Endosymbiosis
Endosymbiosis is the theory that eukaryotic cells were formed when a prokaryotic cell ingested some aerobic bacteria. The first step of the evolution of a eukaryotic cell is the infolding of the cellular membrane. This process takes place when the plasma membrane folds inwards and develops an envelope around a smaller prokaryotic cell. Once the smaller cell is engulfed, it becomes dependent upon its host cell. It relies on the host cell for organic molecules and inorganic compounds. However, the host cell also benefits because it has an increased output of ATP for cellular activities and becomes more productive. This ATP comes from the mitochondrion (the aerobe) that is engulfed.
All eukaryotic cells contain the mitochondrion that is made through this process. However, only some of the eukaryotic cells (plant cells) form chloroplasts through endosymbiosis after the mitochondrion is formed. Some of the prokaryotic cells ingest cyanobacteria. These bacteria contain photosynthetic pigments that are useful in photosynthesis. The cyanobacteria become dependent upon the host cell and can no longer survive on its own. Over time, it becomes the chloroplast, a main organelle of plant cells. The chloroplast is then able to convert energy from the sun to energy-rich sugar molecules which are then converted to chemical energy in the form of ATP. (1)
The evidence for endosymbiosis is most prevalent in the mitochondria and chloroplasts of cells. The ribosomes of mitochondria and chloroplasts resemble that of prokaryotic ribosomes because of their similar size, 70s. Mitochondria, chloroplasts, and prokaryotes all divide by binary fission. The genome of mitochondria and chloroplasts most resemble prokaryot...
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...he nucleus as well.
In conclusion, the nucleus is an endosymbiont of bacteria and archaea. The host cell most likely did not come from the bacteria. The host cell, chronocyte, was not a prokaryotic cell but one that had a cytoskeleton composed of actin and tubulin and a complex membrane system. The chronocyte contributed to the end product that is the euaryotic cell. Its contributions were the cytoskeleton, endoplasmic reticulum, Golgi apparatus, and major intracellular control systems. (3)
References
1) Prescott, Lansing. Microbiology: 6th Edition. McGraw Hill: Boston. 2002.
2) Microbe Ecology: Lecture 18. http://jan.ucc.nau.edu/~bah/BIO471/Lecture18/Lecture18.html. Accessed via Internet: 26 November 2004.
3) Hartman, Hyman, and Fedorov, Alexei. The Origin of the eukaryotic cell: A genomic investigation. 5 February 2002.
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).
There are many different cells that do many different things. But all of these cells fall into two categories: prokaryotic and eukaryotic cells. Eukaryotic cells contain a nucleus and are larger in size than prokaryotic cells. Prokaryotic cells do not contain a nucleus, are smaller and simpler than eukaryotic cells. Two of their similarities are they both have DNA as their genetic material and are covered by a cell membrane. Two main differences between these two cells are age and structure. It is believed that prokaryotic cells were the first forms on earth. They are considered primitive and originated approximately 3.5 billion years ago. Eukaryotic cells have only been around for about a billion years. There is strong evidence that suggests eukaryotic cells may be evolved from groups of prokaryotic cells that became interdependent on each other (Phenotypic analysis. (n.d.).
Eukaryotic Cells are Deemed as a Result of the Evolution of Symbiotic Prokaryotes Both Prokaryotic and Eukaryotic cells over time have sustained very dynamic changes from one another. More specifically we have seen the appearance of a more complicated and organized cell structure, the nucleus. However the big question amongst scientists today is how did these changes first occur? A fundamental concept of this evolution is the belief in the natural progression 'from the simple, to the more complex.' However one popular theory that argues that Prokaryotic symbiosis was responsible for forming the Eukaryotic nucleus is the 'Endosymbiotic Theory' this theory was first proposed by a former Boston University Biologist known as Lynn Margulis in the 1960's.
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 process of photosynthesis is present in both prokaryotic and eukaryotic cells and is the process in which cells transform energy in the form of light from the sun into chemical energy in the form of organic compounds and gaseous oxygen (See Equation Below). In photosynthesis, water is oxidized to gaseous oxygen and carbon dioxide is reduced to glucose. Furthermore, photosynthesis is an anabolic process, or in other words is a metabolism that is associated with the construction of large molecules such as glucose. The process of photosynthesis occurs in two steps: light reactions and the Calvin cycle. The light reactions of photosynthesis take place in the thylakoid membrane and use the energy from the sun to produce ATP and NADPH2. The Calvin cycle takes place in the stroma of the chloroplast and consumes ATP and NADPH2 to reduce carbon dioxide to a sugar.
Gardiner, L. (2004). Organelles of Eukaryotic Cells. In Windows to The Universe. Retrieved December 8, 2013, from http://www.windows2universe.org/earth/Life/cell_organelles.html.
The start of any evolutionary story told about us lies within the origin of the eukaryote cell. This remarkable event consisted of a revolution of cell type matched in momentousness by the arrival on the biological scene of the prokaryote (O’Malley). Bacteria had a couple billion years head start on eukaryotes and have given rise to many biochemical processes that are essential to the ecosystem (Wernergreen). One organism living within another defines endosymbiosis. Nobody can say the exact origin of the eukaryote cell. The endosymbiosis theory dates back to the earliest 20th century and devotion to different models of its origins is strong and adamant (O’Malley).
The nucleus is one of the most important organelles in a eukaryotic cell. The shape of the nucleus is generally spherical, it should be oval, disc formed reckoning on the sort of cell. The nucleus was found by Robert Brown in 1831 while he was looking at orchids under a microscope. He discovered a blurred area in the cells of the flowers and called it the areola or the nucleus.
In the most general terms, the nucleus is the command center of a eukaryotic cell. Although the origin of the organelle is unclear, it is believed that it is derived from a symbiosis relationship between a bacterium and an archaea (Martin W. 2005). Being the main hub for the inner workings of a cell involves different functions overall. These nucleic functions are determined by the genes within the DNA of the cell. Functions of the cell are also regulate by soluble proteins that come in and out of the cell via the membranes and specific channels or the nuclear pore complexes. The overall objectives of the nucleus include; gene expression, compartmentalization, and processing pre-mRNA. The functions of the organelles and sub-regions
Photosynthetic pigments are essential for life because they allow photosynthesis to occur by capturing sunlight which is then used alongside carbon dioxide and water to form organic compounds such as glucose and oxygen. The pigments allow the conversion of light energy to chemical energy which other organisms can benefit from. Oxygen is utilised by other organisms in aerobic respiration. The different pigments present in the chloroplasts allow a wide variety of wavelengths of light to be absorbed for efficient photosynthesis and provide colours to the plant to attract pollinators.
The membrane surrounding the nucleus in eukaryotic cells, separate the nucleus from the cytoplasm. Most of the cells we used in the experiments held, were multicellular or consisting of more than one cell. A variety of cells were used in completing the experiments. We used union cells, cheek cells, potato cells, and Elodeo cells. We also used Planaria which is a unicellular organism.
Photosynthesis is a process in plants that converts light energy into chemical energy, which is stored in bonds of sugar. The process occurs in the chloroplasts, using chlorophyll. Photosynthesis takes place in green leaves. Glucose is made from the raw materials, carbon dioxide, water, light energy and oxygen is given off as a waste product. In these light-dependent reactions, energy is used to split electrons from suitable substances such as water, producing oxygen. In plants, sugars are produced by a later sequence of light-independent reactions called th...
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.
Photosynthesis is a process in which plants and other organisms convert the light energy from the sun or any other source into chemical energy that can be released to fuel an organism’s activities. During this reaction, carbon dioxide and water are converted into glucose and oxygen. This process takes place in leaf cells which contain chloroplasts and the reaction requires light energy from the sun, which is absorbed by a green substance called chlorophyll. The plants absorb the water through their roots from the earth and carbon dioxide through their leaves.
Photosynthesis and cellular respiration help sustain life on planet earth as both are metabolic processes in their own way. Photosynthesis is the process by which plants and other organisms use energy from the sun to form glucose from water and carbon dioxide. From there, glucose is then converted to ATP by way of cellular respiration. To convert nutrients that are biochemical energy into ATP, a process such as cellular respiration that has reactions needs to take shape in the cell of an organism, releasing waste products at the same time. For the continuous energy cycle that tolerates life on Earth as we know it Photosynthesis and Cellular respiration very essential. They have a few stages where energy and various connections occur within the eukaryotic cell. Cellular respiration takes place in the lysosome, an organelle that is found in the cytoplasm of eukaryotic cells. It uses enzymes to break down biomolecules including proteins, nucleic acids, carbohydrates, and lipids. Photosynthesis involves the chloroplasts, which contain pigments that absorb the sunlight and then transfigure them to sugars the plant can use. Those specific processes are crucial in how far and diversified evolution has