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From these conclusions about plants and animals, two of the three tenets of cell theory were postulated. 1. All living organisms are composed of one or more cells 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert ...
In evolutionary biology, the term cellularization (cellularisation) has been used in theories to explain the evolution of cells, for instance in the pre-cell theory, [1] [2] [3] dealing with the evolution of the first cells on this planet, and in the syncytial theory [4] attempting to explain the origin of Metazoa from unicellular organisms.
The eukaryotic cell seems to have evolved from a symbiotic community of prokaryotic cells. DNA-bearing organelles like mitochondria and chloroplasts are remnants of ancient symbiotic oxygen-breathing bacteria and cyanobacteria , respectively, where at least part of the rest of the cell may have been derived from an ancestral archaean prokaryote ...
The cell cycle is a sequence of activities in which cell organelles are duplicated and subsequently separated into daughter cells with precision. There are major events that happen during a cell cycle. The processes that happen in the cell cycle include cell development, replication and segregation of chromosomes.
DNA replication, or the process of duplicating a cell's genome, [2] always happens when a cell divides through mitosis or binary fission. This occurs during the S phase of the cell cycle. In meiosis, the DNA is replicated only once, while the cell divides twice. DNA replication only occurs before meiosis I.
Eukaryogenesis, the process which created the eukaryotic cell and lineage, is a milestone in the evolution of life, since eukaryotes include all complex cells and almost all multicellular organisms. The process is widely agreed to have involved symbiogenesis , in which an archeon and a bacterium came together to create the first eukaryotic ...
The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell that causes it to divide into two daughter cells. These events include the growth of the cell, duplication of its DNA ( DNA replication ) and some of its organelles , and subsequently the partitioning of its cytoplasm, chromosomes and other ...
Every cell interacts with its eight neighbours, which are the cells that are horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur: Any live cell with fewer than two live neighbours dies, as if by underpopulation. Any live cell with two or three live neighbours lives on to the next generation.