I have learnt that there are 2 types of hormones:  peptide hormones (hydrophilic, mostly bind to receptors on cell membrane) steroid hormones (hydrophobic, can pass through cell membrane and bind to receptors on nucelus membrane)  I know that steroid hormones are enclosed by a protein (Is it lipoprotein or others?) when transported in blood. But I think the protein should be  relatively big outer layer should be hydrophilic (since it can dissolve in blood easily).  If these 2 descriptions are true, then how can it EASILY pass through the cell membrane and enter cytoplasm directly?
123431
I get that steroid hormones need hydrophilic plasma protein carriers (eg albumin, TBG) to travel in the plasma because they're not soluble in the plasma. However, I don't see any sources talking about how these hormones can then traverse through the (presumably also hydrophilic) cytoplasm to get to their receptors either in the cytoplasm or nucleoplasm. Anyone have any clarifications on this?
3492
One of the wonderful properties of water (as my high school biology teacher would say) is that in its solid form, it is lighter than its liquid form. This means that when temperatures drop below 0 degrees Celsius, the top layer of water on, say, a lake freezes first. This works out pretty well for any fish or other aquatic creatures living underneath, because the lower layers of water will not freeze.  I know that this is an exception to the general rule of solid and liquid states: A given substance, when transformed into its solid state, will generally sink in a container of its liquid state. My question is this: What other substances are exceptions to this rule (if any?). What features do they share with water that are responsible for this?
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I've begun cooking Asian food in the past year or so, and in many Korean and Chinese beef recipes, I see instructions to soak beef in water. Just plain water, not salt water or anything. And every recipe seems to have a different  time - from 5 minutes to like, multiple hours.  I inquired about this and was given various reasons for this step, including "to remove the blood (because it is simply undesirable", "To remove the blood, because it gives the meat a bad taste" or "To soften the beef".  I'm wondering:   Does soaking meat in water really remove that much blood? How much of a flavor component is blood and why would it give it a bad taste (especially since i've never soaked beef before and I've like the taste just fine)? What is the action of solute-free water on a piece of beef immersed in it? Can it really tenderise it to any degree, or is there any osmosis occurring or other such physical/chemical action?
63750
I would like to know why does electrons flow through a wire connected to a battery as said in .It tells that "the electrons that are stripped from the carbon electrode is collected on the zinc can" and then tells     The electrons at the negative terminal want to go to positive terminal, they just need a way to get there. In our light bulb circuit, the way to get there is through the wire.   Why couldn't the electrons go to the positive terminal through the electrolyte(potassium hydroxide) instead of going through the wire?
95163
At high school we were told that a function has a domain and a range, the function maps from the domain to the range. Such that the domain contains all and only the possible inputs and the range contains all and only the possible outputs.  Now at University I'm told a function has a domain and a codomain, and that the codomain contains all the possible outputs but may also include other numbers. What is the point of having values in the codomain that can not be output by the function, how does that aid in describing the function? Does this also mean that the domain can include numbers that the are not inputs to the function?  Surely this means you could say the codomain of any function (that outputs numbers) is the complex set (so all numbers)?   EDIT:  the function $f : x \rightarrow x^2$ has codomain $\mathbb{R}$ but it's image (what I guess I knew as range in high school) is $\mathbb{R}^+_0$, so why not just say the codomain is $\mathbb{R}^+_0$.  EDIT2: And is it also then true that is a function is "onto" the codomain is the same as the image? So surely any function can be "onto" if you just change the what the codomain is?  What I'm really trying to ask I guess is the range/image of a function is defined by the function, what defines the codomain?
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My doctor ordered some blood tests for me.  I would like to understand what each test is for, meaning what information could be gathered from the results.   W.B.C. Platelets E.S.R. C.R.P. Alpha feto protein   C.E.A.   I have read that some of these, such as CRP, are no longer relevant or often used. Is that true?
109929
We know that the protons in a nucleus are positively charged, whereas the neutrons do not possess a charge; we also know that unlike charges attract. So why does the nucleus stay intact, even though there isn't supposed to be any electrostatic force of attraction within it? Instead, why isn't there any repulsion between the protons which are like-charged?
110807
OK, lets formulate it differently and say water works as a blue passing / red restricting filter.  It is actually observable. Just do a dive in a swimming pool with white light (maybe even at night) and a pool with a metal casing or white tiles. The further you look, the more blue it is.  So why is this so? Why is water not transparent?  And how does it happen on a molecular, subatomar or electron shell level?  Do 'red' waves become absorbed and retransmitted as 'blue' light waves or do only the 'red' waves get absorbed and the 'blue' can pass?  Can Maxwell help?
68567
\begin{table}     \begin{tabular}{|c|c|c|c|c|}     \hline     \multicolumn{5}{|c|}{\textbf{Table 1:}Unfiltered Water}\\     Concentration of analyte in sample   &amp; Avg &amp; Std Dev &amp;  RSD &amp; 90\% CI \\      \hline     Total hardness (ppm $CaCo_3$ equiv)  &amp; 97  &amp;    2   &amp;  2\%  &amp; \pm 5   \\     Calcium hardness (ppm $Ca^{2+}$)     &amp; 57  &amp;    3   &amp;  5\%  &amp;  \pm 5   \\     Magnesium hardness( ppm $Mg^{2+}$)   &amp; 40  &amp;    3   &amp; 7.5\% &amp;  \pm 5 \\     \hline     \end{tabular}   This table is giving me an error. That says   ! Missing $ inserted. &lt;inserted text&gt; $ l.41 ...Co_3 equiv\) &amp; 97 &amp; 2 &amp; 2\% &amp; \pm 5 \I've inserted a begin-math/end-math symbol since I think   you left one out. Proceed, with fingers crossed.  What is the cause of this error?  I can't seem to find any thing that is mismatched.
113076
I'd like to clear something up about antibodies that I'm not sure I've understood in the articles I've read. Looking at concepts such as "affinity maturation", "monovalent antigens" and "polyvalent antigens" it seems as if there are multiple antibodies which can bind to the same antigen. (Although I think I'm right in saying that individual antibodies can only bind to one antigen?) However, when I read sentences like "It has been estimated that humans generate about 10 billion different antibodies, each capable of binding a distinct epitope of an antigen" on the Wikipedia page (for antibody) it does make it sound like it's one antibody per antigen? Is this the case? Or is it one antibody per epitope. Either way, to put this question in a nutshell:  Is it true to say that the same substance could bind with (and, therefore, be recognised by) more than one antibody, or not?  Also, if the answer is no, does that mean that antibodies with different binding affinities are classed as the same antibody or not?
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and they are on opposite ends of the electromagnetic spectrum, then why can't light travel through walls which is right in the middle of the spectrum?    This question has already been asked . However, I am not entirely satisfied by the answer given on that page which relies on fanciful analogies and metaphors of ants, elephants etc. I am looking for a better explanation.    I think the crux of the matter, and my dilemma, relates to formula for . This is a well known formula used to explain the fact that low frequency waves have more penetration than high frequency waves.     But then how come gamma waves have such high penetration?     Are there some assumptions behind derivation of this formula which break when we consider very high frequency waves?    Or, are there some new factors that need to be taken into account as we move into the high frequency regime?     If given a radio source and a gamma source of equal intensity, then will the radio source have more penetrability than the gamma source per formula for ? If not, why not?  Thanks for all those who posted answers to this question. The answer being proposed is that light waves have the right energy to interact with atoms and electrons in the matter and thus get absorbed. This is a quantum mechanical explanation. The skin depth, on the other hand, is derived purely on basis of classical electrodynamics. So I see there are two mechanisms at work here? Does anyone agree with this? If so, the net absorption will be the sum of absorption due to skin effect + absorption due to atomic physics. Now if we take gamma rays - agreed there will be no absorption due to atomic physics but there should be absorption in accordance with skin effect. And so I come back to original problem.
83641
How long will it remain potent outside an organism?  I'm thinking in the context of if it can survive a couple of weeks or a month in the mail for the recipient to get infected.  Edit:  I tried looking at the WHO's page dedicated to the virus, have not found anything pertaining to my question in the PDFs there (maybe I overlooked something, I guess I'm just lacking the proper keyword to use for the search)  I tried looking at the coronavirus Wikipedia page and have not found anything there.  I did find somewhere that a flu virus would typically not remain potent for more than 14 days outside of an organism, but I'm not sure if this applies to all viruses.
99164
So obviously, viruses are nonliving. But when my teacher was teaching viruses in the video (we're doing "flip" learning this semester), the way he described it, it seemed like the viruses responded to their environment in that they moved around until they found a cell of the right type, and then they latched on and hijacked it.   I had always thought of it more like that they were just kind of floating around, carried by the host system (blood in animals for example), until they "bumped into" the right kind of cells and both sets of membrane proteins "docked". But my theory/idea doesn't really make sense because it doesn't account for how viruses would be able to infect bacteria.  But, the idea that viruses propel themselves doesn't make much sense either, because viruses are nonliving, and one of the characteristics of life that they do not meet is that living things acquire and use energy.  In summary my question is, how are viruses propelled? Do they move themselves, or are they moved by external forces?
106519
My question is whether translation can be done, either naturally or artificially, through a ribosome reading (single-stranded) DNA directly. If not, I would like to know what allows ssRNA to be translated but not ssDNA.
79167
I am trying to run a linear regression model (ideally) to see whether age (continuous variable) affects levels of stress hormone (also continuous, dependent variable), i.e. hypothesis testing. My hormone level results are right-skewed and non-normal, and the residuals of a simple linear model have a similar distribution (see plots of residuals below). Age is normally distributed.  Scatter of raw data (has a couple outliers):  Histogram of residuals:    I have also tried various transformations of my dependent variable (hormone levels) to improve the outcome of the model. The best normality plots came from the Tukey transformation. See plots below.  Scatter of transformed hormone level on age:  Histogram of residuals:    However, the transformation yields a lower multiple R-squared and adjusted R-sqaured value than the original.  Further to this post (), I tried a model where the hormone level is log transformed and fitted with the exponent of age to correct for the log transformation. This is because I didn't know what the opposite of Tukey transformation would be and log seems to be the next best transformation for my data. The normality of residuals is good but the R2 values are even lower.  Given this information, which model is best - the one with best normality of residuals and lowest R2 or worst normality of residuals and highest R2?  Alternatively, is there another form of regression better suited to this data, given that it is continuous and has non-normal residuals?
61759
As we all know, aspirin doesn't actually thin the blood, as it has been explained to me, it makes it "slippery". Slippery blood doesn't stick to itself hence this helps prevent internal blood clots (or allows blood to pass more easily around an existing clot). I also understand that having your blood too "slippery" can lead to the body attempting to counteract that and making it too "sticky".   Anyhow, my question regarding that is this, how does aspirin work? How does it make the blood "slippery"? (If there is a more medically correct term for "slippery" and "sticky", I'm all ears).  P.S. I paid the Mayo Clinic's website a visit before coming here, the information about aspirin's mechanism wasn't particularly helpful to me.
50672
The synaptic cleft is the gap between the pre-synaptic and post-synaptic neurons, and neurotransmitters are transferred between the neurons within this region. What substance exits in this space, is it water? If so, what force makes the neurotransmitters move toward the receptors despite colliding with water molecules?