Heterochromatic regions, silenced genes, and gene-sparse regions of chromosomes are typically localized to the nuclear periphery.

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#Id: 2605

#Unit 13. Methods in Biology

Many different alleles are present in a population, but each person has only two alleles of any given SSR locus.

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#Id: 1209

#Unit 7. System Physiology – Animal

In humans, Only one of the follicles in one ovary starts to grow rapidly and becomes the dominant follicle, while the others regress, forming atretic follicles.

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#Id: 3298

#Unit 6. System Physiology – Plant

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#Id: 9561

#Unit 11. Evolution and Behavior

Ronald A. Fisher, John B. S. Haldane and Sewall Wright - which showed that mutation and natural selection together cause adaptive evolution.

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#Id: 7075

#Unit 3. Fundamental Processes

isoleucyl-tRNA synthetase has a nearby editing pocket (a deep cleft in the enzyme) that allows it to proofread the product of the adenylylation reaction. AMP-valine (as well as adenylylates of other small amino acids, such as alanine) can fit into this editing pocket, where it is hydrolyzed and released as free valine and AMP. In contrast, AMP-isoleucine is too large to enter the editing pocket and is therefore not subject to hydrolysis. As a consequence, isoleucyl-tRNA synthetase discriminates against valine twice: in the initial binding and adenylylation of the amino acid (discriminating by a factor of 100), and then in the editing of the adenylylated amino acid (again discriminating by a factor of 100), for an

overall selectivity of 10,000-fold (i.e., an error rate of 0.01%).