Biogenesis in the context of "Common descent"

A generation is all of the people born and living at about the same time, regarded collectively. It also is "the average period, generally considered to be about 20–30 years, during which children are born and grow up, become adults, and begin to have children." In kinship, generation is a structural term, designating the parent–child relationship. In biology, generation also means biogenesis, reproduction, and procreation.

Generation is also a synonym for birth/age cohort in demographics, marketing, and social science, where it means "people within a delineated population who experience the same significant events within a given period of time." The term generation in this sense, also known as social generations, is widely used in popular culture and is a basis of sociological analysis. Serious analysis of generations began in the nineteenth century, emerging from an increasing awareness of the possibility of permanent social change and the idea of youthful rebellion against the established social order. Some analysts believe that a generation is one of the fundamental social categories in a society; others consider generation less important than class, gender, race, and education.

The biosphere (from Ancient Greek βίος (bíos) 'life' and σφαῖρα (sphaîra) 'sphere'), also called the ecosphere (from Ancient Greek οἶκος (oîkos) 'settlement, house' and σφαῖρα (sphaîra) 'sphere'), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to matter, with minimal inputs and outputs. Regarding energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 100 terawatts. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis (life created naturally from non-living matter, such as simple organic compounds) or biogenesis (life created from living matter), at least some 3.5 billion years ago.

In a general sense, biospheres are any closed, self-regulating systems containing ecosystems. This includes artificial biospheres such as Biosphere 2 and BIOS-3, and potentially ones on other planets or moons.

Lazzaro Spallanzani (Italian pronunciation: [ˈladdzaro spallanˈtsaːni]; 12 January 1729 – 11 February 1799) was an Italian Catholic priest (for which he was nicknamed Abbé Spallanzani), biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and animal echolocation. His research on biogenesis paved the way for the downfall of the theory of spontaneous generation, a prevailing idea at the time that organisms develop from inanimate matters, though the final death blow to the idea was dealt by French scientist Louis Pasteur a century later.

His most important works were summed up in his book Expériences pour servir a l'histoire de la génération des animaux et des plantes (Experiences to Serve to the History of the Generation of Animals and Plants), published in 1785. Among his contributions were experimental demonstrations of fertilisation between ova and spermatozoa, and in vitro fertilisation.

In molecular biology, circular ribonucleic acid (or circRNA) is a type of single-stranded RNA which, unlike linear RNA, forms a covalently closed continuous loop. In circular RNA, the 3' and 5' ends normally present in an RNA molecule have been joined together. This feature confers numerous properties to circular RNA, many of which have only recently been identified.

Many types of circular RNA arise from otherwise protein-coding genes. Some circular RNA have been shown to code for proteins. Some types of circular RNA have also recently shown potential as gene regulators. The biological function of most circular RNA is unclear.

Extracellular vesicles (EVs) are lipid bilayer-delimited particles that are naturally released from almost all types of cells. EVs range in diameter from near the size of the smallest physically possible unilamellar liposome (around 20–30 nanometers) to as large as 10 microns or more, although the vast majority of EVs are smaller than 200 nm. EVs can be divided according to size and synthesis route into exosomes, microvesicles and apoptotic bodies. The composition of EVs varies depending on their parent cells, encompassing proteins (e.g., adhesion molecules, cytoskeletons, cytokines, ribosomal proteins, growth factors, and metabolic enzymes), lipids (including cholesterol, lipid rafts, and ceramides), nucleic acids (such as DNA, mRNA, and miRNA), metabolites, and even organelles. Most cells that have been studied to date are thought to release EVs, including some archaeal, bacterial, fungal, and plant cells that are surrounded by cell walls. A wide variety of EV subtypes have been proposed, defined variously by size, biogenesis pathway, cargo, cellular source, and function, leading to a historically heterogenous nomenclature including terms like exosomes and ectosomes.

Numerous functions of EVs have been established or postulated. The first evidence for the existence of EVs was enabled by the ultracentrifuge, the electron microscope, and functional studies of coagulation in the mid-20th century. A sharp increase in interest in EVs occurred in the first decade of the 21st century following the discovery that EVs could transfer nucleic acids such as RNA from cell to cell. Associated with EVs from certain cells or tissues, nucleic acids could be easily amplified as markers of disease and also potentially traced back to a cell of origin, such as a tumor cell. When EVs are taken up by other cells, they may alter the behaviour of the recipient cell, for instance EVs released by colorectal cancer cells increase migration of fibroblasts and thus EVs are of importance in forming tumour landscapes. This discovery also implied that EVs could be used for therapeutic purposes, such as delivering nucleic acids or other cargo to diseased tissue. Conversely, pharmacological inhibition of EV release, through Calix[6]arene, can slow down progression of experimental pancreatic cancer. The growing interest in EVs as a nexus for therapeutic intervention was paralleled by formation of companies and funding programs focused on development of EVs as biomarkers or therapies of disease, the founding of an International Society for Extracellular Vesicles (ISEV), and establishment of a scientific journal devoted to the field, the Journal of Extracellular Vesicles.