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Viruses

QuestionAnswer
What do all cells have? All cells have a cell membrane and cytoplasm. Eukaryotic cells also have organelles (not prokaryotic).
Depending on the virus, what do they have regarding genetic material? DNA or RNA
What can't viruses do that living cells can? Unlike cells, they cannot metabolize, synthesize their own proteins, or divide in two. Viruses lack the cellular structures needed to undergo these processes. Viruses do not have a cell membrane, cytoplasm, or organelles.
How does a virus reproduce? A virus can reproduce only by using the resources of a host cell. To reproduce, a virus hijacks the host cell’s transcription and translation mechanisms. The cell translates viral genes into proteins, enabling the virus to reproduce.
All viruses are __________________ ___________________. Obligate Parasites
What happens to a cell that reproduces a virus? The cell dies. Infection by a virus often causes illness in the infected organism.
What is the protein coat that surrounds viral genetic material? A Capsid. Some viruses have other structures, such as a membrane-like envelope surrounding the capsid, or a protein tail.
True or False: Most viruses are highly specialized for the types of cells they can infect. True!
In order to infect a cell, a virus has to do what? To infect a cell, a virus must bind to receptor proteins on the cell’s surface.
Once a virus is bound, what happens? After the virus is bound, the cell takes in the virus or at least the virus’s genetic material.
When the cell starts to produce pieces of new virus, what happens? The pieces form new virus particles (called virions), which exit the host cell and infect other cells. Viral infection usually destroys the host cell. However, in some cases, the genetic material of the viruses may be incorporated into the host DNA.
Explain the lytic cycle. Stage of viral reproduction during which new viral DNA and proteins are produced in the host cell, followed by lysis of the cell and release of assembled virus particles.
What happens to viruses that do not immediately replicate within the host cell? They enter the lysogenic cycle.
What happens in the lysogenic cycle? Stage of viral reproduction during which viral DNA is incorporated into the host cell chromosome. The virus can lay dormant (in which they do not damage the cell) for several generations before becoming lytic.
How do scientists classify viruses? What are the classifications? By their shape. These include helical, envelope, icosahedral, and complex.
In a helical virus, how is the DNA or RNA arranged? The nucleic acid is arranged in a spiral. The genetic material is surrounded by, and bound to, a protein capsid of long, hollow tubes.
In an envelope virus, how is the DNA or RNA arranged? The capsid is surrounded by the viral envelope, similar to the membrane of a cell. The lipid bilayer of the viral envelope protects the virus.
How is an icosahedral virus arranged? It is nearly spherical with 20 triangular faces and 12 corners. This shape is an efficient way to form a closed shell, which protects the genetic material from the environment.
What is a complex virus? A complex virus is a combination of two or more viral structures. Most commonly, they comprise helical and icosahedral structures. They may also have other parts, such as protein tails or a complex outer wall.
True or False: Viruses are not parasites. False. Viruses are the most abundant parasites on Earth. Every type of organism, including animals, plants, and bacteria has viruses capable of infecting them.
What is a vaccine? A vaccine is made of a weakened version of the virus or a preparation that contains parts of the virus. The body’s immune system produces antibodies to attack the virus.
What is a pandemic? Widespread incidence of a disease
What are symptoms of the Ebola virus? Set within 2-21 days, symptoms include fever, headache, aching muscles, sore throat, and fatigue. Soon after, diarrhea, vomiting, and stomach pain set in. Rashes, bloodshot eyes, hiccups, bleeding, and organ failure are also seen in many cases.
What are symptoms of the Avian Flu (Bird Flu)? Mostly affects birds, but in humans symptoms can include nausea, conjunctivitis, pneumonia, and complications leading to death.
What is SARS? Severe acute respiratory syndrome (SARS) is an intense and possibly life-threatening type of viral pneumonia. SARS is particularly dangerous because it can spread quickly.
How far away would a person with SARS have to be to infect another after coughing? 3 feet. It is spread by close proximity.
What does HIV cause? HIV causes acquired immune deficiency syndrome (AIDS). HIV is particularly dangerous because it attacks cells of the immune system called CD4+T cells.
How is HIV spread? The virus travels by the exchange of body fluids including blood, semen, and vaginal fluid. Most people catch HIV through unprotected sex with an infected partner.
True or False: 15% of cancers may be caused by viruses. True! Viruses interfere with the genetic processes in the cell, and cancer arises when cells grow and reproduce uncontrollably.
True or False: Viruses that cause cancer this way are called tumor viruses. These viruses normally do not cause cancer in infected people. True. Lifestyle, genetic, and environmental factors can trigger the onset of a cancer that is related to viral infection.
What are some of the seven viruses known to be linked to human cancers? These include the Epstein-Barr virus, the hepatitis B (HBV) and hepatitis C (HBC) viruses, and the human papillomavirus (HPV).
What is prophage? In the lysogenic cycle, when the virus enters the cell, its genetic material becomes incorporated into the genetic material of the host and is called a prophage.
Why do viral mutations pose such a threat to human health? Viruses mutate faster than the humane immune system can build antibodies.
A virus requires a host cell in order to ________. Reproduce
Which of the following can be infected by a virus? Mouse, E. coli bacteria, oak tree, all of them All of them
What best describes the contents of a flu vaccine? deactivated particles of the flu virus
The outer layer of an envelope virus might help a virus ________. attach to a host cell
Unlike organisms, many viruses do not contain: DNA
Which of the following is not an example of an extra part complex viruses can have? flagella, protein tail, complex outer wall, all of them Flagella
What is a good example of how viruses replicate? they use the organelles inside a host cell
Which of the following host cell structures do viruses need in order to synthesize proteins? cell membranes, ribosomes, chloroplasts, lysosomes Ribosomes
Most animal viruses are ________. icosahedral
True or False: viruses can survive while waiting to come in contact with a host to infect. True
The genes for capsid proteins are ________. part of the viral genetic material
Created by: JustEmma