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Cell metabolism is the process by which individual cells process nutrient molecules. Metabolism has two distinct divisions: catabolism , in which the cell breaks down complex molecules to produce energy and reducing power , and anabolism , in which the cell uses energy and reducing power to construct complex molecules and perform other ...
Marine cyanobacteria are to date the smallest known photosynthetic organisms; Prochlorococcus is the smallest at just 0.5 to 0.7 micrometres in diameter. [11] [2] The coccoid shaped cells are non-motile and free-living.
Zygote – A cell that is the result of fertilization (the fusing of two gametes). Egg – The zygote of most birds and reptiles, resulting from fertilization of the ovum. The largest existing single cells currently known are (fertilized) eggs. Meristemic cell – Undifferentiated plants cells analogous to animal stem cells.
These vacuoles make up most of the cell. As these vacuoles swell, the cell grows considerably which is the primary factor contributing to the record sizes of Thiomargarita cells. T. namibiensis holds the record for the world's second largest bacterium, with a volume three million times more than that of average bacteria. [29]
With a mass of approximately 1.95 grams (0.069 oz) and a length of 5.5 centimetres (2.2 inches), the bee hummingbird (Mellisuga helenae) is the smallest known dinosaur as well as the smallest bird species, and the smallest warm-blooded vertebrate. Called the zunzuncito in its native habitat on Cuba, it is lighter than a Canadian or U.S. penny.
Eukaryotic cells contain membrane bound organelles. Some examples include mitochondria, a nucleus, or the Golgi apparatus. Prokaryotic cells probably transitioned into eukaryotic cells between 2.0 and 1.4 billion years ago. [31] This was an important step in evolution. In contrast to prokaryotes, eukaryotes reproduce by using mitosis and meiosis.
Diagram of a prokaryotic cell, a bacterium with a flagellum. A prokaryote (/ p r oʊ ˈ k ær i oʊ t,-ə t /; less commonly spelled procaryote) [1] is a single-celled organism whose cell lacks a nucleus and other membrane-bound organelles. [2]
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.