THE ORIGIN OF CELL (TIMELINE) by Gloria Salas https://padlet.com/gloriasalas/raasgasg151aciyjy9 By Gloria Salas, Macarena Cubillas, Alessandra Serkovic, Valentino Contreras, and Rodrigo Mazzini. en-us 2021-07-05 17:44:59 UTC 2026-02-25 23:22:24 UTC hello@padlet.com The cell macarenacubillas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1637623175 The first cells were on our planet 3500 x 106 and 3800 x 106 years ago. They rarely survived because of the environment. Scientists looked for explanation of how they appeared and it's a controversial topic.]]> 2021-07-05 17:59:36 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1637623175 1859 - Darwin theory gloriasalas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643320243 It is a two-step mechanism at each stage of development that explains cell differentiation. 
At first, gene expression was unstable, but thanks to cellular interactions it stabilized.
The first sign of cell differentiation was created by diffusion of the substrate within growing cell populations. This gave the cells more metabolism, so they can use more food resources. Also, cell differentiation can be seen as an extension of natural selection within organisms.]]> 2021-07-09 13:23:55 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643320243 1988 - Wachtershause macarenacubillas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643415816 Wachtershause had a theory that said that cells were formed from surface bound protoplasm but his theory failed because he couldn't explain how the absence of a component from the cells would make a diference and form other ones.]]> 2021-07-09 14:56:59 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643415816 1920s - Endosymbiotic theory alessandraserkovic https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643608686 The endosymbiotic theory explains how the eukaryote cell could have evolved from the prokaryotic cell.
Over 2 billions years ago there were a variety of prokaryotes, some had photosynthetic abilities, others could use oxygen to produce ATP and other was that large that could consume other prokaryotes.
The theory says that the larger cells swallowed these bacteria and some of they remained intact and lived together, the bacteria that could produce ATP evolved and became mitochondria and the bacteria with photosynthetic abilities evolved and became chloroplasts.
The theory was rejected in the 1920s and was repopularized in the 1960s.
]]> 2021-07-09 19:00:27 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643608686 1990s - The 'adder' principle gloriasalas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643684302 It is a process of cell division that controls cell size and homeostasis in bacteria. 
Some bacterial species correct their variations in cell size by adding a constant volume between birth and division. It balances biosynthesis by accumulating FtsZ proteins during steady-state growth at the unicellular level. Thanks to this, we can explain the mechanistic origin of size homeostasis in bacteria. 
FtsZ is an essential protein that is required for division in bacteria. It accumulates at the middle of the cell during cell elongation. They are produced at the same rate as the cell elongation rate, so when a cell divides, they have the same number of FtsZ proteins.]]> 2021-07-09 21:16:45 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643684302 2003 - Shenhav macarenacubillas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643744895 Shenhav's theory stated that the cells came form protocells. It is more likely for this to happen but the protocell would have had to appear spontaneosly on one place.]]> 2021-07-09 23:29:21 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643744895 2000 - Dobson macarenacubillas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643749490 Aerosol droplets counting as precellular organisms could be the origin of cells is Dobson's theory.]]> 2021-07-09 23:40:56 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643749490 1999 - Wilson macarenacubillas https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643752193 This is the neighborhood selection theory. Different types of organisms that were near formed a cell and then it started to multiply.]]> 2021-07-09 23:46:48 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1643752193 The theory of panspermia valentinocontreras https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644165972 This theory is about an extraterrestrial origin of the cells that then went to the planet. This thing that entered to the earth was named "seed" that was more or less complex than organic molecules, but there is no evidence that this theory is real.]]> 2021-07-10 17:33:30 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644165972 How the first cell apeared valentinocontreras https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644170988 The most possible thing that could have happened to create the first cell was that a simple molecule transformed into a cell and there is no agreement in how many steps there were.]]> 2021-07-10 17:48:43 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644170988 Cavalier-Smith rodrigomazzini https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644750100 Cavalier-Smith argued that nuclear and endoplasmic reticulum membranes originated through invaginations of the plasma membrane of a prokaryotic cell. He suggested that the prokaryote initially lost its cell wall and thereby gained the ability to phagocytose food particles. Ribosomes, primarily attached to the plasma membrane, became internalized, but still attached to the membrane, resulting first in the rough endoplasmic reticulum and out of it the nuclear envelope. ]]> 2021-07-11 23:15:02 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644750100 1979 Gould & Dring rodrigomazzini https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644812403 Gould & Dring had a theory that said that endospore formation of Gram-positive bacteria resulted in the origin of the nucleus. The protoplast of a single cell divides during endospore formation in such a manner that the cell engulfs a portion of its own cytoplasm, which than becomes surrounded by a double membrane resulting in the cell's nucleus. ]]> 2021-07-12 00:20:40 UTC https://padlet.com/gloriasalas/raasgasg151aciyjy9/wish/1644812403