clear why Simple diffusion is not saturable but in cases like the movement of molecules through ligand gated channels I'm finding difficult to see how they're not saturable. ...
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Osmotic gradient across cell membranes

In a typical cell in the human body, is the intracellular fluid typically hyper- or hypoosmotic to the extracellular fluid, e.g., is the osmolality of cytoplasm higher or lower than that on the ...
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How are lipid-coated mRNA-based vaccines transported into cells for expression?

In CNN's video Scientist says Coronavirus vaccine could be ready by 2021 after about 00:25 'Robin Shattock, the Head of Mucosal Infection and Immunity at Imperial ...
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Outlining cell edges of an epithelium

Is there any free software (for Windows, preferably) to detect cell edges in pictures of an epithelium, for example? I know Packing Analyzer does this, any other suggestions? Ideally, I would like ...
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Why don't membrane-bound cells frequently collapse or spill their contents?

According to the fluid mosaic model, cells that are bound by a phospholipid bilayer membrane are divided from the environment by a rather thin boundary. Some compare the membrane to a soap bubble. If ...
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How are newly synthesised proteins targeted to the plasma membrane?

There does not seem to be a definitive answer to how proteins destined to be intrinsic plasma membrane proteins are directed there. Presumably, assuming starting at a cytosolic ribosome, the pathway ...
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What makes iodine an effective antiseptic?

I'm thinking about tincture of iodine, potassium iodide (Lugol's), and povidone-iodine (PVP-I) specifically, which, as is my understanding, work by solubilizing elemental iodine in an aqueous solution....
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What happens to embedded membrane proteins after a vesicle is formed?

When an animal cell is going through endocytosis it cell surrounds a food particle, and the membrane swallows it, creating a vesicle within the cell. However, what happens to the embedded ...
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How does lipoid pneumonia lead to acute respiratory distress syndrome (ARDS)?

How does lipoid pneumonia lead to acute respiratory distress syndrome (ARDS)? The vaping illnesses that have been happening on the news in the United States are being caused by the federal ...
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Why don't all my cell membranes “smush” when I fall?

I've read the question about cell membranes breaking apart, which is close to what I'm asking, though I'm trying to probe a bit deeper. I understand that there are hydrophobic forces keeping the cell ...
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How are filopodia and membrane lengths related

I wonder how cell protrusions, in particular filopodia, form and how much of the cell membrane do they use. Is new membrane formed whenever a filopodium is created, or is the membrane simply deformed ...
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Do carrier proteins constantly open and close or do they only work when a substance binds to them?

What causes carrier proteins to change shape ? Do they need energy to change shape? If that is true, how are they involved in Facilitated diffusion ? By changing shape, do we always mean opens from ...
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When is voltage generated across a membrane?

I'm very confused so bear with me please. Electrogenic pumps are carrier proteins that generate voltage through the movement of ions, right ? When is a voltage generated ? When there's a net ...
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Protein rafts over the Phospholipidic bi-layer

Does any of you know the specific name of the protein rafts that allow proteins to float over a double layer of phospholipids, (cell membrane)? I just feel there should be another name rather than ...
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same osmotic pressure of different solution

For example, There is a sugar solution with concentration $A_{1}$, how to determine the concentration of a NaCl solution which produce same osmotic pressure as the previous sugar solution toward ...
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How does the glycocalyx of cells attach together if they are negatively charged?

Context Thus, the entire outside surface of the cell has a loose carbohydrate called the glycocalyx. The carbohydrate moieties attached to the outer surface of the cell has several important ...
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What is the difference between filopodia and lamellipodia?

I'm rather new to biology (I'm an applied mathematician) and I'm currently studying models of Notch-Delta dynamics between cells with filopodia and lamellipodia. What is exactly the difference ...
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Is plasma membrane permeable to sucrose

I searched a lot in the net but don't found a clear answer. I just want to know if plasma membrane is permeable to sucrose.
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Pharmacokinetics and cell-membrane permeability of Adenosine triphosphate disodium hydrate

【My Question】 (1) Please tell me the pharmacokinetics of this ATP (or Adenosine triphosphate disodium hydrate) when it is administered orally or intravenously. In particular, Does this material has ...
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What is the end-point of material from an apoptotic cell, after phagocytosis?

Apoptosis occurs. The organelles and interior material form apoptotic bodies that are packed in vesicles. The cell membrane breaks apart (cell no longer exists) and apoptotic bodies enter the ...
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Which proteins can lose adherence to cell surface by energical agitation?

According to this link https://www.cell.com/cell-reports/pdfExtended/S2211-1247(14)00121-1 CD44 protein lose adherence to cell surface by energical agitation Apart from CD44, which proteins can lose ...
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Can monoclonal antibodies work only if the target of it is located in the cell's surface?

Can monoclonal antibodies work only if the target of it is located in the cell's surface? or it can be used to targeting a protein located inside the cell?
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Osmosis/ Facilitated diffusion

Water can move across the (Semipermeable non polar lipid) membrane by simple diffusion (osmosis). But polar molecules cannot pass through the non polar lipid bilayer, they require carrier proteins to ...
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Why do larger diameter myelinated axons have greater conduction velocities than small diameter myelinated axons?

A canonical statement I have frequently read is that "large diameter axons conduct action potentials at faster velocities than small diameter axons". After recently learning the effect of increased ...
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Are large cell bodies of neurons harder to depolarize than small cell bodies of neurons?

In order for the axon to initiate an action potential, we know that the axon initial segment must be brought to threshold. So my question is as follows: Say we have the minimum charge input, "X", ...
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What is the difference in the electrical excitability between a “large diameter soma” and a “large diameter axon”

There are two stereotyped statements that I have seen during my coursework regarding electric properties of neurons: Large diameter axons propagate action potentials more quickly than small diameter ...
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At What Rate Do Ions Leak Out of a Plasma Membrane Segment That Has No Ion Channels?

In reading about the purpose of myelin during action potential propagation, I came across a point of confusion. From what I understand, one of the primary "benefits" of myelin is that it aids in ...
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What are the (evolutionary) advantages of secondary transport?

Secondary active transport uses electrochemical gradients as a source of energy for the uphill transport of substrates (coupled to downhill transport of the ion). However except for in a few cases (e....
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Can sperm cells penetrate the cell membrane of non-ovum cells?

Sperm cells have tiny bags of enzymes on their tip (the acrosome) which allow them to penetrate the ovum. My question is whether or not the process that allows sperm cells to penetrate the cell ...
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Reference request: Lipid composition in bacterial, yeast and human membranes

I would like to know about the lipid composition of different kinds of cellular membranes. I remember going through such a table once in a paper, but I am unable to find it anymore. What I am looking ...
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What regulates cyclic AMP?

After reading a textbook chapter on GPCRs I am still confused by what regulates cAMP. I took in my notes that cAMP is made by adenylyl cyclase and destroyed by cAMP phosphodiesterases (also another ...
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What do the text annotations in an electron micrograph mean?

I saw a photograph taken from an electron microscope, with some text. I want to know what is the meaning of these numbers and letters? Thank you! Regards.
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Neuronal membrane resting potential for large cells

I'm reading Medical Physiology by Boron and Boulpaep (a really terrific book). In the chapter Electrophysiology of the Cell Membrane, section Membrane Potential Is Generated by Ion Gradients, Not ...
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What's inside the perinuclear space?

The cell proper contains the cytoplasm in general and the cytosol in particular when referring to the fluid/gel without notable organelle. Once we move inside the nucleus there is the nucleoplasm and ...
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Is the reason why lipid-soluble molecules can pass through membrane because [duplicate]

I have been studying about cell membranes and how water molecules are able to pass through it. (https://www.wiley.com/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm) It ...
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Why does carbon dioxide diffuse easier through the bilipid layer than oxygen?

When gas exchange occurs during respiration, the pressure of oxygen in alveoli is around 105 mmHg, whereas in the blood vessels in close contact with alveoli is 40 mmHg. For carbon dioxide the values ...
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Plasma Membrane Proteins and Cytoskeletal Attachment

Regarding membrane protein functions, which of the following statements is CORRECT? a. Membrane proteins are responsible for both cell to cell recognition and cell anchoring and are ...
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Confused about definition of bulk flow of water by osmosis

As a teacher of high school and introductory college chemistry, I used textbooks that defined osmosis as a flow of water (only) through a membrane that prevents other substances such as dissolved ...
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What does “PDPN+ cells” means?

Are they podoplanin positive cells (cells that tested positive for podoplanin)? "...though it has been shown that podoplanin (PDPN+) cells analogous to mouse FRCs are found in human secondary ...
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Why does tetracycline have such a broad spectrum of activity?

What are the structural and chemical characteristics that make tetracycline uniquely broad spectrum? I understand it acts on the A-site of the prokaryotic ribosome, but there exist many ribosome-...
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What is the difference between a signal peptide and a transit peptide?

From what I know, the two names are used interchangeably and I haven't found any resource which says otherwise either. Is there at all any difference, is there a transit peptide that is not a signal ...
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Why don't the heads of phospholipid bilayers repel hydrophobic molecules?

What I Think I Know: Hydrophilic and hydrophobic things repel each other. Since the cell membrane contains hydrophobic tails, it is difficult for hydrophilic molecules to pass through the cell ...
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Why do soap molecules not break down your skin cells when you wash your hands?

Soap molecules are similar in structure to phospholipids and interact with the cell membrane. They can clearly cause damage to the cell membrane. If this is the case, why then, does soap not break ...
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What change would you expect in phospholipid orientation of the membrane if the enviornment were mostly heptane?

The external and internal environment of the cell is basically water, thus phospholipids organize themselves the way they do (bilayer). If the environment were to magically become mostly heptane, how ...
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T-Cell Motility: does motility require direction specific actin polymerization?

T-cells have been shown to migrate inside concentration gradients - both in the direction of the source or away. Even under shallow gradients, t-cells move. I argue that, to be able to move in a ...
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Tight Junctions in Cell Types

I took a quiz today on cell structure basics, which included cell junction types. I disagree with the "correct answer" according to the teacher. Here is the question: ...
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Glucose Carrier Proteins in Cell Membranes

I'm using Campbell's Biology textbook, and it states that certain carrier proteins transport glucose across the cell membrane much faster than would occur normally. It states that the "glucose ...
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Ambiguity about the relation between membrane potential and concentration gradient in neuron cells

I am stuck in an ambiguity about the equilibrium potentials of neuron cells. The following text is picked up from khanacademy website: In one part it is said that: We'll start out with K at a higher ...

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