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Microevolution is the change in allele frequencies that occurs over time within a population. [1] This change is due to four different processes: mutation , selection ( natural and artificial ), gene flow and genetic drift .
Bacterial growth is proliferation of bacterium into two daughter cells, in a process called binary fission. Providing no mutation event occurs, the resulting daughter cells are genetically identical to the original cell. Hence, bacterial growth occurs. Both daughter cells from the division do not necessarily survive.
Bacteria are prokaryotic microorganisms that can either have a bacilli, spirilli, or cocci shape and measure between 0.5-20 micrometers. They were one of the first living cells to evolve [9] and have spread to inhabit a variety of different habitats including hydrothermal vents, glacial rocks, and other organisms.
The increased cell length can protect bacteria from protozoan predation and neutrophil phagocytosis by making ingestion of cells more difficult. [1] [3] [4] [5] Filamentation is also thought to protect bacteria from antibiotics, and is associated with other aspects of bacterial virulence such as biofilm formation. [6] [7]
Transduction: Bacteriophages (virus) move genes from one bacterial cell to another; Once one of these mechanisms has occurred the bacteria will continue to multiply and grow resistance and evolve by natural selection. HGT is the main cause of the assimilation of certain genetic material and the passing down of antibiotic resistance genes (ARGs).
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. Bacterial conjugation has been extensively studied in Escherichia coli , but also occurs in other bacteria such as Mycobacterium smegmatis .
The 12 E. coli LTEE populations on June 25, 2008. [1]The E. coli long-term evolution experiment (LTEE) is an ongoing study in experimental evolution begun by Richard Lenski at the University of California, Irvine, carried on by Lenski and colleagues at Michigan State University, [2] and currently overseen by Jeffrey Barrick at the University of Texas at Austin. [3]
Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. [1] Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than the overall rate of cellular degradation (the destruction of biomolecules via the proteasome, lysosome or autophagy, or catabolism).