Answer:
The presence of organelle DNA in mitochondria and chloroplast supports the theory that mitochondria and chloroplast originated as independent prokaryotic organism.
Explanation:
- The more well documented and generally accepted theory for the origin of eukaryotic organelles is Endosymbiotic Theory. (Margulis 1970).
- Recent evidences justify that organelles have originated from the endosymbiotic association of ingested aerobic and and photosynthetic prokaryote, the precursors of mitochondria and chloroplast respectively.
- Molecular data have played an important role in supporting the xenogenous origin rather than autogenous origin of organelles.
- The idea of independent existence of mitochondria and chloroplast are: they are replicators; they carry genetic information; they have protein synthesising machinery; they have ribosome of prokaryotic type.
- The prokaryotic or bacterial origin of mitochondria and chloroplast is supported by the fact like their DNA is simple ,closed and circular with single point of origin; DNA controls the synthesis of their rRNA and tRNA etc.; They have their own ribosome; antibiotic specificity.
A histone is a protein that interacts with DNA to coil it into a nucleosome.
A nucleosome is a small unit of DNA coiled around 8 histone proteins.
Therefore, the major difference is that a nucleosome is a small structure and histones are the proteins that help form the structure.
Stem cells<span> are a class of undifferentiated </span>cells<span> that are able to differentiate into specialized </span>cell<span> types. Commonly, </span>stem cells<span> come from two main sources: Embryos formed during the blastocyst phase of embryological development (embryonic </span>stem cells<span>) and. Adult tissue (adult </span>stem cells<span>).
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