I am hoping that you can help me improve my understanding of transcription. :)  I have tried searching for the answers to all of these questions online already, but I have either had trouble finding relevant information or I have had trouble understanding it (i.e. it was too high-level for me).  I have also tried to answer my questions by browsing through different maps of genes (like this one: ), but my questions are still unresolved.  Please note that I have come up with the following questions in my independent learning - these questions are NOT assigned homework.  In all questions, I'm referring to eukaryotic (linear) DNA.   Am I correct to believe that in a single chromosome, one strand of DNA is not the template strand for all genes within that chromosome?  For instance, let's call one ssDNA molecule "A" and the complementary ssDNA molecule "B"; together, A and B make up a single chromosome.  Am I correct to believe that in a single chromosome, the template strand for some genes will be A, and for other genes will be B? If my statement in question #1 is correct, then does that mean that multiple genes within a chromosome can be transcribed in opposite directions?  Note that when I say direction, I do NOT mean 5' to 3' vs 3' to 5'.  What I mean by "direction" is looking from left to right. Is it true that both strands of the double helix cannot be transcribed for a single gene in question?  Is this because the promoter will only be found on one of the strands?   Thank you in advance for your time!
I'm studying molecular biology and I'm trying to understand an experiment which shows the importance of promoters in the relative transcription level (RT). The image below comes from Rolf Knippers' book "Molekulare Genetik" (8th edition).    The legend says (among other things):     Die erste Zeile gibt die normale "Wildtyp"-Sequenz der 5'-flankierenden Region wieder.   Which, in english, means something like:     The first line repeats the normal wild-type sequence of the 5' flanking region.   The column on the right gives the relative transcription (RT) level, 1.0 being the highest possible level of transcription. As we can see, the lines where some parts of the "5' region" have been deleted give quite low RT levels, since some regions of the promoter are missing.  My questions are the following:  1) According to  and , I understand that RNA polymerase reads and uses both coding and non-coding strands in order to synthesize RNA. Therefore, how did they manage to use the sequences strands regions had been deleted to make a polymerase "read them" and perform transcription?  2) If the polymerase reads the template strand in the 3' -> 5' sense, shouldn't we talk of "ATAT box" or "TAAC box" instead of "TATA" or "CAAT" boxes? Does it mean that the "promoter" regions they are using on the graphic above are actually on the coding strand?  Thanks a lot for your help.
Why must I wait two days before accepting my own answer? I got this message today while trying to accept my answer on my own question.  Why must I wait this time, if I am sure that the answer I answered is the right one, just want to understand the point of view?  I faced that just today on Super user and didn't get this message before. Are "w/o", "w/", "b/c" common abbreviations in the US? Proving replacement theorem? I want to see if I am understanding the proof of the replacement theorem correctly.   Let $V$ be a vector space that is spanned by a set $G$ containing $n$ vectors.  Let $L \subseteq V$ be a linearly independent subset containing $m$ vectors.  Then $m\leq n$ and there exists a subset H of G containing exactly $n-m$ vectors s.t. $L \cup H$ generates $V$.   The proof in the book says to start with $m=0$. In that case $L=\varnothing$, the empty set.        Let's assume this theorem is true for some integer $m \geq 0$.   Let $L = \{v_j\}_{j=1}^{m+1}$ and define it as a linearly independent subset of $V$ consisting of $m+1$ vectors.  Since any subset of a linearly independent set is linearly independent as well ($S_1 \subseteq S_2 \subseteq V$), then $\{v_j\}_{j=1}^m$ is linearly independent also.   It then says to use the induction hypothesis to say that $m \geq n$. Well, ok, but that seems sort of pulled out of nowhere to me. The next step is to say that there is therefore another subset, $\{u_k\}_{k=1}^{n-m}$ of G such that $\{v_j\}_{j=1}^m \cup \{u_k\}_{k=1}^{n-m}$ spans $V$.   That being the case there are scalars $(a_j)_{j=1}^m$ and $(b_k)_{k=1}^{n-m}$ which you can multiply by the vectors $v_j$ and $u_k$. You can then add the two sets of vectors, yielding $$\sum_{j=1}^m a_j v_j + \sum_{k=1}^{n-m} b_k u_k = v_{m+1}$$  At this point I am not sure I understand things. Because we are assuming $n-m&gt;0$ -- otherwise $v_{m+1}$ is linearly dependent. But then it says not only is $n&gt;m $ but $n&gt;m+1$, and that is where I am losing the plot to get to the next step. Analogue of spherical coordinates in $n$-dimensions What's the analogue to spherical coordinates in $n$-dimensions? For example, for $n=2$ the analogue are polar coordinates $r,\theta$, which are related to the Cartesian coordinates $x_1,x_2$ by  $$x_1=r \cos  \theta$$ $$x_2=r \sin  \theta$$  For $n=3$, the analogue would be the ordinary spherical coordinates $r,\theta ,\varphi$, related to the Cartesian coordinates $x_1,x_2,x_3$ by  $$x_1=r \sin  \theta  \cos  \varphi$$ $$x_2=r \sin  \theta  \sin  \varphi$$ $$x_3=r \cos  \theta$$  So these are my questions: Is there an analogue, or several, to spherical coordinates in $n$-dimensions for $n&gt;3$? If there are such analogues, what are they and how are they related to the Cartesian coordinates? Thanks. 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Is it a system/.NET call?  Is there some call in a dll buried somewhere in System32 that needs to be made?    (Edit: it looks like WIX uses MSI under the hood.  See my comments in the accepted answer.)  Final edit: It looks like the correct way to install an assembly to the GAC is using windows installer, and nothing else.  I'm going to give Wix a try.  Thanks all! Clarifying question on meaning of derivative of a linear transformation In my analysis class, my professor (and the textbook) reference the fact that $\mathbf{D}T(\bar{x}) = T$ for any $\bar{x} \in \mathbb{R}^n$ where $T \in \mathcal{L}(\mathbb{R}^n,\mathbb{R}^n) $. I'm wondering about the precise meaning of this statement. Is it that the differential of any linear transformation is also linear? Or is that the differential of any linear transformation is itself (and therefore also linear)? The second seems confusing to me because the derivative of a function is often not itself. For example, $f(x) = 2x$ is a linear transformation but $f'(x) = 2 \ne 2x$ for all $x \in \mathbb{R}$. Proof that the coefficients in an OLS model follow a t-distribution with (n-k) degrees of freedom Moon photography Hi I am a photography hoobyist. At the moment I am using a Nikon D3100 with the standard kit lens (18-55mm). I am interested in taking photos of the moon. I am debating whether to buy a 55-200mm lens or a 55-300mm lens. Which one would be better?  P.S I am on a tight budget and I am looking for a lens for personal use, not commercial.  Would appreciate any answers!  Thank you! I recently saw a question about a problem (or possible bug) with some product on Stack Overflow. At first, I wanted to suggest that the asker post his question to that product's support forum.  When searching for the URL of that forum, I noticed that the product developer closed its support forums and now advises users to post all their questions on Stack Overflow instead.  Is this within the intended use cases of Stack Overflow, or is this abuse? Convert continuous numeric values to discrete categories defined by intervals Using sed what is an one liner to print the first n characters?  I am doing the following:  grep -G 'defn -test.*' OctaneFullTest.clj  | sed .... Do cards with abilities that target trigger heroic? Sometime I see many application such as msn, windows media player etc that are single instance applications (when user executes while application is running a new application instance will not created).  In C#, I use Mutex class for this but I don't know how to do this in Java. I have a php file which I will be using as exclusively as an include. Therefore I would like to throw an error instead of executing it when it's accessed directly by typing in the URL instead of being included.  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I am a bit "fuzzy" about how not to plagiarize myself in my thesis (I have had no problem regarding my journal publications).  (* In all publications mentioned I am the first -but not sole- author.) Why are the IV (constant) values fixed for HMAC/SHA? Why do HMAC/SHA IV's have a fixed value? I refer to the arbitrary H constants which are included in the algorithm prior to any data being fed in.  Why aren't they exposed to the user, so one can decide on an IV and modify it accordingly (for example, in java they are provided at hash function specification, instead of being supplied by the user at init)?  How does modifying these IVs affect the algorithm? How do I parse a string to a float or int? In Python, how can I parse a numeric string like "545.2222" to its corresponding float value, 545.2222? Or parse the string "31" to an integer, 31?  I just want to know how to parse a float str to a float, and (separately) an int str to an int.