Summary. Base pairs<span> occur when </span>nitrogenous bases<span>make hydrogen bonds with each other. Each </span>base<span> has a specific partner: guanine with </span>cytosine<span>, </span>adenine<span> with thymine (in </span>DNA<span>) or </span>adenine<span> with uracil (in RNA). The hydrogen bonds are weak, allowing </span>DNA<span> to 'unzip'.</span>
Immune system that is the answer to you question I think
Answer: B (GTP serves as the energy input for AMP synthesis from IMP)
Explanation:
In the de novo synthesis of purine nucleotide, IMP represents a branch point for purine biosynthesis. IMP can be converted to either AMP or GMP.
The formation of AMP from IMP requires GTP; similarly formation of GMP requires ATP. The conversion of IMP to either AMP or GMP is highly regulated – AMP and GMP inhibits their own formation by feedback inhibition of adenlyosuccinate synthetase and IMP dehydrogenase.
Answer:
This is through the process of methylation and phosphorylation of histones tails.
Explanation:
The addition of a methyl group to the amino acid of the histones of the nucleosomes that compacted DNA in the nucleus is called mehtylation, while the addtion of phodpahte is phosphorylation
Its effects on gene expression depends on the number of <u> methyl groups, and type of amino acid that methylated. During transcription. </u>
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The DNA double strands are compacted and therefore hidden from transcription factors and enzymes of transcription by the hitones tails of the neuclosomes, Methylation weaken the binding bonds between the tails and DNA structure ; thereby aiding the uncoiling of DNA from the tails.(nucleosomes).This chemical reaction aided DNA strands exposure to transcription factors and enzymes, for initiation of transcription. This explains the dyanmic activity of methylation
Futhermore phophorylation also favours unwrapping of DNA, by imitating modifying enzymes e.g H3Y41E and H3T45E and convert it to→→ H3Y41phopspahte to aid DNA unwrapping and accessibility to transcription factors and RNA polymerase Enzymes,