Download Bacteria - TeacherWeb

Bacteria
Bacteria are prokaryotic (no nucleus), singlecelled organisms. Bacteria are considered living
organisms because they have the characteristics of
living things like growing, reproducing, using energy,
and responding to their environment. Bacterial cells
have one of three basic shapes: spirilla or spiral,
bacilli or rod-like, cocci or spherical. Most bacterial
cells are surrounded by a rigid cell wall that helps to protect the cell. Inside the cell
wall is the cell membrane. Bacteria also have cytoplasm, the gel-like material that
contains ribosomes that are the chemical factories where proteins are produced.
Some bacteria have flagella to help move. Most bacteria that do not have flagella
cannot move on their own and have to be carried from place to place by the air,
water currents, objects, or other methods. Some bacteria are able to survive in
extreme conditions that kill most other life. These are called extremophiles. Some
that can live in extremely hot places are called thermophiles. Those that live in very
salty places are called halophiles.
Some bacteria are autotrophs while others are heterotrophs obtaining food by
consuming autotrophs or other heterotrophs. Some bacteria break down decaying
leaves on the forest floor, or other dead organisms. They are decomposers. This
is how bacteria help to clean up and recycle the environment.
When bacteria have plenty of food, the right temperature, and other suitable
conditions, they thrive and reproduce frequently. Bacteria reproduce asexually by
binary fission, a process in which one cell divides to form two identical cells that
involves only one parent and produces offspring that are identical to the parent.
They can reproduce rapidly. Just two bacteria can become 562,929,940,000,000,in
a 24 hour period.
Some bacteria perform a simple form of sexual reproduction called
conjugation that involves two parents who combine their genetic material to
produce a new organism that differs from both parents. During conjugation, one
bacterium transfers some of its genetic material into another.
Many bacteria can survive harsh conditions, such as water shortage,
temperature change, etc. by forming endospores, small, thick-walled resting cell
inside a bacterial cell. They can live like this for years and then when the right
conditions occur, they begin to grow and multiply.
Eubacteria are everywhere, on your skin, in the air, in your body, etc. 560,000
bacterium can fit on a pinhead. It’s a good thing that most bacteria are either
harmless or helpful to people. Bacteria are involved in oxygen and food production,
environmental recycling and cleanup, and health maintenance and medicine
production. Diabetics benefit from insulin-making bacteria, which is grown in vats,
purified and made into medicine. Some bacteria are used to eat up gasoline and oil
spills. Other bacteria make the nitrogen in the air useable for plants in the soil who
then pass it on to consumers. Your intestines are hosts to good bacteria that help
you digest food and keep harmful bacteria from sticking to them. These bacteria
actually help to make vitamins your body needs. Helpful bacteria produce foods
such as cheese, yogurt, and pickles.
However, some bacteria cause food to spoil. One method to slow down food
spoilage is pasteurization, where food is heated to a temperature that is high
enough to kill most harmful bacteria without changing the taste of the food.
Canning and dehydration are also ways to keep bacteria from spoiling food and
from causing disease to those who eat the food.
Bacteria can also be harmful and cause disease in other organisms. In
humans, some diseases are strep throat, stomach ulcers, pneumonia, lyme
disease, tuberculosis, staph infections, tonsillitis, plague, and others. Bacteria can
live inside another organism and harm the host or host cells they live in. These
bacteria are parasites.
Fortunately, antibiotics (drugs such as penicillin) have been successful in
killing these pathogens (disease-causing microbes). However, misuse of antibiotics
may be causing antibiotic resistance where the drugs that normally kill a type of
bacteria are no longer effective, requiring more potent antibiotics to be used and
even created.
Name: _________________________________
Bacteria
Date: __________ Class: ______ Seat # ______
1. Bacteria are ___________________ which means the genetic material in their cells is not
contained in a nucleus.
2. True or False? Bacteria are living organisms because they use energy, grow, and reproduce.
3. What three shapes can bacterial cells have?
a. ____________________ b. _________________ c. _____________________
4. Circle the letter of the cell structures where proteins are made.
a. cell wall
b. cytoplasm
c. ribosomes
d. flagellum
5. True or False? Bacteria that do not have flagella are never moved from one place to another.
6. Label the parts of a bacterial cell in this diagram.
a
2
7. Extremophile bacteria that live in extremely hot environments are called ________________________
and those that live in extremely salty environments are called __________________________.
8. True or False? Bacteria are only heterotrophs.
9. Bacteria that clean up and recycle the environment by eating dead organisms are called
__________________.
10. Bacteria reproduce asexually in a process called _______________________________________.
11. Binary fission can occur very rapidly where 2 bacteria can become ______________________ in 24
hours.
12. Bacteria can also reproduce sexually during ______________________________ when genetic
material is exchanged.
13. When do bacteria form endospores? ____________________________________________
_____________________________________________________________________________
14. Circle the letter of each sentence that is true about bacteria.
a. All bacteria are harmful and cause disease.
b. Some bacteria are autotrophic.
c. Bacteria help produce foods such as cheese, yogurt, and pickles.
d. Bacteria do not cause food to spoil.
15. Bacteria take _______________________ from the air and make it useable for plants in soil.
16. True or False? Bacteria are used to clean up oil spills and gasoline leaks.
17. List two ways that bacteria are helpful to your body.
a. ______________________________________________________________________________
b.______________________________________________________________________________
18. What are disease-causing bacteria called? _______________________________________________
19. List some diseases caused by bacteria. _________________________________________________
20. What can be taken to kill bacteria? _____________________________________________________
21. Why is there a concern about taking too many antibiotics?___________________________________
__________________________________________________________________________________
Review Vocabulary
_____ 1. antibiotics
a. where one bacterium divides to form two identical bacteria cells
_____ 2. endospore
b. a small, thick-walled resting cell that forms inside a bacterial cell
_____ 3. binary fission
c. whip-like structure that helps a cell to move
_____ 4 epidemic
d. used to destroy disease-causing bacteria
_____ 5 decomposer
e. where one bacterium transfers genetic material into another bacterium
_____ 6 sexual reproduction
f. bacteria that harm the host or host cells they live in
_____ 7. flagellum
g. organism that breaks down dead organisms into small chemicals
_____ 8. asexual reproduction h. where one parent reproduces offspring identical to that parent
.
_____ 9. conjugation
j. when a disease spreads around the world
_____10. pandemic
k. when a disease spreads over a very large area
_____11.parasites
l. a disease causing microbe
_____12.pathogen
m. where two parents combine their genetic material to produce a
new organism that differs from both parents
Name_________________________
Bacteria
1. How are bacterial cells different from the cells of eukaryotes?
____________________________________________________________________________________
2. List four ways that bacteria are helpful to people.
a.__________________________________________________________________________________
b. __________________________________________________________________________________
c. __________________________________________________________________________________
d. __________________________________________________________________________________
Building Vocabulary
Match each term with its definition by writing the letter of the correct definition on the line beside the term.
_____ 3. cytoplasm
a. where one bacterium divides to form two identical bacteria cells
_____ 4. endospore
b. a small, thick-walled resting cell that forms inside a bacterial cell
_____ 5. binary fission
c. the region inside the cell membrane
_____6. parasites
d. used to destroy disease-causing bacteria
_____ 7 decomposer
e. organism that breaks down dead organisms into small chemicals
_____ 8 sexual reproduction
f. where one bacterium transfers genetic material into bacterium
_____ 9. flagellum
g. the cell's chemical factories where proteins are produced
_____ 10. asexual reproduction h. the process of breaking down food to release energy
_____11. conjugation
i. whip-like structure that helps a cell to move
_____12. respiration
j. where one parent reproduces offspring identical to that parent
_____13. ribosome
k where two parents combine their genetic material to produce a new
organism that differs from both parents
_____14. antibiotics
l. bacteria that harm the host or host cells they live in