what effect does trypsin have on cell detachment?
99518
Certain types of cells attach themselves to, let's say, the walls of a cell culture flask by adhesion molecules, which are specific membrane surface proteins. If you add trypsin, which is a protease (enzyme capable of cleaving proteins), it digests these molecules and causes the cells to detach. Of course, trypsin can digest other cell surface proteins as well, therefore cells might eventualy die if overexpossed to trypsin.
870168
For a cell without a cell wall, cytokinesis begins with the pinching inward of the cell membrane caused by the action of a ring of special contractile proteins called actin and myosin. The pinching inward forms a deep grove, often called the cleavage furrow. Eventually, the opposite sides of the furrow meet and the cell splits into two new daughter cells. \n\nWhereas cytokinesis in cells lacking a cell wall occurs through a pinching inward, organisms with a cell wall undergo a process through which a so-called cell plate is built from the middle of the cell outward to the membrane. Vesicles from the Golgi bodies flatten and fuse in the center of the cell, forming the cell plate, which elongates toward the cell membrane as more vesicle are added. When the cell plate reaches the cell membrane, the parent cell is effectively separated into two new daughter cells, which then proceed to build a cell wall along the cell plate.
341529
Inside our cells -it is a blind, mute and deaf world of roaming/floating molecules! Molecules (including the macromolecules like proteins) wonder almost aimless but can have influence on each other -like, breaking or joining others. But these interactions have to specific. The specific contact and the influence on each other is possible only due to the compatibility in the physico-chemical features on their surfaces, which are directly dependent on the structure.\n\nIt is the proteins that carry out most of the functions in cells. Hence, protein structure is very important for cell function. Because actin is such a basic structural protein and cytochalasin B can interact with it (and affect it), their interactions seem influence activities in different cells and events like fertilization and immune functions. You can look up for literature on this aspect.\n\nI am quoting one abstract from the NCBI's PubMed database (Journal -Biochim Biophys Acta. 1980 Dec 16;626(2):494-500.; PMID: 6894243)of research work by  Maruyama K, Hartwig JH &Stossel TP.:\n\nCytochalasin B and the structure of actin gels. II. Further evidence for the splitting of F-actin by cytochalasin B.\nCytochalasin B decreased the flow birefringence and s20,w and increased the extinction angle of actin filaments in salt solutions favoring polymerization of the protein. These changes occurred without a detectable increase in the equilibrium actin monomer concentration determined by a radioassay. These results complement earlier observations indicating that cytochalasin B shortens actin filaments without net depolymerization. Analyzed in terms of Flory's classical network theory, this shortening accounts for the marked effect of cytochalasin B in dissolving the gel structure of F-actin crosslinked by actin-binding protein concentrations near the critical concentration for incipient gelation. Cytochalasin B decreased the annealing rate of low concentrations of actin filament fragments prepared by sonic disruption. The result is consistent with the idea that cytochalasin B binds to the ends of actin filaments, and may explain how cytochalasin B causes filament shortening.
189624
lysogenic, it is not lytic because it doesn't make the cell rupture or explode, it actually attaches to the cd4 receptor site on a cell
71840
Apoptosis is characterized by maintenance of intact cell membranes during the suicide process so as to allow adjacent cells to engulf the dying cell so that it does not release its contents and trigger a local inflammatory reaction. Cells undergoing apoptosis usually exhibit a characteristic morphology, including fragmentation of the cell into membrane-bound apoptotic bodies, nuclear and cytoplasmic condensation and endolytic cleavage of the DNA into small oligonucleosomal fragments (Steller, 1995). The cells or fragments are then phagocytosed by macrophages.\n\nSignals that can trigger apoptosis can include\n\nlineage information \ndamage due to ionizing radiation or viral infection \nextracellular signals. \nExtrinsic signals may either suppress or promote apoptosis, and the same signals may promote survival in one cell type and invoke the suicide program in others (Steller, 1995). For example, death receptors that are members of the tumour necrosis factor receptor (TNFR) family sit in cell membranes, but their intracellular domains have direct access to the cell death machinery that lies ready and waiting within the cell (Ashkenazi and Dixit, 1998). When members of the TNF ligand family bind to their receptors some of the pathways activated can include those that bring about cell death. Conversely, there are other factors, such as the neurotrophins, that bind to cell surface receptors and which act to prevent cell death!\n\nInvocation of the suicide program involves the synthesis of specific messenger RNA molecules and their translation. PCD can sometimes be suppressed by inhibiting transcription or translation (Steller, 1995), which provides evidence that cell death is mediated by intrinsic cellular mechanisms.\n\nI'm interested in life! Why do I want to think about death?\nCell death is currently the subject of considerable research activity. This interest stems, in part, from the potential for understanding oncogenesis and the possibility of exploiting the cell death program for therapeutic purposes. For example, inhibition of cell death might contribute to oncogenesis by promoting cell survival instead of death. Likewise, triggering cell death might provide the means for eliminating unwanted cells (e.g., tumor cells).\n\nWhat on Earth has death got to do with development?\nRecognition of PCD as a developmental mechanism dates back well over 100 years (Clark and Clark, 1996; this is an excellent account of old descriptions of "apoptosis" before there was "apoptosis"). Developmental processes that involve PCD include:\n\nElimination of transitory organs and tissues. Examples include phylogenetic vestiges (pronephros and mesonephros in higher vertebrates), anuran tails and gills and larval organs of holometabolous insects. \n\nTissue remodeling. Vertebrate limb bud development (Fig. 11.42, Saunders, 1982; Fig. 1, Saunders, 1966) is an example. If PCD fails, in formation of the digits, digits remain joined by soft tissue. Compare, for example, the situation in the chick and duck hind limbs. If chick limb mesoderm is combined with duck ectoderm, PCD fails and the digits remain joined (Saunders, 1966). This observation implicates the ectoderm in providing the signal to trigger PCD. Another example is formation of heart loops during vertebrate development. Depletion of cells in spinal ganglia occurs during development of the chick embryo. As shown in Table 11.1 (Saunders, 1982), there is precise chronological and spatial control over this process. Interestingly, injections of nerve growth factor reduce the frequency of cell death in the spinal ganglia. This observation provides a link between growth control and PCD.
958171
Protein damage through sulfydryl group interactions.  Proteins within the cell are damaged and the cell cannot proliferate (dies).
748764
The only thing I can think of ATM is a negative feedback loop. What that is:\n\nThe end product (lets say product C) can bind to your enzyme (E) and 'shut it off.' Normally a product is made in more than one step and enzymes are designated E1-En and our product C can have a binding site at any of these enzymes. The negative feedback loop is used to ensure that there is only the needed amount of final product and not too much of it which can cause damage to the cell. \n\nI hope this helps. If I think of anything else that it could be I'll let you know. Attached is an abstract that talks about endpoint inhibition of a protein on an enzyme and the gene expression.
199023
k, let's see if i remember...\n\nfirst you get cut, next proteins and cytokines are released by the local cells to recruit platelets (for clotting), neutrophils, and macrophages.  The neutrophils and macrophages are there to clean up all the dead cells that die in the attack and also to take any bad stuff to the nearest lymph node.  They antibodies can be made against the foreign body.  Therefore, if any of the lil buggers got away from the site of the cut, the antibodies will hopefully soon find them and kill 'em dead. ;)  those are the simplest words I could use to explain it.
656699
The venom of this species has been extensively studied. It contains specific phospholipases (enzymes capable of destroying cell membranes), and also a platelet inhibitor called applaggin (anticoagulant), as well as a specific lectin (these are glycoproteins that can agglutinate red blood cells).\nI'm sure there are other components, just use the links!\n\nSome publications (some are abstracts):\nhttp://www.pnas.org/cgi/reprint/86/20/8050\nhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3082870&dopt=Abstract\nhttp://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10484740&dopt=Citation\n \nTry searching using Google Scholar :-)\nhttp://scholar.google.com
95058
Cells have what is called an extracellular matrix, which includes proteins that anchor everything togteher (things like collagen and elastin, etc.).
442497
Abstract. \n...membranes, microvilli, and membrane projections, and act as crosslinkers between the actin cytoskeleton and proteins of the cell surface...\nhttp://147.52.72.117/IJO/2002/volume21/number5/935-940.pdf \n\n \nforthcoming meetings\nAim: to learn techniques commonly used to analyse signal transduction ... and cell adhesion (cytoskeleton, cell adhesion proteins, extracellular\nhttp://www.usgeb.ch/skmb2005.html \n\n \nBTO\n...and function of proteins, methods of ... Cytoskeleton and cell motility. ... Describe and use structure determination techniques to analyse\nhttp://www.bto.ed.ac.uk/courses/year1/index0506.phtml \n\n \nRandall Division o f Cell and Molecular Biophysics\n...actin cytoskeleton during migration. I use a number of different advanced imaging techniques to analyse ... analysis of interacting proteins by\nhttp://www.kcl.ac.uk/depsta/biomedical/randall/mparsons.html \n\n \nGlossaire (ULg)\nAnkyrins. A family of membrane-associated proteins responsible for the attachment of the cytoskeleton. Note: membrane proteins \nhttp://www.ebm.lib.ulg.ac.be/prostate/gloss.htm \n\n \nThe role of the axolemma in the initiation of traumatically induced...\n...proteins. Transmembrane proteins such ... matrix to the cytoskeleton via the ... Biophysical investigations have used novel techniques to\nhttp://www.jnnp.com/cgi/content/full/64/3/285 \n\n \nThe tiniest parts of \n...are as dispart as the techniques and ... natural science, is to analyse the ... energy or information, signal transducers, cytoskeleton...\nhttp://www.uni-leipzig.de/~philos/psarros/preprints/the_tiniest_parts_of.html \n\n \nGenome Biology | Full text | Analysis and functional classification\n...as well as the development of new techniques for ... genes encoding cytoskeleton proteins (such as myosin, actin, UNC-87, troponin T) and\nhttp://genomebiology.com/2003/4/4/R26 \n\n \nStudy Abroad 2004 INTRODUCTION 2 Deakin University's unique Study \nUnit Handbook GUIDE TO UNIT DESCRIPTIONS ACD206/306 Dance Production and Analysis Second semester, 1 credit point Prerequisite ACD203 or Level One \nhttp://www.deakin.edu.au/international/Documents/Brochures/SAHandbook.pdf \n\n \nAdrian Harwood\n...genetic, biochemical and cell biological techniques to analyse the ... has both a cytoskeleton and a network ... SH2 domain proteins,\nhttp://www.ucl.ac.uk/LMCB/pages/harwood.html
335320
Trypsin cleaves c side of arg and lys so this fragment is probably the c terminus
931863
Great question! And no, I won't call it cheating if you add another follow-up query. It's good to be inquisitive.\n\nNow, to answer your question precisely, there was no evolutionary pressure that caused polynucleated cells to form in protists as such. The factors that affect evolution viz. natural selection, genetic drift, gene migration, recombination and mutation cannot (with the exception of mutation) cause the appearance of a certain morphological trait as effectively as they can help the organism to sustain it.\n\nThe answer actually lies in the second question you asked. Yes, mitosis. To state it briefly, yes, each nucleus *does* contain an identical set of DNA. \n\nThe reason why cells are different functionally in multicellular organisms is because of the effects of certain gene mechanisms that "switch off" and "switch on" the production of enzymes under specific conditions thus, altering their functionality.\n\nNow, to answer your primary query-- as you already might be aware that during the cell-division, it is the nucleus that first divides into two: (Mitosis). Sometimes, the outer membrane of the protist fails to separate due to the lack of phospholipid membrane material. This delay in cell division back in the days of the beginning might have resulted in a polynucleated cell.\n\nThe success of this polynucleated cell may be easily justified due to the increased efficiency of the metabolism as the decentralisation of regulating power i.e. nuclear material could have resulted in division of labour and thus, in perhaps the first *ever* "pseudo"-multicellular animal.\n\nAs for your follow-up queries, I think I have provided enough detail in the paragraph above, which you can use as a *very* basic outline and explore the subject further by studying the topic in detail in your book(s).
1007385
Most chemotherapy drugs kills cells while they are dividing. Cancer cells divide faster then normal cells.  That is why the chemo kills cancer cells more than normal cells.  Other cells that divide fast are immune cells, blood cells, hair cells and the cells in the lining of the stomach.  This is why the side effects of may chemo agents are immunosuppression, anemia, hair loss and mucositis/stomatitis.  \n\nDifferent chemo agents stop the cell cycle in different ways.  Some are antimetabolites and block the use of vitamin necessary for cell division.  Some bind to the tubules and don't allow the cell to divide.  The mechanisms vary but the end result is the same.  Cell death.
366797
THe enzyme is rennin.\nI'm pretty sure it's released from Gastric Parietal cells(the same ones that make acid) either that's it the Chief cells ( that make pepsinogen)\nRennin is produced for the function of clot milk so it stays in the stomach for longer to allow the low pH and stomach enzymes to digest as much as possible, before passing through the pyloris to the small intestine, where the pH rises to 7ish.\n\nWhat you don't confuse Rennin with Renin.  Renin is an enzyme released from the kidney involved in Sodium, water and blood pressure homeostasis.
932892
Proteases (proteinases, peptidases, or proteolytic enzymes) are enzymes that break peptide bonds between amino acids of proteins. The process is called proteolytic cleavage, a common mechanism of activation or inactivation of enzymes, especially those involved in blood coagulation or digestion. They use a molecule of water for this and are thus classified as hydrolases.\n\nDigestion typically begins in the stomach when pepsinogen is converted to pepsin by the action of hydrochloric acid, and continued by trypsin and chymotrypsin in the intestine. The amino acids and their derivatives into which dietary protein is degraded are then absorbed by the gastrointestinal tract. The absorption rates of individual amino acids are highly dependent on the protein source; for example, the digestibilities of many amino acids in humans differ between soy and milk proteins[2] and between individual milk proteins, beta-lactoglobulin and casein.[3] For milk proteins, about 50% of the ingested protein is absorbed between the stomach and the jejunum and 90% is absorbed by the time the digested food reaches the ileum.[4]
819615
Hydrochloric acid has several functions during digestion.  Gastric acid has a pH of around 2.0, which is highly acidic.  Since proteins have a narrow pH threshhold, gastric acid denatures them and exposes peptide bonds for proteolysis.  \n\nThe real work of breaking the peptide bonds is done by pepsin though.  However, since pepsin targets proteins and there are many proteins in body that we don't want pepsin to break up, pepsin has to be produced and transported around in the form of it's inactive precursor, pepsinogen.  Once the pepsinogen encounters the HCl in the stomach, it is activated into pepsin and proteolysis can occur.  \n\nStomach acid is also useful in killing any bacteria that have entered the stomach through the esophagus and keeping the beneficial bacteria in the colon from migrating into the small intestine and causing problems.