Living or Not...
Definition: A virus is a very tiny particles that has some of the properties of life and can only be seen with an electron microscope. They are an infective agent that typically consists of a DNA or RNA and is able to multiply only within the living cell of a host.
I think viruses are not living. They may have some characteristics of living things like having DNA or RNA that can mutate like a humans DNA, but I don't think they are living because they contain no cytoplasm or any other organelles, they can't do any of the chemistry of life by themselves, they can be crystallized and they can't reproduce on their own.
I think viruses are not living. They may have some characteristics of living things like having DNA or RNA that can mutate like a humans DNA, but I don't think they are living because they contain no cytoplasm or any other organelles, they can't do any of the chemistry of life by themselves, they can be crystallized and they can't reproduce on their own.
Lytic and Lysogenic...
Lytic Cycle
1.Attachment- the virus attaches to the host cell.
2.Entry- the DNA or RNA of the virus is injected into the host cell and it forms a circle.
3.Replication- the cell makes proteins to form new viruses from the viral DNA or RAN instead of making proteins to help itself.
4.Assembly- the host cell now assembles new viruses from the proteins it has made.
5.Lysis- the host cell bursts or "lysis" and releases all the new viruses it has made.
*the herpes virus, in this cycle, would be present and showing. If you had a cold sore on your lip this would be the herpes virus in the lytic cycle.*
Lysogenic Cycle
1.Attachment- the virus attaches to the host cell.
2.Entry- the DNA or RNA of the virus is injected into the host cell and it forms a circle.
3.Integration- the host DNA and the viral DNA combine to make what's called prophage DNA.
4.Cell Multiplication- the host cell divides and divides making more cells with the same prophage DNA.
5.where the viral DNA can from its own circle again and enter the lytic cycle or can remain multiplying in the lysogenic cycle.
*the herpes virus, in the lysogenic cycle, would still be present in your skin but you would not be able to see it at this time until the virus enters the lytic cycle.*
1.Attachment- the virus attaches to the host cell.
2.Entry- the DNA or RNA of the virus is injected into the host cell and it forms a circle.
3.Replication- the cell makes proteins to form new viruses from the viral DNA or RAN instead of making proteins to help itself.
4.Assembly- the host cell now assembles new viruses from the proteins it has made.
5.Lysis- the host cell bursts or "lysis" and releases all the new viruses it has made.
*the herpes virus, in this cycle, would be present and showing. If you had a cold sore on your lip this would be the herpes virus in the lytic cycle.*
Lysogenic Cycle
1.Attachment- the virus attaches to the host cell.
2.Entry- the DNA or RNA of the virus is injected into the host cell and it forms a circle.
3.Integration- the host DNA and the viral DNA combine to make what's called prophage DNA.
4.Cell Multiplication- the host cell divides and divides making more cells with the same prophage DNA.
5.where the viral DNA can from its own circle again and enter the lytic cycle or can remain multiplying in the lysogenic cycle.
*the herpes virus, in the lysogenic cycle, would still be present in your skin but you would not be able to see it at this time until the virus enters the lytic cycle.*
Body Defences...
First line of defence is to keep pathogens out of the body in the first place. The first line of defence includes skin, mucus, sweat, and tears. The first line of defence acts as a physical barrier against infections and pathogens. Our bodies most important non-specific defence is our skin. Next to nothing can enter the body through the skin and once the skin is broken, such as a cut, pathogens can freely enter the body. Other members of the fist line of defence are liquids made by the body such as mucus, saliva, and tears. These three liquids contain lysozyme which is an enzyme that breaks down cell walls of many bacteria, killing them before they can enter the body. Also oil and sweat make an acidic environment on the skin that kills many bacteria.
Second line of defence if pathogens pass through the first line of defence they can start to multiply. This is when the inflammatory response is activated. The inflammatory response is another non-specific defence that acts on tissue damage. Once a pathogen is spotted, white blood cells are made to fight the infection. Almost all of the white blood cells produced are *phagocytes. The fever is another part of the second line. Seeing as many pathogens can only survive at a normal body temperature, your body will heat itself up to kill off pathogens that have entered the body. Some other ways the body attacks invading pathogens are:
Second line of defence if pathogens pass through the first line of defence they can start to multiply. This is when the inflammatory response is activated. The inflammatory response is another non-specific defence that acts on tissue damage. Once a pathogen is spotted, white blood cells are made to fight the infection. Almost all of the white blood cells produced are *phagocytes. The fever is another part of the second line. Seeing as many pathogens can only survive at a normal body temperature, your body will heat itself up to kill off pathogens that have entered the body. Some other ways the body attacks invading pathogens are:
1. *Phagocytosis- white blood cells that go around and "eat" the virus by grabbing on to it and destroying it with enzymes in their lysosomes. 2. Interferon- a protein made by an infected host cell, a message to other cells, right before it dies to warn them that a virus is on its way and asking for help. 3. Antibodies- highly specific proteins made by white blood cells that latch on to viruses and clump them together to keep them from going else where. Now that the receptors of the virus are clamped on to the virus can no longer infect other host cells. |
Binary fission and Conjugation...
Bacteria can reproduce sexually and asexually, through two processes call binary fission and conjugation. Conjugation is a sexual form of reproduction that involves two parent cells. This form of reproduction results in offspring that are geneticly different from their parents cells and one another. During conjugation there are two different types of cells, a recipient cells that will retrieve a plasmid and a donor cell that gives a plasmid and has the F factor which means they are able to form a conjugation tube (sex pilus). An advantage to conjugation is that there is genetic diversity and the population is more likely to survive a change in the environment. Disadvantage are, there are two cells required and the population doesn't increase in fast. Binary fission is the asexual way bacteria reproduces. Binary fission only requires one parent cell and results in two geneticlly equal daughter cells. During binary fission the DNA is replicated and spreads to either side of the cell. The cell then pinches off to form two identical cells. Binary fission is the most common way bacteria reproduces. Advantages are the large number of offspring in a short amount of time, we only need one cell to repopulate and they adapt to their environment at a rapid pase. The disadvantage of binary fission is that one virus can kill them all because all the cells are geneticly equal. The similarities between the two are, they both produce offspring, DNA is copied in both, they are both methods of reproduction and the plasmid is present in both.
Tansformation and Trasduction...
Transformation- the process where a bacteria gets bits of DNA from its environment. When a bacteria is killed there DNA is "up for grabs" by any other bacteria that wants it. If an antibiotic resistant bacteria dies and a bacteria that isn't resistant to antibiotics comes along and takes the genes from the dead bacteria and integrates its DNA into its own this bacteria now becomes resistant to antibiotics.
Transduction- the process where genes are moved using viruses. A virus can take some DNA out of one bacteria and go find another bacteria to put the DNA into. Say a virus takes DNA out of an antibiotic resistant cell and injects it into one that wasn't resistant, the cell that wasn't resistant now is resistant. Then this newly resistant bacteria can go and make other bacteria resistant too.
Transduction- the process where genes are moved using viruses. A virus can take some DNA out of one bacteria and go find another bacteria to put the DNA into. Say a virus takes DNA out of an antibiotic resistant cell and injects it into one that wasn't resistant, the cell that wasn't resistant now is resistant. Then this newly resistant bacteria can go and make other bacteria resistant too.
Antibiotics and "superbugs"...
Antibiotics used only when needed and as directed usually over whelm the bugs, but too much antibiotics use selects for more resistant mutants. If someone taking antibiotics doesn't take the last day of pills because they fill better, all they're doing is killing off the non-resistant bacteria and by not finishing the treatment, leaving the resistant ones to reproduce and multiply. We have to cut back on our use of antibiotics or some day they will have no effect on bacteria any more. People thing antibiotics are the core to everything, but they are wrong! Antibiotics only effect bacteria and not viral diseases. Scientists are trying to find new ways to kill resistant bacteria and are having a hard time. They are urging patients and doctors to limit the use of antibiotics and save them for emergencies only. Antibiotics are being pumped into animals on farms every day to keep them health when they're not even sick. This just eliminates the non-resistant bacteria and lets the resistant bacteria thrive. These animals that are filled with resistant bacteria end up on our dinner tables every day for use to consume. Over use of antibiotics will limit there effectiveness and eventual we will be back to where we started when we didn't have the luxury of antibiotics.