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 question is incomplete. The complete question is as follows:
Which of the following mutations is most likely to cause a phenotypic change?
A) a duplication of all or most introns
B) a large inversion whose ends are each in intergenic regions
C) a nucleotide substitution in an exon coding for a transmembrane domain
D) a single nucleotide deletion in an exon coding for an active site
E) a frameshift mutation one codon away from the 3' end of the nontemplate strand
Answer: D) a single nucleotide deletion in an exon coding for an active site
Explanation:
Deletion or insertion of a single nucleotide in an axon coding for an active site is called frameshift mutation.
The sequence of codons is read during translation, in order to synthesize a amino acids chain and form a protein from the nucleotide sequence. Frameshift mutations occur when the usual codon sequence is broken by the deletion or addition of one or more nucleotides. For example, if only one nucleotide is removed from the axon sequence during the RNA splicing process, then there will be a disrupted reading frame for all codons before and after the mutation. This may result in several incorrect amino acids being introduced into the protein. Disruption in protein sequence will cause phenotypic change.
Hence, the correct option is D) a single nucleotide deletion in an exon coding for an active site
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Answer:
moth is biotic
Explanation:
biotics are living things
I believe you use the pH scale with comparing acids and bases.
