Microbes Notes
Microscopic Organisms and Your
Body’s Immune System
What is a microbe?

Microbe:
A microscopic organism that has the potential
to cause disease.
 4 Categories:

 Virus
 Bacteria
 Protist
 Fungus
What is a virus?

A tiny nonliving particle that enters and
then reproduces inside a living cell.
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Viruses can only reproduce inside a living cell.
Viruses take on many shapes from rod, round, bricks, threads,
bullets, and even robot like shapes.
Viruses have two basic parts:
 A protein coat that protects the virus
 An inner core made of genetic material
How do viruses multiply?
1. Virus attaches to a host cell.
2. Virus enters the host cell in a
vesicle through endocytosis.
3. The virus DNA is copied by the
host cell.
4. New viruses form inside the host
cell.
5. New viruses are released to the
body via exocytosis.
What is bacteria?
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
Bacteria are single celled organisms.
They are prokaryotes:
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Bacteria take one of three shapes:
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
meaning their genetic material in the cell is not
contained in a nucleus.
spherical, rodlike, or spiral.
Bacteria reproduce one of two ways;
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asexually (involves only one parent) by binary fission
sexually (involves two parents) by conjugation.
What does bacteria look like?

Draw and label this diagram into your notes.
What are the two kingdoms of bacteria?
Eubacteria
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Larger of the two kingdoms and very common.
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Producer Eubacteria:
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Make their own food through photosynthesis.
Consumer Eubacteria
Archeabacteria
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Smaller of the two kingdoms and found in the most
extreme conditions. ( ex. Hot springs, Dead Sea, Great
Salt Lake)
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Archeabacteria are used in sewage treatment plants.
Bacteria in Your Life
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We cannot live without bacteria.
Good Guys:
-
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Antibiotics:
- A chemical produces by some bacteria that limits the growth of other harmful bacteria.
- Examples:
- Bacillus: Used in antiseptic ointment.
Saprophytes:
- Bacteria that uses dead organism as their food source
- Used in sewage treatment plants.
Food:
- Examples:
- Yogurt, Cheese, Vinegar, Pickles, Olives, Soy Sauce, etc.
Industry:
- Cleaning supplies, methane gas energy, etc.
Bad Guys:
-
The bad guys cause disease and are known as pathogens.
Example: Streptococcus- Causes strep throat
How viruses and bacteria affect
your health?
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Bacteria and viruses are known as infectious
diseases when they enter your body and make
you sick. (spread by contact with an infected
person, object, animal, or source)
Bacteria can be treated with antibiotics
(remember that it also kills the good bacteria
inside your body).
Viruses can’t be treated with antibiotics, rather
you are given a weakened strand of the virus
known as a vaccine and your body builds its own
treatment to the virus.
What is a protist?

Protist are eukaryotes (have a nucleus)
that can be classified as animals, plants,
or fungi.
What are the types of Protists?

Three major types of protist
 Animal-like protist are able to move from place to
place (ex: amoeba and paramecium)
 Animal like protist are categorized by the way they
move: pseudopods, cilia, flagella, or parasites.
Plantlike protist usually don’t move.
(ex: algae, diatoms, dinoflagellates, and
euglenoids)

 There
are six types of plantlike protists. They are
diatoms, dinoflagellates, euglenoids, red algae,
green algae, and brown algae.

Funguslike protist have cell walls, and use
spores to reproduce.
 The
three types of funguslike protists are slime
molds, water molds, and downy mildews.
What are fungi?
Fungi have both characteristics of a plant
and animal. They are eukaryotes that
have cell walls, are heterotrophs that feed
by absorbing their food, and use spores to
reproduce.
 Fungi play important roles as
decomposers and recyclers on Earth, they
are food, and are used to fight diseases.
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What are pathogens?
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Pathogens are organisms that cause a disease.
Pathogens are spread through contact with an
infected person, object, or animal; or by soil,
food, or water.
Four types of pathogens are
 Bacteria
 Viruses
 Fungi
 Protists
How does the body fight off
pathogens?
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The body has three lines of defense against
pathogens.
First line of defense is the skin, breathing
passages, and stomach. They act as a barrier
to pathogens, keeping them out or trapping and
killing the pathogen.
Second line of defense is the inflammatory
response. Here the body responds with fluid
and white blood cells. White blood cells leak
from the blood into the tissue and fight off the
pathogens.
Immune system continued

Third line of defense is the immune
response where the cells of the immune
system can distinguish between different
types of pathogens.
T-cells are sent out to identify the pathogen
(take a picture)
 B-cells produce the protein to fight off the
pathogen (build proteins)
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