Molekulaar- ja rakubioloogia konspekt
The centromeric DNA is normally in a heterochromatin state, which is essential for the recruitment of
the cohesin complex that mediates sister chromatid cohesion after DNA replication as well as
coordinating sister chromatid separation during anaphase. In this chromatin, the normal histone H3 is
replaced with a centromere-specific variant, CENP-A in humans.
5. Peamine erinevu prokarüootse ja eukarüootse mRNA vahel. (1p)
The mRNAs of many bacteria and bacteriophages are polygenic or polycistronic. A polycistronic
mRNA is transcribed by the several structural genes of an operon. It contains several sites for
initiating and terminating polypeptide synthesis. On the other hand all known eukaryotes have only
one site for initiation of protein synthesis. Thus eukaryote mRNAs are monocistronic.
In most bacterial mRNAs translation begins while the mRNA is still being transcribed on DNA. In
eukaryotes the mRNA transcribed on the chromosomes passes through the nuclear pores into the
cytoplasm
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