Answer:
D
DNA, cytoplasm and cell membranes
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 first three are the same as those found in DNA, but in RNA thymine is replaced by uracil as the base complementary to adenine. This base is also a pyrimidine and is very similar to thymine. Uracil is energetically less expensive to produce than thymine, which may account for its use in RNA.
Answer:
The answer is A.
Explanation:
Since only 1 of the options is wrong, i assume you are looking for that one.
Two types of immunity systems, innate immunity and adaptive immunity. Adaptive immunity is formed when it is exposed to a harmful substance, vaccines for example create adaptive immunity.
Innate immunity is present at birth which consists our skin protects us physically, chemical substances in our blood that protect us from bacteria and infections and also our blood cells such as T cells.
Since innate immunity forms one of the first lines of defense in our immune system and is the first to respond to a threat in a few hours down to as little as minutes, it is not slower than adaptive immunity in its response to infections and pathogens.
I hope this answer helps.
