The endosymbiotic theory is a theory that explains how very simple single celled prokaryotes that lacked a nucleus (control center), membrane bounded organelles, and mitochondria evolved into more complex cells called eukaryotes. Eukaryotes, unlike prokaryotes, contain a nucleus that stores genetic information, membrane bounded organelles, and mitochondria that allow the cell to perform cellular respiration (the use of oxygen to break down sugar and release energy). An endosymbiont is defined as a small cell living inside another host cell. The two cells form a mutualistic relationship where each cell benefits in some way from the other. The host often provides protection for the smaller cell, while the other cell provides nutrients for the …show more content…
One of the major pieces of evidence, is that both mitochondria and plastids use a process similar to binary fission to replicate on their own time, independent of their host cells. Binary fission is the process by which cells split to produce an identical copy of the original cells. Binary fission is an example of asexual reproduction (reproduction performed by a single organism). The performing of binary fission is not found in eukaryote cells. Since prokaryote cells reproduce asexually using binary fission, it seems feasible that the mitochondria and chloroplast were at one-time prokaryote cells. A second distinct piece of evidence that supports the endosymiotic theory is that both mitochondria and chloroplast have many morphological (structure) features similar to those of prokaryotes. For one, both mitochondria and chloroplast contain two outer membranes. The inner resembles that of a prokaryote while outer membrane resembles that of a eukaryotic cell. A second structural feature the endomsymbionts share with prokaryote cells is that they contain circular chromosomes rather then the linear chromosomes found in eukaryotes. A third structural feature that prokaryotes have in common with mitochondria and plastids is the similarity of their ribosomes (structures capable of performing protein production). The ribosomes in prokaryotes, mitochondria, and chloroplast are more similar in size to one another, then the
The building of the grocery store is like the cell membrane, because it gives it structure and keeps everything inside safe. The security guard of the front door in the grocery store is like the cell membrane, because it says what can come in and out of the cell. The boss of the store is like the nucleus, because they tell the employes what to do and what needs to be done. The floors of the grocery store is like the cytoplasm, because it hold everything in it place, where it need to be. The illes in the store is
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.
During interphase, the cells in both animals and bacteria carry out their division general functions according to the type of their cells. Unlike in plants, a preprophase group of cytoskeletal proteins emerge at a future location of the cell plate. At prophase stage, duplicated chromosomes compress in a way that can be seen with the help of a microscope. On the other hand, the mitotic spindle is formed at one side of nucleus, whereas in plants, spindle is formed around the nucleus. During prometaphase in animals and bacteria, the nuclear membrane disappears, the chromosomes attach themselves to mictotubules and start to move. In plants, however, the preprophase group dissolves while at metaphase stage, the chromosomes get aligned at the core of the cell. At anaphase, there are fewer differences between animals and plants. The chromosomes shift apart towards the both par...
During her presentation, Bonnie Bassler expends many different aspects of communication in a bacterial level and how successful communication is important to survival and efficient functioning. It is evident from her presentation that without a common language to communicate with, bacteria could not work as efficiently as they do, neither to immunize people nor create havoc in them. In her presentation, Bassler asserts the importance of the use of language in communication in bacteria, using rhetorical appeals – logical, ethical and emotional – and how it is consequently related to humans.
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,
In contrast, eukaryotic organisms typically include (but are not limited to) membrane-bound organelles such as the nucleus, mitochondria, endoplasmic reticulum (E.R.), golgi body, lysosome and peroxisome. The main defining difference between a eukaryote and prokaryote is that the latter does not contain a nucleus or any such organelles. Such a definition, however, can be argued to be a poor discriminator between organisms of Eukarya and Prokarya, because it describes only what prokaryotes are lacking, not what they fundamentally are. This essay aims to detail a more comprehensive definition of why these two kingdoms are so different from each other. A key example of this thinking is that, while prokaryotes are often singly responsible for metabolic processes, reproduction and cell repair, eukaryotes are often highly specialised in order to perform certain functions and rely upon other cells to fulfil different functions. For exa...
The endothelium is a cell layer that is lined on the interior surface of lymphatic vessels and blood vessels, which are made up of endothelial cells (Dorland, 2012).
Eukaryotic cells, whether from animals, plants, protists, or fungi, are the most structurally advanced of the major cell types. Eukaryote are single-celled or multicellular organism whose cells contain nucleus and any other structures (organelles) enclosed within the membrane that perform specific functions. The surface of the cell is covered with a thin film or plasma membrane, which is the boundary that separates the living cell from its nonliving surroundings. Plasma membranes are composed mostly of proteins and lipids (Simon, 02/2012, p. 59-60).
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).
16. Describe two evolutionary consequences if the process of crossing over in meiosis ceased to occur. If crossing over in meiosis ceased to occur there would be less genetic variations and no diversity among a species. This would essentially mean that a species would not be able to adapt to an issue that could arise in the future, meaning that its species could potentially become extinct due to climate change or other arising events.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
Mitochondria are small granular or filamentous bodies which are called the power house of the cell. They are associated with cellular respiration and are the sources of energy. In 1850, the German biologist Rudolph Kolliker first observed mitochondria as granular structures in striated muscle [Powar, C.B. 2010; Albert et al. 2010]. In 1898, the scientist Benda developed the crystal violet staining technique and called the structures mitochondria. The average length of the mitochondrion is 3-4 microns and the average diameter 0.5 to 1.0 micron. In muscles, most of the mitochondria are 2-3 microns long. Mitochondria have different shapes. The number of mitochondria is different in different types of cells of different organs. They are distributed evenly in the cytoplasm. In sperms they are present in tail, in muscles they lie between the myofibrils. Mitochondria may move freely in some cells. Where ever ATP required. Movement is less in animals than plants. In plants they change their shape and volume [Powar, C.B. 2010; Albert et al. 2010].
Leboffe, M. J., & Pierce, B. E. (2010). Microbiology: Laboratory Theory and Application, Third Edition 3rd Edition (3rd Ed.). Morton Publishing
Cell biology is the study of cells and how they function, from the subcellular processes which keep them functioning, to the Their main purpose is to survive and their functions allow them to do so. All cells have common features whether they are eukaryotic or prokaryotic cells. The common features include a plasma membrane, cytoplasm, ribosomes, and DNA. A plasma membrane which is also known as a cellular membrane, surrounds all cells and its primary function is to protect them.