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Prokaryotes

Visual Learning Company1-800-453-8481 www.visuallearningco.com

Instructor’s

Manual

BIOLOGY

Editors: Brian A. Jerome Ph.D. Stephanie Zak Jerome

Assistant Editors: Louise MarrierHeidi Berry

Reviewers: Stephen Trombulak Ph.D.Professor of BiologyMiddlebury College

Graphics: Fred Thodal

Visual Learning Company 1-800-453-8481

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The purchase of this video program entitles the user the right to reproduce or duplicate, in whole or in part, this instructor’s manual and the black line master handouts for the purpose of teaching in conjunction with this video, Prokaryotes. The right is restricted only for use with this video program. Any reproduction or duplication, in whole or in part, of this manual and student masters for any purpose other than for use with this video program is prohibited.

The video and this instructor’s manual are the exclusive property of the copyright holder. Copying, transmitting, or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506).

Copyright © 2012

ISBN 9781592345984

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A Message from our Company .............................

Viewing Clearances ..............................................

Use and Copyright ................................................

Student Learning Objectives ...............................

Assessment .........................................................

Introducing the Program ......................................

Program Viewing Suggestions ..............................

Video Script ..........................................................

Answer Key to Student Assessments ...................

Answer Key to Student Activities ..........................

Preliminary Assessment ....................................... Post Assessement ................................................

Video Review ........................................................

Prokaryotes Vocabulary ........................................

Prokaryotes and Eukaryotes .................................

Prokaryotic Characteristics ................................... Archaea vs. Bacteria ............................................

Preserving Food ...................................................

Table of Contents


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• 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.

Upon viewing the video and completing the enclosed activities, students will be able to do the following:

Student Learning Objectives


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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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karyotes Introducing the Program

Program Viewing SuggestionsThe 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.

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.


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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 Cells13. 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 Prokaryotes23. 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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karyotes 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 Prokaryotes37. 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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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-Archaea63. 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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karyotes Video Script: Prokaryotes

79. Graphic Transition- Bacteria80. 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 Action95. 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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Video Script: Prokaryotes105. 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 Review108. 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 Quiz115. 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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Answer Key to Student AssessmentsPreliminary Assessment (p. 15-16) Post Assessment (p. 17-18)

Video Review (p. 19)

1. b - prokaryotes 2. d - over 3.4 billion years ago 3. a - nucleus 4. b - cell walls 5. d - gram stain 6. b - pili 7. b - cell organelles 8. a - DNA 9. c - pinching of parent cell into two identical cells10. d - two11. b - extreme environments12. c - very salty water13. a - photosynthetic or chemosynthetic14. c - bacilli15. a - a process that returns elements from the environment to organisms.16. 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.17. Prokaryotic cells don’t possess a nucleus, but eukaryotic cells do. Prokaryotic cells lack many of the specialized cell organelles found in eukaryotic cells.18. 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.19. 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.20. 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 - bacilli10. c - very salty water11. d - two12. a - DNA13. b - pili14. b - cell walls15. d - over 3.4 billion years ago16. 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 Assessment (p. 19)

Vocabulary (p. 20)

1. d - prokaryotes 2. i - peptidoglycan 3. g - gram stain 4. a - pili 5. o - eukaryotic cell 6. e - nucleoid region 7. m - plasmids 8. b - binary fission

9. k - mutation10. h - archaea11. l - methanogens12. c - cocci13. f - spirilla14. j - fixation15. n - decomposition

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. 3.4 6. DNA2. nucleus 7. binary3. everywhere 8. autotrophic4. peptidoglycan 9. spirilla5. stain 10. decomposing


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Answer Key to Student ActivitiesProkaryotes and Eukaryotes (p. 21)

Archaea vs. Bacteria (p. 24)

Prokaryotic Characteristics (p. 22-23)

Preserving Food (p. 25)Characteristic Prokaryotic Cells Eukaryotic CellsFirst appeared at least 3.4 billion years

agoabout 2.4 billion years ago

Heredity material DNA in nucleoid region DNA in nucleus

General form relatively small, unicellular larger and more complex

Size very small larger, can form multicellular organisms

Internal structures relatively few, no nucleus, nucleoid region

many organelles, have nucleus, DNA in nucleus

Reproduction binary fission mitosis or meiosis

1. cell wall 2. pili 3. flagella 4. ribosomes 5. plasmid 6. nucleoid region 7. cell membrane 8. Prokaryotes are single-celled organisms possessing a cell wall, but lacking a nucleus. 9. 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.

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.

Food Preservation Method

eggs, yogurt, cheese, deli meats, butter

refrigeration

milk, juice, apple cider, cream

pasteurization

hamburg, peas, chicken, fish, corn

freezing

green beans, pickles, peaches, pineapple, tuna

canning

pasta, jerky, raisins, prunes,

drying

Visual Learning Company15Prokaryotes

Name:

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 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

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

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

Preliminary Assessment

Directions: Circle the best answer for each of the following: questions.


Name:Preliminary AssessmentDirections: 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.


Name:Post Assessment

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

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

5. 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

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

8. The most abundant living things on Earth are: a. plants b. prokaryotes c. animals d. mosses

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. 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

13. On the surface of some bacteria are short hair- like structures called: a. bacilli b. pili c. hair follicles d. membranes

14. 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

Directions: Circle the best answer for each of the following: questions.


Name:Post AssessmentDirections: 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.


Name:

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 ReviewDirections: Answer these questions as you watch the video:

Video AssessmentDirections: 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.


Name:Prokaryotes

Vocabulary

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.

f. Spiral-shaped bacteria.

g. A technique used to differentiate categories of bacteria.

h. Domain of bacteria once thought to solely inhabit extreme environments.

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

____ 1. korysoetpra ___________________________

____ 2. npaecpytligdo _________________________

____ 3. agmr tnisa ______________ ______________

____ 4. iipl _______________

____ 5. yroatkiuce lelc _________________________ ______________

____ 6. ulidcoen eingro ________________________ ______________________

____ 7. sspdiaml _______________________

____ 8. aiynbr niiossf __________________ _________________________

____ 9. ttnamoui _______________________

____ 10. acaarhe _________________________

____ 11. tnemanhsgeo __________________________

____ 12. occic _______________

____ 13. iilrplsa ____________________

____ 14. otxfiian ___________________________

____ 15. ctopoenmisdio ________________________

Directions: Unscramble the vocabulary words in the first column. Match the words to the definitions in the second column.


Name:Prokaryotes and EukaryotesBackground: 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,

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 Prokaryotic Cells Eukaryotic CellsFirst appeared

Hereditary material

General form

Size

Internal structures

Reproduction

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.


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.

Prokaryotic Characteristics

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.


Name:Prokaryotic CharacteristicsDirections: 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.

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.

Prokaryotic cell - internal features

Prokaryotic cell - external features

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3.

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5.6.

7.


Name:Archaea vs. Bacteria 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

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.

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.

Directions: Answer the following questions using complete sentences.

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.


Name:Preserving FoodBackground: 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 Preservation Method

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