Placenta (Definition) The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply.
Lesson Summary. The nucleoid region is the irregularly-shaped section of a prokaryotic cell where DNA is housed. It lacks the membrane that is found around the nucleus of eukaryotic cells. In addition to DNA, the nucleoid may also contain RNA, proteins, and enzymes that can be used for cellular processes.s the cells grow, the DNA in the nucleoid may extend into the cytosol, or cellular fluid. The nucleoid region may also contain proteins, enzymes, which are biological catalysts, and RNA. These proteins are necessary for several processes that take place in this region.
Nucleosomes are responsible for the familiar beaded appearance of chromatin seen in the electron microscope. The nucleosome is a wedge-shaped disk, about 110 A in diameter and about 55 A high, with a pseudo-dyad axis of symmetry close to which the entering and exiting DNA duplexes lie.owever, results obtained for a nucleosome reconstituted on to Xenopus 5S rRNA gene, which contains a strong nucleosome positioning sequence (see Chromatin), suggested a fundamentally different picture, with the globular domain bound away from the dyad axis and inside the DNA gyres, contacting only one duplex (6).