Nervous Breakdown Disorder Causes and Symptoms free essay sample

Nervous breakdown disorder (NBD) is a general non-medical terminology to describe a stressful and abnormal situation in which a person becomes temporarily, or permanently unable to function in a day- to day life. Nervous breakdown can happen in different situations, and it can lead to major depression by causing CNS abnormalities. In Depression, a decrease in dopamine, serotonin, and norepinephrine play a major role. Nervous breakdown is normally occurring when lifes demands become physically and emotionally overwhelming. Nervous reakdown is more or less a general term to describe various types of mental health problems, and it can also be an indication of serious medical illness, so seeking medical attention is very important. Nervous breakdown can be assessed with the following signs: panic attack, anxiety, phobias, sexual problems, hallucination, delusion, feeling unable to cope with tasks you would not have thought about twice before, sleep problems, difficulty concentrating, and employment problems. We will write a custom essay sample on Nervous Breakdown Disorder: Causes and Symptoms or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page NBD can be also be seen in the DSM multi axial system, in other words Nervous breakdown an be seen in patient in all the five axes in the DSM system. As indicated above, nervous breakdown can be an indication of other mental problems such as schizophrenia, depression and bipolar disorders. let look the abnormalities in a person with schizophrenia; the person with schizophrenia will have an excess of the five common sense ( hears, sees, smell, taste, feels), the person will experience auditory, visual, olfactory, gustatory, and tactile hallucination. Nervous breakdown can cause a person to lack of insight, Judgment, logic, and ability to carry out effective ecision. Nervous breakdown is also seen in people with eating disorders such as Anorexia nervosa, resting type, binge type and bulimia nervosa. In addition, people experiencing post-traumatic disorder (PTSD) can also exhibit signs of nervous breakdown. This is a flash back of a traumatic or threatening event, victims of PTSD may experience nightmares of a bad event, they can also experience anxiety, panic, depression, guilt, hypervigilance and irritability and anger. Nervous breakdown can occur as a cause or effect. In any case however, the term refers to abnormal behavior. Some nursing diagnoses of nervous breakdown include: Acute confusion, disturb sleep pattern, disturb sensory perception, self-care deficit RIT depression, and risk for injury. According to WIKIPEDIA, Nervous breakdown has not been formally defined through a diagnostic system as DSM-IV or ICD-IO, however, the term refers to a specific acute time limited reactive disorder, involving symptoms such as anxiety or depression, usually precipitated by external stressors. Nervous Breakdown Disorder: Causes and Symptoms By mariamlovesld

Autism Effect on Children

Autism Effect on Children Introduction Autism is a neurodevelopment condition that lowers several mental capabilities of individuals. Children suffering from autism have reduced social interaction skills and become slow learners.Advertising We will write a custom research paper sample on Autism Effect on Children specifically for you for only $16.05 $11/page Learn More Numerous cases of autism are reported all over the world, but people living with autism have become integrated well into the society due to the scientific advancements in medicine. Children suffering from autism not only get drugs that help to ease their condition, but they also learn how to interact with other people. It suffices to mention that children who have autism get opportunities for education, despite being slow learners (Mastropieri Scruggs, 2010). In some countries, they have special schools that have teachers who are skilled in teaching them. In other countries, the children are not separated from the oth er children in class. In the past, teaching other children together with children suffering from autism was a problem because the children with autism were perceived to be aloof (Scruggs, 2008). However, teachers have taken the initiative to understand autism and draft new and better ways of teaching children with autism. This paper will analyze how autism affects children and their social interactions from an academic point of view. Behaviors of Children with Autism It is crucial to understand the behavior of children with autism in the school set up in order to understand how autism affects children and their social interactions. Scruggs (2008) reveals that children with autism are usually perceived aloof because they do not interact with other children in the classroom.Advertising Looking for research paper on education? Let's see if we can help you! Get your first paper with 15% OFF Learn More In many instances, they are alone sitting in a corner and doin g their own things. An interruption or any attempt by other children to indulge in play with the affected child usually ends up in a disaster. Mastropieri and Scruggs (2010) argue that children with autism have a hard time associating with other children due to two main reasons. First, the children know that they are different from the rest. The difference is more pronounced in the older children compared to the younger ones. The second reason children with autism do not interact with other children freely is the fact that their condition gives them limited social interaction skills. Consequently, they do not feel comfortable being around other people. As Scruggs (2008) observes, many of the children with autism do not like to be touched and can get hysterical if it happens. It is also necessary to point out that children with autism do not care about the feelings and reactions of the other students. They rarely imitate the actions and reactions of the other students in the class. R esultantly, they are perceived to be mean and rude to the other students. Imitation of behavior is important in school because it gives children a predictable idea of what to do next (Scruggs, 2008). For example, if a child smiles at another child, it is very normal and expected that the other child will smile back. However, this is rarely the case with a child who has autism because of their limited social skills. In the same vein, such children shy away from such friendly gestures from the other kids. In turn, they lack the form of social interaction that is enjoyed by other children.Advertising We will write a custom research paper sample on Autism Effect on Children specifically for you for only $16.05 $11/page Learn More Poliakova and Palkhivala (2008) also add that children with autism mostly portray some characteristics that push the other children away, making it difficult for them to interact with the other kids. One such behavior is screaming. Scr uggs (2008) observes that children suffering from autism have a tendency to scream whenever they feel scared, mainly because most of them do not like to be touched. Other things that can trigger screaming include impatience and wanting their parents. The screaming is not only ear deafening, but it also scares the other children in the class away. In other words, the other pupils become scared of interacting with the child out of the fear that the child may start screaming. Another behavior exhibited by children with autism is the unwillingness to communicate, which limits their social interaction further. Meadan and Monda-Amaya (2008) argue that there are times when the child will refuse to talk. For instance, the child may refuse to respond to the teacher or fellow students. In the past, many teachers would relish such acts because the child would appear quiet and calm. However, recent studies show that the child feels vulnerable if he exhibits such behavior, which is portrayed in the form of tendency to refuse to talk. Many draw on their books, instead of interacting with the rest because the communication process is too complicated. It further hampers their academic and social development. The lack of proper social interaction makes it difficult for the child with autism to advance in their studies. As they grow up, they refuse to be paired with other children for assignments. They also fail to make friends who can help them with school work or just talk regarding everyday issues that may linger in their minds.Advertising Looking for research paper on education? Let's see if we can help you! Get your first paper with 15% OFF Learn More Teachers act as the meeting point between the child who has autism and the other children in the classroom. It is up to the teacher to ensure that the child is comfortable enough to interact with the other kids. Improving the social skills of children with autism is not easy. However, it can be achieved through a series of behavior change models created by the teacher. Teachers’ Interventions As mentioned, teachers are the pivot of the relationship between the children who suffer from autism and the other children in the classroom. All the children, including those who have autism, know and trust the teacher. The child with autism will be more comfortable with a teacher they have known for a long time compared to the students in the class because they are many and may be newer to the child. The first thing a teacher can do to help a child with autism is to encourage the development of social skills. Scruggs (2008) argues that there are teachers who force children with autism to partner with the other kids on school assignments in order to get them to open up. Improving social skills can be achieved using a series of well-defined lessons on the same. For instance, the teacher can take time to help the child learn non-verbal cues. Nonverbal cues are the most important form of communication for a person suffering from autism (Mastropieri Scruggs, 2010). Understanding how space, time, and gestures affect other people can help the individual interact freely with other people. Understanding nonverbal cues can also assist the child when they do not want to talk. The second thing a teacher can do is to create an inclusive educational environment for the child (Santoli et al., 2008). It is true that children with autism have a hard time interacting with other children. It is also true that they cannot be forced to interact with the other children. However, shaping the classes to suit the child will help in keeping them calm enough to interact with the other kid s. If the child likes painting and drawing, then the teacher can first give every child drawing materials and leave them draw. The teacher can then pair the students to analyze and talk about their drawings. At this point, the teacher should pair with the child because they will prove calmer when with the teacher than another child. The child can then slowly start pairing up with the other children. It is crucial for the teacher to use an activity that the child enjoys the process of fitting into the school setting. In the same manner, the teacher can instill patience in the other students. It is easier for children to understand that a person is not feeling well and respect that. The teacher should encourage the other children not to make fun of the child who has autism and not to feel offended whenever the child becomes aloof. The positive reaction that the other kids give may encourage the child to open up. Teachers should also monitor the child and learn their responses (Scruggs , 2008). It is not enough for the teacher to just make sure that the child is feeling okay and calm. Instead, the teacher has to ensure that they monitor the behavior of the child. Monitoring will help the teacher find out some of the things that make the child irritated and aloof. Similarly, monitoring the child’s reaction will show the teacher what the child likes, which can then be incorporated into the class work to make learning easier for the child. Santoli et al. (2008) argue that not all children who have autism are slow learners. However, monitoring can help the teacher be in a position to decide the pace that is required for the child to understand the concepts that are taught in class. Particular attention in the sense of a special teacher should be provided for the students who are extremely slow. However, the teacher has to come up with a teaching model that will suit the pace of the child who has autism if the child is not very slow. Using the example of a child who likes to draw, the teacher can use drawings to teach. The other children will not have a problem using such customized learning activities, given that they have average learning speeds. Conclusion In conclusion, teaching children with autism does not have to be as difficult as it was a decade ago. Many teachers have the skills and tools that allow equip them to help these children fit in a typical class. One of the major things that make it difficult for the child who has autism to form relationships with the classmates is abnormal behavior. For instance, the child may scream and make the other children scared of interacting with the child. Teachers are encouraged to create an inclusive learning environment for the child to solve such problems. The teacher has to monitor the development and reactions of the child who has autism in order to establish a suitable environment. Additionally, the teacher has to draft suitable learning and teaching methods that target the development of social skills of the child who has autism, thereby improving the cognitive development of the child. References Mastropieri, M., Scruggs, T. (2010). The inclusive classroom: Strategies for effective differentiated instruction. Upper Saddle River, NJ: Pearson Meadan, H., Monda-Amaya, L. (2008). Collaboration to promote social competence for students with mild disabilities in the general classroom: a structure for providing social support. Intervention in School Clinic, 43(3), 158-167 Poliakova, N., Palkhivala, A. (2008). Social impairment in children with autism spectrum disorder. Canadian Council of Learning, 1(1), 50-51. Santoli, S., Sachs, J., Romey, E., McClurg, S. (2008). A successful formula for middle school inclusion: Collaboration, time, and administrative support. Research in Middle Level Education Online, 32(2), 1-13. Scruggs, A. (2008). Effective reading instruction strategies for students with significant cognitive disabilities. Electronic Journal for Inclusive E ducation, 2(3), 1-11

Cross-cultural management & HRM Research Paper Example | Topics and Well Written Essays - 3000 words

Cross-cultural management & HRM - Research Paper Example IHRM is concerned about managing the human capital at the international level at multinational companies (MNC). It is especially requisite to manage three types of employees’ i.e. domestic employees, host country employees as well as employees of the different countries. For this reason, it is a vital challenge for the human resource manager to handle the diversity effectively along with efficiently. This is because it is effectively related to the productivity of the organization when working collectively with the people of different cultures. According to Bernard Baruch stated regarding cross-cultural communication that â€Å"We did not all come over on the same ship, but we are all in the same boat† (Hord & et. al., 2009). In accordance with today’s working culture for the effective implementation of globalization, it is rapidly becoming enormous, as the business environment has expanded to the various geographical locations. Therefore, it is a major challenge for the HR managers of the MNCs to understand the cultural aspects of the different countries and geographical locations to promote the business and expand the market share, along with interacting and collaborating across boundaries using global communication technologies (Self, n.d.). However, there are also enormous positive aspects of cross-cultural diversity in the organization because it considers creativity along with innovation as well as provides various advantages which include helping an organization to enter the international arena. ... According to Bernard Baruch stated regarding cross cultural communication that â€Å"We did not all come over on the same ship, but we are all in the same boat† (Hord & et. al., 2009). In accordance with today’s working culture for the effective implementation of globalization it is rapidly becoming enormous, as the business environment has expanded to the various geographical locations. Therefore, it is a major challenge for the HR managers of the MNCs to understand the cultural aspects of the different countries and geographical locations to promote the business and expand the market share, along with interacting and collaborating across boundaries using global communication technologies (Self, n.d.). However, there are also enormous positive aspects of cross-cultural diversity in the organisation because it considers creativity along with innovation as well as provides various advantages which include helping an organisation to enter in the international arena. Diver sity among the team also is very helpful to improve elasticity and ensure quick response to any kind of challenges. A company with a diverse workforce can better serve and compete in the assorted market exceptionally beyond their imagination. Nevertheless, managing cross cultural elements in the organisation is very challenging, for this reason there is requirement to established open communication among all, supporting ongoing training and monitoring the various programmes to achieve the organisational targets (Crowe& Hogan, 2007). Therefore, the objective of the essay is to discuss the topic of measuring process in terms of workforce diversity taking care of national as well as organisational

Significance and Implications of Research Ethics to Nursing Essay

Significance and Implications of Research Ethics to Nursing - Essay Example Research ethics plays an important role in the nursing management and leadership. Since leaders and managers of healthcare institutions should abide by the highest ethical standards, they can guarantee ethical nursing practice only through research ethics. Both qualitative and quantitative research provides evidence that nurses can use to treat their patients or prevent specific medical conditions. Leaders and managers in nursing depend heavily on nursing research to provide effective directions and decisions that nurses can prefer in their medical undertakings. It implies that research ethics merits objectivity in nursing management through the provision of concrete results. Effective nursing management entails nursing practice and decision-making that is anchored on concrete evidence from research. Such research could either be qualitative or quantitative but either way, it must embrace ethical principles. Burns, Grove, and Gray list consequentialism, principlism, virtue ethics, an d deontology as four major nursing ethical theories that concern research ethics. These ethical theories inspire the thinking of leaders and managers in healthcare institutions to make ethical decisions in nursing practice. With regard to consequentialism, the outcome of nursing research determines the morality of the research. It means that the response in connection with certain medical undertakings can only be valid if they are positive irrespective of the decision-making process or the ethical principles applied to the research.

Endosymbiotic Theory of Eukaryotic Cell Development

Endosymbiotic Theory of Eukaryotic Cell Development Abstract The defining feature of eukaryotic cells is that they contain membrane-bound organelles and a true nucleus. The endosymbiotic theory is based upon the idea that eukaryotic cells evolved in steps beginning with the stable incorporation of chemo-organotrophic and phototrophic symbionts from the domain bacteria. This essay reviewed the evidence that supports this theory. After investigating the molecular, physiological and morphological evidence, it is almost certain that chloroplasts and mitochondria are from the domain bacteria, and that many of the genes required for the survival of these organelles are contained within the nuclear DNA of the eukaryotic cell rather than the organelles own independent DNA. It is for this reason that I believe that endosymbiosis was the process whereby eukaryotes began to form and evolve. It was found that the genome of a protozoan, Reclinomonas, contained all the protein-coding found in sequenced mitochondrial genomes, providing support for the specul ative process of endosymbiotic gene transfer. The hydrogen hypothesis seems to be the most likely scenario for the formation of eukaryotes, which explains the need for compartmentalisation with increasing host genome size to improve efficiency of function throughout the cell, and the chimeric nature of eukaryotes. Introduction Based upon data collected from slow decaying radioactive isotopes, Earth is thought to have formed approximately 4.55 billion years ago. From this time of origin, a continual process of geological and physical change has occurred, which created conditions leading to the origin of life about 4 billion years ago. Life is thought to have undergone the process of evolution, defined as DNA sequence change and the inheritance of that change, often under the selective pressures of a changing environment. (1) Microfossil evidence suggests that unicellular eukaryotes arose on Earth approximately 2 billion years ago, after the development of an oxic environment and the invention of respiratory metabolism in cyanobacteria. This timing infers that the availability of oxygen was a large influence on the biological evolution that led to the emergence of Eukarya. (1) The defining characteristic of eukaryotes is the presence of a well-defined nucleus within each cell. (2) Typical eukaryotic cells contain a membrane bound nucleus and organelles enclosed by an outer plasma membrane; these organelles are organised into compartmentalised structures which have their own function(s) within the cell, often working together with other organelles to complete vital biological processes. This compartmentation in cells is essential in organisms as it allows differing compositions of nutrients to exist inside each compartment as opposed to outside, creating perfect conditions for biochemical reactions to occur.(3) The differences between eukaryotes and prokaryotes are shown in Table 1: Mitochondria are membrane-bound organelles found in the cytoplasm of most eukaryotic cells and are most concentrated in cells associated with active processes, such as muscle cells which constantly require energy for muscle contraction. The two surrounding membranes that encompass a mitochondrion differ in function and composition, creating distinct compartments within the organelle. The outer membrane is regular in appearance and composed of proteins and lipids, in roughly equal measure, whilst the outer membrane contains porin proteins rendering it more permeable. The inner membrane is only freely permeable to oxygen, water and carbon dioxide; it contains many infoldings, or cristae, that protrude into the central matrix space, significantly increasing the surface area and giving it an irregular shape. As can be seen in Figure 1, mitochondria contain ribosomes and have their own genetic material, mitochondrial DNA (mtDNA), separate from the nuclear DNA. (4) Mitochondria are the principle sites of ATP production- in a process known as oxidative phosphorylation. Products of the Krebs cycle, NADH + H+ and FADH2, are carried forward to the electron transport chain (ETC) and are oxidised to NAD+ and FAD, releasing hydrogen atoms. These hydrogen atoms split to produce protons and electrons, and the electrons are passed down the ETC between electron carriers, losing energy at each level. This energy is utilised by pumping the protons into the intermembranal space causing an electrochemical gradient between the intermembranal space and the mitochondrial matrix. The protons diffuse down the electrochemical gradient through specific channels on the stalked particles of the cristae, where ATPsynthase located at the stalked particles, supplies electrical potential energy to convert ADP and inorganic phosphate to ATP. In mammalian cells, enzymes in the inner mitochondrial membrane and central matrix space carry out the terminal stages of glucose and fatty acid oxidation in the process of ATP synthesis. Mitochondria also play an important role in the regulation of ionised calcium concentration within cells, largely due to their ability to accumulate substantial amounts of calcium. (3)(5) Chloroplasts are membrane-bound organelles found within photosynthetic eukaryotes. Chloroplasts are surrounded by a double membrane, the outer membrane being regular in appearance whilst the inner membrane contains infoldings to form an interconnected system of disc-shaped sacs named thylakoids. These are often arranged in to stacks called grana. Enclosed within the inner membrane of the chloroplast is a fluid-filled region called the stroma, containing water and the enzymes necessary for the light-independent reactions (the Calvin cycle) in photosynthesis. The thylakoid membrane is the site of the light dependent reactions in photosynthesis, and contains photosynthetic pigments (such as chlorophyll and carotenoids) and electron transport chains. Chloroplasts, like mitochondria, contain ribosomes and their own independent DNA (ctDNA), which is central to the theory of endosymbiosis. The structure of a typical chloroplast is shown by Figure 2: Radiant energy is trapped by photosynthetic pigments and used to excite electrons in order to produce ATP by photophosphorylation. The light dependent reactions occur in the thylakoid membrane (Photosystem II or P680) and ultimately, these reactions produce the ATP and NADPH required for photosynthesis to continue in the stroma (where Photosystem I or P700 is located). A series of light independent reactions occur within the stroma producing carbohydrates from carbon dioxide and water using ATP and NADPH. The most supported hypothesis (put forward by Lynn Margulis) for the origin of the eukaryotic cell is that of endosymbiosis which is suitably named as symbiosis occurs when two different species benefit from living and working together. When one organism actually lives inside the other its called endosymbiosis.'(6) The endosymbiosis hypothesis states that the modern, or organelle-containing eukaryotic cell evolved in steps through the stable incorporation of chemo-organotrophic and phototrophic symbionts from the domain Bacteria. In other words, chloroplasts and mitochondria of modern-day eukaryotes arose from the stable incorporation into a second type of cell of a chemoorganotrophic bacterium, which underwent facultative aerobic respiration, and a cyanobacterium, which carried out oxygenic photosynthesis. The beneficial association between the engulfed prokaryote and eukaryote would have given the eukaryote an advantage over neighbouring cells, and the theory is that the prokaryote and eukaryote lost the ability to live independently. (1) Oxygen was an important factor in endosymbiosis and in the rise of the eukaryotic cell through its production in photosynthesis by the ancestor of the chloroplast and its consumption in energy-producing metabolic processes by the ancestor of the mitochondrion. It is worth noting that eukaryotes underwent rapid evolution, most probably due to their ability to exploit sunlight for energy and the greater yields of energy released by aerobic respiration. Support for the endosymbiosis hypothesis can be found in the physiology and metabolism of mitochondria and chloroplasts, as well as the structure and sequence of their genomes.(1) Similarities between modern-day chloroplasts, mitochondria, and prokaryotes relative to eukaryotes are shown in table 2: Molecular Evidence When Margulis proposed the endosymbiotic theory, she predicted that if the organelles really were prokaryotic symbionts, they would contain their own independent DNA. This was proven to be the case in the 1980s for mitochondria and chloroplasts.(7)Furthermore, mitochondrial DNA (mtDNA) was found to have a proportionally higher ratio of guanine-cytosine base pairs than in eukaryotic nuclear DNA, as found in bacteria. These findings are significant as they strongly suggest that mitochondria and chloroplasts are of prokaryotic origin and nature, supporting the possibility that the eukaryotic cell evolved from the stable incorporation of symbionts from the domain Bacteria. Another striking similarity between mitochondria and bacteria is that they both contain 70S ribosomes and contain a comparable order of genes encoding ribosomal proteins a shown in Figure 4: It is only fair that the molecular problems associated with the endosymbiosis hypothesis that have been put forward are considered. Firstly, mitochondria and chloroplasts can only arise from pre-existing mitochondria and chloroplasts, having lost many essential genes needed for survival. It has been suggested that this is because of the large timespan that the mitochondria/chloroplasts have co-existed. During this time, systems and genes that were no longer needed were either simply deleted or transferred into the host genome. Hence, mitochondria and chloroplasts have lost the ability to live independently over time. This supports the endosymbiotic theory as it provides a reason as to why the ancestors of the chloroplasts and mitochondria were able to survive independently whilst chloroplast and mitochondria are unable to do so now. The study of mitochondrial genomes so far has suggested that mitochondrial genomes actually encode less than 70 of the proteins that mitochondria need to function; most being encoded by the nuclear genome and targeted to mitochondria using protein import machinery that is specific to this organelle.(7) It has been found that the genome of Reclinomonas contains all the protein-coding genes found in all the sequenced mitochondrial genomes: (8) The importance of Figure 5 is that it shows that the mitochondrial genome no longer contains many of the protein-coding genes, and hence, mitochondria are no longer able to live independently. The mitochondrial endosymbiont is believed to have belonged to the proteobacteria since several genes and proteins still encoded by the mitochondrial genome branch in molecular trees among homologues from this group. Interestingly, mitochondrial proteins such as the 60- and 70-kDa heat shock proteins (Hsp60, Hsp70), also branch amongst proteobacterial homologues, but the genes are encoded by the host nuclear genome.(9) This can be explained by a theory called endosymbiotic gene transfer which states that during the course of mitochondrial genome reduction, genes were transferred from the endosymbionts genome to the hosts chromosomes, but the encoded proteins were reimported into the organelle where they originally functioned. (7) This theory is central to the endosymbiotic theory, as it explain s the inability of chloroplasts and mitochondria to live independently even though these organelles are believed to have originated from the domain Bacteria. It is also believed that this gene transfer has provided an essential way in which mitochondrial or chloroplast activity can be regulated. The studies of protists raise  the possibility that mitochondria originated at essentially  the same time as the nuclear component of the eukaryotic cell  rather than in a separate, subsequent event. (10) T This would fit in with the hydrogen hypothesis as described later. A further problem to consider is the extent to which genes were transferred to the cell nucleus. Why did some genes remain in the cytoplasmic organelles? This question has been addressed by the Co-location for  Redox  Regulation (CoRR) hypothesis, which states that the location of  genetic information  in  cytoplasmic  organelles  permits regulation of its expression by the reduction-oxidation  (redox) state of its  gene products. Therefore, evolution by natural selection would have favoured mitochondrial or chloroplast cells that had deleted or transferred some genes to the host genome but had kept those that were still beneficial in the regulation of the organelles activity. (11) Physiological Evidence Evidence for the endosymbiosis theory can be found in the physiology of mitochondria and chloroplasts. For example, both mitochondria and chloroplasts have their own protein-synthesising machinery which closely resembles that of Bacteria rather than that of Eukaryotes. Ribosome function in mitochondria and chloroplasts are inhibited by the same antibiotics that inhibit ribosome function in free-living bacteria. Hence, it is no surprise that both these organelles contain 70S ribosomes typical of prokaryotic cells, and show 16S ribosomal RNA gene sequences, a characteristic of certain Bacteria such as Escherichia coli.(1) For example, human mitochondrial ribosomes can be affected by chloramphenicol (an antibiotic used to inhibit protein synthesis), further evidence that mitochondria are likely to be of bacterial origin. Chloramphenicol is a relatively simple molecule containing a nitrobenzene ring responsible for some of the toxicity problems associated with the drug: Chloramphenicol inhibits protein synthesis due to its high affinity for the large (50S) ribosomal subunit, which when bound to chloramphenicol, blocks the action of peptidyl transferase, preventing peptide bond synthesis. It has also been discovered that chloramphenicol prevents the maturation of the 30S ribosomal subunits, decreasing the number of competent subunits and significantly decreasing the proportion of mitochondrial ribonucleoprotein present as monomers. (12) Also, the antibiotic rifampicin which inhibits the RNA polymerase of Bacteria has been found to inhibit the RNA polymerase within bacteria. Proteins of chloroplast or mitochondrion origin, like bacteria, always use N-formylmethionine as their initiating amino acid of their transcript.(13) Mitochondria replicate, like bacteria, only by the process of binary fission inferring that mitochondria did indeed originate from prokaryotes. The completion of the genome sequence of the cyanobacterium Synechocystis, has provided e vidence for the origin of chloroplast translocation apparatus. Just as the endosymbiosis theory predicts, analysis of this sequence showed that three key translocation components within chloroplasts, Toc75, Tic22 and Tic20, evolved from existing proteins within the cyanobacterial genome.(14)Mitochondria and chloroplasts have remarkably similar mechanisms by which ATP is produced. These ATP-generating pathways often include electron transport chains and proton pumps, similar to that found in prokaryotic energy production mechanisms. One of the most recent problems with the endosymbiosis theory is found within the physiology of mitochondria. Mounting evidence suggests that key components of the mitochondrial transcription and replication apparatus are derived from the T-odd lineage of  bacteriophage  rather than from an ÃŽÂ ±-Proteobacterium, as the endosymbiont hypothesis would predict.'(15) It has been discovered that three of the essential elements of the replication and transcription apparatus; the RNA polymerase, the replicative primase-helicase and the DNA polymerase do not resemble those of eubacteria as predicted by the symbiosis theory, but instead appears to resemble proteins encoded by T-odd bacteriophages. However, this does not disprove the theory of endosymbiosis as it is conceivable that numerous mitochondrial genes were acquired together from an ancestor of T-odd phage early in the formation of the eukaryotic cell, at the time when the mitochondrial symbiont was incorporated. (15) Morphological Evidence Another characteristic that further supports the hypothesis is that mitochondria and chloroplasts contain small amounts of DNA that is different from that of the cell nucleus which is arranged in a covalently closed, circular structure, with no associated histones, typical of Bacteria. Mitochondria are surrounded by two membranes, separated by the inter-membranal space and each with a different composition. Mitochondrial membranes more closely resemble membranes found in Gram-negative bacteria in terms of lipid composition than eukaryotic membranes. (16) The inner-membrane infoldings in the mitochondria lends more credibility to the endosymbiosis theory as the cristae are adaptations that increase the surface area of oxidative enzymes, evolutionary analogues to the mesosomal membranes of many prokaryotes (16)Further evidence that mitochondria and chloroplasts are of a prokaryotic origin is the lack of cholesterol in their membranes. This is significant because it is an essential stru ctural component in many eukaryotic membranes, mainly in mammalian cell membrane, but it almost completely absent amongst prokaryotes. Another problem is that recent genetic analysis of small eukaryotes that lack many characteristics that are associated with eukaryotic cells, most importantly mitochondria, show that they all still retain genes involved in the synthesis of mitochondrial proteins. In 1983, the taxon Archezoa was proposed to unite this group of odd eukaryotes, and the belief was that these cells had diverged from other eukaryotes before these characteristics evolved and hence represented primitive eukaryotic lineages. Before the recent genetic breakthrough that shows that these eukaryotes contain genes involved in mitochondrial protein synthesis, molecular work supported their primitive status, as they consistently fell deep into the branches of eukaryotic trees. This recent genetic analysis implies that all these eukaryotes once had mitochondria, suggesting that they evolved after the mitochondrial symbiosis. There is also the question of how the eukaryotic cell arose, including the nature and propert ies of the cell that acquired mitochondria and later chloroplasts, and how the nuclear membrane was formed which touches upon the compatmentalisation within cells and its importance in the functioning of the eukaryotic cell. (7) Formation of the eukaryotic cell There have been two hypotheses put forward to explain how the eukaryotic cell arose. One states that eukaryotes started as a nucleus-bearing lineage that later acquired the bacterial ancestor of the mitochondrion and the cyanobacterial ancestor of the chloroplast by the process of endosymbiosis. This nucleated line then diverged into the lineages giving rise to animals and plants. It is thought that the nucleus arose spontaneously in an early cell. One possible cause for the spontaneous formation of the nucleus is that it arose in response to the increasing genome size of early eukaryotes. (1) The second hypothesis, also known as the hydrogen hypothesis, states that the bacterial ancestor of the mitochondrion was taken up by a member of the Archaea via endosymbiosis, and from this association, the nucleus later emerged, followed by a later acquisition of the cyanobacterial ancestor of the chloroplast. The main difference between these two hypotheses is the position of the mitochondrion relative to the formation of the nucleus in time and hence on the universal phylogenetic tree. The hydrogen hypothesis put forward by William F. Martin and Miklos Muller in 1998, proposes that the eukaryotic cell arose from a symbiotic association of an anaerobic, hydrogen dependent, autotrophic archaebacterium (the host) with a hydrogen producing, oxygen consuming eubacterium (the symbiont), which released molecular hydrogen as a waste product of anaerobic heterotrophic metabolism. (17) The dependence of the host upon the molecular hydrogen as an energy source, produced as a waste product b y the symbiont is thought to be what lead to the association. In this scenario, the nucleus arose following the formation of this stable association between these two kinds of cells, and genes involved in lipid synthesis were transferred from the symbiont to the host chromosome. This may have lead to the synthesis of bacterial (symbiont) lipids by the host, eventually leading to the creation of an internal membrane system, the endoplasmic reticulum and the early stages of a eukaryotic nucleus. As the size of the host genome increased with time, changes were made to maximise the efficiency of replication and gene expression via the process of evolution. Hence, over time, this kind of cell compartmentalised and sequestered the genetic coding information within a protected membrane away from the cytoplasm. The formation of a mitochondrion-containing nucleated cell line was complete, which then later acquired chloroplasts by endosymbiosis. The hydrogen hypothesis has explains the observ ation that eukaryotes are of chimeric nature, containing attributes of both Bacteria and Archaea. (1) Conclusions In summary, molecular, physiological and morphological evidence can be found to support the endosymbiosis theory put forward by Lynn Margulis. Most compelling of which is the numerous similarities between organelles such as chloroplasts and mitochondria with prokaryotes, coupled with the inability of the organelles to live independently despite having their own independent DNA due to most of the genes required for the survival of the organelle being stored in the nuclear DNA of the host. The importance of this should not be underestimated, as it does all but prove that the ancestors of mitochondria and chloroplasts were of a prokaryotic origin and thus were once able to live independently. Therefore, this does lend credibility to the endosymbiosis theory as the symbionts that were allegedly incorporated were likely to have been from the domain bacteria, and that something must have occurred which stopped the symbionts being able to live independently, an event which many scientists n ow believe to be the process of endosymbiotic gene transfer. The hydrogen hypothesis appears to be the likely scenario for how the eukaryotic cell evolved, as it explains the formation of the nucleus as being a response to the growing size of the nuclear genome of the host, which would have maximised efficiency of gene expression. Endosymbiosis also explains why the eukaryotic cell appears to be of a chimeric nature; containing attributes of Archaea (e.g. similar transcription and translation apparatus) and Bacteria (e.g. contain same type of lipids).

Term Essays -- essays research papers

Dreams   Ã‚  Ã‚  Ã‚  Ã‚   Every ninety minutes of every night we’re asleep, a dream unfolds. The short dreams at the beginning of the night are usually no more exciting that the idle thoughts that randomly pop into our heads when we’re awake. But as the night progresses, the length of each dream increases (the last dream can be up to twenty minutes long), the body responds more intensely (increased heartbeat, respiration, muscle twitching), and the dreams become deeper.   Ã‚  Ã‚  Ã‚  Ã‚  Dreams are sometimes said to be ordinary sequences of images that are experienced by the mind during sleep. For thousands of years they were regarded as divine visitations or predictions. Dreams were not really scientifically studied until the 19th century. Today they are still being studied to learn more about man’s nature. Dreaming is a natural ability- we all dream every night. Every one dreams when sleeping at least three to four times every night. The problem however is remembering the dream. But there is a way to remembering dreams. It is believed that dreams are remembered more accurately immediately after awakening during the night rather than in the morning. Remembering dreams takes time, effort, and patience. Researchers discovered that people who tend to forget their dreams show a greater amount of rapid eye movement, which is associated with greater amounts of activity in the dream. However, when these people did remember the content of their dreams, it wa...

Operation Management Case Studies Essay

Operation Management Case Studies Intoduction Case study on Salmon processing facility Question 1 E= $ 6,333.33 Therefore, the additional expenditure for the productivity of the two systems to equal will be $ 6, 333.33 Question 4                   If the cost of energy increases in future, the productivity of facility will be affected negatively and it will decrease. If the cost of the energy increases beyond the estimated additional expenditure of $ 6,333.33, the productivity of the new facility will be much lower than that of the old system and therefore, it will not be advantage to the firm. This will also affect reduce the profitability of the company. Case 2 on Hard Rock Cafe Question 1                   The Hard Rock strategic changes that it has experienced include globalization and changes in its brand through unique services that include rock music. The music has led to the growth of this company. It has managed to open 157 cafe facilities in more than 57 countries. The cafe has also diversified brands to fish and lobsters in Britain. Moreover, it has started shifting its target market from tourists to non tourists’ cities in United Kingdom in addition to leasing cafes in tourism cites such as Nottingham (Heizer, & Render, 2013). Question 2                   Hard Rock has various PRODUCTS that vary from Hamburger, beef, and other tourism attracting meal. The cafe is has also diversified its products to fish and lobsters thus widening its market and meeting the needs of the customer.                   Hard rock cafe moved its LOCATION from domestic market to global market. In addition, it has started opening in new non tourisms LOCATIONS such as Manchester united to prevent risks associated with economic fluctuations that arise from tourism business poor performance.                   Hard rock HUMAN RESOURCE has participated in developing new strategies that has helped to improve the performance the business. For example, the introduction of sound and visuals in dinner events that attract more customers and recruitment of highly trained employees that provides quality services.                   The Hard Rock has improved its  SERVICE by adding unique services that cannot be found in any other place in the world such as music on both quality visual and sounds. They serve food with enthusiasm on their customers (Heizer, & Render, 2013). Question 3 -123825158750Introduction Growth Maturity Decline Standardization Less rapid product changes – more minor changes Optimum capacity Increasing stability of process Long production runs Product improvement and cost cutting Little product differentiation Cost minimization Overcapacity in the industry Prune line to eliminate items not returning good margin Reduce capacity Forecasting critical Product and process reliability Competitive product improvements and options Increase capacity Shift toward product focused Enhance distribution Product design and development critical Frequent product and process design changes Short production runs High production costs Limited models Attention to quality Best period to increase market share R&D product engineering critical Practical to change price or quality image Strengthen niche Cost control critical Poor time to change image, price, or quality Competitive costs become critical Defend market position OM Strategy/Issues Company Strategy/Issues HDTV CD-ROM Color copiers Drive-thru restaurants Fax machines Station wagons Sales 3 1/2† Floppy disks Internet 00Introduction Growth Maturity Decline Standardization Less rapid product changes – more minor changes Optimum capacity Increasing stability of process Long production runs Product improvement and cost cutting Little product differentiation Cost minimization Overcapacity in the industry Prune line to eliminate items not returning good margin Reduce capacity Forecasting critical Product and process reliability Competitive product improvements and options Increase capacity Shift toward product focused Enhance distribution Product design and development critical Frequent product and process design changes Short production runs High production costs Limited models Attention to quality Best period to increase market share R&D product engineering critical Practical to change price or quality image Strengthen niche Cost control critical Poor time to change image, price, or quality Competitive costs become critical Defend market position OM Strategy/Issues Company Strategy/Issues HDTV CD-ROM Color copiers Drive-thru restaurants Fax machines Station wagons Sales 3 1/2† Floppy disks Internet                   The company is still in the growth stage but approaching maturity. This is from the fact that Hard Rock is trying to change its products from beef and Hamburger to lobster and fish, it can be noted that it is trying to improve its products in order to increase its competitiveness. The company is still forecasting on its future market where it want to change from tourists-dependent market to non-tourism dependent market (Heizer, & Render, 2013). The cafe has products that are reliable with little improvement. Reference Heizer, J., & Render, B. (2013). Principles of operation ,management: Sustainability and supply chain management. Pearson Source document