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Cells are broadly categorized into two types: eukaryotic cells, which possess a nucleus, and prokaryotic cells, which lack a nucleus but have a nucleoid region. Prokaryotes are single-celled organisms such as bacteria , whereas eukaryotes can be either single-celled, such as amoebae , or multicellular , such as some algae , plants , animals ...
Mammalian red blood cells, which do not contain nuclei, are considerably smaller than those of most other vertebrates. [10] Mature red blood cells of birds have a nucleus, however in the blood of adult females of penguin Pygoscelis papua enucleated red blood cells (B) have been observed, but with very low frequency.
The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells.Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
In the eukaryotic cell, the cytosol is surrounded by the cell membrane and is part of the cytoplasm, which also comprises the mitochondria, plastids, and other organelles (but not their internal fluids and structures); the cell nucleus is separate. The cytosol is thus a liquid matrix around the organelles.
The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles [1] and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm. The main components of the ...
Eukaryotic cells have a variety of internal membrane-bound structures, called organelles, and a cytoskeleton which defines the cell's organization and shape. The nucleus stores the cell's DNA , which is divided into linear bundles called chromosomes ; [ 19 ] these are separated into two matching sets by a microtubular spindle during nuclear ...
The nuclear envelope, also known as the nuclear membrane, [1] [a] is made up of two lipid bilayer membranes that in eukaryotic cells surround the nucleus, which encloses the genetic material. The nuclear envelope consists of two lipid bilayer membranes: an inner nuclear membrane and an outer nuclear membrane. [4]
They are cells that possess a large smooth nucleus, a large area of cytoplasm, and many internal vesicles for processing foreign material. Although they can be derived from monocytes, a large proportion is already formed prenatally in the yolk sac and foetal liver.