Endosymbiosis is important as it enables us to understand the evolution of eukaryotes from the common ancestor. This essay will focus on: the early evolution of our eukaryote ancestor during Precambrian period, plastids origin along the algae family due to second endosymbiosis; discuss the evidence that supports the theory, including further examples of endosymbiosis.
The theory, as discussed by Lynn Margulis, states that mitochondria originated from α-proteobacteria bacterium which was engulfed by the ancestral anaerobic eukaryotic cell, through endocytosis, and retained within the cytoplasm due to atmospheric oxygen increase. Prokaryote organism produced ATP, through oxidative phosphorylation, by receiving organic compounds from the eukaryote, causing the eukaryote to become dependent on prokaryote for ATP production and the prokaryote to become dependent on the eukaryote for other cellular functions. Consequently, both organisms evolved in symbiosis with each other and most the genes of a unicellular organism were transferred to the genome of the host, getting enclosed in the nucleus. Due to the advantageous relationship between the host and symbiont, prokaryote organism lost their ability to survive independently and, was reduced into mitochondria which were transmitted to future generation vertically (Debashish et al., 2003). The evolutionary history of plants involves at least two independent endosymbiotic events (as shown in Figure 1); because plastids such as chloroplast evolved when a primary endosymbiotic event caused photosynthetic cyanobacteria to be engulfed by some non-photosynthetic host cells (Dyall et al., 2004).
Chlorophyta, Rhodophyta and Glaucophyta are three clades, belonging to the group Archaeplas...
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...n, P.J., 2004. Ancient Invasions: From Endosymbionts to Organelles. Science, 304 (5668), pp. 253-257.
Lake, J.A., 2009. Evidence for an early prokaryotic endosymbiosis. Nature, 460, pp. 967-971.
McFadden, G. I., 2001.Primary and Secondary Endosymbiosis and the Origin of Plastids. Journal of Phycology, 37(6), pp. 951–959.
Rumpho, M.E., Worful, J.M., Lee J., Kannan, K., Tyler, M.S., Bhattacharya, D., Moustafa, A. and Manhart, J.R., 2008. Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica. PNAS, 105(46), pp. 17867-17871.
Smith, A.M., Coupland, G., Dolan, L., Harberd, N., Jones, J., Martin, C., Sablowski, R. and Amey, A., 2010. Plant biology. New York: Garland Science; Taylor & Francis distributor.
Tomitani, A., 2006. Origin and early evolution of chloroplasts. Paleontological Research, 10 (4), pp. 283-297.
Recreating the evolutionary history of dinoflagellates has been challenging as they possess a known ability to transform from noncyst – to cyst – forming strategies (unreferenced/Wikipedia). The dinoflagellate nucleus lacks histones, nucleosomes and maintains continually condensed chromosomes during mitosis (Dodge 1966), making their classification difficult (Hackett et al 2004). Though being classified as eukaryotes, the dinoflagellate nuclei are not characteristically eukaryotic (Dodge 1966). However, typical eukaryotic organelles, such as Golgi bodies, mitochondria and chloroplasts are present in dinoflagellates (Morrill et al 1983). Since dinoflagellate nuclei possess intermediate characteristics between the coiled DNA areas of prokaryotic bacteria and the well-defined eukaryotic nucleus it was termed ‘mesokaryotic’ by Dodge (1966).
The majority of life on Earth depends on photosynthesis for food and oxygen. Photosynthesis is the conversion of carbon dioxide and water into carbohydrates and oxygen using the sun’s light energy (Campbell, 1996). This process consists of two parts the light reactions and the Calvin cycle (Campbell, 1996). During the light reactions is when the sun’s energy is converted into ATP and NADPH, which is chemical energy (Campbell, 1996). This process occurs in the chloroplasts of plants cell. Within the chloroplasts are multiple photosynthetic pigments that absorb light from the sun (Campbell, 1996).
2)Campbell, Neil A., and Jane B. Reece. Biology. San Francisco, CA: Benjamin Cummings, 2008. Print.
ABSTRACT: Chloroplasts carry out photosynthetic processes to meet the metabolic demands of plant cells (Alberts, 2008). They consist of an inner thylakoid membrane and a stroma. (Parent et. al, 2008).In this experiment we demonstrate the unique protein compositions of isolated thylakoid and stromal fractions from broken and whole spinach chloroplasts. Because these compartments carry out different metabolic processes, we confirm our hypothesis that performing SDS-PAGE on these fractions will result in distinct patterns on the gels. In isolating and analyzing nucleic acid from broken, whole, and crude chloroplast samples we demonstrate that genes for photosynthetic protein psbA are found in chloroplast DNA, while genes for photosynthetic enzyme
The greater overall rate of absorbance change in all chloroplast samples (Figure 1) confirms role of chloroplasts’ in photosynthesis. However, the use of the supernatant sample as a negative control was expected to yield no activity, which was shown to be untrue (Figure 1) and is contributed to the contamination of the supernatant sample with chloroplast. The fragile envelope of the chloroplasts can be eas...
6 Jones, M. , Fosbery, R. , Taylor, Dennis. , (2007), Biology 1, Cambridge University Press, Cambridge
Eukaryotic cells share several distinguishing features, such as: cytoplasm within specialized organelles such as the mitochondria, chloroplast, the Golgi complex, both a rough and smooth endoplasmic reticulum, a nuclear envelope that isolates DNA from the cytoplasm, and a endomembrane system that provides structure and function to the organelles of the cell. Both the mitochondrion and chloroplast are energy transducing organelles, meaning that they transform energy from one form to another, and are believed to be evolved from free living prokaryotes as held by the theory of endosymbiosis. This theory suggests that infolding of the plasma membrane coupled with the absorption of a prokaryotic cells by other prokaryotes could evolve into a later, more complex and specialized type of cell and is proofed by related morphological features such as between cytobacteria and chloroplasts, and between mitochondria and aerobic prokaryotes. Further substantiation includes mitochondria and chloroplasts reproduction through binary fission like prokaryotes, the presence of DNA in both free living prokaryotes and in energy transducing organelles (apart from in the nucleus), protein synthesis and the presence of enzymes and ribosomes where the ribosomes of prokaryotes are comparable to those in mitochondria and chloroplast,
Liubicich, D.M., et al. 2009. Knockdown of Parhyale Ultrabithorax recapitulates evolutionary changes in crustacean appendage morphology. PNAS 106 (33): 13892-13896
...hemical energy from cyanobacteria (the only bacteria that can perform photosynthesis) 2.4 billion years ago (Wernergreen). The first chloroplast came into being about one billion years ago when a single-celled protist and a cyanobacterium came together through endosymbiosis, and this first photosynthesizing eukaryotic lineage was the ancestor of land plants, green algae, and red algae. Cyanobacteria and algae endosymbionts have spread photosynthetic capabilities in such a broad range (Wernergreen). In other words, heterotrophic prokaryote cells had taken in autotrophic photosynthetic bacteria cells. The ingested cell continued to provide glucose and oxygen by photosynthesis. The host cell protected as well as provided carbon dioxide and nitrogen for the engulfed cell and overtime both cells lost the aptitude to survive without each other (Weber and Osteryoung).
Mitochondria and chloroplasts have the likenesses with microscopic organisms that prompted the endosymbiont hypothesis. This hypothesis expresses that an early a castor of eukaryotic cell inundated an ocygen utilizing nonphotosynthetic prokaryotic cell. In the long run, the overwhelmed cell shaped an association with the host cell in which it was en shut, turning into an endosymbiont. Through the span of advancement the host cell and its endosymbiont converged into a solitary living being, an eukaryotic cell with a mitochondrion. As opposed to being limited by a solitary layer like organelles of the endomembrane framework, mitochondria and common chloroplasts have two layers encompassing them. Evidence the hereditary overwhelmed prokaryotes
that the Rhodophyta is a distinct eukaryotic lineage that shares a most common ancestry with the
541 million years ago, the most important revolutionary event in the history of life occurred. This event, later named the Cambrian Explosion, began in the Paleozoic era, and “refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains” (Royal Ontario Museum); the Cambrian Explosion lasted 53 million years. In the fossil record, the marks where worms made horizontal
According to Carl Woese, a professor of microbiology at the University of Illinois, eukaryote cells are more structurally complex than those of their prokaryotic counterparts. Eukaryote evolved from prokaryotic cells as they adapted to their environment. Evidence shows that mitochondria, an organelle found in all eukaryotic cells, are actually the product of two independent bacteria’s becoming one. This process is known as endosymbiosis or teamwork. Some evidence supporting the idea of endosymbiosis follows; the chloroplasts and the mitochondria are similar to bacteria in size as well as structure, both mitochondria and chloroplasts contain limited amounts of genetic material which could be from splitting, and both of these organelles are surrounded by a double membrane which suggest that the out membrane may be derived from the engulfing vesicle, and the inner
This organelle is the site of photosynthesis in plants and other organisms. In the structure, the chloroplasts has a double membrane, the outer membrane has a continuous boundary. This organelle can be found in a vast group of organelles called the plastid, chloroplasts are usually found in many plant cells but never in animal cells. Chloroplasts organelles are large; they are 4-10um long and 2-3um wide. They are very important to plants because chloroplasts are what plants use to create food from sunlight. Chloroplasts are not found in humans.
Campbell, N. A. & J. B. Reece, 8th eds. (2008). Biology. San Francisco: Pearson Benjamin Cummings.