What is Reverse: Definition and 309 Discussions

A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by certain viruses such as HIV and hepatitis B to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, and by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes. Contrary to a widely held belief, the process does not violate the flows of genetic information as described by the classical central dogma, as transfers of information from RNA to DNA are explicitly held possible.Retroviral RT has three sequential biochemical activities: RNA-dependent DNA polymerase activity, ribonuclease H (RNase H), and DNA-dependent DNA polymerase activity. Collectively, these activities enable the enzyme to convert single-stranded RNA into double-stranded cDNA. In retroviruses and retrotransposons, this cDNA can then integrate into the host genome, from which new RNA copies can be made via host-cell transcription. The same sequence of reactions is widely used in the laboratory to convert RNA to DNA for use in molecular cloning, RNA sequencing, polymerase chain reaction (PCR), or genome analysis.

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  1. Q

    Reverse engineering potential and kinetic energy

    The equation for momentum (potential energy) is PE=M*V. The equation for kinetic energy is KE=(1/2)*(M*V^2). You will notice that PE is the derivative of KE. and then you might add that M, simply Mass, is the derivative of PE. However, because M is simply a scalar quantity, and the other...
  2. gabi123

    B Can you reverse Einstein's famous E=mc^2 equation?

    E=mc^2 states that when you speed up matter to the speed of light, it becomes pure energy, of mc^2 joules. Now, if that is true, can you reverse the equation? Wouldn't energy speed up to the negative speed of light(-c^2), turn into matter? Or is that the wrong balance?
  3. Dr. Courtney

    I Solving a Reverse Series Problem in College Calculus

    So all these college classes are really a growing experience for my teenage boys (home schooled). Last night my older son kept us up late persevering on a Calculus problem. Now, I remember a lot about sequences and series from my own days in Calculus and from teaching Calc 1, 2, and 3 at the Air...
  4. Fayyaz Ahmed

    Reverse Bias in Semiconducter diode

    Why don't we consider the current produced by voltage source in plotting reverse bias characteristics?if this current is considered then the saturation current will depend on the the external voltage.
  5. cyberdiver

    Using electrochemical hydrogen compressor in reverse

    Electrochemical hydrogen compressors (https://en.wikipedia.org/wiki/Electrochemical_hydrogen_compressor) basically convert an electrical potential difference into a pressure difference. Would it be possible to run one of these in reverse, i.e. using a pressure difference to create a voltage? If...
  6. M

    Reverse Rotating Pump: Does it Add Head to Fluid?

    Hi What happens when a centrifugal pump rotate inversely? Does it add Head to fluid?
  7. D

    Regarding a MOSFET's reverse recovery power loss

    Hello everyone, so I'm currently trying to find out how much power will be lost during reverse recovery of a MOSFET's diode. I'm using this paper for reference, https://www.fairchildsemi.com/application-notes/AN/AN-6005.pdf the equation they end up with is P= Qrr*Vin*Freq_sw the problem is...
  8. M

    Voltage across reverse biased diode

    Hi all, I think I know the answer to this question but I'm having trouble explaining why it is so. If I have a circuit with a fixed resistor connected in parallel with a reverse biased diode, I believe the voltage drop across each will be the same. Is this correct? If so can someone explain the...
  9. krater

    Power XFMR magnetization currents in a "reverse" connection

    If my understanding is correct, with respect to dry-type building power transformers, due to the virtues of the transformer as a dumb machine it really doesn't care which side of itself is the primary versus the secondary. In other words a 480D-208Y tranformer can be correctly connected such...
  10. S

    Reverse relay and travel limit switch - PLC

    Homework Statement Hi, I'm currently studding a module on PLC and have a question on "what will happen if you do this ...". Homework Equations I don't have a problem with explaining operation of each rungs of the ladder diagram, I need some help on explaining the function of the reverse relay...
  11. S

    Reverse relay and travel limit switch - PLC

    Hi, I'm currently studding a module on PLC and have a question on "what will happen if you do this ...". As I don't have a problem with explaining operation of each rungs of the ladder diagram I need some help on explaining the function of the reverse relay and travel limit switches. Can anyone...
  12. R

    Reverse Cancer, Prevent aging and Take control

    Hey all, It's been quite a while since I've been on here, I'm an IT Technician and recently lost a student to brain cancer at the age of 11 so i thought I'd brainstorm until i worked out a possible and feasible way to beat cancer, this might be sci-fi or false information as I'm not entirely...
  13. T

    Catalyst increasing both forward and reverse reaction rate

    The question is: Which takes place when a catalyst is added to a reaction at equilibrium? A. The point of equilibrium is shifted to the right. B. The point of equilibrium is shifted to the left. C. The forward and reverse reactions rates are increased unequally. D. The forward and reverse...
  14. E

    Reverse FFT of a ratio of two FFTs

    Dear all, I don't know if this is the correct place for this question, but I did a little search on the forum and I saw that most FFT related questions have been posted here. My question is this: I need to deconvolve two real signals (in my case they are two probability density functions), so I...
  15. A

    Proof that in Brayton reverse cycle heat is negative

    Homework Statement I was given the Brayton reverse cycle and asked to prove that the total heat is negative (hence the heat pump cools the system). I was to assume that all the steps are reversible. Homework Equations An ideal diatomic gas. 1st step: adiabatic compression. 2nd step...
  16. S

    Why is component reverse in Conical Pendulum?

    Hello. In class today, we studied conical pendulum but I was confused at the part about its components. In all the diagrams ( http://dev.physicslab.org/img/90c0fb7a-ffb4-4573-b389-b50a559732c8.gif ) if shows The x-component as being sine, but I always thought x-comp was cos?? (...
  17. R

    C/C++ C++ prog. to reverse each word in sentence

    #include<iostream.h> #include<conio.h> #include<stdio.h> #include<string.h> void main(){ clrscr(); char a[10],b[40]; cout<<"Enter sentence\n"; gets(a); cout<<a ;\\ How to reverse here? getch();} I don't know the proper code how to do the program of reversing each word in a sentence. How does...
  18. Nemika

    Can Earth Rise Upwards to Touch an Apple?

    This is a really silly question though... Newton said that the apple fell on the ground due to gravity but can we say that the Earth rose upwards to touch the apple. Is it possible to prove this by any physics law? Thnx for any reply.
  19. P

    PN Junction: Current flow in Reverse Bias

    Can someone explain why after a certain voltage, current flows. We were taught that in pn junction when a reverse voltage is applied the depletion region grows wider. Using this no matter what the voltage current should not increase. So why does a current flow when a reverse current is applied.
  20. D

    Does any current flow in reverse PN junction?

    Homework Statement Homework Equations [/B] When a diode is reverse biased positive donor ions are left in the N semiconductor and negative acceptor ions in the P type. And since the N is conected to + and its donnor ions has a large +charge, why no electrons from P cannot cross the junction and...
  21. D

    Why Don't Electrons Flow from P-type to N-type in a Reverse Biased PN Junction?

    [Mentor's Note: Thread moved and edited by mentor.] Sorry I am new and I had problems creating the thread. But I will post my question here:-D. So in reverse biased pn junction the width of the depletion layer increases. But on the N side a large positive charge from the donnor ions is...
  22. T

    Compressed Air Reverse Thruster

    Hello everyone, I'm attempting to determine the impulse that can be generated by expelling compressed air from a pressure vessel stored aboard a moving craft through nozzles in the nose of the craft. The vessel has a forward momentum of roughly 2,000,000 Ns. EDIT: For semantics sake, consider...
  23. A

    I How do you reverse this equation

    From the equation below, how do we get the X,Y,Z if the only numbers given are the L,M,N (0.5839, 0.1682, 0.2477)? Thank you! X = 1.57 Y = 5.45 Z = 3.70 T = (1/X+1/Y+1/Z)*100 = 109.0699 A = (1/ (X*T))*100 = 0.5839 B = (1/ (Y*T))*100 = 0.1682 C = (1/ (Z*T))*100 = 0.2477 L = 0.5839 M =...
  24. A

    Solve for XYZ Given LMN: 0.5839, 0.1682, 0.2477

    From the equation below, how do we get the XYZ if the only numbers given are the LMN (0.5839, 0.1682, 0.2477)? Thank you! X = 1.57 Y = 5.45 Z = 3.70 T = (1/X+1/Y+1/Z)*100 = 109.0699 A = (1/ (X*T))*100 = (L) 0.5839 B = (1/ (Y*T))*100 = (M) 0.1682 C = (1/ (Z*T))*100 = (N)...
  25. T

    Photodiode - Reverse Bias Operation

    Hello, I'm attempting to use a photodiode as a light intensity sensor. However, I have a question regarding the operation of a photodiode in a reverse biased position. The current going through the photodiode is dependent on the light received, and is not affected much by the reverse biased...
  26. L

    MHB Trying to reverse structure a calculation to arrive at original variable

    Trying to reverse-calculate an equation to achieve one of the original variables when not present. 1) You have a number... A (which is always a positive number) 2) A is multiplied by 1.75% 3) This result is then added to A, and the resulting sum being B, i.e. (A x 0.0175) + A = B In my...
  27. P

    How to reduce the current of a signal by an exact amount?

    Hello all, The root problem is that I can't put all my analogue inputs onto one input card (each card has 4 inputs) on the project I'm working on. We have four sensors, they should all output 4-20mA. Two are source type outputs, supply voltage goes in, sensor current comes out, current is...
  28. Stephanus

    Why is sinh-1(x) not equal to 1/sinh(x)?

    Dear PF Forum. I saw once that sinh-1(x) is arcsinh(x). The reverse of sinh Why not sinh-1(x) is 1/sinh(x)? While x-1 = 1/x Is it just a 'convention' between mathematician? Thanks.
  29. ognik

    MHB Reverse direction for complex functions

    Hi An exercise asks to show $ \int_{a}^{b}f(z) \,dz = -\int_{b}^{a}f(z) \,dz $ I can remember this for real functions, something like $ G(x) = \int_{a}^{b}f(x) \,dx = G(b) - G(a), \therefore \int_{b}^{a}f(x) \,dx = G(a) - G(b) = -\int_{a}^{b}f(x) \,dx $ I have seen 2 approaches, either...
  30. ognik

    MHB Reverse triangle inequality with a + sign

    Thought I knew this, but am confused by the following example: Show $ |z^3 - 5iz + 4| \ge 8 $ The example goes on: $ |z^3 - 5iz + 4| \ge ||z^3 - 5iz| - |4|| $, using the reverse triangle inequality It's probably right, but I don't get why the +4 can just be made into a -4 ?
  31. F

    'Reverse' derive correct dataset when given mean + std dev

    If I know the mean and standard deviation, but I don't have an original data set, is it possible to reverse calculate a data set that has this known mean and std dev? Is there an excel function I could use to do this easily? I know there could be multiple correct datasets and that's fine, I'm...
  32. F

    MHB Calculating Data Set w/ MEAN=100 & STD DEV=15 & n=3

    If I know the mean and standard deviation, but I don't have an original data set, is it possible to reverse calculate a data set that has this known mean and std dev? Is there an excel function I could use to do this easily? I know there could be multiple correct datasets and that's fine, I'm...
  33. U

    Reversing Indices in Contractions: Can it be Done?

    Suppose I have something like \left( \nabla_\mu \nabla_\beta - \nabla_\beta \nabla_\mu \right) V^\mu = R_{\nu \beta} V^\nu Can since all the terms involving ##\mu## on the left and ##\nu## on the right are contractions, can I simply do: \left( \nabla^\mu \nabla_\beta - \nabla_\beta \nabla^\mu...
  34. thankz

    Can a 1n4009 protect a LED from reverse breakdown voltage when powered by mains?

    I want to power a led off mains, here's my thinking on it: resistor-->led-->1n4009 to protect against reverse breakdown voltage, is there anything I'm missing and will it be reliable?
  35. L

    How does a forward and reverse power meter work?

    I know they have a diode that gets reversed to see forward V reverse power but how does that diode just respond to the one direction of energy? I have a bird wattmeter and it uses two slugs, one pointed in the other out to get simultaneous forward and reverse power and VSWR and such but why does...
  36. K

    Determine the reverse saturation current for the diode

    Determine the reverse saturation current for the diode below, given that VS = 5V, R = 360Ω produces a diode current of 10mA. Use h = 1.3 and VT = kT/q = 25mV. I believe this is the formula needed. Id = Is(e^(VD/(h*25mV))-1) The problem I had was I've done several questions similar to this but...
  37. Suraj M

    Reverse Translation: Could DNA be Synthesized?

    Is this a true phenomenon?? I just read 1 article, but i don't believe it Could DNA really be synthesized using The amino acid sequence?
  38. T

    Reverse Recovery Current of a diode

    Hello, When the diode is in forward bias phase and suddenly we apply a reverse bias voltage, the diode takes time to be fully blocked because of the excess of minority charges that are stored in P and N region. Thus a reverse current appears in the diode for a short time before it is blocked...
  39. ognik

    If T unitary show H hermitian (and the reverse)

    Homework Statement An operator T(t+ε,t) describes the change in the wave function from to to t+ε. For ε real and small enough so that ε2 may be neglected, considering the eqtn below: (a)If T is unitary, show H is hermitian (b)if H hermitian, show T is unitary. Homework Equations $$ T(t+ε,t)=...
  40. L

    Reverse Saturation Current in P-N Junction

    Homework Statement An abrupt Si p-n junction of cross sectional area 10-4cm-2 has the following properties: p side: number densities of acceptor impurity atoms: NA = 1017cm-3 minority carrier lifetime: τn = 0.1 us hole mobility: μp = 200cm2/Vs electron mobility: μn = 700cm2/Vs n side...
  41. ognik

    Legendre polynomials in the reverse direction

    I have just written a program to calculate Legendre Polynomials, finding for Pl+1 using the recursion (l+1)Pl+1 + lPl-1 - (2l+1).x.Pl=0 That is working fine. The next section of the problem is to investigate the recursive polynomial in the reverse direction. I would solve this for Pl-1 in...
  42. E

    NPN BJT in reverse active mode - base current direction

    Hi! I was wondering what happens with Base current direction if NPN BJT works in reverse active mode? In forward active and in saturation mode currents are like this: Collector and emitter currents in reverse active mode would be in opposite direction: :
  43. B

    How is this sound generated? / reverse engineer sound

    http://mynoise.net/NoiseMachines/twilightSoundscapeGenerator.php does anyone know how this sound is generated? are do anyone how to reverse engineer? Audacity to record the sound and do a fft ... anyone else know what I can do to reverse engineer this sound?
  44. T

    Can you reverse engineer a number?

    If you create a sequence such as 1/4 +1/5+1/6...1/n it will tend to a limit and result in a specific number or something very close to a specific number. Is there a way using some method, algorithm, or formula to do the reverse? Can I start with a number and find the sequence that creates it...
  45. R

    Can a Flip Phone Be Converted into a Portable Battery Pack?

    So I have an old flip phone here that I wanted to turn into a portable battery pack because its winter break and I am bored. Whole thing is apart and good to go but I was wondering if there is any way to reverse the current. Obviously charging it one way, and then when you use it as a battery...
  46. gracy

    Why Isn't There More Current in Reverse Diode?

    I am not getting why there can't be (or very negligible )current in reverse diode.According to this image positive terminal of battery would suck electrons from n-type and pass them to negative terminal of battery.And Negative terminal would provide electrons to p type and from there we can see...
  47. Muhammad Uthman

    Flywheel -- Why does it reverse direction after spinning to a stop?

    Why does fly wheel return in opposite motion after it comes to rest due to friction?
  48. ubergewehr273

    Can We Reverse Time? Exploring the Possibilities

    Is it possible to reverse time? According to special relativity, time slows down as one approaches the speed of light and completely stops when one travels at the speed of light, which is exactly ##c##. Then if one travels faster than the speed of light, is it possible that time will reverse or...
  49. J

    MHB Can anyone help me reverse a list in Lisp without using the reverse function?

    Hi, I'm trying to reverse a list in Common Lisp without using the reverse function. I've had a go but it's not working. Can anyone help? (defun my-reverse(my-list) (cond ((null my-list) nil) (t (append (my-reverse(cdr my-list)) (list (car my-list)))))) Thanks.
  50. P

    Why catalysts affect forward and reverse reactions?

    Based on the very basic understanding on enzymes I have gained from Year 12 Biology and Chemistry, I don't undesrtand why the enzymes specific shape also helps the reverse reaction. I guess my trouble would be due to the simplified diagrams I've seen from Biology, where only the forward reaction...
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