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6

There is one main reason: Amplification of the signal. You can start a signal downwards the cascade with relatively few receptors which need to be activated which allows even for weak signals to be translated into the nucleus. This figure shows this for G protein coupled receptors (from here): For example one molecule of cAMP can activate many molecules ...


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So if you're reading the flowchart, understanding the notation of the arrows is important: We have rectangles around the gene products There's a circle, denoted by DNA, noting that the proteins are expressing the product that follows through interaction with DNA The solid line with an arrowhead means there's some sort of interaction The solid line with the ...


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First of all MHC stands for major histocompatibility complex. There are two types of MHC. MHC type one is present on all of our cells with a nucleus. The purpose of these protein complexes is called antigen presentation. T-cells cannot recognize free antigens on their own, it has to be presented to them in the proper way. This is what these proteins do. In ...


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Not in human but you can use this technique with genetically modified model organisms as described here. The procedure is quite simple, you express the luciferase enzyme under the control of a specific promoter (specific for your cell type, like cancer) and provide luciferin via intravascular or intraperitoneal injection. The targeted cell type (for example ...


3

Pathways in biology are very hard to interpret without being an expert in the subject. Here a link to The Standard Graphical Notation for Biological Networks that might help you understanding the notation used. Pathway are generally based on evidences of links between the players. These links do not require to be found using one particular technique. Those ...


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The critical element here is that building materials that need to be absorbed, or waste materials that need excretion have to cross the cell membrane. The larger the surface of the cell's membrane relative to its volume, the faster the exchange rate. The book section you linked in the comments mentions the following on p.14: The volume [of a spherical ...


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From this article: iPSC's or induced pluripotent stem cells are somatic cells that have been driven to acquire an induced pluripotent cell state. Somatic cells can be any cell of the body except sperm cells, egg cells and undifferentiated stem cells. Investigators can induce these cells to 'return' to a stem cell like state by forcing the expression of key ...


2

Nucleic acids are not structural components of cell membranes (ribosomes and nucleus are the main places where they are found). However, being open system, cell exchanges chemicals with its surrounding and cellular membrane can transport nucleic acids as well. This is why these acids can potentially be detected in the cell membranes. If you have the exact ...


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The tricky part is to define what is the volume of a biomolecule as it is a folded chain full of bumps and holes. Water is all around and in the folded structure and is actually important to keep the conformation of at least some of the proteins/RNA/DNA. At the same time we know that 60% of your body in mass is water. Let's visualize that. Bio molecules ...


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The electrons for shuttling are mainly generated in the cytosol from glycolysis. NADH can easily pass the outer membrane, but must be shuttled over the inner membrane. It is important to consider that the electrons must be fed to oxidative phosphorylation from the matrix of the mitochondrion, and not the intermembrane space.


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No. DNA, and RNA have a polarity in the orientation of their sugar-phosphate backbones, based on the numbering of the carbon atoms in the sugar rings. So, for example, we say that the sequence of this RNA is being read from the 5' to the 3' end, which indicates that the first nucleotide is exposing the hydroxyl at the 5’ carbon on its sugar ring. At the ...


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From the Biology Online Dictionary, refractile refers to: ... the ability of cellular granules to refract or scatter light. Tumor cells can be more "dense", as they are usually rapidly dividing, and so need extra ribosomes to maintain protein production, may have a higher DNA/RNA content reflecting increased transcription and duplication, more ...


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Because all available ATP will likely be quickly spent by various cellular machinery. If there was 20-30mM of ATP, what would stop muscle from contraction and how could you keep ATP level constant at rest, be ready for rapid movement? By blocking all myosin? This creates enormous regulatory problems for the cell. Phosphocreatine buffers energy for a period ...


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According to the Molecular Biology of the Cell, (4th Ed), the cell is ~70% water, the remaining 30% of which is composed of macromolecules (proteins, nucleic acids, and carbohydrates). While this is just a single citation, there are lots of other sources in the literature that cite similar values.


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Great question. Turns out, there is some information about it. For example, consider following resource: Membrane Protein Lipid Composition Atlas. Published by University of Michigan, it provides information on, primarily, protein content of different membranes from different species, but also has a list of lipid content. Just as an example, consider ...


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Two things... Rapidly proliferating tissues (esp tumours) rewire their energy metabolism anyway to aerobic glycolysis where you have energy being produced by lactic acid fermentation even if oxygen is present. This is called the Warburg effect.Here's the thing about "low yield" though - glycolysis chucks out less ATP per reaction at the end, but you can ...



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