HP1 is recruited to regions in which histone H3 has been methylated at lysine 9, a modification involved in heterochromatin formation. It turns out that HP1 can also interact with Dnmt1, which can promote DNA methylation in the vicinity of HP1 binding. Furthermore, Dnmt1 can directly interact with the methyltransferase responsible for H3K9 methylation, creating a positive feedback loop to ensure continued DNA and histone methylation.

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#Unit 3. Fundamental Processes

Valine cannot coordinate the Zn2+ in this way and hence does not undergo adenylation by ThrRS. A separate editing site deal with misacylated Ser–tRNAThr.

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#Unit 13. Methods in Biology

Notice that S1 mapping and primer extension are well suited to mapping transcripts made in vivo; by contrast, run-off transcription relies on transcription in vitro.

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#Unit 10. Ecological Principles

Water makes life possible, due to its

1. Thermal properties

2. Density

3. Viscosity

4. Solvent for inorganic nutrients

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#Unit 4. Cell Communication and Cell Signaling

Cancer cells influence the behavior of the fibroblasts and immune cells.

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#Unit 11. Evolution and Behavior

Bateman’s principle

In most cases, it is the male’s secondary sexual traits that are exaggerated.

This shows that sexual selection is more common and intense on males than females