What is Expression: Definition and 999 Discussions

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. These products are often proteins, but in non-protein-coding genes such as transfer RNA (tRNA) and small nuclear RNA (snRNA), the product is a functional non-coding RNA. Gene expression is summarized in the central dogma of molecular biology first formulated by Francis Crick in 1958, further developed in his 1970 article, and expanded by the subsequent discoveries of reverse transcription and RNA replication.The process of gene expression is used by all known life—eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea), and utilized by viruses—to generate the macromolecular machinery for life.
In genetics, gene expression is the most fundamental level at which the genotype gives rise to the phenotype, i.e. observable trait. The genetic information stored in DNA represents the genotype, whereas the phenotype results from the "interpretation" of that information. Such phenotypes are often expressed by the synthesis of proteins that control the organism's structure and development, or that act as enzymes catalyzing specific metabolic pathways.
All steps in the gene expression process may be modulated (regulated), including the transcription, RNA splicing, translation, and post-translational modification of a protein. Regulation of gene expression gives control over the timing, location, and amount of a given gene product (protein or ncRNA) present in a cell and can have a profound effect on the cellular structure and function. Regulation of gene expression is the basis for cellular differentiation, development, morphogenesis and the versatility and adaptability of any organism. Gene regulation may therefore serve as a substrate for evolutionary change.

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  1. Steve Zissou

    I Is g(x) Equal to g(a) If Their Integrals Are Equivalent?

    Howdy all, Let's say we have, in general an expression: $$ \int f(x) g(x) dx $$ But in through some machinations, we have, for parameter ##a##, $$ \int f(x) g(x) dx = \int f(x) g(a) dx $$ ...can we conclude that ## g(x) = g(a) ## ???? Thanks
  2. chwala

    Find the values of ##A,B## and ##C## given that the expression has a constant value for all ##x## values

    My working follows here, Let ##(x-2)[Ax(x+3)+Bx] + (x+3)[Cx +(x-2)]=0## ##(x-2)(x+3) \left[Ax+\dfrac{Bx}{(x+3)}\right]+(x+3)(x-2)\left[\dfrac{Cx}{(x-2)} +1\right]##=0 ##⇒Ax+\dfrac{Bx}{(x+3)} = -\left[\dfrac{Cx}{(x-2)} +1\right]## ##Ax(x+3)(x-2)+Bx(x-2) = -[Cx(x+3)+(x-2)(x+3)]## On comparing...
  3. ab200

    Constructive Interference from Speakers on an x-axis

    The first part of this question asks for the maximum amplitude produced, which I found to be 12.86 Pa. I was able to set up the expression for the combined wave equations. However, I am struggling to understand how to set up and solve an expression to find the distance I could move one of the...
  4. A

    What Does Procedural Grounds Mean in Legal Contexts?

    What is the meaning of the expression procedural grounds in the text: Butler attended Boise State University for a year.[9] In 1991, Butler was convicted of assault during his freshman year of college.[5] His appeal was unsuccessful on procedural grounds, as a judge ruled that Butler's defense...
  5. M

    Identifying the type of expression

    TL;DR Summary: ##(1+ \frac1x)^2 - (1-\frac1x)^2## ##(z+2)^2 -5(z+2)## Upon simplifying the first I get ##\frac4x##. So isn’t the first expression fractional? Upon simplifying the second I get a Quadratic expression.
  6. phyTens

    How to show that this expression with tensors reduces to zero?

    I simply just wrote down the definition of ##\Gamma'^a_{bc}##, and inserted the transformations of ##g'^{ad}##, ##g'_{dc,b}##, and the like terms. After some rearranging and cancelling out, $$\Gamma'^a_{bc}=\frac{\partial x'^a}{\partial x^e}\frac{\partial x^f}{\partial x'^b}\frac{\partial...
  7. P4Penguin

    Chemistry Derive an expression for mean free path from survival eqn exp(-x/λ)

    If the distance between the centres of two molecules is σ, then imagining a a cylinder with radius σ the number of molecules can be given by πσ²cn where c = average velocity. So mean free path can be given by λ = c/πσ²cn = 1/nπσ². But do I derive it from exp(-x/λ)?
  8. haha0p1

    Chemistry Finding equilibrium expression for an equilibrium equation

    In the d(i) part, we are asked to write an equilibrium constant. It was mentioned in the chapter that solids and liquids will not be added in the equation. So, I think that there is not going to be any Expression for this reaction as all the reactants and products are liquids. Is my answer right?
  9. S

    I Orthonormal basis expression for ordinary contraction of a tensor

    I'm reading Semi-Riemannian Geometry by Stephen Newman and came across this theorem: For context, ##\mathcal{R}_s:Mult(V^s,V)\to\mathcal{T}^1_s## is the representation map, which acts like this: $$\mathcal{R}_s(\Psi)(\eta,v_1,\ldots,v_s)=\eta(\Psi(v_1,\ldots,v_s))$$ I don't understand the...
  10. K

    I Velocity operator, its expression and eigenvalues

    Cohen Tannoudji pp 215 pp 225 pp 223 From above we can say that there exists a velocity operator ##\mathbf v=\frac{\mathbf p}{m}## ,whose eigenvalues are the observed values of velocity. 1. I've seen multiple times that we can't define velocity in quantum mechanics, but here I find that...
  11. J

    Derive an expression for the radial charge distribution of an E field

    I know we're supposed to attempt a solution but I'm honestly super confused here. I think the second an third terms of the del equation can be cancelled out because there is only an E field in the r hat direction, so no e field in the theta and phi directions. That leaves us with ##\nabla \cdot...
  12. F

    A Expression of Shot noise when expanding ##a_{\ell m}## coefficients

    I would like to arrive at the following expression for the quantity ##o_{\ell}## ( with "DM" for Dark Matter ): ##o_{\ell}=b_{s p}^2 C_{\ell}^{D M}+B_{s p}## with Poisson noise ##B_{s p}=\frac{1}{\bar{n}}(\bar{n}## being the average number of galaxies observed). the index "sp" is for spectro...
  13. C

    Comp Sci Regular Expression in Theory of Automata and Computation

    In first part,since every block of 4 consecutive symbol contain at least 2 a's The answer in notes is given (aa(a+b)(a+b)+a(a+b)a(a+b)+a(a+b)(a+b)a+(a+b)aa(a+b)+(a+b)a(a+b)a+(a+b)(a+b)aa)+ But this wont be true since if we choose aabbbbaa which is possible according to the above regular...
  14. shivajikobardan

    What is [50-99] in regular expression?

    As the slide says, it's not 50-99 characters so what it is? Source: https://www3.cs.stonybrook.edu/~pfodor/courses/CSE307/L02_Programming_RE.pdf Also, please tell me how to learn regular expressions? Recommend some university/any courses to take for learning regular expression for backend...
  15. S

    I Deriving expression for resistance in terms of current density

    Is there a way to obtain equation 9.42 (I is current, j is current density, and sigma is conductivity) in the following image (from Modern Electrodynamics by Andrew Zangwill, the part on electromotive force) besides using V=IR and substituting the line integral of j/conductivity for V? The...
  16. G

    Canonical ensemble <(Delta E)^3> expression

    I try involving differentiating ^2 but I get an expression of different proportionality.
  17. PhysicsRock

    Exploring an Unexplored Expression for the Beta Function

    So, I've recently played around a little with the Gamma Function and eventually managed to find an expression for the Beta Function I have not yet seen. So I'm asking you guys, if you've ever seen this expression somewhere or if this is a new thing. Would be cool if it was, so here's the...
  18. crememars

    Simplify this expression for the period

    hi ! I'm having a lot of trouble simplifying my expression for one of my homework questions. I know someone asked about this homework problem already, but the answers didn't really help me figure out how to simplify it.. I really have no idea what steps to take, and I've even consulted all my...
  19. homeworkhelpls

    Help simplifying this algebraic expression please

    14) here i tried 3x^3 + 3/8x^3 to to get 27/8x^3 but the answer is 3/2 x^3, why? 15) here i did 9x^3/2 - 1/x^3/2 to get 9x^9/4 - 1/x^3/2 but that's not in the right form, how do i do it correctly?
  20. Harikesh_33

    B Question regarding using the expression $dE_{int}$=nC_vdT$

    The first law of Thermodynamics states that the change in Internal energy is equal to the sum of Heat gained or lost by the system and work done by the system or on the system . $dE=Q-W$...(1). In an Adiabatic process ,Q=0 . Therefore $dE=-W$ . Now...
  21. F

    I General expression of wind force on a sail....

    Hello everyone, In trying to better understand how sailboats work, how they can sail upwind (not directly), how the go faster than the wind speed, I have been thinking about the magnitude of the wind force and its equation: $$F_{wind}= \frac {1}{2} \rho_{air} A v_{wind}^2$$ Instead of ##...
  22. brotherbobby

    Possible values an expression can take : ##\dfrac{x^2-x-6}{x-3}##

    Problem statement : Let me copy and paste the problem as it appears in the text : Attempt 1 (from text) : The book and me independently could solve this problem. I copy and paste the solution from the book below. Attempt 2 (my own) : The problem should afford a solution using the second idea...
  23. Dan78

    Engineering Boolean expression for ladder diagram

    Hi, I wonder if I am on the right way """""""""""""""""""""""""""______"""______ F = X000 . ( M1 + ( M2 . X002 ) . X003
  24. murshid_islam

    I Matrix representation for closed-form expression for Fibonacci numbers

    From the wikipedia page for Fibonacci numbers, I got that the matrix representation for closed-form expression for Fibonacci numbers is: \begin{pmatrix} 1 & 1 \\ 1 & 0\\ \end{pmatrix} ^ n = \begin{pmatrix} F_{n+1} & F_n \\ F_n & F_{n-1}\\ \end{pmatrix} That only works...
  25. shivajikobardan

    Comp Sci Regular expression to NFA -- confusing regular expressions-:

    R=(01+010)* For it I made the below nfa which i believe seems correct. Plus the tutorials that I am following also make sure it’s correct. Q0 is initial state(forgot to mention in figure). R=(01)*+(010)* But idk how to convert this to NFA What will be languages accepted by this NFA? Won’t...
  26. shivajikobardan

    MHB Regular expression to NFA-confusing regular expressions-:

    R=(01+010)* For it I made the below nfa which i believe seems correct. Plus the tutorials that I am following also make sure it’s correct. Q0 is initial state(forgot to mention in figure)...
  27. shivajikobardan

    Comp Sci Is the DFA Solution for Regular Expressions Accurate?

    but the solution site says otherwise-: https://cyberzhg.github.io/toolbox/nfa2dfa I feel correct mine also, but not sure. Check it please.
  28. Eobardrush

    Ball rolling down a slope problem: Find an expression for time taken

    Question: Galileo released a metal ball from rest so that it could roll down a smooth inclined plane. The time t taken to roll a distance s was measured. He repeated the experiment, each time recording the time taken to travel a different fraction of the distance s. Write an expression for the...
  29. guyvsdcsniper

    Finding an expression for the efficiency of a heat engine

    My book states the answer to this problem is . I have gotten very close to the answer. My problem is my Tc/th and tc/tm are flipped compared to the solution. I feel like I am missing something in my algebra but can't see where I am going wrong. Could I get some help identifying where my...
  30. Arman777

    A Evaluating an expression for peculiar acceleration

    I am trying to obtain this graph from this expression but somehow I cannot obtain it. In the same article it is given that $$r_s = r_v/c$$, $$r = R_c\theta / cos(\beta)$$ and $$C = (\log(1+c)-\frac{c}{1+c})^{-1}$$ So for Virgo cluster my values are, ##R_C = 15 Mpc##, ##r_v=2.2 Mpc##, ##c=4##...
  31. I

    Converting an expression of a particular k-mode to the spatial domain

    $$n_\vec{k} = \omega a^2(\vec{k})\tag{1}$$ One way is to write the inverse Fourier transforms of the terms above. So, eqn (1) becomes $$\int\mathrm{d}^3x\ n(\vec{x})e^{-i\vec{k}\cdot\vec{x}} = \omega \int\mathrm{d}^3x^\prime\ a(\vec{x^\prime})e^{-i\vec{k}\cdot\vec{x^\prime}}...
  32. C

    Comp Sci Validating Braces Placement for Expression Evaluation

    Here's what I've done: Mentor note: replaced icode tags with code=python and \code pair. def valid_braces_placement(s, L): if len(L)==0: return False string = '' for element in L: string = string + str(element) D = ['+','-','*'] return...
  33. Physil

    An expression for the vertical velocity as a function of time

    A rocket of initial mass m0 is launched vertically upwards from the rest. The rocket burns fuel at the constant rate m', in such a way, that, after t seconds, the mass of the rocket is m0-m't. With a constant buoyancy T, the acceleration becomes equal to a=T/(m0-m't) -g. The atmospheric...
  34. S

    Biology Which method would be wrong to use for gene expression?

    I've been struggling, no matter what I try to do I can't come up with a solution. The answer is in situ, but in my mind it would work perfectly fine. The only thing we would do is just use an RNA probe complementary to the gene we are trying to detect and it should light up the moment the gene...
  35. S

    How should a program make a function out of a symbolic expression?

    Suppose a program computes or reads-in a symbolic mathematical expression like ##2x^2 - xy + y##. What's an effective way to cause the program to implement the expression as a function (e.g. implement ## f(x,y) = 2x^2 - xy + y##) when the programmer doesn't know in advance what the expression...
  36. L

    I Prove that the limit of this matrix expression is 0

    Given a singular matrix ##A##, let ##B = A - tI## for small positive ##t## such that ##B## is non-singular. Prove that: $$ \lim_{t\to 0} (\chi_A(B) + \det(B)I)B^{-1} = 0 $$ where ##\chi_A## is the characteristic polynomial of ##A##. Note that ##\lim_{t\to 0} \chi_A(B) = \chi_A(A) = 0## by...
  37. karush

    MHB 1.1.21 simplify rational expression

    simplify $\left(\dfrac{a^2b^3-2a^{-3}b^3}{2a}\right)^2=$ OK this could get confusing quickly but I don't think we want to square it first
  38. mcastillo356

    How to conclude a mathematical expression with the provided background

    Hi PF In my textbook, the Spanish 6th edition of "Calculus", by Robert A. Adams, at Chapter 3.2, Theorem 1 states: If ##x>0##. $$\dfrac{d}{dx}\ln{x}=\dfrac{1}{x}$$ PROOF For ##x>0## and ##h>0##, ##\ln{(x+h)}-\ln{(x)}## is the area of the shaded part (...) Regard the shaded area at Figure...
  39. M

    I Derivation of an angular momentum expression

    Hello! I found this formula in several places for the total angular momentum of a particle with intrinsic spin 1/2 and angular momentum l=1 in the non-relativistic limit: $$\frac{1}{\sqrt{4 \pi}}(-\sigma r /r )\chi$$ where ##\sigma## are the Pauli matrices and ##\chi## is the spinor. Can someone...
  40. karush

    MHB 8.aux.27 Simplify the trig expression

    $\tiny{8.aux.27}$ Simplify the expression $\dfrac{{\cos 2x\ }}{{\cos x-{\sin x\ }\ }} =\dfrac{{{\cos}^2 x-{{\sin}^2 x\ }\ }}{{\cos x\ }-{\sin x\ }} =\dfrac{({\cos x}-{\sin x})({\cos x}+{\sin x\ })}{{\cos x}-{\sin x}} =\cos x +\sin x$ ok spent an hour just to get this and still not sure suggestions?
  41. Leo Liu

    How to simplify an iterated trigonometric expression

    eg ##\cos (\sin x)## Asking this question out of curiosity.
  42. N

    Rewrite an Expression to Eliminate Absolute Value

    See attachment. I don't understand the solution given by David Cohen. 1. Note: x^2 is nonnegative for any real number x. This is because any value for x when squared is positive. Yes? 2. If x is greater than or equal to 0, then I can say that -2 - x^2 is negative in value, right? 3. What...
  43. N

    Simplify An Expression Containing Absolute Values

    See attachment. I don't understand the solution given by David Cohen. I am sure this is a shortcut explanation. I don't like shortcut explanations. 1. What in the problem indicates that x > 1? 2. What in the problem indicates that x < 2?
  44. F

    A Analytical expression of Cosmic Variance - Poisson distribution?

    I have an expression of Matter Angular power spectrum which can be computed numerically by a simple rectangular integration method (see below). I make appear in this expression the spectroscopic bias ##b_{s p}^{2}## and the Cosmic variance ##N^{C}##. ## \begin{aligned}...
  45. F

    A Expression of the mean and variance of spectroscopic Shot Noise

    Hello, I would like to know the right expression for the expression of variance of Shot noise in spectroscopic probe. Sometimes, I saw ##\sigma_{SN,sp}^{2} = 1/n_{sp}## with ##n_{sp}## the average density of galaxies, whereas my tutor tells me that ##\sigma_{SN,sp}^{2} = 1/n_{sp}^{2}## , so I...
  46. eric11201120

    Expression for Electric Field Outside Sphere

    I'm not quite sure where to start. If someone could help me I would very much appreciate it.
  47. A

    B Explicit expression for ideal membership

    Derive an explicit expression for all ##f\in\langle q\rangle\subseteq \mathbb{Q}[x]##. I think it's doable and was wondering if there is a published formula?
  48. imbadatphysics212

    Writing an expression for work done by frictional force

    I took a stab at the question, but I don't think I did it right. I know that Work = Change in Energy thus, Work = final energy - initial energy Because there is no energy at the final position, then final energy = 0 (I'm not sure if this is correct). So I got the equation W = 0 - (1/2kA^2 +...
  49. C

    Proving Poincare Algebra Using Differential Expression of Generator

    Using differential expressions for the generator, verify the commutator expression for ##[J_{\mu\nu},P_{\rho}]=i(\eta_{\mu\rho}P_{\nu}-\eta_{\nu\rho}P_{\mu})## in Poincare group Generator of translation: ##P_{\rho}=-i\partial_{\rho}## Generator of rotation...