RAT Reading Guide 3
RAT Reading Guide 3 BIOL1302/10025
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This 9 page Class Notes was uploaded by Sara Ali on Monday September 12, 2016. The Class Notes belongs to BIOL1302/10025 at University of Houston Downtown taught by Rachel Hudspeth in Fall 2016. Since its upload, it has received 2 views. For similar materials see General Biology 2 in Biology at University of Houston Downtown.
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Date Created: 09/12/16
RAT 2 Concept 17.2 The textbook means when it says, “Viruses lead a kind of borrowed life," because viruses are capable of causing many diseases, researchers in the late 1800s saw a parallel with bacteria and proposed that viruses were the simplest living forms. Most biologists studying the viruses today would likely agree that they are not alive but exist in a shady area between life-forms and chemicals Viruses are composed of two types of macromolecules which are nucleic acid surrounded by a protein coat. Two types of polynucleotides that a virus could carry are DNA and RNA, Viral capsid is the protein shell enclosing the viral genome and viral envelopes are derived from the membranes of the host cell, they contain host cell phospholipids and membrane proteins. For the influenza virus, the origin of the viral envelope is that they have different RNA molecules, each wrapped in a helical capsid, and an outer envelope studded with glycoprotein spikes. Two different origins for the proteins or the glycoproteins found within the viral envelope is that glycoproteins are proteins with carbohydrates covalently attached. Bacteriophages are many of the most complex capsids found among the viruses that infect bacteria. The first phages included seven that infect E.coli, such as Type (T1), Type 2 (T2), Type3 and so forth. Their capsids have elongated icosahedral heads enclosing their DNA. Attached to the head is a protein tail piece with fibers by which the phages attach to bacterium. Concept 17.2 a. When virus enters a host cell, it releases the viral DNA and capsid proteins. RAT 2 b. After the viral genome is released into a host cell, the host enzymes replicate the viral genome. c. The host cells transcribe the viral genome into mRNA, because this is then used for protein synthesis. d. The viral proteins 2. Many plant and animal viruses can enter the cell through a process called endocytosis, a process in which the cell membrane engulfs and surrounds the entire virus. Some enveloped viruses enter the cell through a process when the viral envelope fuses directly into the cell membrane. 3. In the Lytic cycle consists of virulent or temperate phage, destruction of host DNA, Production of new phages, and Lysis of host cell causes release of progeny phages. In the Lysogenic cycle consists of a template phage, genome integrates itself inside the bacterial chromosome as prophage, which is 1) is replicated and passed on to daughter cells and 2) can be induced to leave the chromosome and initiate a lytic cycle. In the Lytic cycle the host cell is destroyed. Prophage is formed in the lysogenic cycle. Viral DNA is replicated in the lysogenic cycle. 4. Viral proteins that extend from the viral envelope bind to specific receptor molecules on the host cell, prompting viral entry into the cell. 5. The mRNA is the structure within the animal host cell that synthesizes glycoproteins. Concept 17.3 How do each of the following processes contributing to the emergence of new viral disease : Mutation of existing viruses : Dissemination from an isolated human population: Crossing the species barrier: 2. Influenza viruses have the following names H1N1 or H5N1 : RAT 2 a. The name of the enzyme that the letter H refers to is b. The name of the enzyme that the letter N refers to is 3. Birds, bats, and other animals are referred to as viral vectors because 4. It’s important that the Global Health Organization monitors the appearance of viruses in migrating bird populations, because Concept 24.2 The general characteristics of a prokaryotic cell are that 1) they lack an organized nucleus and membrane- bound organelles 2) Prokaryotic DNA is found in a central part of the called the nucleoid and 3) the cell wall of prokaryotic cell acts an extra layer of protection, helps maintain cell shape, and prevents dehydration. Both Bacteria and Archaea are prokaryotic cells because they both have no nucleus and membrane- bound organelles. Gram-negative cell wall is different from Gram-positive cell wall because Gram Positive bacteria has a thick cell wall layer and Gram negative bacteria has a thin cell wall layer. The Peptidoglycan layer in Gram positive is thick and Gram Negative is thin. The outer membrane is absent in gram positive and its present in Gram negative. Bacterial capsule is a sticky layer of polysaccharide or protein that can help cell adherence and/or evasion of a host’s immune system. An endospore is to allow the survival of bacteria’s cell lines through harsh conditions that would kill a member of species. These conditions include starvation, ultraviolet light, desiccation and chemical damage. An endospore is unusually small and largely dehydrated by a bacterium with a germ cell wall, surrounded by walls of protein and peptidoglycan that cover it. A fimbriae are hair like appendages that help cells adhere to other cells or to a substrate. A capsule is a sticky layer of polysaccharide or protein that can help RAT 2 cell adherence and/or evasion of a host’s immune system. Virulence factor are molecules produced by pathogens (bacteria, viruses, fungi and protozoa), that contribute to the pathogenicity of the organism and enable it to achieve the following: colonization of a niche in the host (attachments to cells). A capsule and a fimbriae are both virulence factors because capsule A heterotrophic bacteria consists of both chemoheterotrophic and photoheterotrophic. Photoheterotrophic bacteria are unique to certain aquatic and salt-loving prokaryotes, their energy source is light and their carbon source are organic compounds. Chemoheterotrophic bacteria’s energy source are organic compounds, their carbon source is organic compounds and the types of organisms that they include are many prokaryotes and protists; fungi; animals and some plants. Photoautotrophic bacteria are photosynthetic prokaryotes (for example cyanobacteria), plants, certain protists (for example algae), their light source is light and their carbon source is carbon dioxide, Hydrogen carbonate or another related compound. Prokaryotes undergo a type of cell division which is called binary fission, meaning it refers to this process and to the asexual reproduction of single-celled eukaryotes, such as the amoeba. However, the process in eukaryotes involves mitosis; the process in prokaryotes does not. Concept 24.3 Three factors that contribute to genetic variation in bacterial populations are transformation, transduction and conjugation. The probability that a DNA mutation will occur with an E.coli gene each time a cell reproduces is about one in 10 million. Transformation is a major source of variation in prokaryotic populations, where the genotype and possibly the phenotype of a prokaryotic cell are altered RAT 2 by the uptake of foreign DNA from its surroundings. Transformation occurs when a nonpathogenic cell takes up a piece of DNA carrying the allele for pathogenicity and replaces its own allele with the foreign allele, an exchange of homologous DNA segments. In Transduction, the phages carry prokaryotic genes from one host cell to another cell. In most cases, transduction results from accidents that occur during the phage replicative cycle. A virus that carries prokaryotic DNA may not be able to replicate because it lacks some or all of its own genetic material. A plasmid is a small DNA molecule within a chromosomal cell, which is separate from the rest of the part of the cell. Plasmids usually exist in structural cells and in bacteria. Genes present in plasmids provide the cell with genetic resistance such as antibiotic resistance. An F plasmid is that the F factor in its plasmid form, cells which contain the F plasmid, are designated as F^+ cells, they function as DNA donors during conjugation. Bacteria also have resistance genes, which code for enzymes that specifically destroy or otherwise hinder the effectiveness of certain antibiotics, such as tetracycline and or ampicillin. Resistance genes are often carried by plasmids known as R plasmids. R plasmids carry ten times genes for resistance to that of many antibiotics. Steps involved in the transfer of a plasmid from a donor cell to a recipient cell: A cell carrying an F plasmid (a F positive cell) forms a mating bridge with a F negative cell. One strand of the plasmid DNA’s breaks at the point marked by the arrowhead. Using the unbroken strand as a template, the cell synthesizes a new strand. Meanwhile, the broken strand peels off and one end enters the F negative cell. There synthesis of its complementary strand begins. DNA replication continues in both donor and recipient cells, as the transferred plasmid strand moves farther onto the recipient cell. RAT 2 Once DNA transfer and synthesis are now completed, the plasmid in the recipient cell circularizes. The recipient cell is now a recombinant F positive cell. Concept 24.5 Exotoxins are proteins secreted by certain bacteria and other organisms. Cholera, is a dangerous diarrheal disease, is caused by an exotoxin secreted by the proteobacterium Vibrio cholera. The exotoxin simulates intestinal cells to release chloride ions into the gut, and water follows by osmosis. Endotoxins are lipopolysaccharide components of the gram-negative bacteria. In contrast, to exotoxins, endotoxins are released only when the bacteria idea and their cell walls break down. The role that transduction plays in the appearance of a highly virulent E.coli strain O157:H7 is that it’s one of the most dangerous strains and it’s a global threat in the United States alone, there are 75,000 cases of O157:H7 infection per year, often from contaminated beef or produce. MRSA is Methicillin Resistant Staphylococcus Aureus infection is caused by a bacteria that has become resistant to many types of antibiotics that have been used to treat ordinary staph infections. MRSA infections usually occur to people in hospital care setting, health care settings, nursing homes and dialysis centers. MRSA infections are usually associated with invasive procedures or devices, such as surgical devices, surgeries or artificial joints. MRSA infections can affect your bloodstream, lungs, heart, bones and joints. One health threat posed by MRSA is that it’s a major global health threat, which continues at an alarming rate. Concept 25.1 Eukaryotic cells are different from prokaryotic cells is that unlike the cells of prokaryotes, the cells of all eukaryotes have a nucleus and other membrane- RAT 2 enclosed organelles, such as mitochondria and the Golgi apparatus. Such organelles provide specific locations such where particular cellular functions are accomplished, making the structure and organization of eukaryotic cells more complex than that of prokaryotic cells. Another key characteristic of eukaryotic cells is that they possess a well-developed cytoskeleton that extends throughout the cell. The cytoskeleton provides structural support that enables eukaryotic cells to have asymmetric forms.as well as to change shape as they feed, move, or grow. Phagocytosis is the process through which a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membranous sac called a food vacuole. The particle will be digested after the food vacuole fuses with a lysosome containing hydrolytic enzymes. For a single celled eukaryote, the role of cytoskeleton in capturing their prey is that the cytoskeleton is that it provides structural support which enables eukaryotic cells to have asymmetric forms, to change shape as they move, feed, and to grow. The origin of the endomembrane system is that DNA sequence analyses indicate that eukaryotes contain a mixture of archaeal and bacterial genes and cellular characteristics. According to the endosymbiont theory, this mixture of features likely resulted because eukaryotes originated when an arterial host engulfed a bacterium that would later become an organelle found in a eukaryote, the mitochondrion. Endosymbiosis is the hypothesized process by which prokaryotes gave rise to the first eukaryotic cells is known as endosymbiosis, and certainly ranks among the most important evolutionary events. Endosymbiotic theory explain the origins of eukaryotic cell organelles such as mitochondria which are found in fungi and chloroplasts in plants was greatly advanced by the seminal work of biologist Lynn Margulis in the 1960s. Mitochondria are one of the many different types of RAT 2 organelles in the cells of all eukaryotes. In general, they are considered to have originated from proteobacteria (likely Rickettsiales) through endosymbiosis. Chloroplasts are one of the many different types of organelles in the plant cell. In general, they are considered to have originated from cyanobacteria through endosymbiosis. Endosymbiosis has gained ever more acceptance in the last half century, especially with the relatively recent advent of sequencing technologies. There are many variants to the theory, regarding what organism(s) engulfed what other organism(s), as well as how many times and when it occurred across geological time. Concept 25.3 The four super groups that categorize protists are Excavata, “SAR” clade, Archaeplastida, and Unikonta. The SAR clade includes some major clades such as stramenopiles, alleviates and rhizarians. The super group of protists that represent a polytomy are Archaeaplastida. The four super group of protists are Excavata, “SAR” clade, Archaeplastida, and Unikonta. The Protistagroup Excavata was originally proposed based on morphological studies of the cytoskeleton. The name derives from the fact that some members of this diverse group feature an “excavated” feeding groove on one side of the cell body. The clade Excavata includes the diplomonads, the parabaslids, and the euglenozoans. Molecular data indicate that each of these three groups is monophyletic, and recent genomic studies have supported the monphyly of the super group Excavata. The protists in these types of two groups: the diplomonads and the parabaslids they lack plastids and have highly modified mitochondria. Most diplomonads are found in anaerobic environments. The “SAR” clade is a monophyletic subgroup. One major subgroup of the SAR clade are the stramenopiles, RAT 2 which arose by secondary endosymbiosis and they include some of the most important photosynthetic organisms. - The Diatoms are a key group of photosynthetic protists, they are unicellular algae that have a unique glass-like wall made of silicon dioxide embedded in an organic matrix. Alveolates are a clade where the members include species that have membrane-bound sacs under the plasma membrane. -The Alveolates include three different clades: 1) the Dinoflagellates 2) the Apicomplexans and 3) the Ciliates. - Dinoflagellates are characterized by cellular plates with two flagella, the dinoflagellates are found in both marine and freshwater plankton. These organisms are responsible for red tide, they release a neurotoxin that can be magnified in filter feeding shellfish and can cause respiratory distress and/or even death. Many of the species are mixotrophs. - The Excavata include 3 major groups: Diplomonads, Parabaslids, and Euglenozoans. The SAR group include 3 major groups: Stramenopiles, Alveolates and Rhizarians. Some subgroups of Archaeplastida are Land Plants, Red Algae, and Green Algae. Subgroups of Unikonta are Amoebozoans and Opisthokonts.
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