Questions tagged [cell-signaling]

Tag for questions related to the process of cells receiving a stimulus from its environment, or from itself (autocrine signaling), and responding as a result of the stimulus.

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Terminology for quantitative response of T cells to antigen complexes

In the article, there is a statement which is: Although DCs are remarkably efficient in evoking T cell responses with few antigen– MHC complexes (1–100 per DC) (1–3), they must first ...
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Hedgehog AP Bio question

Could someone please explain this AP Biology question? I know the answer is C but I do not understand why. Doesn't Smo prevent gene transcription? If you "block its activity" then wouldn't it cause ...
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What is the step by step procedure that leads the T cell to release chemokines?

When T cell receptors bind to the receptor of an antigen presenting cell, is this what leads to the release of chemokines? I know that T cell release of chemokines leads to the migration of other T ...
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378 views

Do two hormones have the same effect on a cell if the second messenger is the same?

There are so many hormones/cytokines/neurotransmitters and receptors, all of which act through about 4-5 second-messenger systems. So if one particular cell has receptors for say, two different ...
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How do chameleons signal cells to change color?

I have read about how they can change color, but is there literature about the chemical signaling process they use to do so? I read that it could be some combination of hormones and neurotransmitters,...
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Retrograde/anterorade transport; kinesin/dynein; COP1/COP2; Endoplasmic reticulum/Golgi

I am getting slightly confused with all of the terms above and was wondering if someone could see if I have got this right: I think transport from the ER to Golgi is almost always from the plus end ...
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825 views

Is the signal peptide always cleaved during protein synthesis in the ER?

My university supervisor said that the signal sequence is always cleaved, however my text book differs. What I gather from my text book (though it isn't very clearly stated so i'm not sure) is that: ...
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How do cells determine what size to grow to before dividing? [closed]

How do cells determine size to grow to before dividing?
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1answer
202 views

Do all plant hormones of one group show the same qualitative effect with respect to their target pathway(s) and the biological response?

I wonder, terms like "Auxin", "Cytokinin", "Gibberellin" etc means NOT a single compound; but a class of compound. For example "Auxin" does-not mean a single compound, but several compounds such as :...
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How exactly apoptosis starts? [closed]

I read article about apoptosis on Wikipedia, but didn't understand, how exactly the organism learns that it is necessary to launch process of apoptosis in certain cell. In other words, on what signs ...
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50 views

How does carcinoma enter into blood or lymphatic vessels?

When carcinoma begins to metastasize, it enters into blood vessel or lymphatic vessel to migrate to the site of metastasis. In that case, although I think breaking down the basement membrane is ...
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1answer
48 views

Can a protein kinase phosphorylate both a threonine and tyrosine residue?

I know that some kinases can phosporylate both serine and threonine residues because of their structural similarities, but can such a kinase phosphorylate a tyrosine residue as well? If not, then why?...
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Insulin and leptin action on Anorexigenic Neurons in Hypothalamus?

Receptors for Insulin are present on liver, adipose tissue and muscles. In addition, there are Insulin Receptors present in arcuate nucleus of hypothalamus, which influences anorexogenic neurons ...
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391 views

Why are both glucagon and cortisol released in hypoglycemia?

Cortisol is released in response to prolonged stresses; one situation when cortisol is released is when blood glucose level is low. In this situation cortisol acts on adipose tissue promoting fatty ...
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1answer
101 views

What information do bipolar cells encode?

Short version: I don't see what information on-centre bipolar cells are actually capturing. Longer: Actually, the question could be extended to on-centre retinal cells as well, but I'll focus on ...
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How is receptor production (recycling) regulated?

My understanding of receptor downregulation is that when activated, a receptor then gets absorbed into its cell, as shown in this weird video. It then gets either recycled or degraded. Tolerance ...
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215 views

Cell biology books

I'd like to know, what is the best list of books for non-biologist to understand, how signalling between organels is organized inside of eukaryotic cells. I really want to get how cell as separate ...
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Is EGF-mediated proliferation symmetric?

It's known that the MAPK signaling cascade (say, ERK) is downstream of EGFR in epithelial cells, and that EGFR activation can cause proliferation in some cell types in some situations. My question is ...
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1answer
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Advantage of GCPRs over RTKs or other receptor protein kinases

My book lists two important differences between GCPRs and receptor protein kinases: GCPRs do not directly activate a signal transduction pathway. It only does so indirectly, via a G protein. On the ...
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155 views

Why are truncations in Receptor Tyrosine Kinases so sommon in transformations?

Receptor Tyrosine Kinases (RTKs) present themselves on the surface of a cell as monomers until a ligand (such as a mitogen) binds and causes the formation of the active dimer. However I do not ...
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If so many different hormones/molecules work by activating adenylyl cyclase, how do they have different effects?

It seems that many hormones and molecules work by activating adenylyl cyclase to convert $\text{ATP}$ to $\text{cAMP}$, such as adrenaline and glucagon. Both of these seem to bind to $\text G$ protein ...
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What's the purpose of Cdk activity having more than one method of becoming inactive?

Cdk becomes partially active once its bound to cyclin and then gets phosphorylated and fully active once a Cdk-activating kinase (CAK) phosphorylates the partially active Cdk. This fully activated Cdk ...
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1answer
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To have a drug travel to a specific place in the body can you just coat the drug in extracellular signals recognized by target cells?

In a lecture of mine the professor was talking about the issue faced in regards to drug therapy when it comes to targeting lung cells in cystic fibrosis. It was said that if unless the drug gets ...
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What is the essence of difference of how different chemicals affect the same receptor?

It is known that various chemicals can bind to the same receptor type, producing different effects. Be these chemicals agonists or antagonists, there are more variations in how they influence the ...
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What is a mechanical cue?

I was attending a talk related to neurogenesis. So one professor was asking a question related to biochemical cues and mechanical cues (related to signaling pathways I believe). Cue as far as I ...
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What is the lifetime of the vasopressin receptor V2?

I was looking at the production of vasopressin receptor 2, also known as V2R or ADH-R. What I found is that it is coded by the AVPR2 gene and degraded by the Alix protein (source). But I did not get ...
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What happens to IP3 molecules after release from IP3 receptors?

IP3 molecules bind to IP3 receptors and open up the calcium channels on the endoplasmic reticulum. I am wondering what happens to IP3 molecules after they have been released from the IP3 receptor? Do ...
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How do steroids travel in the bloodstream?

Cholesterol, which is hydrophobic, cannot simply travel in the bloodstream, and instead is enclosed in lipoprotein (LDL, HDL). Steroids, which are derived from cholesterol, are also hydrophobic (right?...
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How can a ligand be an integral membrane protein?

My background is in mathematics, and not biology, so please bear with me. I am currently working on a project involving the effects of Epidermal growth factor treatment (EGF) on cell migration. I am ...
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When and How do pacemaker cells develop during the cell aggregation process of Dictyostelium discoideum?

I was reading a paper by Tang & Othmer about oscillations and waves in Dictyostelium discoideum. Under certain condition like starvation period in the life cycle of a Dictyostelium discoideum ...
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912 views

Why does a “cascade” of events happen during signal transduction?

I've been watching some videos on signal transduction and it says that because there are enzymes being activated by the signal, then there is a "cascade" which happens afterwards...I don't understand ...
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Can your immune system's cells destroy you? (Critical thinking and Fictional sense)

In an imaginary sense, If you alone were replicated into 2 so that there should now be 2 of "you" (meaning you both have the same DNA). Then let's say one of you shrunk to the size of a bacteria, and ...
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Apoptosis vs necroptosis

I understand that apoptosis and necroptosis share the same upper part of the pathway, but I cannot seem to distinguish when is each one activated? From my readings, it seems that when procaspases 8 or ...
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How does the cell regulate different metabolic pathways?

I heard somewhere that cells use different nucleosides bound to triphosphates e.g. ATP, GTP, CTP and other modified compounds: NADH, NADPH to distinguish between different metabolic pathways and so ...
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Does the cellular response to every receptor work the same way?

I heard somewhere that activating any receptor results in the same intracellular response (signaling) which involves NF-κB. If that is true, I hardly understand how the cells distinguish between ...
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2answers
535 views

Localization of Protein Kinase-A

Is protein kinase-A located in the cytosol/cytoplasm of cells or in the plasma membrane? Also, is it considered a receptor molecule since it is dependent on cAMP? Any and all help is appreciated. ...
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What's the duration between the binding of adrenaline to β-AR and the first translated protein?

Binding of adrenaline (epinephrine) to the β-Adrenergic receptor leads to formation of cAMP (via G protein activation), activation of protein kinase A and subsequently to the expression of specific ...
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1answer
653 views

What is the functional significance of the difference in cardiolipin/cholesterol ratio in different membranes?

I have read somewhere that the plasma membrane has little cardiolipin but excess cholesterol whereas the inner mitochondrial membrane is rich in cardiolipin and has little cholesterol.I just wanted to ...
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1answer
171 views

Why do oncogenes show genetic dominance?

As we know that tumor suppressor gene causes cancer only when both the alleles are recessive in nature.But in case of oncogenes if only one allele is dominant it can cause cancer.Why in case of ...
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Effect of steroid hormone on specific cells?

As steroid hormones can pass through the plasma membrane by simple diffusion because they are lipid derived hormones, it means that they are capable of passing through every cell of our body, BUT why ...
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1answer
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Regarding signalling pathways

Do all signalling pathways have something that can inhibit them? If the signal pathway is benefitial and it is inhibited would the inhibitor be caused by a biological problem? Are all inhibitors ...
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which signalling pathway is involved in cancer?

Columnar epithelial cells from the colonic mucosa are studied to identify abnormalities in cell signaling pathways. Abnormal epithelial cells from colonic adenocarcinoma are shown to have a mutation ...
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Effect of testosterone hormone on cell signalling and behaviour?

A steroid, testosterone was injected in female body which led to development of secondary sexual characters but these characters were not developed over night (Response was very slow). What could be ...
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Why does Hunger lead to the aggressive behavior?

I have observed that frequently when people are hungry; they tend to get angry more easily on pointless issues. Does this mean that our fight or flight response is more active when a person is hungry? ...
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Specificity of Protein Kinases in Signaling Pathways..?

In most of the signaling pathways the activated receptor when activates Protein Kinase through the action of secondary messenger, then these protein kinases almost always phosphorylate on the specific ...
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1answer
332 views

Can (any) human cells learn?

I'm not talking about single celled organisms, but actual cells in your body. Is there any evidence that they can learn to, say, navigate an environment or avoid an aversive stimulus like an animal ...
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536 views

How do GPCRs transmit a signal across the plasma membrane?

How do G-coupled protein receptors (GPCR) transmit signals through the plasma membrane? Links containing information about this and pictures will be very helpful.
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Why can't intermediate filaments be used as tracks by motor proteins?

A motor protein like kinesin-1 cannot use an IF as a track because it lacks polarity. Can someone elaborate on this answer?
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1answer
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Meaning of “auto” in trans autophosphorylation?

Why this process called "auto"? Is it because each tyrosine kinase receptor subunit of the RTK dimer has the ability to phosphorylate tyrosine or other amino acid residue present in other subunit of ...
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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 ...