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. N

    [semiconduction] Does reverse bias decrease depletion region?

    Hello, For simplicity's sake, let's take a np junction. Say we connect the left side (n-pole) to a POSITIVE voltage; this is called a reverse bias, because it will result in a small current from n to p. In other words: electrons will travel from p to n across the junction (and holes will...
  2. Char. Limit

    Reverse Induction for Proving Negative nth Derivatives of x*e^(x)

    Homework Statement Say I had a problem like this: Prove that the nth derivative of x*e^(x) is (x+n)*e^(x) for all integer n. Can I use reverse induction to prove for negative n? For example... Say I proved it for my base case, n=0. In this case, the proof is trivial. Then I prove...
  3. M

    Harvard scientist claims to reverse aging in mice wow

    http://bigthink.com/ideas/25265
  4. C

    : chemistry qs: write the equillibrim constant for the reverse reaction

    URGENT: chemistry qs: write the equillibrim constant for the reverse reaction Homework Statement 2. The equilibrium constant for the following reaction is 2.0 10^ 4 2HBr(g)  H2(g)  Br2(g) Homework Equations b) What is the equilibrium constant for the reverse reaction? The...
  5. M

    Reverse Carnot Engine (Heat Pump)

    Homework Statement A house is heated by means of a carnot engine operating in reverse (Heat Pump). The outside Temperature (Tc) is 270k, and the required inside temperature (Th) is 300k. If heating the house to this temperature normally requires 10kW of electrical heating, how much power is...
  6. S

    Is there some reverse of annihilation?

    When heavy nuclei split up we get energy,when light nuclei join together we get energy. When elemental particles split up in annihilation we get energy (photons). What if we join certain photons together?Could we obtain energy in this way and make analog of nuclear fusion?
  7. S

    How Can I Use Reverse Linear Interpolation in My Computer Simulation?

    I've run into a problem programming a computer simulation. I have a discrete grid of values and a point an the middle with a value and I need to take the value and put it into the grid. I've been working on the 1 dimensional problem, and I can't get it. I know it's something simple I'm missing...
  8. X

    Reverse Bias: Diode, Resistor, Voltage & Current

    In forward bias the supplied voltage is distribute among the resistor and the diode (diode and resistor are connected in series) but in reverse bias the Current across the resistor remain zero because the conduction starts when very high voltage is supplied ...am i right ? but why the Voltage...
  9. A

    Newton third law and finding the reverse distance

    hi am new here ... and sorry for my weak English i have a question and a problem in physics that i need to know it's solution i will give you the main idea without numbers and you can assume any numbers that you find it suitable for the problem... the problem say: if a small ball is...
  10. S

    Multibody dynamics: reverse bungee

    [b]1. I need to simulate a reverse bungee ejection seat (carnaval ride). This is a vehicle attached to two masts with bungee cords. I know the mass, air drag and acceleration (4.8 g). The first step is to calcutate the spring constants of the bungee cords and the damping constant (relative...
  11. Math Is Hard

    Reverse gear on manual transmission cars

    When I was younger I drove stick shift cars. Reverse gear was always all the way over to the right and down in the cars I drove (MGB and Jetta). I'm car shopping now and thinking about getting a car with manual transmission again. I noticed that some have reverse gear down and right, but...
  12. O

    Exploring Reverse Triangle Inequality Norms

    I'm interested in thing that are norms except for the fact that they satisfy the reverse triangle inequality ||x+y|| \geq ||x|| + ||y||. The obvious example is taking p-norms for 0<p<1. Does anyone know of others or if there's any theory developed on this topic?
  13. N

    MATLAB Matlab: Reverse FFT - Naftali's Question

    Hi, I'm analyzing a laser diffraction experiment. Does Matlab has a reverse FFT function? Thank you Naftali
  14. G

    Why heat of combustion is not the reverse of the heat of formation

    Using Methane gas as an example (CH4 gas), explain why one can not assume the heat of combustion is the reverse of the heat of formation. I can't find a decent answer to this anywhere.
  15. R

    Can our eyesight framerate capability be improved through reverse magnification?

    Hi.Non-physics student posting here for first time purely out of curiosity. I was wondering if we could improve our ability to percieve high speed objects which move to fast to see, by, for want of a better phrase, using a big magnifying glass backwards. For instance, if a car moves down a 500...
  16. N

    Reverse the order of integration

    why sometime we need to reverse the order of integration? and how to determine the new limit? for example: for integration of dydx, the limit of y and x: y=2x , y=2; 0<=x<=1. after we reverse the order become dxdy, how to determine the new limit of x and y?
  17. T

    LED States in Current and Reverse Bias Circuit

    Homework Statement Indicate which of the 6 LEDs are ON and which are OFF Homework Equations V=IR The Attempt at a Solution Okay, I know LEDs 4,5 and 6 will be ON and LED 2 and 3 will be OFF but what about LED 1? Because LED 2 has a very high resistance as it is reverse biased thus...
  18. T

    Reverse Piezoelectric Effect - how much?

    Hello Everyone, Thank you for the help! I'm trying to better understand the reverse piezoelectric effect. More specifically what the reaction of the material would be with an applied energy. Is there deformation or just vibration? Is it controllable? Is it repeatable? Does it diminish over...
  19. A

    Amplifying reverse saturation current

    Forgive me for the noobish question, but here goes. My objective is to feed the reverse saturation current in a circuit into a DAQ device for detection. However I want to amplify it from the micro to milli or ampere range before doing so, due to DAQ specifications. I'm confused as to how...
  20. A

    Sudden Increase in Reverse Saturation Current: Exploring Breakdown Voltage

    why there is sudden increase in the small reverse saturation current at the breakdown voltage?...
  21. W

    MATLAB Reverse ASCII to Number in MATLAB | char(100)

    i know >>char(100) gives some kind of ascii letter as an answer my question is, is there a function to convert the ascii letter back to 100? Thank you! edit - The language is MATLAB
  22. R

    Cellular phones and reverse SETI

    Many years ago we started broadcasting radio signals for terrestrial use which inadvertently also radiated out into space. Possibly a civilization with appropriate equipment many light years away could have already detected these signals. But recently things have changed. By some estimates...
  23. U

    Reverse polarities by a device

    There is nothing I have tell before I go about on this madcap search. The problem is that I'm only 12 and searching for a device (or a circuit) which changes, or swaps, polarities, every time the switch (a switch made from a phototransistor and a resistor, in essence, getting activated...
  24. V

    Reverse Universe: Investigating Deductive Conclusions from Reversible Laws

    "Reverse Universe": In general, we could say that looking to the ultimate particles of matter, enough physical laws subsist in the reverse universe to determine, from the positions and velocities of all particles of matter at a given instant, the entire past and future of the universe. The...
  25. R

    Reverse crankshaft movement

    Hi guys Let a single cylinder ic engine. Now when we start the engine , then depending upon the position of crank the last time we switched off the engine, it is possible it may rotate in reverse direction because piston just has to reciprocate so acco to crank position at rest it may move...
  26. V

    Reverse Universe: Acceleration and Time Reversibility

    Among the physical laws it is a general characteristic that there is reversibility in time; that is, should the whole universe trace back the various positions that bodies in it have passed through in a given interval of time, but in the reverse order to that in which these positions actually...
  27. D

    Finding reverse saturation current.

    Homework Statement Hi, I have a problem to find the reverse saturation current for a piece of diode. I have a question - given conductivity, a I-V curve with forward bias information (a table of I vs V values), how can i proceed? I have other information abt the diode such as its mobility...
  28. B

    Reverse Product Rule: Understanding its Application in Integration

    Homework Statement i'm sorry i know I've been bombarding physics forums with questions but i need help :p using reverse product rule \int uv' = uv - \int vu' and say i have a*b i noticed my teaher said that a=u and b=v not v' and he simly made that into a v' by deriving. is there a point...
  29. C

    Reverse Runge-Kutta: Solving e^(x) + y = dy/dx [-1,1]

    Homework Statement e^(x) + y = dy/dx, [-1,1], y(0) = 1, N = 4. Homework Equations The Attempt at a Solution h = b-a / N = 0.5 x0= 0, y0 =1 x1= 0.5, y1 = 2.472 x2= 1, y2 = 5.433 x3= 1.5, y3= 11.195 x4=2, y4= 22.146 ===================== These were the values I got for the...
  30. T

    Operations in Reverse Polish Notation

    Recently I was doing various equations in RPN to teach myself the notation. Everything went fine until I wanted to do a limit. How would one go about expressing limits (and any other operation that isn't addition, subtraction, division, or multiplication) in RPN?
  31. I

    : PM Generator in Reverse

    URGENT: PM Generator in Reverse If you have a permanent magnet generator being driven by a turbine and the generator outputs some power level, how would the configuration of a generator change if it is suppose to drive a turbine's compressor stage with the same power? I think the meaning is...
  32. C

    Calculate the activation energy for the reverse reaction

    For the decomposition of one mole of nitrosyl chloride, Delta H = 38kJ. NOCl(g)-->NO(g)+Cl2(g). The activation energy of this reaction is 100kJ. Calculate the activation energy for the reverse reaction in kJ. I attempted this question but cannot find the process or equation to finish the...
  33. Z

    Can Functions Be Reconstructed from Their Derivatives Without Using Integrals?

    Okay, there are two different questions, but are answered the same way (I believe). Homework Statement (1)Which function has a derivative equal to ex sin 2x (2)Which function has a derivative equal to tan x * tan 2x * tan 3x The Attempt at a Solution I thought (since the teacher...
  34. L

    BJT common emitter collector to emitter reverse bias confusion

    Iam sorry if it is a very basic question but iam unable to understand this if u take a common emitter configuration of npn transistor the emitter is common to both the input and output terminals and to operate in the active region 1. the emitter to base should be forward biased i.e n and p...
  35. S

    Human Carbon Dioxide Emissions Reverse 2000 Years of Arctic Cooling

    http://www.ucar.edu/news/releases/2009/arctic2k.jsp The associated albedo flip will amplify the warming.
  36. T

    12v reverse speed control circuit diagram

    Hi I have a 9v motor (can run to 24v). I need to control the speed of the motor and reverse the direction. I also wanted to control it with a duel-potentiometer, but i can't seem to find any way to do this. can someone help with a circuit diagram please? (This is my first time building a...
  37. R

    Oxidizing iron bacteria made to work in reverse

    My employer operates a biological water filtration plant. The first stage of filtration has the raw water passing through a filter embedded with bacteria, the processes used here is aerated biological treatment where oxidizing processes (bio-oxidation) are used and the microbes gain energy when...
  38. M

    Reverse osmosis perpetual motion machine

    The original problem was as follows: Closed-loop system, with complete isolation. Salt water is green, fresh water blue, porous plug (AB) is red. Fresh water spills into the salt water column at C if the fresh water is lifted higher than the salt water, maintaining continuous flow...
  39. K

    An amplifier that works in reverse?

    I am making a circuit of a car toy. Actually, i have already done its first step. The next step i want to make a one which is able to reverse and i think i will need an amplifier which can work in both biases (foward and reverse). So do exist amplifiers that can work in reverse as well as in...
  40. D

    What could cause a battery to read negative voltage and how common is it?

    This isn't an engineering question, but I don't know which forum is better suited to ask. I pulled two AA batteries out of my daughter's toy this morning after it had been left running all night. One of the batteries read 0.80 volts, and the other read -0.24 volts! That's right, one was...
  41. I

    Determining Ideality Factor and Reverse Saturation Current

    Homework Statement Ideality factor and reverse saturation current http://3.bp.blogspot.com/_h90yJnbZXIE/SfMcs8FCF8I/AAAAAAAAAFk/dJ7cnqLGntk/s1600-h/circuit_fordiodeparameterextraction.JPG Use the circuit above to determine the I-V characteristic over 3 decades of current from 0.01 mA to 10...
  42. B

    Understanding Reverse HFE in Transistors for Audio Circuit Protection

    What is "reverse Hfe"? Hey everyone, I'm looking over a synthesizer schematic that has a 2SC2878 transistor in shunt with the main output - I think it's connected up in some kind of power on muting circuit for protecting speakers against turn-on thumps. Interestingly, this transistor has...
  43. M

    How come when you reverse a diode the current/voltage? is zero?

    Hi I have been looking through my book, and even online for the answer because I don't understand why this happens, but I can't find the proper answer anywhere...can someone help me? Thanks.
  44. M

    How come when you reverse a diode the current/voltage? is zero?

    Hi I have been looking through my book, and even online for the answer because I don't understand why this happens, but I can't find the proper answer anywhere...can someone help me? Thanks.
  45. Y

    Minimum Pressure applied by reverse osmosis?

    Homework Statement Seawater is approximately .60M NaCl. What is the minimum pressure that must be applied at 25 degrees Celsius to purify seawater by reverse osmosis? Assume i=2.0 for NaCl. Homework Equations Osmotic pressure = MRT R= gas constant, .0821 Latm/mol K The Attempt at a...
  46. Y

    Calculating the x-component of a vector with magnitude and direction

    The magnitude of vector A is 35.1 units and points in the direction 301° counterclockwise from the positive x-axis. Calculate the x-component of this vector. So...35.1=sqrt(vx^2 + vy^2) and 301°= vy/vx How do I do this?
  47. G

    Reverse orientation of eliptically polarised light

    Hello, How can you reverse the orientation (handedness) of elliptically polarised light? Thanks! Graham.
  48. K

    What is the Efficiency of a Carnot Refrigerator?

    In the textbook, it reads: the reverse of carnot cycle is just a refrigerator or heat pump. In this sense, except for the direction of carnot cycle is reverse, could I say the way to calculate the efficiency of the carnot refrigerator is the same? That is, could be still use \eta = 1 -...
  49. A

    How to calculate reverse of Mean.

    Hi guys, suppose that we have list of numbers 83+115+156 = 354 mean = 354/3 = 118 how can we get reverse of that . Can recover the above three numbers (83,115,156) from 118 by doing some mathematical tricks ( subtraction/ addition) etc. -- Regards, Asif
  50. A

    Exploring the Reverse Twin Paradox: Predicting Age Differences at .6c Speeds

    HI My question is what would the outcome be if the twins started out in 2 ships traveling at uniform .6c relative to Earth and one of them then took her ship and traveled to Earth and back? Which twin would be older?
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