Chemical tags such as phosphate, methyl, or acetyl groups can be added to histone proteins and DNA. What do these tags signal to the cell?
AThe exact nucleotide sequence to be transcribed next
BWhich ribosome should translate the resulting mRNA
CWhether the cell should undergo mitosis immediately
DWhether a chromosomal region should be open or closed
Answer & Solution
Correct answer: D. Whether a chromosomal region should be open or closed
1. How the histone proteins move depends on signals found on both the histone proteins and the DNA.
2. These signals are chemical tags, such as phosphate, methyl, or acetyl groups, added to histones and DNA.
3. The tags tell the cell whether a chromosomal region should be open or closed.
4. The tags do not alter the DNA base sequence itself, which rules out the option about signaling the exact sequence to transcribe.
5. Selecting a ribosome or triggering mitosis are not functions described for these epigenetic tags.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 16 "Gene Expression", section Epigenetic Control_
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