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Cell Wars 1.16 – pg. 50-51
NAME:
1. Explain what disease is in your own words.
Disease is a foreign cell, called a virus, that gets into or bodies and attacks our normal cells. The virus
attaches to our normal cells and injects its genetic material into our cell. When the genetic material
reaches the nucleus it takes over control of our cell. It directs the hijacked cell to reproduce many
more viruses and then bursts our cell, killing it, and sends out the many reproduced viruses to repeat
the cycle again. This invasion of viral cells is called an infection. The viral infection interferes with our
cells ability to do its job and can make us sick enough to die.
2. What types of invaders cause infections in humans?
The types of invaders that can cause infections in humans are living organisms such as bacteria, fungi,
or parasitic worms. The other types of invaders could be non-living things such as viruses or toxic
chemicals.
3. Identify two ways in which white blood cells protect the body from disease.
One way that white blood cells protect the body against disease is by producing specific antibodies to
attack and kill specific invading organisms. The antibodies attach themselves to the molecules on the
cell membranes of viruses. The molecules on the viruses are known as markers. These markers have a
specific shape and the antibodies that the white blood cells make to attach to the markers must have
the same shape in order to be able to attach to the markers and kill them. White blood cells also kill
invading organisms by attacking them, swallowing them up and then releasing special chemicals from
their lysosomes that digest both the invading organism and themselves.
4. How does your body benefit when a white blood cell kills a cell that has been infected by a
virus?
When a white blood cell engulfs and kills one of our own cells that have been infected by a virus, it
prevents that virus from reproducing many other viruses within the normal cell and then spreading
those reproduced viruses to other normal cells in our body after that one infected cell bursts. So even
though we lose one of our own cells and a white blood cell, the benefit is that many other normal cells
will not become infected which would make our infection worse. If we sacrifice a few normal cells and
white blood cells in this manner we can recover, but if many cells are infected and we have to kill
many cells in this way, it might not be possible for us to recover.
5. Vaccines work by introducing dead or weakened invaders into the body. The body will
develop antibodies against the weak invaders. If a strong invader of the same kind enters
the body later, the antibodies can be used to destroy it before it takes over any cells. Using
diagrams, show how a vaccine might protect the body from invaders.
Normal
cell
White
Blood
cell
FLU 1
antibody
FLU 1
strong
virus
FLU 1
weakened
virus
Weakened virus
injected into our
body
Attacks normal
cell – makes us
sick
Strong virus
now enters our
body
White blood cell arrives and because it
has already produced many antibodies
against the same weakened virus it
already has an army of antibodies ready
for strong virus – virus defeated before
it can do damage to any normal cells
White blood cell arrives
and produces many
antibodies – easily kills
weakened virus