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. larginal

    Proof of Electromagnetic Identity: Puzzling Last Expression

    I tried to understand proof of this identity from electromagnetics. but I was puzzled at the last expression. why is that line integral of dV = 0 ? In fact, I'm wondering if this expression makes sense.
  2. M

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    This seems rather straight forward, but I can't figure out the details... Generally speaking and ignoring prefactors, the Fourier transformation of a (nicely behaved) function ##f## is given by $$f(x)= \int_{\mathbb{R}^{d+1}} d^{d+1}p\, \hat{f}(p) e^{ip\cdot x} \quad\Longleftrightarrow \quad...
  3. binbagsss

    Maple Maple- simplifing an expression in terms of pre-defined variables?

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  4. TechieDork

    Find an expression for a magnetic field from a given electric field

    Here this is my attempt : Reference Textbook : Zangwill's Modern Electrodynamics I stuck at the last step , I really have no idea what to do next.
  5. anemone

    MHB Evaluate Algebraic Expression

    Let $a,\,b,,c \in \mathbb R$ such that $ab+bc+ca=0$ and $abc\ne 0$. Evaluate $\dfrac{a^5+b^5+c^5-1}{abc}$.
  6. U

    MHB Expectation of Conditional Expression for Exponentially Distributed RV

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  7. V

    MHB A function given by a logical expression write in the truth table.

    Hi I need help I'm lost Assignment: A function given by a logical expression Y = A.B.D + A.not (C) .D + A.not (B) .C.D + A.D write in the truth table.
  8. M

    Finding Expression for Emitted Field: A Confused Student's Journey

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  9. Y

    How to simplify this complex expression?

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  10. U

    MHB How to solve an expression with inverse of exponential distribution

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  11. Andrei0408

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  12. DaTario

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  13. bob012345

    I Exact Expression for Sine of 1 Degree

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  14. John Greger

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  15. TytoAlba95

    Why is the miRNA expression increasing?

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  16. M

    Derive a general expression for the dilution of saltwater

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  17. E

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  18. S

    Value of this trigonometric expression

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  19. JD_PM

    I Simplifying an expression given (on-shell & off-shell) conditions

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  20. PainterGuy

    I Laplace transform of an expression using transform tables

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  21. V

    Find the expression for Power in circuit

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  22. A

    B Is there a simple way to graph this transcendental expression with pi?

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  23. VictorMedvil

    Expression of Pol-Gag in different viruses

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  24. M

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  25. M

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  26. R

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  27. jisbon

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  28. ColoradoGrrrl

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  29. K

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  30. K

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  31. G

    Prove expression for N using inclusion-exclusion principle

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  32. M

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  33. K

    MHB Evaluating/Simplifying an Expression

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  34. M

    How should I simplify this product expression?

    I see that when n is an even number, the product can be represented as ## \frac {2n} {(n+1)} ##. When n is an odd number, the denominator seems to be changing and I am not able to define an expression for it. How should I go about solving this? Thanks
  35. jisbon

    Deriving expression for magnetic field at point P due to current

    So I think I do understand how to do this, but the thing is my answers are always incorrect. Will need some guidance/help on this. ##B =\frac{\mu_{0}I}{4\pi}\int\frac{dysin\theta}{r^2} ## ##y = Rtan\phi## ##dy = Rsec^2\phi d\phi## ##B = \frac{\mu_{0}I}{4\pi}\int\frac{dysin\theta}{r^2} =...
  36. M

    Kinematics Homework Question- Deriving an expression

    I have been attempting this physics problem for a while now. I am not sure how to begin to attempt this problem with the equations of motion formulas.
  37. C

    Deriving an Expression for an Electric Field along the Z axis

  38. TheBigDig

    Derive an expression for the applied field of a superconducting wire

    So far the best I've been able to come up with is to use ##\vec{B} = \mu_0 \vec{H}## which gives me i_c = H 2\pi r j_c = \frac{H 2\pi r}{\pi r^2} = \frac{2H}{r} \therefore B = \mu_0 \frac{r j_c}{2} I'm fairly confident this is just terrible math and physics on my behalf but I'm struggling to...
  39. naji0044

    Find an expression for the shear stress of this figure

    Summary: I have trouble to define the y distance in my coordinatesystem I need to find an expression for the shear stress on the I figure, where the green parabola illustrates the function. I made a cut, where I defined the length from the start of figure I to the cut as z1. The formula for...
  40. DanielMB

    I Implication, Boolean Expression and Venn Diagrams

    Hello, I’m having difficulties understanding logical relations “A implies B” and “A if and only if” using Boolean expressions and Venn diagrams, there is something where I’m wrong, but I could not find it out. Please, be benevolent and tell me where I’m wrong. Thanks Note : Obviously I’m...
  41. J

    How can I expand this expression in powers of 1/c²?

    As I said before, I really have no idea on how to proceed.
  42. R

    Argument of a complex expression

    Problem Statement: What is the correct way of computing the argument of the following equation? Relevant Equations: I am trying to compute the argument ##\Phi## of the equation $$\frac{r-\tau\exp\left(i\varphi\right)}{1-\tau r\exp\left(i\varphi\right)} \tag{1}$$ which using Euler's equation...
  43. PainterGuy

    B Expression where a certain quantity is proportional to the force squared

    Hi, I'm trying to find an expression or phenomenon where a certain quantity is proportional to force squared or power squared. For example, we have Force ∝ acceleration and Power ∝ I². I'm not sure if my question is a legit. I was trying to understand something and this question came to my...
  44. D

    MHB Simplify expression with laws of indices

    Helping my daughter with her math and hit this one and not sure how to advise. All help welcome(x-2y10)3 / (x-4yz4)-5 This one throws me off because I don't know how to deal with the z, as only on the right side of the divide
  45. Eclair_de_XII

    How do I derive this expression for conditional probability?

    ##P(T=1|W=w)=\frac{P(\{T=1\}\cap\{W=w\})}{P(W=w)}=\frac{\binom {n-2} {w-1} p^{w-1}(1-p)^{(n-2)-(w-1)}}{\binom n w p^w (1-p)^{n-w}}=\frac{(n-2)!}{(w-1)!(n-w-1)!}\frac{w!(n-w)!}{n!}\frac{1}{p(1-p)}=\frac{w(n-w)}{n(n-1)}(p(1-p))^{-1}##. I cannot seem to get the terms with ##p## out of my expression.
  46. H

    Find an expression for the power developed at the given rotation rate

    So for part (a), I used the fact that 1/N = the period = T. I solved for the velocity, where i got v=2πRN. I plugged that v into F=(m v^2)/R, which is the centripetal force, but also the force of friction. My answer to part (a) is 4(π^2)mR(N^2). I'm a bit confused on part (b). I know that...
  47. M

    Proving Even Parity for this Expression

    My idea was straight forward calculation: $$\begin{align*}\bar { \psi }' ( x' ) \gamma ^ { \mu } \partial _ { \mu }' \psi ( x' ) &= \psi^\dagger\gamma^{0\dagger}\gamma^0\gamma^\mu \partial_\mu'\gamma^0\psi = \bar\psi\underbrace{\gamma^0\gamma^\mu\gamma^0}_{=\gamma^{\mu\dagger}=-\gamma^\mu}...
  48. M

    Finding an expression for acceleration

    Homework Statement A 5.21 kg block is sliding down a slope at an angle of 4.22° to the horizontal. The block is initially moving down the slope at a speed of 1.45 m s−1 and the coefficients of friction between the block and slope are, μs = 0.500, and μk = 0.100. Find an expression for the...
  49. Thorscira

    Expression for effective potential energy

    << Mentor Note -- Poster has been reminded to use the Template when starting new schoolwork threads >> Two particles of identical mass m interact with each other via central potential energy Vcentral(r) = -V0(1-|r|/a), if 0 <= |r| <= a 0, if a < |r| Constants are V0 > 0...
  50. anemone

    MHB Inequality involves radical, square and factorial expression 3√{x}+2y+1z^2⩽ 13

    If $x^2+y^2+z^2+xyz=4$ and that $x,\,y,\,x\ge 0$, prove $3!\sqrt{x}+2!y+1!z^2\le 13$.
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