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.
Answer:
1= In living organisms cells are composed of water or we can say that water is one of the important constituent of cells.
2= Hydrogen bonding import man properties to the water such as cohesion, high heat of vaporization, high heat capacity etc.
3= Because of high polarity, all polar substance get dissolve and make it universal solvent.
Explanation:
Solvent is the that part of solution which is present in large proportion and have ability to dissolve the solute. In simplest form it is something in which other substance get dissolve. The most widely used solvent is water, other examples are toluene, acetone, ethanol, chloroform etc.
Water is called universal solvent because of high polarity all polar substance are dissolve in it. Hydrogen is less electronegative while oxygen is more electronegative and because of difference in electronegativity hydrogen carry the partial positive charge while oxygen carry partial negative charge.
Hydrogen bond:
The hydrogen bond is the attraction between the toms which already take part in the other chemical bons. The one atom is hydrogen while other may be oxygen, nitrogen or fluorine.
The hydrogen bonding in water import man y properties in it such cohesion, high heat of vaporization, high heat capacity etc. The hydrogen bond hold the water molecules together.
Water create electrostatic interaction with other polar molecules. The negative end of water attract the positive end of polar molecules and positive end of water attract negative end of polar substance and in this way polar substance get dissolve in it.
Example:
when we stir the sodium chloride into water the cation Na⁺ ions are surrounded by the negative end of water i.e oxygen and anion Cl⁻ is surrounded by the positive end of water i.e hydrogen and in this way all salt is get dissolved.
Answer:
electromagnetic energy
Explanation:
sunlight is a radiation, from the electromagnetic spectrum we have visible light and ultraviolet radiation whose source is the light
The nasty fine ash is the smallest of the particles produced in a volcanic eruption. It can kill you if you breathe it in:)
