A very different form of RNA editing is found in the RNA transcripts that encode proteins in the mitochondria of trypanosomes.

#Id: 2530

#Unit 13. Methods in Biology

The specificity of the PCR depends crucially upon the primers. The following factors are important in choosing effective primers

Primers should be 17 to 30 nucleotides in length

A GC content of about 50% is ideal. For primers with a low GC content, it is desirable to choose a long primer to avoid a low melting

 temperature.

Sequences with long runs (i.e., more than three or four) of a single nucleotide should be avoided.

#Id: 4611

#Unit 13. Methods in Biology

#Id: 3359

#Unit 3. Fundamental Processes

Another example of direct reversal is the removal of the methyl group from the methylated base O6 –methylguanine  In this case, a methyltransferase removes the methyl group from the guanine residue by transferring it to one of its own cysteine residues. This is costly to the cell because the methyltransferase is not catalytic; having once accepted a methyl group, it cannot be used again.

#Id: 6106

#Unit 3. Fundamental Processes

Thymine dimers cause mutations in two ways. (1) Dimers perturb the structure of DNA double helices and interfere with accurate DNA replication. (2) Errors occur during the cellular processes that repair defects in DNA, such as UV-induced thymine dimers To identify chemicals that are converted into mutagens in the liver, the Ames test treats potential indirect mutagens with a mixture of liver extract

#Id: 6726

#Unit 8. Inheritance Biology