Essay on Endosymbiosis

When life arose on Earth about 4 billion years ago, the first types of cells to evolve were prokaryotic cells. For approximately 2 billion years, prokaryotic-type cells were the only form of life on Earth. The oldest known sedimentary rocks found in Greenland are about 3.8 billion years old. The oldest known fossils are prokaryotic cells, 3.5 billion years in age, found in Western Australia and South Africa. The nature of these fossils, and the chemical composition of the rocks in which they are found, indicates that these first cells made use of simple chemical reactions to produce energy for their metabolism and growth. Eukaryotic cells evolved into being between 1.5 and 2 billion years ago. Eukaryotic cells appear to have arisen from prokaryotic cells, specifically out of the archaea. Indeed, there are many similarities in molecular biology of contemporary archaea and eukaryotes. However, the origin of the eukaryotic organelles, specifically chloroplasts and mitochondria, is explained by evolutionary associations between primitive nucleated cells and certain respiratory and photosynthetic bacteria, which led to the development of these organelles and the associated explosion of eukaryotic diversity. Today Prokaryotes

Evidence to support Margulis’s Endosymbiotic Theory has grown over the years. This evidence includes a double membrane surrounding the organelles with an inner layer that

The genes which encode for the mitochondria’s component proteins are in 2 separate genetic systems in 2 different locations. One of which is the cell nucleus, but the other is inside the organelle itself. There are relatively few genes inside the

7. The theory of endosymbiosis says that mitochondria and plastids used to be small prokaryotes living within larger cells. The prokaryotic ancestors of mitochondria and plastids were bacteria engulfed by a larger cell. Because they both benefited from this situation, the bacteria living inside the cell was passed down from generation to generation. The evidence is that mitochondria reproduce and move independently within the cell.

Ribosomes then started copy themselves into cell-like structure with a thin membrane and cytoplasm. Eventually, cells starting storing DNA. Lateral transfer diversified the cells genetic makeup. From this community of cells came the three domains, known as bacteria, eukaryotes, and archaea. Bacteria and archaea are together called

The part of the mitochondria in cell digestion, glucose oxidation comes upon in the mitochondria and is isolated into two parts. Cell breath is additionally partitioned into the Krebs cycle and terminal electron transport, which occurs in the essential laminae and the type of the mitochondria. The part of the chloroplasts in cell digestion, carbon obsession happens in the chloroplast and is isolated into the light retainer and light autonomous conservatism then it produces ATP and NADPH. Additionally, it drives the light-free into the responses of Calvin cycle where CO2 gets lessened to glucose.

Endoplasmic Reticulum is present in eukaryotic cells. There are two types of ER: Smooth and rough. “This organelle is formed of a network of

Chloroplasts are important photosynthetic organelles that present in plant cells. It is believed that chloroplasts evolve from an endosymbiotic event; engulfment of a photosynthetic cyanobacterium by a large heterotrophic host cell (1, 2). During this process proteins in the cyanobacterium has been transferred to the nucleus and also the proteins that are essential for organelle biogenesis has been transferred to the cyanobacterium making it dependent on the host. Although chloroplast proteins have estimated to consist of 3500-4000 different types of polypeptides, the protein coding capacity in chloroplast genes is approximately 200 polypeptides (3, 4). This data further suggest that most of the proteins found in chloroplast are encode by nuclear genome and transport to the chloroplast. At least, a few proteins are use secretory pathway in which first targeted to the endoplasmic reticulum and then transfer to the chloroplast through vesicles (5-7).

13. Who is largely responsible for proposing the endosymbiosis theory? 
A. Schimper, Wallin, Margulis
B. Lyon, Margulis, Schimper
C. Schimper, Wallin, Barr
D. Barr, Lyon, Margulis

The Endosymbiotic theory is an assumption based on experience and/or limited information about the evolution of the cell. Bacteria are one of the oldest single cellular organisms. They began to make their own food using photosynthesis which then produced enough oxygen to reshape Earth 's atmosphere. This change brought upon diverse bacterial life which include clear evidence that chloroplasts and mitochondria were, at one point, crude bacterial cells. Over the years, chloroplasts and mitochondria became dependent on a host cell. After millions of years of evolution, chloroplasts and mitochondria cannot survive outside of the cell. This is the Endosymbiotic theory. Although this is labeled a theory, there is striking evidence that shows similarities in both bacteria, and mitochondria and chloroplasts. They all have their own DNA (separate from the nucleus), and they both use this DNA to produce proteins and enzymes for their functions.

Once a upon time, there was a lonely mitochondria named Sophia Mitochondria. Sophia Mitochondria had been alone for a while and she does not know where her parents are. She want to find her parents so she decided to talk someone to help her which is her childhood best friend, David Chloroplast. However, before she called him, she did her normal routine. She took nutrients from one of their cells, breaks it down and turn it into energy. This routine is also known as cellular respiration. After that, she call her David Chloroplast and thirty minutes later, David Chloroplast was in front of her house. David Chloroplast and Sophia Mitochondria came to Bacteria Garden which Sophia Mitochondria’s parents favorite place to go every weekend. When they

After time the hot surface of the Earth was cooled down with rain that gave formation to oceans. In oceans prokaryotes, single celled organisms , were formed. Eventually prokaryotes merged with one another to create eukaryotes, more complex single celled organisms. Prokaryotes and eukaryotes became the building blocks of all organisms.

This is an example of a rotating motor in nature. The prokaryotic flagellum does not have the same the same structure as eukaryotic flagellum. The cytoplasm contains all the enzymes needed for all metabolic reactions, since there are no organelles. Nutrients and reserves may be stored in the cytoplasm in the form of granules of glycogen, lipids, polyphosphate, or in some cases, sulphur or nitrogen. The ribosomes are for protein synthesis just like eukaryotic ribosomes but they are smaller than eukaryotic ribosomes.

Mitochondria are the powerhouse of the cell with versatile operating systems (i.e. converts energy derived from foods into cellular energy e.g. ATP, Amino Acid and lipid metabolisms, iron-sulphur clusters and haem biosynthesis, and also the regulation of apoptosis) (Harbauer et al., 2014, Bolender et al., 2008, Wiedemann et al., 2004). Equally, chloroplasts are also very versatile and operates several metabolic and cellular processes (i.e. photosynthesis, amino acid and lipid metabolism, cellular signalling and

Another cellular feature shared by both Archaea and Bacteria is size and arrangement of ribosomes. Their ribosomes are much smaller in comparison to eukaryotes. The function of their ribosomes is similar to the ones in eukaryotes; for translating mRNA codons to sequence of amino acids for the synthesis of proteins. Both have 70S Ribosomes composed of 30S and 50S sub units that are joined to make a 70S unit. They contain “three ribonucleic acid molecules” consisting of “16S, 23S AND 5S”. On the other hand, the “primary structure of Archaea r-RNA and r-Proteins” is much similar to the ones in eukaryotes and less similar to that of bacteria. Additionally, the Archaea ribosome is much firm compared to mesophilic bacteria’s ribosomes, this is particularly beneficial in terms of their adaptation to extreme environmental conditions. (Archaeal Ribosomes, Paola Londei, university of Rome, “Sapienza”