Point mutation (i.e., a change in a single base pair) in a proto-oncogene that results in a hyperactive or constitutively active protein product.

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#Id: 2619

#Unit 13. Methods in Biology

More than 350 different type II endonucleases with over 100 different recognition sequences are known.

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#Id: 5526

#Unit 10. Ecological Principles

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#Id: 8954

#Unit 11. Evolution and Behavior

As a chromosome with a new gene duplicate spreads through a population, there is polymorphism in the number of copies of the gene that individuals carry. This situation, called copy number variation.

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#Id: 6807

#Unit 3. Fundamental Processes

The precursor RNA for the siRNA pathway is a longer dsRNA. As a consequence of this different initial substrate, Drosha is not needed for the generation of siRNAs. Cleavage by Dicer is still required, however, and again generates a suitable 21- to 22-nucleotide RNA for incorporation into RISC.

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#Id: 4528

#Unit 11. Evolution and Behavior

There are four known forces that are involved in evolution:

1)mutation,

2) genetic drift

3) gene flow or migration

4) selection.