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Gene transcription

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1.Why was the gel probed with GAPDH cDNA? Briefly describe how the level of GAPDH mRNA varied between different lanes?

GAPDH is referred to as a 'housekeeping' gene, it is expressed at significant levels all the time, so it should be detectable in all samples. This is important as a positive control to show the Northern blot has worked, as no signal would indicate a technical problem. It also acts an an internal standard. As the level of this mRNA remains approximately constant in each cell, regardless of the age of the mouse, it gives a measure of how much sample has been added to each lane. By comparing the signals from the test mRNAs with the GAPDH signal for mice of each age, you can normalize expression of all the test genes relative to GAPDH across mice of different ages. For example if the GAPDH signal was markedly higher in mice of some ages, then the test mRNA signals would also be higher, but they could only be compared with the samples from the mice at other ages after determining expression relative to the GAPDH signal.

The level of GAPDH mRNA was similar in ...

Solution Summary

This solution performs one of many tasks: describe the changes in Egr-1 mRNA expression in the liver of animals from embryonic age E18 to 9 months of age.

See Also This Related BrainMass Solution

Genetics problems, basic definitions, the Hershey Chase experiment, the genetic basis of sickle cell disease and DNA in cells.

Please Explain Each Problem

(Excerpted from attachment)

1: The term phenotype refers to the _________ of an individual.
2: With respect to sickle cell anemia, I write that the genotype of an individual is AS. Which of the following statements are true?
3: If, in the Hershey Chase experiment, only 35S entered the bacterial cell in significant amounts, the conclusions would have:
4: During the replication of DNA:
6: Mutations at more than one gene can cause the same phenotype. For example several enzymes are used to make methionine. Defects in any of them produce an organism that cannot synthesize its own methionine. Oculocutanious albinism can also be caused by defects in several different genes. Of the following statements which are true?
7: In a double-stranded DNA molecule, the percentage of thymine is 28%. What percentage of cytosine is present?
8: Many types of research about genes' roles in cancer employ mice. Why use mice when we wish to cure cancer in humans?
10: If you were going to look for a gene that was often transcribed, where would you look and why?

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