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Instructor’s
Prokaryotes
Editors:
Brian A. Jerome Ph.D.
Stephanie Zak Jerome
Assistant Editors:
Louise Marrier
Heidi Berry
BIOLOGY
Graphics: Fred Thodal
Manual
Reviewers:
Stephen Trombulak Ph.D.
Professor of Biology
Middlebury College
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Prokaryotes
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Prokaryotes
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Prokaryotes. The right is restricted only for use with this video program. Any
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Copyright © 2012
ISBN 9781592345984
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Prokaryotes
Table of Contents
A Message from our Company .............................
2
Viewing Clearances ..............................................
2
Use and Copyright ................................................ 3
Student Learning Objectives ...............................
5
Assessment .........................................................
6
Introducing the Program ......................................
7
Program Viewing Suggestions .............................. 7
Video Script ..........................................................
8
Answer Key to Student Assessments ................... 13
Answer Key to Student Activities .......................... 14
Preliminary Assessment .......................................
15
Post Assessement ................................................
17
Video Review ........................................................
19
Prokaryotes Vocabulary ........................................
20
Prokaryotes and Eukaryotes ................................. 21
Prokaryotic Characteristics ................................... 22
Archaea vs. Bacteria ............................................
24
Preserving Food ...................................................
25
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Prokaryotes
Student Learning Objectives
Upon viewing the video and completing the enclosed activities, students will be able
to do the following:
• State that fossil evidence shows the earliest prokaryotes existed at least 3.4 billion years ago.
• Know that prokaryotes were the only living things on Earth for a billion years.
• Explain that prokaryotes are abundant, diverse, and are found just about everywhere on
the planet.
• Describe prokaryotes as single-celled organisms possessing a cell wall but lacking a nucleus.
• Differentiate between the two major groups of prokaryotes: archaea and bacteria.
• Understand that bacteria are often described as being gram positive or gram negative; a reaction caused by a staining process.
• Identify pili as short, hair-like structures found on the surface of some prokaryotes.
• Know that prokaryotic cells lack many of the specialized structures found in eukaryotic cells. These include various cell organelles and a nucleus.
• Explain that prokaryotes reproduce via the process of binary fission in which a parent cell splits into two identical daughter cells.
• Understand that genetic variation can occur in prokaryotes.
• Explain that archaea live in a wide range of environments even though they were once thought to live only in extreme environments.
• Know that archaea don’t have peptidoglycan in their cell walls as do bacteria. Also know that archaea possess different RNA, ribosomal proteins, and plasma membranes than those in bacteria.
• Differentiate between the following groups of archaea: methanogens, halophiles, and thermophiles.
• Explain that bacteria can be autotrophic or heterotrophic, and aerobic or anaerobic.
• Identify the three main bacterial shapes: spirilla, cocci, and bacilli.
• List some of the harmful and beneficial effects of prokaryotes.
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Prokaryotes
Assessment
Preliminary Assessment (p. 15-16):
The Preliminary Assessment is an assessment tool designed to gain an
understanding of students’ preexisting knowledge. It can also be used as a
benchmark upon which to assess student progress based on the objectives
stated on the previous pages.
Post Assessment (p. 17-18):
The Post Assessment can be utilized as an assessment tool following student
completion of the program and student activities. The results of the Post
Assessment can be compared against the results of the Preliminary Assessment
to assess student progress.
Video Review (p. 19):
The Video Review can be used as an assessment tool or as a student activity.
There are two sections. The first part contains questions displayed during the
program. The second part consists of a ten-question video assessment to be
answered at the end of the video.
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Prokaryotes
Introducing the Program
Before showing students the video ask them what they think are the most abundant
organisms on the planet. Explain that these organisms are found just about everywhere.
Tell them there are millions of them in their mouth, on their skin, and even inside their
body! Explain that these super-abundant organisms are prokaryotic cells (generally
referred to as bacteria).
Write the term prokaryote on the board. Explain how prokaryotes were the first living
things on Earth, appearing over 3.4 billion years ago. Also explain that more complex
eukaryotic cells arose from prokaryotic cells. Discuss how our bodies are made up of
eukaryotic cells.
Ask students to describe some of the things they already know about prokaryotes.
They may state information about diseases caused by bacteria, or information about
prokaryotic cell structure. Tell students to pay close attention to the video to learn
more about the characteristics, types, and impact of prokaryotes.
Program Viewing Suggestions
The student master “Video Review” (p. 19) is provided for distribution to students. You may
choose to have your students complete this master while viewing the program or do so upon
its conclusion.
The program is approximately 20 minutes in length and includes a ten-question video
assessment. Answers are not provided to the Video Assessment in the video, but are
included in this manual on page 13. You may choose to grade student assessments as an
assessment tool or to review the answers in class.
The video is content-rich with numerous vocabulary words. For this reason you may want to
periodically stop the video to review and discuss new terminology and concepts.
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Prokaryotes
Video Script: Prokaryotes
1. Within your body are billions of tiny organisms.
2. The same holds true for the surface of your skin.
3. These organisms have thrived on the planet for billions of years and are found
just about everywhere.
4. You can’t see these organisms but they have the ability to decompose organic
matter,…
5. …help living things extract needed elements from the environment,…
6. …and even cause living things to become very sick.
7. These organisms are prokaryotes.
8. What exactly are prokaryotes?
9. What are some of their general characteristics?
10. And, what are some of the different types of prokaryotes?
11. During the next few minutes we’re going to answer these questions and others,
as we investigate prokaryotes.
12. Graphic Transition- The Earliest Cells
13. The oldest reliable evidence of life exists in the form of microfossils found in
ancient rocks dating back at least 3.4 billion years.
14. It’s even probable that life existed long before this.
15. What were these early life forms like?
16. It’s interesting that the earliest organisms found in ancient fossils are quite
similar to modern-day prokaryotes.
17. Prokaryotes are tiny microscopic organisms with a relatively simple body plan.
18. A prokaryotic cell lacks a nucleus.
19. The fossil record shows that it took over a billion years for organisms with a
cell nucleus, eukaryotes, to develop. They developed from the formation of
symbiotic relationships between certain prokaryotes.
20. So, for over a billion years prokaryotes were the only living things on Earth.
21. During that time, it’s likely that prokaryotes evolved into widely diverse forms
including those that were heterotrophic, chemosynthetic, and photosynthetic.
22. Graphic Transition- Prevalence of Prokaryotes
23. Prokaryotic cells are abundant.
24. A teaspoon of soil contains billions of prokaryotes.
25. Amazingly there are over 300 different kinds in the human mouth alone!
26. Prokaryotes can be found virtually everywhere on the planet. Deep in the
oceans,…
27. …in boiling hot springs,…
28. …embedded in bedrock 1,500 meters below earth’s surface,…
29. …and even in the guts of animals.
30. Today there are thousands of different kinds of known prokaryotes.
31. Many millions more have yet to be discovered and classified.
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Prokaryotes
Video Script: Prokaryotes
32. In the 1970’s and 1980’s new discoveries of various kinds of prokaryotic cells
led scientists to think about these organisms differently.
33. This information helped scientists divide prokaryotes into two major groups:
archaea and bacteria.
34. Archaea and bacteria are the oldest, and structurally the simplest organisms on
the planet.
35. They’re also the most abundant life forms on Earth.
36. Graphic Transition- Characteristics of Prokaryotes
37. Prokaryotes are singled-celled organisms possessing a cell wall but lacking a
nucleus.
38. The cell wall is an important structure because it maintains the shape of the cell
and also protects it.
39. In bacteria, the cell wall consists of peptidoglycan, a network of polysaccharide
molecules. Archaea do not have peptidoglycan.
40. In some bacteria, peptidoglycan forms a thick, complex layer around the cell.
41. When these types of bacteria undergo a staining process called a gram stain
they turn a purple color.
42. Because of this they’re generally referred to as gram-positive bacteria.
43. In other types of bacteria, a relatively thin layer of peptidoglycan is sandwiched
between two plasma membranes.
44. You Describe! Describe the color of these stained bacteria.
45. These bacteria are red. They’re referred to as gram-negative.
46. Prokaryotes have a wide variety of physical characteristics. Some prokaryotes,
for example, have flagella that act like propellers, pushing the cell through the
water.
47. Shorter hair-like structures called pili are found on the surface of some
prokaryotes.
48. Pili enable these cells to attach themselves to specific things, and exchange
genetic information.
49. A key characteristic of prokaryotes is their relatively simple internal structure as
compared to eukaryotic cells.
50. For example, prokaryotes do not possess a nucleus, whereas eukaryotes do.
51. Prokaryotes also lack many of the specialized cell organelles found in eukaryotic cells.
52. However, prokaryotes tend to have some important internal structures. For
example, instead of a nucleus they have a portion of the cell called the nucleoid
region that contains DNA.
53. Some also have small circles of DNA called plasmids.
54. Prokaryotes also possess ribosomes, but the nature of their RNA and certain
proteins make them different from eukaryotic cells.
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Prokaryotes
Video Script: Prokaryotes
55. Prokaryotic cells reproduce via cell division in a process called binary fission.
56. In binary fission the cell simply pinches into two cells, with the new cells being
identical to the parent cell.
57. The process of binary fission can occur very rapidly, with thousands of cells
reproducing from a single cell in a matter of hours.
58. Genetic variation can result during this process.
59. Rapid changes in genetic variation of some harmful bacteria have made
them resistant to many known antibiotic cures. For example, certain strains
of Staphylococcus bacteria that cause infections have shown resistance to
antibiotics.
60. You Decide! Why is this a problem?
61. This has made these potentially dangerous prokaryotes difficult to control when
they infect a patient, which can lead to serious medical problems.
62. Graphic Transition-Archaea
63. Prokaryotes likely split into two different lines early in the history of life. The lines
were archaea and bacteria, forms which still exist today.
64. Let’s first discuss Archaea.
65. The domain Archaea, often referred to as ancient bacteria were once thought to
live only in extreme environments such as in geothermal springs,…
66. …or in very salty waters.
67. But more recent discoveries have observed that Archaea actually live in a wider
variety of habitats.
68. Archaea are different from bacteria in several ways. For example, unlike bacteria
they don’t have peptidoglycan in their cell walls.
69. Also, their plasma membranes contain peptides different from those in bacteria.
70. And their RNA and ribosomal proteins are quite different than those in bacterial
cells.
71. Sometimes Archaea are divided into three groups based on the environments in
which they live.
72. Methanogens are archaeabacteria that live in oxygen-free environments and
produce methane gas.
73. They can be found in swamps, wet soils, and even in the digestive tracts of
animals such as cows.
74. A second group of archaeabacteria called halophiles live in very salty conditions
such as in the Great Salt Lake in Utah,…
75. …and in very salty pools in Death Valley, California.
76. A third group of archaeabacteria thrive in extremely hot water.
77. This group, called thermophiles can be found in deep sea vents,…
78. …and in hot geothermal pools.
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Prokaryotes
Video Script: Prokaryotes
79. Graphic Transition- Bacteria
80. Bacteria are the other major phylum of prokaryotes.
81. Thought to be even older than Archaea these organisms are abundant and
diverse, with many identified groups. They can be heterotrophic or autotrophic.
82. For example, cyanobacteria are autotrophs, producing their food via
photosynthesis.
83. Cyanobacteria, also referred to as blue-green algae, are photosynthetic bacteria
most commonly found in and around water.
84. Other autotrophic bacteria are chemosynthetic. For example, bacteria found
living around superheated, deep sea vents meet their nutritional needs by
synthesizing food from chemicals in surrounding waters.
85. Heterotrophic bacteria can be found in soil, air, food, water, and even inside
living things.
86. Common ways of describing bacteria are via the Gram Stain test we previously
discussed,…
87. …or by their shape.
88. Bacteria come in three main shapes.
89. Spiral-shaped bacteria are referred to as spirilla.
90. Round-shaped bacteria are called cocci.
91. You Observe! Describe the shape of these bacteria.
92. These bacteria, called bacilli have a rod-shape.
93. These are just a couple of ways bacteria are described and grouped.
94. Graphic Transition – Bacteria in Action
95. Chances are at some point in your life you’ve had a cut that got infected.
96. The source of the infection was most likely bacteria.
97. With the help of your body’s defenses, and possibly antibacterial medicine, you
were able to stop the infection.
98. But, unfortunately sometimes bacteria can cause serious illness.
99. For example, tuberculosis, cholera, diptheria, and typhus are bacterial diseases
that have claimed the lives of millions over time.
100. Other harmful bacteria are responsible for lyme disease.
101. While some prokaryotes pose serious problems for living things, most bacteria
are not harmful.
102. And some are quite beneficial. For example, prokaryotes along with fungi play a
very important role in decomposing once living things.
103. In this process they break down organic matter and return valuable nutrients to
the environment.
104. Other prokaryotes play a key role in fixation, a process that helps return
elements from the environment to living things.
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Prokaryotes
Video Script: Prokaryotes
105. For example, nitrogen-fixing bacteria help some plants such as pea plants
obtain nitrogen from the environment so the plant can use it.
106. These are just a couple of ways prokaryotes are working around us everyday.
107. Graphic Transition – Video Review
108. During the past few minutes we’ve explored many of the fascinating
characteristics of prokaryotes.
109. We began by taking a look at the nature of the earliest prokaryotes billions of
years ago.
110. We discussed the abundance and diversity of prokaryotes.
111. Some general characteristics of prokaryotes were highlighted.
112. A more detailed discussion of the characteristics of Archaea and Bacteria
followed.
113. We rounded out our exploration of prokaryotes by exploring some of the
negative and positive impacts that these organisms have had on us and the
environment
114. Graphic Transition - Video Quiz
115. Fill in the correct word to complete the sentence.
1. Prokaryotes appeared on Earth over ____ billion years ago.
2. A prokaryotic cell lacks a _________.
3. Prokaryotes can be found ____ on the planet.
4. The cell walls of bacteria consist of ___________.
5. Gram-positive bacteria turn color due to an applied ______.
6. The nucleoid region of prokaryotic cells contains ______.
7. Prokaryotic cells reproduce via cell division in a process called ______ fission.
8. Many bacteria are ________ and are capable of synthesizing their own food.
9. These spiral-shaped bacteria are broadly referred to as ________.
10. Prokaryotes, along with fungi, play a key role in __________ once living things.
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Prokaryotes
Answer Key to Student Assessments
Preliminary Assessment (p. 15-16)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
b - prokaryotes
d - over 3.4 billion years ago
a - nucleus
b - cell walls
d - gram stain
b - pili
b - cell organelles
a - DNA
c - pinching of parent cell into two identical cells
d - two
b - extreme environments
c - very salty water
a - photosynthetic or chemosynthetic
c - bacilli
a - a process that returns elements from the environment to organisms.
Prokaryotic cells were the first living things on Earth. The fossil record reveals they appeared at least 3.4 billion years ago, but it’s likely they appeared earlier.
Prokaryotic cells don’t possess a nucleus, but eukaryotic cells do. Prokaryotic cells lack many of the specialized cell organelles found in
eukaryotic cells.
Prokaryotic cells reproduce via cell division in a process called binary fission. In binary fission the cell simply pinches into two cells, with the new cells identical to the parent cell.
Bacteria can cause infections. They can also cause serious illnesses such as tuberculosis, cholera, diphtheria, and typhus. Bacteria can also cause chronic problems such as lyme disease, pneumonia, stomach ulcers, and tooth decay.
Prokaryotes, along with fungi, play a very important role in decomposing once-living things. Some prokaryotes also play a key role in fixation, a process that helps return elements from the environment to living things.
1. a - a process that returns elements from the environment to organisms.
2. a - photosynthetic or chemosynthetic
3. b - extreme environments
4. c - pinching of parent cell into two identical cells
5. b - cell organelles
6. d - gram stain
7. a - nucleus
8. b - prokaryotes
9. c - bacilli
10. c - very salty water
11. d - two
12. a - DNA
13. b - pili
14. b - cell walls
15. d - over 3.4 billion years ago
16. Prokaryotic cells reproduce via cell division in a process called binary fission. In binary fission the cell simply pinches into two cells, with the new cells identical to the parent cell.
17. Prokaryotic cells were the first living things on Earth. The fossil record reveals they appeared at least 3.4 billion years ago, but it’s likely they appeared earlier.
18. Bacteria can cause infections. They can also cause serious illnesses such as tuberculosis, cholera, diphtheria, and typhus. Bacteria can also cause chronic problems such as lyme disease, pneumonia, stomach ulcers, and tooth decay.
19. Prokaryotes, along with fungi, play a very important role in decomposing once-living things. Some prokaryotes also play a key role in fixation, a process that helps return elements from the environment to living things.
20. Prokaryotic cells don’t possess a nucleus, but eukaryotic cells do. Prokaryotic cells lack many of the specialized cell organelles found in eukaryotic cells.
Video Review (p. 19)
Vocabulary (p. 20)
1. These bacteria are red.
2. This has made these potentially dangerous prokaryotes difficult to control when they infect a patient, which can lead to serious medical problems.
3. These bacteria have a rod-shape.
1.
2.
3.
4.
5.
6.
7.
8.
Video Assessment (p. 19)
1.
2.
3.
4.
5.
13
Post Assessment (p. 17-18)
3.4
nucleus
everywhere
peptidoglycan
stain
6.
7.
8.
9.
10.
DNA
binary
autotrophic
spirilla
decomposing
d - prokaryotes
i - peptidoglycan
g - gram stain
a - pili
o - eukaryotic cell
e - nucleoid region
m - plasmids
b - binary fission
9.
10.
11.
12.
13.
14.
15.
k - mutation
h - archaea
l - methanogens
c - cocci
f - spirilla
j - fixation
n - decomposition
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Prokaryotes and Eukaryotes (p. 21)
Characteristic
First appeared
Preserving Food (p. 25)
Heredity material
Prokaryotic Cells
at least 3.4 billion years
ago
DNA in nucleoid region
General form
relatively small, unicellular larger and more complex
milk, juice, apple cider,
cream
pasteurization
very small
hamburg, peas,
chicken, fish, corn
freezing
green beans, pickles,
peaches, pineapple,
tuna
canning
pasta, jerky, raisins,
prunes,
drying
Size
Internal structures
Reproduction
Eukaryotic Cells
about 2.4 billion years ago
DNA in nucleus
larger, can form
multicellular organisms
relatively few, no nucleus, many organelles, have
nucleoid region
nucleus, DNA in nucleus
binary fission
mitosis or meiosis
Prokaryotes
Answer Key to Student Activities
Food
Preservation Method
eggs, yogurt, cheese,
deli meats, butter
refrigeration
Prokaryotic Characteristics (p. 22-23)
1.
2.
3.
4.
5.
6.
7.
8.
9.
cell wall
pili
flagella
ribosomes
plasmid
nucleoid region
cell membrane
Prokaryotes are single-celled organisms possessing a cell wall, but lacking a nucleus.
Gram positive bacteria show a red color when stained. They have a thick layer of peptidoglycan on their cell wall. Gram negative bacteria turn a purple color when stained. They have a thin layer of petidoglycan sandwiched between cell membranes.
10. Prokaryotic cells do not possess a nucleus, eukaryotic cells do.
11. Prokaryotic cells reproduce via binary fission. In this process, the cell pinches into two cells, with the new cells being identical to the parent cell.
12. Many bacteria possess flagella that push them.
Archaea vs. Bacteria (p. 24)
1. Archaea do not possess a material called peptidoglycan in their cell walls, as do bacteria.
2. Sometimes archaea are grouped based on the environments in which they live. Methanogens are archaea that live in oxygen-free environments and produce methane gas. Halophiles live in very salty conditions such as the Great Salt Lake. Thermophiles are archaea that thrive in extremely hot water and can be found in deep sea vents and hot geothermal pools.
3. Photosynthetic bacteria, such as cyanobacteria are autotrophic. Other autorophic bacteria can be chemosynthetic, synthesizing food from surrounding chemicals.
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Preliminary Assessment
Name:
Directions: Circle the best answer for each of the following: questions.
1. The most abundant living things on Earth are:
a. plants
b. prokaryotes
c. animals
d. mosses
2. Fossil evidence reveals that prokaryotes first appeared when?
a. 10,000 years ago
b. less than one billion years ago
c. approximately 500 million years ago
d. over 3.4 billion years ago
9. What best describes the process of binary fission in prokaryotes?
a. fusing of two gametes
b. production of spores
c. pinching of parent cell into two identical cells
d. sexual reproduction
3. What structure(s) do prokaryotes lack?
a. nucleus
b. cell wall
c. DNA
d. pili
4. In some prokaryotes, a material called peptidoglycan is found in:
a. RNA
b. cell walls
c. the nucleus
d. DNA molecules
5. Bacteria are often grouped on how they react to a staining agent called a:
a. neutral stain
b. cleansing stain
c. cleanser
d. gram stain
6. On the surface of some bacteria are short hair-
like structures called:
a. bacilli
b. pili
c. hair follicles
d. membranes
7. One indicator signifying complexity of eukaryotic cells compared to prokaryotic cells is a greater number of:
a. pili
b. cell organelles
c. paramecium
d. cell walls
8. Instead of a nucleus, prokaryotes have a portion of the cell called the nucleoid region that contains:
a. DNA
b. cilia
c. food vacuoles
d. peptidoglycan
Prokaryotes
15
10. Presently prokaryotes are divided into how many major groups?
a. four
b. three
c. six
d. two
11. Archaea were once thought to live only in:
a. water
b. extreme environments
c. air
d. fire
12. Halophiles are archaea that live in:
a. boiling water
b. geysers
c. very salty water
d. swamps
13. Autotrophic bacteria can be:
a. photosynthetic or chemosynthetic
b. eukaryotic
c. carnivorous
d. heterotrophic
14. Bacteria commonly come in three main shapes. Rod-shaped bacteria are referred to as:
a. cocci
b. rods
c. bacilli
d. spirilla
15. Some bacteria play a key role in fixation. What is fixation?
a. a process that returns elements from the environment to organisms
b. the process of decomposing organic molecules
c. a reaction that occurs as ATP is broken down
d. the process of repairing cells
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Preliminary Assessment
Name:
Directions: Answer the following using complete sentences:
16.
What were the first living things on Earth, and when did they likely first appear?
17. List two main differences between prokaryotic cells and eukaryotic cells.
18. What is binary fission?
19. Describe how bacteria can be harmful.
20. Describe a beneficial aspect of prokaryotes.
Prokaryotes
16
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Post Assessment
Name:
Directions: Circle the best answer for each of the following: questions.
1. Some bacteria play a key role in fixation. What is fixation?
a. a process that returns elements from the environment to organisms
b. the process of decomposing organic molecules
c. a reaction that occurs as ATP is broken down
d. the process of repairing cells
2. Autotrophic bacteria can be:
a. photosynthetic or chemosynthetic
b. eukaryotic
c. carnivorous
d. heterotrophic
3. Archaea were once thought to live only in:
a. water
b. extreme environments
c. air
d. fire
9. Bacteria commonly come in three main shapes. Rod-shaped bacteria are referred to as:
a. cocci
b. rods
c. bacilli
d. spirilla
10. Halophiles are archaea that live in:
a. boiling water
b. geysers
c. very salty water
d. swamps
11. Presently prokaryotes are divided into how many major groups?
a. four
b. three
c. six
d. two
12.
4. What best describes the process of binary fission in prokaryotes?
a. fusing of two gametes
b. production of spores
c. pinching of parent cell into two identical cells d. sexual reproduction
13.
5. One indicator signifying complexity of eukaryotic cells compared to prokaryotic cells is a greater number of:
a. pili
b. cell organelles
c. paramecium
14.
d. cell walls
6. Bacteria are often grouped on how they react to a staining agent called a:
a. neutral stain
b. cleansing stain
c. cleanser
d. gram stain
7. What structure(s) do prokaryotes lack?
a. nucleus
b. cell wall
c. DNA
d. pili
Instead of a nucleus, prokaryotes have a portion of the cell called the nucleoid region that contains:
a. DNA
b. cilia
c. food vacuoles
d. peptidoglycan
On the surface of some bacteria are short hair-
like structures called:
a. bacilli
b. pili
c. hair follicles
d. membranes
In some prokaryotes, a material called peptidoglycan is found in:
a. RNA
b. cell walls
c. the nucleus
d. DNA molecules
15. Fossil evidence reveals that prokaryotes first appeared when?
a. 10,000 years ago
b. less than one billion years ago
c. approximately 500 million years ago
d. over 3.4 billion years ago
8. The most abundant living things on Earth are:
a. plants
b. prokaryotes
c. animals
d. mosses
Prokaryotes
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Post Assessment
Name:
Directions: Answer the following using complete sentences
16.
What is binary fission?
17. What were the first living things on Earth, and when did they likely first appear?
18. Describe how bacteria can be harmful.
19. Describe a beneficial aspect of prokaryotes.
20. List two main differences between prokaryotic cells and eukaryotic cells.
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Video Review
Name:
Directions: Answer these questions as you watch the video:
1. You Describe!
Describe the color of these stained bacteria.
2. You Decide!
Why is this a problem?
3. You Observe!
Describe the shape of these bacteria.
Video Assessment
Directions: After you watch the video, fill in the blank to complete the sentence.
1. Prokaryotes appeared on Earth over _______________ billion years ago.
2. A prokaryotic cell lacks a ____________________.
3. Prokaryotes can be found ____________________ on the planet.
4. The cell walls of bacteria consist of ____________________.
5. Gram-positive bacteria turn color due to an applied _______________.
6. The nucleoid region of prokaryotic cells contains _______________.
7. Prokaryotic cells reproduce via cell division in a process called _______________ fission.
8. Many bacteria are ____________________ and are capable of synthesizing their own food.
9. These spiral-shaped bacteria are broadly referred to as ____________________.
10. Prokaryotes, along with fungi, play a key role in ____________________ once living things.
Prokaryotes
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Prokaryotes
Vocabulary
Name:
Directions: Unscramble the vocabulary words in the first column. Match the words to the definitions in
the second column.
____ 1. korysoetpra ___________________________
____ 2. npaecpytligdo _________________________
____ 3. agmr tnisa ______________ ______________
____ 4. iipl _______________
____ 5. yroatkiuce lelc _________________________
______________
a. Short, hair-like structures found on the surface of some prokaryotes.
b. Process by which bacteria reproduce.
c. Round-shaped bacteria.
d. Tiny microscopic organisms with a relatively simple body plan.
e. The portion of the bacterial cell containing DNA.
____ 6. ulidcoen eingro ________________________
f. Spiral-shaped bacteria.
____ 7. sspdiaml _______________________
g. A technique used to differentiate categories of
bacteria.
____ 8. aiynbr niiossf __________________ h. Domain of bacteria once thought to solely inhabit extreme environments.
______________________
_________________________
____ 9. ttnamoui _______________________
____ 10. acaarhe _________________________
____ 11. tnemanhsgeo __________________________
____ 12. occic _______________
____ 13. iilrplsa ____________________
____ 14. otxfiian ___________________________
____ 15. ctopoenmisdio ________________________
Prokaryotes
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i. A network of polysaccharide molecules that make up cell walls in some prokaryotes.
j. A process carried out by bacteria that helps return elements from the environment to living things.
k. One means by which genetic variations occur; error in DNA replication.
l. Archaea that live in oxygen-free environments and produce methane.
m. Circles of DNA in bacterial cell.
n. Process of bacteria and fungi breaking down organic material.
o. A type of cell that is more complex than prokaryotic cells; contains a nucleus
Visual Learning Company
Prokaryotes and
Eukaryotes
Name:
Background: When did life first appear on Earth? The oldest
reliable evidence of life exists in the form of microfossils found in
ancient rocks dating back at least 3.4 billion years. It’s probable
that life existed long before this. What were these early life forms
like? It’s interesting that the earliest organisms found in ancient
fossils are quite similar to modern-day prokaryotes. Prokaryotes
are tiny microscopic organisms with a relatively simple body plan. A
prokaryotic cell lacks a nucleus. The fossil record shows that it took
over a billion years for organisms with a cell nucleus, eukaryotes,
to develop. So, for over a billion years prokaryotes were the only living things on Earth.
During that time, it’s likely that prokaryotes evolved into widely diverse forms including
those that were heterotrophic, chemosynthetic, and photosynthetic.
Prokaryotes are singled-celled organisms possessing a cell wall and lacking a nucleus.
The cell wall is an important structure because it maintains the shape of the cell and also
protects it. In some prokaryotes, peptidoglycan forms a thick, complex layer around the
cell. A key characteristic of prokaryotes is their relatively small size and simple internal
structure as compared to eukaryotic cells. Prokaryotic cells are much smaller than
eukaryotic cells. For example, prokaryotes don’t possess a nucleus, whereas eukaryotes
do. They also lack many of the specialized cell organelles found in eukaryotic cells.
However, prokaryotes tend to have some important internal structures. For example,
instead of a nucleus they have a portion of the cell called the nucleoid region that contains
DNA. Some also have small circles of DNA called plasmids. Prokaryotes also possess
ribosomes, but the nature of their RNA and certain proteins make them different from
eukaryotic cells. Prokaryotic cells reproduce via cell division in a process called binary
fission. Eukaryotic cells reproduce via the processes of mitosis or meiosis.
Directions: Use your knowledge of prokaryotes and eukaryotes to complete the chart below.
Characteristic
First appeared
Prokaryotic Cells
Eukaryotic Cells
Hereditary material
General form
Size
Internal structures
Reproduction
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Prokaryotic
Characteristics
Name:
Background: Prokaryotes are singled-celled organisms possessing
a cell wall and lacking a nucleus. The cell wall is an important
structure because it maintains the shape of the cell and also protects
it. In bacteria, the cell wall consists of peptidoglycan, a network of
polysaccharide molecules. Archaea do not have peptidoglycan. In
some bacteria, peptidoglycan forms a thick, complex layer around
the cell. When these types of bacteria undergo a staining process
called a gram stain they turn a purple color. Because of this, they
are generally referred to as gram-positive bacteria. In other types
of bacteria, a relatively thin layer of peptidoglycan is sandwiched
between two plasma membranes. The color of these stained
bacteria are red and are referred to as being gram-negative.
Prokaryotes have a wide variety of physical characteristics. Some
prokaryotes, for example, have flagella that act like propellers,
pushing the cell through the water. Shorter hair-like structures called
pili are found on the surface of some prokaryotes. Pili enable these
cells to attach themselves to specific things, and exchange genetic
information.
A key characteristic of prokaryotes is their relatively simple internal structure as
compared to eukaryotic cells. For example, prokaryotes don’t possess a nucleus,
whereas eukaryotes do. They also lack many of the specialized cell organelles found
in eukaryotic cells. However, prokaryotes tend to have some important internal
structures. For example, instead of a nucleus they have a portion of the cell called
the nucleoid region that contains DNA. Some also have small circles of DNA called
plasmids. Prokaryotes also possess ribosomes, but the nature of their RNA and certain
proteins make them different from eukaryotic cells.
Prokaryotic cells reproduce via cell division in a process called binary fission. In binary
fission the cell simply pinches into two cells, with the new cells being identical to the
parent cell. The process of binary fission can occur very rapidly, with thousands of
cells reproducing from a single cell in a matter of hours. Genetic variation can result
during this process. Rapid changes in genetic variation of some harmful bacteria have
made them resistant to many known antibiotic cures. For example, certain strains of
Staphylococcus bacteria that cause infections have shown resistance to antibiotics.
This has made these potentially dangerous prokaryotes difficult to control when they
infect a patient, leading to serious medical problems.
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Prokaryotic
Characteristics
Name:
Directions: Label the structures on the diagrams of the external and internal prokaryotic
cells. After you have identified the structures briefly describe their functions. Then
answer the questions.
Prokaryotic cell - external features
1.
3.
2.
Prokaryotic cell - internal features
7.
4.
6.
5.
Questions:
8. What are prokaryotes?
9. Explain the difference between gram positive and gram negative bacteria.
10. Describe one difference between prokaryotic cells and eukaryotic cells.
11. How do prokaryotes reproduce?
12. Describe one way some bacteria move.
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Archaea vs. Bacteria
Name:
Background: Prokaryotes likely split into two different lines early in
the history of life. The lines were archaea, and bacteria, forms that
still exist today. Let’s first discuss archaea. The domain Archaea,
often referred to as ancient bacteria were once thought to only live in
extreme environments such as in geothermal springs or in very salty
waters. But more recent discoveries have observed that archaea
actually live in a wider variety of habitats. Archaea are different from
bacteria in several ways. For example, unlike bacteria they don’t have
peptidoglycan in their cell walls. Also, their plasma membranes contain
peptides different from those in bacteria. And, their RNA and ribosomal
proteins are quite different than those in bacterial cells. Sometimes
archaea are grouped based on the environments in which they live. Methanogens are archaea
that live in oxygen-free environments and produce methane gas. They can be found in
swamps, wet soils, and even in the digestive tracts of animals such as cows. A second group
of archaea called halophiles live in very salty conditions such as in the Great Salt Lake located
in Utah, or in very salty pools in Death Valley, California. A third group of archaea thrive in
extremely hot water. This group, called thermophiles can be found in deep sea vents, and in
hot geothermal pools.
Bacteria are the other major group of prokaryotes. Thought to be even older than archaea,
these organisms are abundant, and diverse, with many identified groups. They can be
heterotrophic or autotrophic. For example, cyanobacteria, are autotrophs, producing their food
via photosynthesis. Cyanobacteria, also referred to as blue-green algae, are photosynthetic
bacteria, and are most commonly found in and around water. Other autotrophic bacteria
are chemosynthetic. For example, bacteria found living around superheated deep sea vents
meet their nutritional needs by synthesizing food from chemicals in surrounding waters.
Heterotrophic bacteria can be found in soil, air, food, water, and even inside living things.
Common ways of describing bacteria are via the gram strain test, or by their shape. Bacteria
come in three main shapes. Sprial-shaped bacteria are referred to as spirilla. Round-shaped
bacteria are called cocci. Bacteria called bacilli have a rod-shape. These are just a couple of
ways bacteria are described and grouped.
Directions: Answer the following questions using complete sentences.
1. Describe the cell walls of archaea and bacteria.
2. Describe two of the three groups into which archaea can be grouped.
3. Explain two ways in which bacteria can be autotrophic.
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Preserving Food
Name:
Background: Have you ever eaten food that has been left out for a period of time and felt ill
afterward? If so, it may have been due to bacteria that were growing on the food. Through a
better understanding of bacteria, several ways to prevent bacterial growth have been developed.
Over time, food preservation techniques have developed from understanding bacteria’s role in
diseases.
Bacteria tend to thrive in certain types of environments, particularly warm, moist areas. In these
environments, harmful bacteria can quickly grow on food, possibly leading to illness. There are a
variety of methods of food preservation that can help to prevent illness caused by bacteria.
Listed in the table below are five methods of food preservation. Read over the table and follow
the directions.
Method
Food Preserved
Why Effective
Canning
vegetables, fruits,
meats
high temperature kills off bacteria; packaging in a
sealed container prevents entrance of new bacteria
Freezing
meats, cookies,
vegetables
stops reproduction and spreading of bacteria
Pasteurization
drinks, dairy
products
kills bacteria with heat, slows growth of any remaining
bacteria in cooling process
Refrigeration
meats, eggs, dairy
products
slows reproduction and spreading of bacteria
Drying
meats, grains, flour,
starch
removes moisture needed for bacteria to grow
Directions: In the table below, write down eight foods that have gone through a preservation
process to keep them fresh. Try to list some foods that you have eaten during the past 24 hours.
Include the name of the food and the method used to preserve it.
Food
Prokaryotes
Preservation Method
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