How does chromatin structure regulate gene expression?
This is what i got so far...is this some what on the right track?
Eukaryotes have more DNA than prokaryotes. There are various levels of condensation and compaction that are necessary in order to fit a very large amount of DNA into a much smaller nucleus. The degree to which chromatin is compacted greatly affects the accessibility of the chromatin to the transcriptional machinery of the cell, and thus the expression levels of the genes contained within.
- Anonymous1 decade agoFavourite answer
So far so good!
I don't know if you've already learned about:
1. euchromatin vs heterochromatin
These two topics are also essential to how gene expression. An excerpt from Wikipedia about #1:
Euchromatin participates in the active transcription of DNA to mRNA products. The unfolded structure allows gene regulatory proteins and RNA polymerase complexes to bind to the DNA sequence, which can then initiate the transcription process. Not all euchromatin is necessarily transcribed, but in general that which is not is transformed into heterochromatin to protect the genes while they are not in use. There is therefore a direct link to how actively productive a cell is and the amount of euchromatin that can be found in its nucleus. It is thought that the cell uses transformation from euchromatin into heterochromatin as a method of controlling gene expression and replication, since such processes behave differently on densely compacted chromatin, known as the `accessibility hypothesis'.
Regarding #2, histones bind chromatin and cause them to stay compact. For example, if a histone binds the region of a certain gene, it will NOT be expressed because it can't be accessed for transcription. Yup.