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All living things contain two types of large molecule, proteins and nucleic acids, the latter usually both DNA and RNA: these carry the information needed by each species, including the instructions to make each type of protein. The proteins, in turn, serve as the machinery which carries out the many chemical processes of life.
A presentation on information flow in living systems. Living systems are life forms (or, more colloquially known as living things) treated as a system. They are said to be open self-organizing and said to interact with their environment. These systems are maintained by flows of information, energy and matter. Multiple theories of living systems ...
All known living things are made up of one or more cells [13] All living cells arise from pre-existing cells by division. The cell is the fundamental unit of structure and function in all living organisms. [14] The activity of an organism depends on the total activity of independent cells. [15] Energy flow (metabolism and biochemistry) occurs ...
Biochemistry is the study of chemical processes within and relating to living organisms. Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including molecular synthesis, modification, mechanisms, and interactions.
No metabolism, so not living, not an organism, say many biologists; [7] but they evolve, their genes collaborating to manipulate the host [18] Unicellular organism: Paramecium: One cell, with organelles e.g. cilia for specific functions: Yes: Inter-cellular (inter-organismal) signalling [22] Swarming protistan: Dictyostelium (cellular slime ...
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
In 1990, a novel concept of the tree of life was presented, dividing the living world into three stems, classified as the domains Bacteria, Archaea, Eukarya. [1] [50] [51] [52] It is the first tree founded exclusively on molecular phylogenetics, and which includes the evolution of microorganisms.
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 functional ...