The correct answers are:
- Methylation of histone tails in chromatin can promote condensation of the chromatin.
- DNA is not transcribed when chromatin is packaged tightly in a condensed form.
- Acetylation of histone tails is a reversible process.
- Some forms of chromatin modification can be passed on to future generations of cells.
- Acetylation of histone tails in chromatin allows access to DNA for transcription.
Histone modifications are post-translational modifications of histone protein that can affect gene expression by altering chromatin structure or recruiting histone modifiers.The most common modifications are methylation, phosphorylation, acetylation and ubiquitylation. All of them affect the binding affinity between histones and DNA and thus loosening (gene activation) or tightening (gene repression) the condensed DNA.
Histone methylation is a transfer of methyl group by histone methyltransferases to lysine or arginine amino acid of protein. Effect of methylation depends on the type of protein that is modified. Demethylation is the reverse process.
Histone acetylation is the process of adding of an acetyl group(by histone acetyltransferases) to histone proteins and it can also activate or inhibit the gene expression. Deacetilation is reverse process.
The tissue you are referring to here is the xylem, a <u>vascular tissue</u>, whose basic function is to transport water and nutrients from the roots to the rest of the plant.
Hello!
Natural selection is the way that animals evolve.
The theory of natural selection is that the animals that do not have a specific trait to survive in their environment will die. The animals that do have the trait will survive. The animals that survive will then pass the trait down to their offspring, who will also likely survive because they have the trait. This is how species evolve and continue to survive in their environment.
The species evolve because only the fittest survive (this is known as "survival of the fittest"). The animals that do not have the needed traits will die and they cannot have offspring.
I hope this helps answer your question! Have a great day!
