...• The only way in which viruses are like organisms is that they are able to multiply. • Although viruses can multiply, they do so differently than organisms. Viruses can multiply only when they are inside a living cell. • The organism that a virus enters and multiplies inside is called a host. • A host is an organism that provides a source of energy for a virus or another organism. • A virus acts like a parasite, an organism that lives on or in a host and causes it harm. • Almost all viruses destroy the cells in which they multiply. Virus Shapes: • Viruses vary widely in shape. • Some viruses are round, while some are rod-shaped. • Other viruses are shaped like bricks, threads, or bullets. • There are even viruses that have complex, robotlike shapes, such as the bacteriophage. • A bacteriophage is a virus that infects bacteria. In fact, its name means “bacteria eater.” Virus Sizes: • Just as viruses vary in shape, they also vary in size. • Viruses are smaller than cells and cannot be seen with the microscopes you use in school. • Viruses are so small that they are measured in units called nanometers (nm), which is one billionth of a meter. (video clip) The Structure of a Virus • All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material. • A virus’s genetic material contains the instructions for making new viruses. • Like keys, a virus’s proteins fit only into certain “locks,” or proteins...
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...Main features of Plant Viruses and the diseases they cause Essay Viruses are small infectious pathogens, which are too small to be seen under a light microscope. However, despite their size they can cause both mild to severe illnesses. Viruses only activate inside a host cell and can affect all life forms including humans, animals, plants, and even microorganisms like bacteria and archaea. Viruses depend on the cellular system of their host for reproduction. Viruses have three main parts, which are nucleic acid, protein coat and lipid membrane. Nucleic acid is the core of a virion, which holds all the genetic information (DNA and RNA) and helps it multiply. The protein coat or capsid protects the virus by covering it and the capsid is covered by a envelope called lipid membrane. Not all viruses have the capsid and the ones that do not have the capsid known as naked viruses. Viruses are responsible for causing many plant diseases, leading to losses in crop yield and quality all around the world. Plant virology began in the 19th century when Dutch microbiologists Martinus Beijerinck and Russian researcher Dmitrii Iwanowski were investigating the cause behind a disease in tobacco (Scholthof 2001). They described an unusual agent, which caused mosaic disease in tobacco (Zaitlin 1998). There was one factor of this agent, which set it apart from other disease-causing microorganisms, and the factor was its size. It had a size smaller than all other microbes. This agent was the first...
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...Classification of viruses Student name Course Institution Instructor Date due Classification of Viruses Most things living things in our world are classified into five different categories. Scientist, biologist and academics do this so they know the exact organism that is being examined and discussed. The five kingdoms of life are identified as: plant, fungi, animal, moneran and fungus. Although, in my research I discovered that some scientist argue that there should be more categories. Plants are many celled organisms and there are about a quarter million plant species. The animal kingdom has about one million species (Campbell, 2003). They are complex organisms with many cells and are divided into vertebrates and invertebrates. Monerans are one-celled organisms and do not have a nucleus. This kingdom is mostly composed of bacteria that are further grouped into bacteria and cyanobacteria. In addition, bacteria are the most common organisms on earth. Protists are mostly single-celled organisms that have a nucleus. They usually live in water. Some protists move around, while others stay in one place. Examples of protists include some algae and amoebas. There are around 38,000 known protist species. They live in water and some move around while others stay in one place. They include algae, paramecium and amoeba. Fungi may also be one-celled or many celled organisms. They include yeast and...
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...Today, many people rely on computers to do homework, work, and create or store useful information. Therefore, it's important for the information to be stored and kept properly. It's also extremely important to protect computers from data loss, misuse and abuse. For example, businesses need to keep their information secure and shielded from hackers. Home users also need to ensure their credit card numbers are secure when participating in online transactions. A computer security risk is any action that could cause loss of information to software, data, processing incompatibilities or damage to computer hardware. An intentional breach in computer security is known as a computer crime, which is slightly different from a cybercrime. A cybercrime is known as illegal acts based on the Internet and is one of the FBI's top priorities. There are several distinct categories for people that perpetrate cybercrimes, and they are: hacker, cracker, cyberterrorist, cyberextortionist, unethical employee, script kiddie and corporate spy. A hacker is defined as someone who accesses a computer or computer network unlawfully. They often claim that they do this to find leaks in the security of a network. The term cracker refers to someone intentionally accessing a computer or computer network with malice in mind. They access computers with the intention of destroying or stealing information. Both crackers and hackers are having advanced network skills. A cyberterrorist is someone who uses a computer...
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...Introduction and Abstract Copyright(c), 1984, Fred Cohen - All Rights Reserved This paper defines a major computer security problem called a virus. The virus is interesting because of its ability to attach itself to other programs and cause them to become viruses as well. There are two spellings for the plural of virus; 'virusses', and 'viruses'. We use the one found in Webster's 3rd International Unabridged Dictionary Given the wide spread use of sharing in current computer systems, the threat of a virus carrying a Trojan horse [Anderson72] [Linde75] is significant. Although a considerable amount of work has been done in implementing policies to protect from the illicit dissemination of information [Bell73] [Denning82], and many systems have been implemented to provide protection from this sort of attack [McCauley79] [Popek79] [Gold79] [Landwehr83], little work has been done in the area of keeping information entering an area from causing damage [Lampson73] [Biba77]. There are many types of information paths possible in systems, some legitimate and authorized, and others that may be covert [Lampson73], the most commonly ignored one being through the user. We will ignore covert information paths throughout this paper. The general facilities exist for providing provably correct protection schemes [Feiertag79], but they depend on a security policy that is effective against the types of attacks being carried out. Even some quite simple protection systems cannot be proven 'safe' [Harrison76]...
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...Part 1 1. Viruses are both living and non-living as they share characteristics of both. A major non-living characteristic is that viruses do not have cells and cannot reproduce on its own. However, the virus can reproduce if it has a living host, which gives viruses their living characteristics. 2. Viruses cannot be grown agar as bacteria are because they cannot metabolize on their own. They need at least one host cell where it could input its DNA and infect it. After that, both those viruses would commence by infecting other living host cells. 3. Antibiotics work to get rid of the replicating function of bacteria so it cannot spread. However, viruses cannot replicate on their own unless they have living hosts, therefore since the viruses do not replicate, the antibiotics have no use. 4. Viral specificity means that the virus chooses and selects the type of cell, organism to infect and which disease to invoke onto it. 5. a) A-Virus, B-Cell DNA, C-Cell/Cell Membrane, D- Nucleic Acid (DNA or RNA) b) Bacteriophage Life Cycle c) I believe it doesn’t matter what they infect, as they are non-living and as long as they find some kind of living host, they’ll inject their nucleic acid to replicate into many more viruses. 6. Antibiotics literally will have no effect and will not cure the patient. All that the patient will gain are the side effects, for example: drowsiness and such. They will not get cured, as their problem is that viruses aren’t alive and...
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...Going back to the origin of viruses, it was in 1949 that Mathematician John Von Neumann described self-replicating programs which could resemble computer viruses as they are known today. However, it was not until the 60s that we find the predecessor of current viruses. In that decade, a group of programmers developed a game called Core Wars, which could reproduce every time it was run, and even saturate the memory of other players' computers. The creators of this peculiar game also created the first antivirus, an application named Reeper, which could destroy copies created by Core Wars. However, it was only in 1983 that one of these programmers announced the existence of Core Wars, which was described the following year in a prestigious scientific magazine: this was actually the starting point of what we call computer viruses today. At that time, a still young MS-DOS was starting to become the preeminent operating system worldwide. This was a system with great prospects, but still many deficiencies as well, which arose from software developments and the lack of many hardware elements known today. Even like this, this new operating system became the target of a virus in 1966: Brain, a malicious code created in Pakistan which infected boot sectors of disks so that their contents could not be accessed. That year also saw the birth of the first Trojan: an application called PC-Write. Shortly after, virus writers realized that infecting files could be even more harmful to...
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...Computer Viruses While technology advances have brought many benefits to society there have also been technological abuses (1). In today’s generation, with the help of the Internet and the rapid growth of the personal computer in the average household, we are able to talk to and share information with people from all sides of the globe (2). Unfortunately this transformation of data has opened the doors for a new era of high tech crime – the computer virus. The Internet is now a complex gateway for transgression and immoral activities where often the perpetrators of the crime are far removed from the scene of the criminal activity and hidden behind a maze of double speak (3). Computer viruses are enigmatic and grab our attention. They move silently from computer to computer under a shroud of secrecy and deceit. If they are not caught in time, these malicious programs can erase all the data off a hard drive, rearrange numbers in a spreadsheet file, or practically anything else a clever programmer can devise. A computer virus is a potentially dangerous computer program designed with the intent of obliterating or corrupting data that it comes into contact with. Computer viruses are mysteriously hidden beneath seemingly innocuous programs, which explains the reason for their effective dissemination across the Internet. These malicious computer programs are designed to replicate themselves or insert copies of themselves into other programs when executed within the infected program...
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...------------------------------------------------- Computer Viruses are a major threat to business information systems April 23, 2013 Computer Viruses are a major threat to business information systems Computer viruses are programs that infect your system and multiply. Viruses have many symptoms: some can simply slow down your computer whilst others can have more severe effects like moving documents and/or deletion of documents or programs. No matter the severity of the virus and its symptoms they should be dealt with by an up-to-date anti-virus program and security software, as systems with out-of-date protection are more susceptible and at risk. I agree that computer viruses are a major threat to business information systems because it is a way for hacker to gather useful information about a company and harm them. According to CNN workplace computer virus infections are up forty-eight percent over last year due to the increased spread of macro viruses usually found in files attached to E-mail, according to the International Computer Security Association, Inc. The number of infections per one thousand personal computers was twenty-one point fourty-five in nineteen ninty-seven; it's now at thirty-one point eighty-five, said the ICSA, in Carlisle, Pa. The study is based on a survey of some 300 corporations and corporate sites, representing some 750,000 PCs and servers. The rising virus epidemic can be blamed on macro viruses in Microsoft Word documents sent as attached files...
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...A computer virus is a computer program that can copy itself and infect a computer. The term "virus" is also used to refer to other types of malicious software, including: adware and spyware programs. A virus can spread from one computer to another. Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer. As stated above, the term "computer virus" is sometimes used as a catch-all phrase to include all types of malware (malicious software). Malware includes computer viruses, computer worms, Trojan horses, most rootkits, spyware, dishonest adware and other malicious and unwanted software, including true viruses. Viruses are sometimes confused with worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks, while a Trojan horse is a program that appears harmless but hides malicious functions. A Trojan horse, or Trojan, is malicious software designed to secretly access a computer system without the owner's permission or approval. It appears to perform a desirable function for the user prior to run or install but instead, it facilitates unauthorized access of the user's computer system. On the other hand, a computer worm is a self-reproductive malware computer program. It uses a computer network to send copies of itself to other computers on the network and it may...
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...Definition of virus "Computer viruses" is the term that defines the class of programs which illegally explore resources of systems. It is an executable code able to reproduce itself. Viruses are an area of pure programming, and, unlike other computer programs, carry intellectual functions on protection from being found and destroyed. They have to fight for survival in complex conditions of conflicting computer systems. Computer viruses have pervaded popular culture at least as successfully as they have the world's computer population. Computer viruses replicate by attaching themselves to a host a program or computer and co-opting the host's resources to make copies of themselves. Symptoms can range from unpleasant to fatal. Computer viruses spread from program to program and computer to computer. There are other computer pathogens, such as the "worms" that occasionally afflict networks, and the "Trojan horses" that put a friendly face on malicious programs, but viruses are the most common computer ill by far. Types of viruses. There are different types of viruses, and they have already been separated into classes and categories. For instance: dangerous, harmless, and very dangerous. No destruction means a harmless one, tricks with system halts means a dangerous one, and finally with a devastating destruction means a very dangerous virus. But viruses are famous not only for their destructive actions, but also for their special effects, which are almost impossible to classify...
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...-Topic C– Are viruses alive? Viruses were first discovered in the late 19th century, through diseases such as rabies and foot in mouth (Villarreal, 2004). They were originally postulated to be poisons and earnt their name virus from the Latin word virulent, meaning poisonous (Villarreal, 2004). Viruses are non- cellular infecting agents which lack the essential systems necessary for metabolic functions. Nevertheless they have the ability to reproduce and evolve within truly ‘living’ cells. As a result the scientific community have been unable to determine whether a virus is a form of life or an organic structure that interacts with living organisms (Villarreal, 2004). Scientist also struggled with the concept of the term ‘living’, and what it may entail scientifically. Viruses are built from nuclear acids that come together to form either DNA or RNA molecules, which carries their genetic information (Reynolds, 2003). In addition to this, viruses are also built from proteins which form a protein coat to protect this genetic information (Reynolds, 2003). Viruses are non-cellular parasites that can infect all life i.e. bacteria, plants, fungi and animals (Ladiges, 2010). As a singular agent viruses are known as a viron (Witzany, 2012). Virons cannot replicate outside of a living cell, but can do so in living cells, which, as a result, affects the behaviour and health of the hosts profoundly (Reynolds, 2003). When a viron enters a cell it disassembles its structure, in order...
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...4 March 2015 “Ancient viruses regenerated from 700- year- old frozen reindeer poop” Scientists have detected two ancient viruses in an ice patch located in Northern Canada. The specimen that scientists have observed is from reindeer feces, dating back about 700 years ago. This discovery is very important to the field of genetics, because it provides evidence upon how the viruses evolved, and the old compared to new biology. Even with the new techniques in molecular genetics, it was still a challenge trying to recreate the ancient virus from such low concentrations, due to the age of the ancient specimen. The team of scientist used “reverse genetics” and injected it into a plant, which it was then able to reproduce into its offspring. Even with this discovery, it has many scientists wondering if global warming will bring back other infectious viruses once the ice melts. But to put those worries aside, it is highly unlikely that the older viruses will return unless they have more advantages compared to the already evolved viruses that we have today. I think that this discovery is just the beginning of what science is capable of. It not only shows that the growing field of molecular genetics is exponentially growing, but also that their new techniques can generate a scientific break through. This discovery opens up many doors for the scientific field, and helps provide information on the difference between the viruses we have now, compared to viruses from centuries ago. Lastly...
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...computer viruses, computer worms, Trojan horses, most rootkits, spyware, dishonest adware and other malicious or unwanted software, including true viruses. Viruses are sometimes confused with worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks, while a Trojan horse is a program that appears harmless but hides malicious functions. Worms and Trojan horses, like viruses, may harm a computer system's data or performance. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious or simply do nothing to call attention to themselves. Some viruses do nothing beyond reproducing themselves. An example of a virus which is not a malware, but is putatively benevolent, is Fred Cohen's theoretical compression virus.[2] However, antivirus professionals do not accept the concept of benevolent viruses, as any desired function can be implemented without involving a virus (automatic compression, for instance, is available under the Windows operating system at the choice of the user). Any virus will by definition make unauthorised changes to a computer, which is undesirable even if no damage is done or intended. On page one of Dr Solomon's Virus Encyclopaedia, the undesirability of viruses, even those that do nothing but reproduce, is thoroughly explained.[1] Academic work The first academic work on the theory of computer viruses (although...
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...hosts for computer viruses are: – Executable files (such as the ‘.exe’ files in Windows machines) that may be sent around as email attachments – Boot sectors of disk partitions – Script files for system administration (such as the batch files in Windows machines, shell script files in Unix, etc.) – Documents that are allowed to contain macros (such as Microsoft Word documents, Excel spreadsheets, Access database files, etc.) ✓ Any operating system that allows third-party programs to run can support viruses. ✓ Because of the way permissions work in Unix/Linux systems, it is more difficult for a virus to wreak havoc in such machines. Let’s say that a virus embedded itself into one of your script files. The virus code will execute only with the permissions that are assigned to you. For example, if you do not have the permission to read or modify a certain system file, the virus code will, in general, be constrained by the same restriction. ✓ At the least, a virus will duplicate itself when it attaches itself to another host document, that is, to another executable file. But the important thing to note is that this copy does not have to be an exact replica of itself. In order to make more difficult the detection by pattern matching, the virus may alter itself when it propagates from host to host. In most cases, the changes made to the viral code are simple, such as rearrangement of the order independent instructions, etc. Viruses that are capable of...
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