Question: Presence of a protein capsule and a well-defined nucleus?
One of the most important features of eukaryotic cells is the presence of a protein capsule and a well-defined nucleus. These structures are essential for the protection and regulation of the genetic material, as well as for the communication and interaction with other cells. In this blog post, we will explore the functions and characteristics of the protein capsule and the nucleus, and how they differ from prokaryotic cells.
The protein capsule, also known as the cell wall or the extracellular matrix, is a layer of proteins and polysaccharides that surrounds the plasma membrane of some eukaryotic cells. The protein capsule provides mechanical support, prevents dehydration, and mediates cell adhesion and recognition. The composition and structure of the protein capsule vary depending on the type and function of the cell. For example, plant cells have a rigid cell wall made of cellulose, while animal cells have a flexible extracellular matrix composed of collagen and other proteins.
The nucleus is the organelle that contains the DNA and controls the gene expression of the cell. The nucleus is enclosed by a double membrane called the nuclear envelope, which has pores that allow the exchange of molecules between the nucleus and the cytoplasm. The nucleus also contains a dense structure called the nucleolus, where ribosomal RNA is synthesized and assembled with proteins to form ribosomes. The DNA in the nucleus is organized into chromosomes, which are further condensed into chromatin during cell division.
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