A virus is a microscopic fragment that have the right to infect a cell. Viruses are mostly composed of a protein coat, called a capsid, and also nucleic acid. In the Virus lytic Cycle Gizmo™, you will learn just how a virus infects a cell and uses the cell to produce more viruses.
Viruses are exceptionally small. A usual virus is around 100 times smaller than a single cell, such as a bacterium. Label the virus and a bacterial cabinet in the photo at right.
Bacteriophages space viruses that infect bacteria. Based upon the diagram at left, brand the head, tail, tail fibers, and also the strand the nucleic mountain in the photo at right. task A: Lytic cycle
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Introduction: Unlike living organisms, viruses can not reproduce on their own. Instead, viruses infect host cells, taking over the cell machinery to produce more viruses. This procedure is referred to as the lytic cycle.Question: What room the actions of the riot cycle? Observe: usage the navigation arrows ~ above the summary tab to read about the stages of the riot cycle. Utilizing your own words, summarize each step of the cycle.
A lytic bacteriophage virus attaches itself to a bacterial cell. The virus is a very an easy structure, created of a protein capsid, main point acid, and also a tail section.
The virus injects its main point acid right into the cell. The nucleic acid provides the cell’s ribosomes to make virus proteins. The proteins break up the cell’s DNA.
The virus capsid and also tail, currently useless, detach native the cell and disintegrate. Inside the cell, the famous nucleic acid takes over and directs the manufacturing of new virus proteins and also nucleic acid.
The virus proteins and nucleic acid assemble into new viruses.
one-of-a-kind proteins developed by the viral main point acid cause the organize bacterial cabinet to lyse (burst), destroying the cell in the process. The numerous brand-new viruses room now complimentary to infect other cells.
(Activity A ongoing on following page)Activity A (continued from previous page) Analyze: The yellow ring within the bacterial cell represents the bacterial DNA. Why go this structure disappear by action 3 of the lytic cycle? In step 2, the famous nucleic mountain takes over regulate of the cell by damaging the hold cell’s DNA. Describe: just how does a virus ruin the hold cell’s DNA? The viral nucleic acid uses the cell ribosomes to do proteins. This proteins break up the bacterial cell DNA. Describe: exactly how are brand-new viruses reproduced? viral nucleic acid takes control of a cell’s mechanisms, consisting of the structures the cell provides to do proteins and also copy main point acid. The viral main point acid provides these instrument to make brand-new virus parts. The components assemble into new viruses. Think and also discuss: Why can not a virus reproduce on its own? Viruses do not have actually the structures essential to make proteins or make copies of main point acid. Justify: come lyse is to burst apart or explode. Why carry out you think a virus’s reproduction cycle is referred to as the “lytic cycle”? after a cell has been offered to reproduce brand-new viruses, a distinct viral protein causes the cell membrane to break open, or lyse. This procedure gives the riot cycle the name.
Reset">Activity B: Spread of infection
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Question: just how does a viral infection spread? Predict: intend that a virus infects a small populace of bacteria. Predict just how the numbers of viruses, infected cells, and uninfected cells will readjust as the epidemic progresses. On the blanks below, write increase, decrease, or stay the same.
Viruses: boost Infected cells: Increase
Uninfected cells: to decrease Observe: Click Play (
), and watch the simulation. Explain what girlfriend see. Sample answer: together the infection progresses, viruses infect uninfected cells at one increasingly quicker rate. Test: Click Reset, and Select the BAR chart tab. Rotate on Show numerical values. Click Play, and also watch each bar together the simulation runs. What perform you notice, and also how walk this to compare to her predictions? Sample answer: The readjust in the number of viruses, infected cells, and also uninfected cells carefully matched mine predictions. Over time, the number of viruses increased, as did the number of infected cells. The number of uninfected cells decreased from 50 down to 0. Record data: pick the TABLE tab, and also use the data to finish the second column that the table below. To finish each cell in the 3rd column, subtract the vault time value from the current time value. For example, if it took 80 minute to reach 40 cells and 100 minute to with 30 cells, then the time difference is 20 minutes. Answers will vary. Sample answers provided below.
number of cells
amount of time come decrease population by 10
(Activity B ongoing on next page)Activity B (continued native previous page) Analyze: What trend execute you check out in the 3rd column of your data table? Sample answer: the moment it took the viruses to damage the very first set the 10 cells was around twice as long as the time it take it to damage the next set of 10 cells. This trend continued for the next 20 cells, but the rate of cell destruction tapered off for the last set of 10 cells. Explain: how would you define this trend? The number of viruses rises with time, thus permitting the price of epidemic to increase. However, the rate of infection tapers off once there space no much more healthy cells to infect. Interpret: pick the GRAPH tab. Run the Gizmo again, and observe what happens in the SIMULATION pane as soon as the graph shows a decrease in the viruses’ populace size. Why does the number of viruses occasionally increase and sometimes decrease? At part points throughout a viral infection, all of the viruses room inside hold cells. During these times, it appears as though the virus populace is zero. sometimes when a virus start a cell, it i do not care dormant for a while. Why can this do it complicated for a doctor to diagnose a viral infection? until an infected cell lyses, the will show up to be a healthy, functioning cell. The human being will have no symptoms until the viruses begin destroying his or her cells.
extend your thinking: AIDS is one an illness caused by a virus infection. The virus strikes immune mechanism cells known as T cells.
Based top top your monitorings from the Gizmo, exactly how would you describe the data displayed on this graph?
Over time, the viruses infect healthy and balanced T cells and also destroy them. An ext viruses are developed in the process. These viruses proceed to epidemic the person’s T cells till the person has actually a T cell count close come zero.