What is in the cells of plants and in animals and all other eukaryotes

eukaryote is any organism whose cells have a cell nucleus and other organelles enclosed within membranes. Eukaryotes belong to the domain Eukaryota or Eukarya, and can be single-celled or multi-cellular.

Or:

Eukaryotes are made up of eukaryotic cells. Eukaryotic cells contain a nucleus and membrane-bound organelles.

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