Transcript Viruses - I Heart Science

Viruses and
Bacteria
Unit 5 – Lesson 2
Which is alive?
What do they do?
VIRUSES
What is a Virus?

For something to be
living look for three
main characteristics:
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DNA
reproduce
obtain and use energy
Is a virus living?

NO!
What is a Virus?

A virus has DNA. It
is surrounded by a
protein coat.
What is a Virus?

Viruses can reproduce. They make copies of
themselves only inside a living host cell.
Viruses
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Achoo!

Be careful! Sometimes
sneezing and spreading
your germs can spread
viral infection.
Viral Reproduction
1. The virus attaches to
a specific host cell.
Viral Reproduction
2. The virus’ DNA
enters the host cell.
Viral Reproduction
3. The DNA of the
virus causes the cell to
make copies of itself!
Viral Reproduction
4. New viruses form
inside the host cell.
Viral Reproduction
5. New viruses are
released as the host cell
bursts open and is
destroyed.
Virus Multiplication
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Active viruses – make the host cell create new viruses,
which kills the host cell.
Latent viruses – hide in the host cell without destroying it.
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Virus hereditary material becomes part of the host cell hereditary
material.
Latent viruses can become active and then destroy the host cells.
I’ll hide out! They’ll
never find me!
Effects on Organisms
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Most viruses infect only specific kinds of cells.
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Viruses are often carried to the host through the air.
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The virus and host cell must fit together exactly to
begin a viral infection.
Fighting Viruses
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Vaccines – weakened virus particles that allow the
host to fight some diseases.
Treating viral diseases
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Public health measures can prevent or slow disease.
What they tell you a shot is like…
What a shot is really like…
BACTERIA
Bacteria

Bacteria has DNA, reproduces, and obtains and
uses energy. Bacteria is living.
Want proof that
bacteria reproduces?
Smell your feet before you put on
shoes, then smell them again at
the end of the day when you take
your shoes off.
Bacteria
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There are six kingdoms of life, two of these
kingdoms are bacteria.
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Archaebacteria
Eubacteria
Bacteria
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Bacteria are prokaryotes.
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No organelles
Free floating DNA
They reproduce by a
method called fission.
Bacteria
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Bacteria can be both beneficial and harmful.
Bacteria can be found and used ANYWHERE
You have more bacteria in/on your body than you
have BODY cells. Are you human or bacteria?
Beneficial Bacteria
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Examples of beneficial bacteria
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Decomposition
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The Human Body – Intestines
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Food (yogurt – probiotics)
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Nitrogen Fixation
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turns nitrogen gas into a compound
organisms can use
bacteria help decompose landfills
bacteria in foods help with
intestinal health
Harmful Bacteria
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Pathogenic bacteria are types of bacteria that
carry disease or cause harm to humans.
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E. Coli
Streptococcus
Bacteria
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Harmful bacteria can be treated by antibiotics.
Frequent use of antibiotics may cause some
bacteria to develop a resistance.
beneficial
harmful
mutated
harmful