Energy metabolism in eukaryotes vs prokaryotes
The possibility that may have an endosymbiotic origin has also been considered, although they lack DNA. proposed that they may have been the first endosymbionts, allowing cells to withstand growing amounts of free molecular oxygen in the Earth's atmosphere. However, it now appears that they may be formed de novo, contradicting the idea that they have a symbiotic origin.
Endosymbiont theory for origin of mitochondria
Endosymbiotic theory, which is often referred to as “symbiogenesis,” is an evolutionary theory that attempts to explain the origin of eukaryotic cells. It is a hypothesis which essentially postulates that prokaryotes were what gave rise to the first eukaryotic cells and, if true, would rank amongst the most important evolutionary events in our history.
Eukaryotic cell organelles include mitochondria that is found in animals or fungi and the chloroplasts that are found in plants. Mitochondria are one of several different organelles that are found in the cells of every single eukaryotic cell.
which get nutrition from their endosymbiotic bacteria
In eukaryotic cells, glycolysis and fermentation reactions occur in the cytoplasm. The remaining pathways, starting with pyruvate oxidation, occur in the mitochondria. Most eukaryotic mitochondria can use only oxygen as the terminal electron acceptor for respiration. In the presence of oxygen, pyruvate enters the mitochondrial matrix and is oxidized to acetyl-CoA, and then to CO2 via the citric acid cycle. The electron transport chain and ATP synthase are located on the mitochondrial inner membrane.
The Endosymbiotic Hypothesis | Just another …
In prokaryotic cells, all the metabolic pathways occur in the cytoplasm, except for chemiosmosis and oxidative phosphorylation, which occur on the plasma membrane. Prokaryotic cells are capable of anaerobic respiration using alternative electron acceptors such as nitrate and sulfate, although they prefer oxygen as the terminal electron acceptor to drive chemiosmotic ATP synthesis. In the absence of any suitable electron acceptor, they use fermentation pathways.
Endosymbiotic hypothesis – Conservapedia
In other words, the eukaryote cell would eat the prokaryote, but would not actually digest it. It would instead keep the bacterium in a symbiotic relationship so that the two co-exist together. The symbiont would then begin to lose some of its genetic material as it forms into a mitochondrion.
A theory on the Origins of Eukaryotic Cells: ..
The Nobel Prize winner Otto Warburg observed that many, and perhaps most, cancer cells derive most of their energy from glycolysis and lactic acid fermentation, even when oxygen is plentiful (see review by Liberti and Locasale, 2016). Several explanations have been proposed. One is that cancer cells can promote biosynthesis and cell growth by NOT respiring organic carbon to CO2, and using the organic carbon to build cellular biomolecules, instead. Another hypothesis is that ramping up glycolysis allows tumor cells to out-compete normal cells or immune system cells for glucose. A third hypothesis is that lactic acid secretion causes changes in the tumor cells’ environment that favors tumor cell growth and spread.
The origin of the eukaryotic cell.
This process would then continue because the eukaryote and mitochondria are still existing in a symbiotic relationship. The theory holds that the eukaryote and mitochondria symbiont would eat an autotrophic eukaryote cell, but again not actually digest it. As before, the new cell would also be kept as a symbiont. The secondary symbiont would also lose some of its genetic material during this process and this would be the foundation of the creation of a chloroplast.