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Biology ch 27-4
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1. Neurologic Aspects of Pain 1.1. Functional Properties of Nerve Fibres 1.1.1. Properties of Peripheral Somatic Nerves Peripheral somatic nerves consists generally of somatic-motor, autonomic-motor and sensible fibres. 18.104.22.168. Somatic-motor fibres for the striated musculature The cell bodys of somatomotor fibres for the striated musculature are always lying in the brainstem (12 pare cerebral nerves) [&hellip]
&ldquoDETERMINATION OF LEVEL OF TOXICITY IN DIFFERENT BRAND OF LATEX (WATER) BASED PAINT&rdquo ABSTRACT All people around the world have been using paint in their household but they have no idea that all this time they have been exposed to toxic substances that can be found in the paint. Paint manufacturer have used heavy metals [&hellip]
Biology Major Essay Example
The one area of biology that I am especially interested in is genetics. Throughout the three years I have taken biology-related courses, I have gotten a taste of the huge world of genetic research, which is what I hope to explore in the future.
One aspect of biology that we studied freshman year was genetics, which is how I became interested in the subject. In particular, I liked studying Mendelian genetics and learning how different traits are inherited. My interest fostered in freshman year biology affected my course choices for the rest of my high school career and subsequently, the college major I have chosen
During sophomore year, I decided to take AP biology. In that class, we learned more about genetics, which further intrigued me. During that year, because I was so interested in the topics we were discussing in class, I spent some of my free time making a family tree of different inherited traits in my family, such as blood types and cancer.
The following year, I took genetics, a full-year elective packed with topics I was interested in. Among other topics, I learned about inherited traits, genetic diseases, and ethical debates surrounding genetic research. I spent a lot of time in the lab working with DNA, viruses, and bacteria, and the experience of this class proved to me that I want to continue doing similar things as my career.
Besides my love for genetics as a subject, I know that it is an up and coming field that has much potential for research in a variety of areas. Because genetic research is so new and so many possibilities for using this new technology are still being uncovered, I could have the ability to do major research in the area through my studies at Johns Hopkins. For example, although scientists know some of the uses of stemcells, they also know that there are many more things they can be used for that have not been found yet. I am hoping that by majoring in biology, I will have an opportunity to work in the field of genetics and do research that will save many lives.
Although a few years ago I could not imagine even enjoying a 45 minute science class, today I dream of majoring in biology and doing research in college and beyond. The biology classes I took in high school were just the beginning of what I hope to continue doing in the future. Because of those classes and the potential for amazing discoveries in the field of genetics, I have chosen biology as my major.
Patient Bill Of Rights
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Create a 10- to 15-minute, 9- to 12-slide voice-over presentation using either Microsoft® PowerPoint® or websites such as Google Slides™, Adobe® Slate, or Prezi presenting your Patient Bill of Rights and explaining what each right will mean for the patient and for the facility or service.
Biology is the science that studies living organisms and their interactions with one another and their environments. Science attempts to describe and understand the nature of the universe in whole or in part by rational means. Science has many fields those fields related to the physical world and its phenomena are considered natural sciences.
Science can be basic or applied. The main goal of basic science is to expand knowledge without any expectation of short-term practical application of that knowledge. The primary goal of applied research, however, is to solve practical problems.
Two types of logical reasoning are used in science. Inductive reasoning uses particular results to produce general scientific principles. Deductive reasoning is a form of logical thinking that predicts results by applying general principles. The common thread throughout scientific research is the use of the scientific method, a step-based process that consists of making observations, defining a problem, posing hypotheses, testing these hypotheses, and drawing one or more conclusions. The testing uses proper controls. Scientists present their results in peer-reviewed scientific papers published in scientific journals. A scientific research paper consists of several well-defined sections: introduction, materials and methods, results, and, finally, a concluding discussion. Review papers summarize the research done in a particular field over a period of time.
1.2 Themes and Concepts of Biology
Biology is the science of life. All living organisms share several key properties such as order, sensitivity or response to stimuli, reproduction, growth and development, regulation, homeostasis, and energy processing. Living things are highly organized parts of a hierarchy that includes atoms, molecules, organelles, cells, tissues, organs, and organ systems. Organisms, in turn, are grouped as populations, communities, ecosystems, and the biosphere. The great diversity of life today evolved from less-diverse ancestral organisms over billions of years. A diagram called a phylogenetic tree can be used to show evolutionary relationships among organisms.
Biology is very broad and includes many branches and subdisciplines. Examples include molecular biology, microbiology, neurobiology, zoology, and botany, among others.
Essays on Biology
The world as we know is to complex, vital, and sensitive to be taken under the arms of organelles who are not ready to govern our province and center of life. What we need to understand as educated organelles is that without the cell membrane.
Gemcitabine is a chemotherapeutic medication used to treat various cancers such as pancreatic, breast, ovarian, bladder, and lung cancers. It was discovered in the early1980s during a pancreatic cancer trial when the researchers discovered that the patients who were injected with Gemcitabine had a longer.
Reproduction is among the most fundamental characteristics of a living cell. The understanding of the intricate workings of cellular reproduction and the startling similarities between the various processes across a wide variety of organisms from yeast to humans, helps to unambiguously assert the fact that.
Mosquitos are becoming more of a threat now in Queensland, the Zika virus is the highest threat, but the Dengue is still up there as it is spreading to further places but not an as poisons as the zika. There are many more mosquitoes that.
Bird flu or avian influenza is a very popular disease of birds, it spreads in a lot of countries, it is a very dangerous disease of not treated efficiently and it also can cause a high mortality to birds. The disease has been known for.
Nanotechnology is a revolutionised method that allows for the manipulation of atoms and molecules. Materials at the nanoscale allow for the enhancement of numerous properties such as lighter weight, higher strength, increased control of light spectrum, and greater chemical reactivity. This ability to create resources.
Dengue is a Spanish word which means “fastidious”, it is derived from “dinga” which means an evil of spirit. Dengue is a viral disease which is caused by the biting of a female mosquito Adese Aegypti. The causative agent of dengue fever is the dengue.
FLT3 Inhibitors in Clinical Trials
A number of FLT3 inhibitors have reached clinical trials as monotherapy in relapsed or refractory AML patients, some or all of whom had FLT3 mutations. 33 , – 35 The results of these trials have been informative. In most studies, the drugs have been well-tolerated as outpatient oral medications. When patients’ blasts have a cytotoxic response to in vitro FLT3 inhibition and adequate levels of inhibition are attained in these patients in vivo, the patients have demonstrated a clinical response. In trials that have treated both FLT3 mutant and wild-type FLT3 AML patients, there is more frequent response to FLT3 TKI in the mutant FLT3 patients, paralleling the increased in vitro response of mutant cells previously observed. The responses in all patients, however, are usually restricted to a clearing of peripheral leukemia cells. Major bone marrow responses are uncommon. In most patients, the clinical response is short-lived with most patients’ peripheral blasts returning within weeks to months. This is in sharp contrast to the results in chronic phase CML where Gleevec results in responses that last a number of years in most patients. Part of the difference in the response to inhibitors of mutated kinases in these diseases is that FLT3 mutations occur in the setting of acute leukemia, where it is but one of several somatic genetic alterations required to fully transform cells. In contrast, CML in chronic phase represents a myeloproliferative disorder in which the BCR-ABL fusion may be the only molecular abnormality. In patients relapsing on Gleevec the most frequent cause appears to be the selection of mutations within BCR-ABL that make it resistant to inhibition by Gleevec. In contrast, only 1 patient thus far on FLT3 inhibitor trials has been shown to have acquired a FLT3 resistance mutation. 36 This again points to other mechanisms outside FLT3 signaling as the reason for the limited duration of response.
Preclinical studies demonstrated synergistic killing of leukemic cells in vitro when FLT3 TKI are combined with conventional chemotherapy in a sequence-specific order. 37 Synergism was seen when the two classes of agents were used simultaneously or the FLT3 TKI followed chemotherapy. Antagonism due to cell-cycle blockade was observed when chemotherapy followed FLT3 TKI treatment. Several current trials of FLT3 TKI are using this approach of combination treatment in either relapsed or newly diagnosed adult AML studies. CEP-701 (Lestaurtinib) combined with chemotherapy is in a phase III trial in relapsed FLT3 mutant AML patients in many institutions in the US, Italy, Israel, and Spain. Another trial of CEP-701 with chemotherapy in newly diagnosed AML patients is now underway through the Medical Research Council (MRC) in Great Britain. A study of PKC412 combined with chemotherapy in newly diagnosed AML patients is planned through a combination of cooperative groups in the US. Presentations at the 2005 American Society of Hematology annual meeting on preliminary results and/or correlative data from both the CEP-701 and PKC412 trials generated enthusiasm for their combination with chemotherapy. 38 , 39
Pediatric trials utilizing combinations of CEP-701 with chemotherapy should be shortly underway in the Children’s Oncology Group in both relapsed FLT3-mutant AML patients and in infants with MLL-rearranged ALL. Preclinical work has shown important roles for FLT3 signaling in both of these groups and preferential sensitivity to induction of cytotoxic responses by FLT3 TKI. 40 , – 43
Anti-FLT3 antibody trials are also being contemplated in AML and ALL because of the frequent expression of FLT3, either mutant or wild-type, in these diseases. Besides the potential for interfering with FLT3 signaling, anti-FLT3 antibodies can also induce ADCC as an additional mechanism for inducing cytotoxicity.
27.4: Conclusion - Biology
Our first chapter introduced the basis of all biology: the cell theory. All living things are made of prokaryotic or eukaryotic cells. Prokaryotes are simpler and do not contain membrane-bound organelles. Eukaryotes contain membrane-bound organelles with highly specialized functions. While eukaryotic organisms (especially humans!) will be the primary focus on Test Day, an understanding of prokaryotic structure and physiology is necessary to understand infection. Viruses are nonliving infectious particles that must invade cells in order to reproduce. Finally, we discussed the smallest infectious particles, prions and viroids.
Our discussions from here on out will focus primarily on eukaryotes, but you will spend significant time in your clinical career battling the pathogens we’ve presented in this chapter. Vaccines are available for a number of bacteria (Bacillus anthracis [anthrax], Corynebacterium diphtheriae[diphtheria], Haemophilus influenzae type B [many upper respiratory and ear infections], Neisseria meningitidis [some cases of bacterial meningitis], Streptoccocus pneumoniae [many cases of bacterial pneumonia], Clostridium tetani [tetanus], and Salmonella typhi [typhoid]) and viruses (varicella zoster virus [chicken pox and shingles], hepatitis A and B viruses, human papillomavirus [HPV], influenza, measles, mumps, pertussis, polio, rabies, rotavirus, rubella, and yellow fever). Those for which we do not have vaccines may be targeted with antibiotic and antiviral therapies the appropriate pharmacotherapy is almost always predicated on an understanding of the bacterial or viral physiology one is targeting and the known resistance patterns in the local area. In other words, the principles presented in this chapter will show up in your everyday life as a physician it is important not to just memorize but to understand the content in this chapter.
We’ve discussed one method of cellular reproduction&mdashthe division of a bacterial cell into two by binary fission. Eukaryotic cells also must replicate, but use a different process: mitosis. It is to this process, as well as meiosis and the human reproductive system, that we turn our attention in the next chapter.
·&emspThe cell theory has four basic tenets:
o All living things are composed of cells.
o The cell is the basic functional unit of life.
o Cells arise only from preexisting cells.
o Cells carry genetic information in the form of DNA. This genetic material is passed on from parent to daughter cell.
·&emspViruses are not considered living things because they are acellular, cannot reproduce without the assistance of a host cell, and may contain RNA as their genetic material.
·&emspEukaryotes have membrane-bound organelles, a nucleus, and may form multicellular organisms.
·&emspThe cell membrane and membranes of organelles contain phospholipids, which organize to form hydrophilic interior and exterior surfaces with a hydrophobic core.
·&emspThe cytosol suspends the organelles and allows diffusion of molecules through-out the cell.
·&emspThe eukaryotic organelles each serve specific functions:
o The nucleus contains DNA organized into chromosomes. It is surrounded by the nuclear membrane or envelope, a double membrane that contains nuclear pores for two-way exchange of materials between the nucleus and cytosol. DNA is organized into coding regions calledgenes.
o The nucleolus is a subsection of the nucleus in which ribosomal RNA (rRNA) is synthesized.
o Mitochondria contain an outer and inner membrane. The outer membrane forms a barrier with the cytosol the inner membrane is folded into cristae and contains enzymes for the electron transport chain. Between the membranes is the intermembrane space inside the inner mitochondrial membrane is the mitochondrial matrix. Mitochondria can divide independently of the nucleus via binary fission they can trigger apoptosis by releasing mitochondrial enzymes into the cytoplasm.
o Lysosomes contain hydrolytic enzymes that can break down substances ingested by endocytosis and cellular waste products. When these enzymes are released, autolysis of the cell can occur.
o The endoplasmic reticulum (ER) is a series of interconnected membranes and is continuous with the nuclear envelope. The rough ER (RER) is studded with ribosomes, which permit translation of proteins destined for secretion. The smooth ER (SER) is used for lipid synthesis and detoxification.
o The Golgi apparatus consists of stacked membrane-bound sacs in which cellular products can be modified, packaged, and directed to specific cellular locations.
o Peroxisomes contain hydrogen peroxide and can break down very long chain fatty acids via &beta-oxidation. They also participate in phospholipid synthesis and the pentose phosphate pathway.
·&emspThe cytoskeleton provides stability and rigidity to the overall structure of the cell, while also providing transport pathways for molecules within the cell.
o Microfilaments are composed of actin. They provide structural protection from the cell and can cause muscle contraction through interactions with myosin. They also help form the cleavage furrow during cytokinesis in mitosis.
o Microtubules are composed of tubulin. They create pathways for motor proteins like kinesin and dynein to carry vesicles. They also contribute to the structure of cilia and flagella, where they are organized into nine pairs of microtubules in a ring with two microtubules at the center (9 + 2 structure). Centrioles are found in centrosomes and are involved in microtubule organization in the mitotic spindle.
o Intermediate filaments are involved in cell–cell adhesion or maintenance of the integrity of the cytoskeleton they help anchor organelles. Common examples include keratin and desmin.
·&emspEpithelial tissues cover the body and line its cavities, protecting against pathogen invasion and desiccation. Some epithelial cells absorb or secrete substances, or participate in sensation.
o In most organs, epithelial cells form the parenchyma, or the functional parts of the organ.
o Epithelial cells may be polarized, with one side facing a lumen or the outside world, and the other side facing blood vessels and structural cells.
o Epithelia can be classified by the number of layers they contain: simple epithelia have one layer, stratified epithelia have many layers, and pseudostratified epithelia appear to have multiple layers because of differences in cell heights, but actually have only one layer.
o Epithelia can be classified by the shapes of the cells they contain: cuboidal cells are cube-shaped, columnar cells are long and narrow, and squamous cells are flat and scalelike.
·&emspConnective tissues support the body and provide a framework for epithelial cells.
o In most organs, connective tissues form the stroma or support structure by secreting materials to form an extracellular matrix.
o Bone, cartilage, tendons, ligaments, adipose tissue, and blood are all connective tissues.
Classification and Structure of Prokaryotic Cells
·&emspProkaryotes do not contain membrane-bound organelles they organize their genetic material in a single circular molecule of DNA concentrated in the nucleoid region.
·&emspThere are three overarching domains of life prokaryotes account for two of these:
o Archaea are often extremophiles, living in harsh environments (high temperature, high salinity, no light) and often using alternative sources of energy, like chemosynthesis. They have similarities to both eukaryotes (start translation with methionine, similar RNA polymerases, histones) and bacteria (single circular chromosome, divide by binary fission or budding).
o Bacteria have many similar structures to eukaryotes, and have complex relationships with humans, including symbiosis and pathogenesis.
o Eukarya is the only non-prokaryotic domain.
·&emspBacteria can be classified by shape:
o Spherical bacteria are called cocci.
o Rod-shaped bacteria are called bacilli.
o Spiral-shaped bacteria are called spirilli.
·&emspBacteria can be classified based on metabolic processes:
o Obligate aerobes require oxygen for metabolism.
o Obligate anaerobes cannot survive in oxygen-containing environments and can only carry out anaerobic metabolism.
o Facultative anaerobes can survive in environments with or without oxygen and will toggle metabolic processes based on the environment.
o Aerotolerant anaerobes cannot use oxygen for metabolism, but can survive in an oxygen-containing environment.
·&emspThe cell wall and cell membrane of bacteria form the envelope. Together, they control the movement of solutes into and out of the cell.
o Bacteria can be classified by the color their cell walls turn during Gram staining with a crystal violet stain, followed by a counterstain with safranin. Gram-positive bacteria turn purple, while gram-negative bacteria turn pink-red.
o Gram-positive bacteria have a thick cell wall composed of peptidoglycan and lipoteichoic acid.
o Gram-negative bacteria have a thin cell wall composed of peptidoglycan and an outer membrane containing phospholipids and lipopolysaccharides.
·&emspBacteria may have one, two, or many flagella that generate propulsion to move the bacterium toward food or away from immune cells. Moving in response to chemical stimuli is called chemotaxis. Bacterial flagella contain a filament composed of flagellin, a basal body that anchors and rotates the flagellum, and a hook that connects the two.
·&emspProkaryotes carry out the electron transport chain using the cell membrane.
·&emspProkaryotic ribosomes are smaller than eukaryotic ribosomes (30S and 50S, rather than 40S and 60S).
Genetics and Growth of Prokaryotic Cells
·&emspProkaryotes multiply through binary fission, in which the chromosome replicates while the cell grows in size, until the cell wall begins to grow inward along the midline of the cell and divides it into two identical daughter cells.
·&emspIn addition to the single circular chromosome in prokaryotes, extrachromosomal material can be carried in plasmids. Plasmids may contain antibiotic resistance genes or virulence factors. Plasmids that can integrate into the genome are called episomes.
·&emspBacterial genetic recombination increases bacterial diversity.
o Transformation is the acquisition of genetic material from the environment, which can be integrated into the bacterial genome.
o Conjugation is the transfer of genetic material from one bacterium to another across a conjugation bridge a plasmid can be transferred from F+ cells to F– cells, or a portion of the genome can be transferred from an Hfr cell to a recipient.
o Transduction is the transfer of genetic material from one bacterium to another using a bacteriophage as a vector.
o Transposons are genetic elements that can insert into or remove themselves from the genome.
·&emspBacterial growth follows a predictable pattern:
o The bacteria adapt to new local conditions during the lag phase.
o Growth then increases exponentially during the exponential (log) phase.
o As resources are reduced, growth levels off during the stationary phase.
o As resources become insufficient, bacteria undergo a death phase.
Viruses and Subviral Particles
·&emspViruses contain genetic material, a protein coat (capsid), and sometimes a lipid-containing envelope.
·&emspViruses are obligate intracellular parasites, meaning that they cannot survive and replicate outside of a host cell. Individual virus particles are called virions.
·&emspBacteriophages are viruses that target bacteria. In addition to the other structures, they contain a tail sheath, which injects the genetic material into a bacterium, and tail fibers, which allow the bacteriophage to attach to the host cell.
·&emspViral genomes may be made of various nucleic acids:
o They may be composed of DNA or RNA and may be single- or double-stranded.
o Single-stranded RNA viruses may be positive sense (can be translated by the host cell) or negative sense (a complementary strand must be synthesized using RNA replicase, which can then be translated).
o Retroviruses contain a single-stranded RNA genome, to which a complementary DNA strand is made using reverse transcriptase. The DNA strand can then be integrated into the genome.
·&emspViruses infect cells by attaching to specific receptors, and then either fusing with the plasma membrane, being brought in by endocytosis, or injecting their genome into the cell.
·&emspThe virus reproduces by replicating and translating genetic material using the host cell’s ribosomes, tRNA, amino acids, and enzymes.
·&emspViral progeny are released through cell death, lysis, or extrusion.
·&emspBacteriophages have two specific life cycles:
o In the lytic cycle, the bacteriophage produces massive numbers of new virions until the cell lyses. Bacteria in the lytic phase are termed virulent.
o In the lysogenic cycle, the virus integrates into the host genome as a pro-virus or prophage, which can then reproduce along with the cell. The provirus then leaves the genome in response to a stimulus at some later time and enters the lytic cycle.
·&emspPrions are infectious proteins that trigger misfolding of other proteins, usually converting an &alpha-helical structure to a &beta-pleated sheet. This decreases the solubility and degradability of the misfolded protein.
·&emspViroids are plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural derangements of the cell and&mdashpotentially&mdashcell death.
Answers to Concept Checks
1. All living things are made of cells. The cell is the basic functional unit of life. All cells arise from other cells. Genetic information is carried in the form of deoxyribonucleic acid (DNA) and is passed from parent to daughter cell.
1. The nucleus stores genetic information and is the site of transcription. The mitochondria are involved in ATP production and apoptosis. Lysosomes break down molecules ingested through endocytosis and cellular waste products, and can also be involved in apoptosis. The rough endoplasmic reticulum synthesizes proteins destined for secretion. The smooth endoplasmic reticulum is involved in lipid synthesis and detoxification. The Golgi apparatus packages, modifies, and distributes cellular products. Peroxisomes break down very long chain fatty acids, synthesize lipids, and contribute to the pentose phosphate pathway.
2. Peroxisomes are dependent on hydrogen peroxide for their functions, so an enzyme deficiency that results in an inability to form hydrogen peroxide would likely result in an inability to digest very long chain fatty acids. These fatty acids would build up in peroxisomes until most of the cellular contents were displaced by oversized peroxisomes. This would ultimately result in cell death.
3. Microfilaments are composed of actin. Microtubules are composed of tubulin. Intermediate filaments differ by cell type, but include keratin and desmin.
4. Centrioles consist of nine triplets of microtubules around a hollow center, while flagella consist of nine doublets on the outside, with two microtubules on the inside.
5. Endothelial cells and &alpha-cells are epithelial cells. Fibroblasts, osteoblasts, and chondroblasts are connective tissue cells.
1. Archaea are similar to bacteria in that both are single-celled organisms that lack a nucleus or membrane-bound organelles, contain a single circular chromosome, divide by binary fission or budding, and overall share a similar structure. They are similar to eukaryotes in that they start translation with methionine, contain similar RNA polymerases, and associate their DNA with histones.
2. The three common shapes of bacteria are spherical (cocci), rod-shaped (bacilli), and spiral-shaped (spirilli).
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