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If single cells are capable of surviving on their own then why did multicellularity evolve? This situation can be compared with the evolution of family and society, in a way; during the time of crisis, the survival chances increase when someone stays in a group. Similar conditions would have resulted in the evolution of multicellularity. The difference ...


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There's a decent presentation here that basically goes over what you're asking. As an inhibitor, azides are similar to cyanide in that they inhibit complex IV by binding cytochrome oxidase, resulting in a sort of chemical asphyxiation. Uncouplers are a little harder to wrap your head around. They embed in the membrane space, and we know that ETC and ...


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When physical damage to the cells occur a biological process called inflammation occurs. When inflammation occurs, white blood cells are rushed to the area in order to fight off any bacteria or harmful waste leakage from damaging the cells further. In order to get the white blood cells to the site of damage faster, the body induces a process called ...


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There are species where cells and even whole organisms can go into a state called cryptobiosis where their metabolism is suspended but can be revived later. This usually happens when the conditions become too bad for survival (dry/cold etc.) and is reversed once the conditions improve again (rehydration warming up). One prominent and fascinating example are ...


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Due to the advantages of doing so for competing with single celled lifeforms. One of thease advantages is that the volume to surface area of a cell gives cells a natural size of a few micrometers. Larger single cells find it increasingly difficult to get enough nutrients or oxygen to there insides. Although amoebas can be larger due to being irregular in ...


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I hope you understand what I'm gonna say. So: Introduction Each living thing has its own homeostasis, the external and internal conditions that are normal for its existence. If those conditions are always the same, then evolution (change) is not necessary for its survival. But, since all life is not the same, and since not all environments are the same, ...


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What we're basically looking at with ADC internalization Courtesy of Bayer So the way an ADC works: The antibody-drug conugate binds to a target antigen like a transmembrane receptor, the cell in response engulfs the entire complex and send it to an endosome. What the cell can do with the endosome depends on the cargo. Digressing, the ADC internalization ...


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I'm not sure about all organelles but mitochondria and chloroplasts are commonly used examples of independent devision in eukaryotic cells. They have independent DNA that forms separate mitotic spindles during division. Similar mechanisms likely existed for other organelles originally but the genetic material may have eventually been combined with the ...


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I think GPCRs are evolutionary more older since tyrosine kinase signalling is relative recent evolved system. This could be one explanation for why their is more diversity in GPCRs By the way GPCRs can actually signal g-protein independent, for example via B-arrestin. Also their are many types of g-proteins witch can all induce signaling via different ...


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There is a lot of confusion and conflicting / imprecise definitions of these terms. It's biology after all :) A mitogen is an agent that causes a cell to enter mitosis. This definition is pretty clear, and there is a good consensus about it. (Well technically, mitosis is not the same as cell division, but we will gloss over this distinction.) The term ...


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You can find a great article about this here. basically, these two groups are very similar in their effects, however they work through different pathways. Mitogens directly promote cell to get through G1 checkpoint through highering the activity of cyclin D/cdk4 (the complex needed to get through the checkpoint.) and according to the article above, also ...


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The 'cleanest' data I am aware of is on studies using density gradient centrifugation. In density gradient centrifugation, a preparation of cells is layered on top of a density gradient media which has higher density than water (water=1g/ml). Centrifugation forces denser cells through the media whereas cells with equal or lower density remain above the ...


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In a healthy body, cells travel. But this is very dependent of the cell type. Some cell type will travel in all the body (lymphocytes, plasmocytes, etc) while other do not have any migration capability. The concept of diffusion is wrong to apply here, indeed the scales at which you are looking are not molecular. Moreover, there are very active mechanism ...


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Well, Sender, Fuchs, and Milo wrote a paper to discuss the total number of cells in the body and compare it to the number of bacteria in the body (http://dx.doi.org/10.1101/036103). Their discussion is quite in-depth. There are a number of ways to calculate it, but an interesting one involved calculating mammalian cell density by a study measuring the DNA ...


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AMP is first converted to ADP in the reaction AMP + ATP $\leftrightarrow$ 2 ADP catalyzed by adenylate kinase. So one phophate group is transfered from ATP to AMP, resulting in two ADP molecules. The ADP formed is then used to synthesize ATP as usual, by the mitochondrial ATP synthase or by the glycolysis enzymes. For other nucleotides and ...


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Endocytosis (specifically you asked about clathrin-mediated endocytosis) is indeed an energy consuming process. the coating of the vesicle may be "spontaneous", but the pinching off of the vesicle, the uncoating of the clathrin, and the transportaion of the vasicle inside the cell all require ATP/GTP hydrolysis. Dynamin - dynamin forms a spiral around the ...


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Practically speaking, microtubule nucleation occurs at the plus end. This is well established in vivo and in vitro. Notably, the minus ends within most cells are "capped", so dynamics do not occur (think of the centrosome). However, recently there is a report of MT polymerization at the minus end in a cell; this is far from the consensus among professionals ...


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The major hurdle for novel treatments to make it into humans is the assessment of its merits and added value over existing, proven treatments. And more importantly, the safety for humans has to be validated to a sufficient extent. The notorious from bench to bedside (Goldblatt & Lee, 2010) bottle neck. To answer your questions: Technically, going from ...


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The short answer: no. First, let's get an understanding of the cell cycle control system, as there are some important molecules involved in this system that regulate mitosis. Think of the control system as a series of stoplights: as you mention, there is one stoplight at the G2 phase. There are two additional checkpoints: one at G1 and one in the M (mitotic) ...


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The vector used in this study is based on the herpes simplex virus genome (HSV). Wildtype HSV mainly infects sensory neurons. After infection, it resides in a latent state in the nervous systems of the host for a lifetime. The viral genome persists in the cell, without integrating into the host genome (Marconi et al., 2000). The article cited is devoid of ...


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Each of us burns approximately twice our body weight in ATP every day. So double your body weight and divide that number by the number of seconds in one day; that will give you the average mass of ATP. N.B. a person with a higher mass will have a higher answer.


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ATP burned per minute is not a useful number because the turnover is so high. 2000 kcal/day is dozens of kilograms of ATP so obviously ATP is turned over more than once a day, but there's probably more than one molecule of ATP being passed around between all the ATP synthases. This blog claims 250 grams. Taking the estimate of ATP concentrations(1-10 mM) ...


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Immunity can be a double edge sword. It is aimed to detect and destroy invading pathogens but it can also target the self, as exemplified in autoimmune diseases. To avoid this, many failsafe mechanisms exists. For example, imagine an innocuous foreign antigen gets into your body and reaches the lymph node. There it may find a naive B cell that has a ...


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From my Campbell's Biology textbook (Ninth Edition): Because of the orientation of tubulin dimers, the two ends of a microtubule are slightly different. One end can accumulate or release tubulin dimers at a much higher rate than the other, thus growing and shrinking significantly during cellular activities. (This is called the "plus end", not because it ...


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Actually, the answer is not obvious. @RoSiv gives the textbook case of symmetric cell division, where the two new cells can indeed be considered identical, and this is valid in many cases. But there are also cases of asymmetric cell division, where the "mother" and "daughter" cell are clearly different. In asymmetric cell division, the parent cell is ...


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There is a large amount of variation in the distribution and number of chiasmata or crossing overs (COs). The total number of chiasmata per cell can vary within the same organism. Where chiasmata occur along the chromosome is also not consistent cell to cell. Hotspots are 1-2kb regions that experience elevated recombination compared to neighboring genomic ...


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Here is a picture to expand on my comment better. From wikipedia: In the above diagram, the red chromosome represents one homolog while the blue chromosome represents the other homolog in the pair. After replication in Interphase, you have two homologs, each consisting of duplicated sister chromatids. You can see how we have the one enlarged cell in ...


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Humans have 46 chromosomes, 23 come from the mother and 23 come from the father. I think The easiest way to remember this is to think of the sex chromosomes--if you are male, you have one X chromosome from your mother and one Y chromosome from your father. During S-phase, the cell will make another copy of the X chromosome and the Y chromosome, so you will ...


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Interestingly, the very own existence of an interphase II between meiosis I and meiosis II is highly questionable, and a search on Pubmed found an article by Vernet et al., according to which interphase II exists only in male meiosis.


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The Stanford article that you read is correct, in the sense that telomeres do not need to be completely removed by cell division before deleterious effects occur and cells start undergoing senescence. This Nature article describes an experiment in which the minimum length of telomeres (beyond which chromosomal fusion occurs) was determined: The ...


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According to the diagram found on this site, chromosomes do unwind during Interphase II of meiosis. Sparknotes, although it's not necessarily a reputable scientific source, seems to concur: Once the nuclear envelope has re-formed after the first meiotic division, the cell enters a short interphase. This interphase is not as specific as mitotic ...


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Yes differentiation is primarily about using only a portion of the genome as you pointed out. However, differentiated cells possess a kind of "memory" which enables the daughter cells to continue the usage of the same set of genes. This "memory" is enabled by epigenetic mechanisms which leave inheritable "marks" on the DNA such as methylation (I won't ...


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Mitosis: 1. Yes, the spindle fibers attach to centromeres at the prometaphase http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/cells3.html Meiosis: 1. The nuclear membrane breaks down in Metaphase 1 and reforms during Telophase. It breaks down again in Prophase 2, reforming after that in Telophase 2 in the daughter cells. The spindles attach ...


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There are. But they are not that universal. See kappa-particle in Paramecium and Wolbachia in insects. Also, there are different origins of plastids (compare red algae and green algae). Some organisms like Rhopallodia gibba even have plastids of multiple origin. So do most organelles just lose all their DNA? Or is it something that occurs fairly ...



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