Tag Info

New answers tagged

4

Wanted to give a one line answer some day!! Lens fiber cells and keratinocytes.


4

Short answer As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus. Background Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be ...


2

This is too long for a comment, so I have to write it in here: Mostly this is because other cell lines are more practical in the lab. Stem cells are much more tricky to maintain - especially if you want to keep their stem cell properties. They only grow very slow, tend to differentiate when they get too much stress, cellular signals and so on and need ...


2

If by enzyme you mean "protein" aka polypeptide, than there are such things as catalitic RNAs. Those are molecules of RNA that facilitate chemical reactions but don't change themselves (definition of catalyst). I think that, based on the discovery of such RNAs, it is now believed that life might have started from or with the help of catalytic RNAs (please ...


1

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 ...


1

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 ...


1

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 ...


0

So, as I pointed out in comments, and requoting: "The direction in which cargo is transported is dependent in part upon the position of the motor domain, which can be located N-terminally (N-kinesins), C-terminally (C-kinesins) or internally (M-kinesins). In general, kinesins with N-terminal motor domains move their cargo towards the plus ends of ...


2

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.


2

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 ...


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 ...


0

No, plasma membrane does not contain any nucleic acids – DNA and RNA. The main components of plasma membrane are lipids, glycol- lipids, phospho lipid bilayer and cholesterol.


0

Mitochondria are granular or filamentous organelle, which are present in the cytoplasm of a cell. They are ovoid in shape, with the presence of double membranes. Mitochondrial fusion is required to distribute mitochondrial DNA to the mitochondrial population and to maintain its respiratory competent and energized organelles. Mitochondrial division is ...


0

Membrane potential The membrane potential in cells can be determined by the distribution of lipophilic ionic molecules between the cells and the suspending medium according to the Nernst equation: Where: ∆ ψ is Membrane potential, R is the gas constant (in J K−1), n is the number of electrons per mole, F is the Faraday constant (in C mol−1), [X]i ...


6

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 ...


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 ...


3

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 ...


3

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 ...



Top 50 recent answers are included