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Diagram of a typical prokaryotic cell. A prokaryote (/ p r oʊ ˈ k ær i oʊ t,-ə t /, less commonly spelled procaryote) [1] is a single-cell organism whose cell lacks a nucleus and other membrane-bound organelles. [2] The word prokaryote comes from the Ancient Greek πρό (pró) 'before' and κάρυον (káruon) 'nut, kernel'.
Lysosome. Centrosome. Cell membrane. A lysosome ( / ˈlaɪsəˌsoʊm /) is a single membrane-bound organelle found in many animal cells. [ 1][ 2] They are spherical vesicles that contain hydrolytic enzymes that digest many kinds of biomolecules. A lysosome has a specific composition, of both its membrane proteins and its lumenal proteins.
Chloroplasts, containing thylakoids, visible in the cells of Ptychostomum capillare, a type of moss. A chloroplast ( / ˈklɔːrəˌplæst, - plɑːst /) [ 1][ 2] is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells.
The clear epidermal cells exist in a single layer and do not contain chloroplasts, because the onion fruiting body (bulb) is used for storing energy, not photosynthesis. [3] Each plant cell has a cell wall, cell membrane, cytoplasm, nucleus, and a large vacuole. The nucleus is present at the periphery of the cytoplasm.
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 ; [ 20 ] these are separated into two matching sets by a microtubular spindle during nuclear ...
List of food origins. Some foods have always been common in every continent, such as many seafood and plants. Examples of these are honey, ants, mussels, crabs and coconuts. Nikolai Vavilov initially identified the centers of origin for eight crop plants, subdividing them further into twelve groups in 1935. [ 1]
v. t. e. Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. [ 1][ 2] All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. [ 3] Cell biology is the study of the structural and ...
The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy is used to assemble sugars from carbon dioxide and a hydrogen and electron source such as water. It is believed that the pigments used for photosynthesis initially were used for protection from the harmful effects ...