function of the nucleus (found only in eukaryotic cells) is simply to keep the huge expanse of DNA in one place.
Maureen -цитирует5 лет назад
nucleus has a phospholipid bilayer membrane of its own, just like the cell’s main membrane. And, of course, it lets things in and out, just as the cell’s membrane does.
Maureen -цитирует5 лет назад
Around certain sections of DNA inside the nucleus is a dense crowding of molecules that constantly produce new ribosomes, the molecular machines that actually build the proteins.
Maureen -цитирует5 лет назад
Schematic diagram of a section of DNA. The green twisting section represents the sugar-phosphate backbone, and the rungs are the nucleobases. A (purple) always bonds with T (orange), and C (yellow) with G (pink).
Maureen -цитирует5 лет назад
eukaryotic cells (and in archaea), the DNA is wrapped every so often along its length around blobs of a protein called histones; the result looks like beads (histones) on a string (DNA). The beaded string is further wrapped around itself, so that it becomes a much fatter string
Maureen -цитирует5 лет назад
a protein is to be made, enzymes unpack and unwind the section of the DNA containing the relevant gene, so that the code becomes exposed.
Maureen -цитирует5 лет назад
end, with eight histone molecules at its core, is called a nucleosome
Maureen -цитирует5 лет назад
first two stages in the process of protein building are copying out the recipe and taking it outside the nucleus.
Maureen -цитирует5 лет назад
(ribonucleic acid), a compound very similar to DNA (deoxyribonucleic acid) but single-stranded.
Maureen -цитирует5 лет назад
RNA is copied from the complementary strand of DNA, not the coding strand.