microbial evolution activity

8/8/2019 Microbial Evolution Activity

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American Society for MicrobiologyEducation Department

1752 N Street, NWWashington, DC 20036

[email protected]

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Author

Robin Patterson, PhD

Butler County Community CollegeButler, PA

[email protected]

Contributor

Liliana Rodriguez, MPH, RM(AAM), M(ASCP)

The University of Texas Health Science Center

School of Public Health at Houston

[email protected]

Intended Audience

K-4

5-8

9-12 X

Activity CharacteristicsClassroom setting X

Uses hands-on manipulatives X

Requires group work X

Requires mathematical skills X


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ASM Microbial Discovery Activity

Earth History: Time Flies, No Matter What the Scale Page2

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DescriptionIn this exercise students apply their mathematical skills to relate a geological time scale to a yearly

calendar to describe Earth's history in a fun and entertaining way.

AbstractIn this two-part activity, which uses discovery and an inquiry approach, the participants will be

given cartoon drawings representing significant events in the history of the Earth and asked to place

them on a timeline made of colored ribbon. Then they mathematically relate the geologic time scale

to a yearly calendar. After the calculations, they return to the timeline to reassess the placement of

the events.

Core Themes AddressedGeneral Science Concepts X

Microbial Cell Biology

Microbial Genetics

Microorganisms and Humans

Microorganisms and the Environment

Microbial Evolution and Diversity X

Other -Common properties of life;

Cellular components

KeywordsEarth history, microbial evolution, historical events, time scales.

Learning ObjectivesAt the completion of these activities students should be able to:

Identify significant events in microbial evolution Translate information from one mathematical scale to another Understand the perennial dominance of microbes, past and present Understand the order of key events in evolution relating to microbes Gain an appreciation about the place of microbes in earth's history

AcknowledgementsThis activity was adapted from Earth History: A Microbial Story authored by Dr. Douglas Zook from

Boston University. It was originally published in his 1992 book The Microcosmos Curriculum Guide

to Exploring Microbial Space, from Kendall-Hunt Publishing. We thank Dr. Zook for grantingpermission to use parts of his exercise and the cartoon illustrations. The artist is Ann Powers, BFA

from Tufts University and the School of the Museum of Fine Arts, Boston. For more information

about his book see the supplementary information section of the Teacher's handout.


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National Science Education Standards AddressedScience Content Standards 9-12

1. Earth and Space Science

Evolution of the earth system

2. Life Science

Biological evolution


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TTTeeeaaaccchhheeerrr HHHaaannndddooouuutttEarth History: Time Flies, No Matter What the

ScaleStudent Prior KnowledgeStudents need mathematical (algebraic) skills, know how to use a calculator, and have some

knowledge about the geological history of Earth.

Teacher Background InformationThis exercise provides a timeline of the evolution of life through the major events in the development

oflife on the planet Earth. Ten cartoon illustrations are provided, each corresponding to a major

event in evolution. Students can work in groups to organize these cartoons in chronological order.

You can use the Earth Time line chart below to start a discussion about major biological or geologicalevents on Earth's history prior to the activity, or give the students an assignment to be completed

before class. You can ask them to research cyanobacteria as the initial inventors of photosynthesis

and the creation of stromatolites. There are several excellent resources and websites for them to

review the topic, such as The Museum of Paleontology at UC at:

[http://www.ucmp.berkeley.edu/exhibits/geologictime.php], and the book The Microcosmos

Curriculum Guide to Exploring Microbial Space, from Kendall-Hunt Publishing.

Class TimeApproximately one hour class time is required but can be shortened by reducing the number ofevents to be studied.

Teacher Preparation TimeAbout 30 minutes to make photocopies and one set of overhead transparencies of the cartoon

illustrations, and taping pieces of ribbon on the classroom walls.


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Materials and Equipment

One set per group:

1. Photocopies of student worksheets and cartoon sheets. The cartoon sheets can be reduced insize and laminated for re-use.

2. Paperclips or clothes pins3. Five colors of ribbon or streamers, each at least 5 feet long, connected together to make one

long string. Color choice is not critical.

4. Masking tape5. Calculator6. Correlation of events worksheet7. Calendar template

Methods1. Photocopy the cartoon illustrations. It is useful to photocopy the illustrations on colored

paper. You can either use one color for each event or you can use one color for each group.

2. You may want to make overhead transparencies to assist with class discussion of the events.3. Before class, tape together the lengths of ribbon and extend the ribbon around the room,

taping to the wall wherever necessary.4. Distribute one set of cartoons, one correlation of events worksheet, and one calendar

template per group.

Safety PrecautionsNone

AssessmentHave the students complete the correlation of events worksheet in small groups and report back to

the larger group about their conclusions.

Supplementary InformationEarth Time line, worksheet, calendar, cartoon illustrations and their descriptions are listed on thefollowing pages.

The 500-page Microcosmos Curriculum Guide to Exploring Microbial Space can be purchased for $40

($35.00 + $5 S&H). Send a check made out to Intl Symbiosis Society to:

Microcosmos Project/ISS

c/o Dr. Douglas Zook

Boston University

Two Sherborn Street

Boston, MA 02215

[email protected]

There is also an updated 16 image new overhead transparency set that replaces the existing one in

the Earth History activity of the book for $35 (Includes shipping and handling).


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Earth Time LineCartoon Era Period Years Ago Billions ofYears Ago Geological and Biological 1. Cosmic Dust 4,600,000,000 4.6* Origins of earth and our s2. Extended Rain

Forecast

Archean4,200,000,000 4.2 Changes that led to creati

3. Primordial Soup 3,900,000,000 3.9 End of major impacts by oform in the hot broth of eaFirst unicellular microorg

4. Oxygen Factory 2,500,000,000 2.5 Photosynthetic microbes (of O2 leads to begining of b

5. Eukaryotic Cell 1,400,000,000 1.5-2.0 First eukaryotic organism6.Let's Get Together

Proterozoic

1,000,000,000 1.0 Begining of multicellular 7. Plants Race Animals Paleozoic Silurian 438,000,000 0.438 First plants able to coloni8. Eek Mammals! Triassic 248,000,000 0.248 (220MYA) First mammals9.Trouble in Pangea

MesozoicJurasic 225,000,000 0.225 Separation of a single lan

10. Homo sapiens Cenozoic Quaternary 2,000,000 0.002 First humans appear

* If you were to count to 4.6 billion (one number per second) it would take nearly 150 years!


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Earth History: Time Flies, No Matter What the Scale Page 7


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Key to Cartoon Illustrations (from the most ancient event).

1. When Cosmic Dust Goes Unswept (4.6 billion years ago)

The earth is about 4.6 billion years old. This cartoon represents the origins of

the universe. It is theorized that the universe began to expand over 8 billion

years ago, quickly passing from the age of energy to the age of matter. The

earth itself was formed about 4.6 billion years ago. The early earth was a

land of molten rock and violent volcanic activity. The earths crust was

solidifying at this time, called the Hadean eon, since no rocks have been

found that exceed 4.3 billion years old. These rocks show no traces of life (or

at least none that can be traced with our current level of technology)

2. 40 Million Years of Rain (4.2 billion years ago)

As the earth was forming, gasses were released from the molten core in

volcanic activity. These gasses formed a cloud around the earth and were

held as an atmosphere by the earths gravity. At first the earth was so hot

that water was present only as a vapor. As the earth cooled and the crustformed the vapor condensed to liquid water and the rain began to fall. It

rained such an enormous quantity over millions of years that the oceans of

the world were formed. The atmospheric gasses were dissolved in this rain.

3. Primordial Soup (4 billion years ago)

The atmospheric gasses that were dissolved in the rain may have reacted

with one another in the presence of the enormous amount of energy present

on the planet to produce small organic molecules. Neither oxidation (there

was no free oxygen) nor decay (there were no bacteria) would have destroyed

these molecules and they would have accumulated in the oceans for hundreds

of millions of years. With the accumulation of the small organic compounds,the oceans became a thick, warm organic soup containing a variety of organic

molecules. The newly-formed organic molecules likely polymerized to

produce still larger molecules and eventually a protocell arose. This structure

would likely have had a lipid - protein membrane that carried on anaerobic

energy metabolism and was a heterotroph (an organism that took in

preformed food), fermenting the food with some degree of enzymatic activity.

Once these protocells were self-replicating, they became true cells and

biological evolution began.

4. Oxygen Factory (2.5 billion years ago)

The evolution of photosynthesizing organisms caused oxygen to enter the

atmosphere. The atmosphere became oxidizing rather than reducing. Oxygen

in the upper atmosphere formed ozone, which filtered UV light. The presence

of oxygen also meant that most environments were unsuitable for anaerobic

prokaryotes. Photosynthetic cyanobacteria and aerobic bacteria proliferated

as new metabolic pathways evolved.


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5. Endosymbiont Recruitment (1.5 - 2 billion years ago)

Most likely the eukaryotic cell evolved from the prokaryotic cell, acquiring its

organelles gradually. The nucleus may have developed by an invagination of

the plasma membrane. The mitochondria may have been free-living aerobic

prokaryotes and the chloroplasts may have been free-living cyanobacteria.

Life was still aquatic at this point.

6. Love at First Sight (1 billion years ago)

It is not known when multicellularity began but the first multicelled

creatures were likely microscopic. Sexual reproduction would have its origins

here and would have been an important first step toward the development of

complex macroscopic organisms. The geologic period is the Precambrian era.

7. Plants Race Animals to Land (438 million years ago)

The Cambrian and Ordovician periods saw the marine algae and marine

invertebrates flourish. During the Silurian period (408 to 438 million years

ago) low lying primitive vascular plants appeared on land and the first jawedfishes appeared in the oceans. During the Devonian period, the first seed

ferns appeared (360 - 408 million years ago).

8. EEK Mammals! (248 million years ago)

The first reptiles appear in the Carboniferous period 286 - 360 million years

ago (mya). During the Triassic period, the first dinosaurs and mammals

appear (200 mya). Placental mammals appear during the Cretaceous period -

about 100 mya.

9. Trouble in Pangea (175 - 225 million years ago)

The Continental Drift theory, proposed by Alfred Wegener, states that thecontinents are not fixed and instead, their positions have changed over time

and continue to change. About 225 mya, the continents were joined to form

one supercontinent called Pangea which then divided into two sub-

continents. These split to form the continents of today. Continental drift

explains why some coastlines are mirror images of each other (Africa and

South America, for example) and why fossils of the same seed fern have been

found on all southern continents. Land masses drift due to movement of slab-

like plates of the earths crust that float on a hot mantle layer. These slabs

are called plates and their movement is called plate tectonics. The plates

move because of seafloor spreading at ocean ridges.

10. Living in Concrete Jungle Cartoon (2 million years ago)

Monkey-like primates appear about 30 mya. The first hominids appear 2 - 6

mya and humans appear during the Pleistocene era, 2 mya.


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Correlation of Events with Modern Calendars Worksheet.One per group

EventTime framea(years ago)

Timeelapsedb

Unitsc(%)

Calendar location (365 dayyear)

1

2

3

4

5

6

7

8

9

10

aTime frame - length of time before present. BYA = billion years ago;MYA = million years ago.

bTime elapsed - length of time since formation of planet. Byr = billionyears; Myr = million years.

cUnits - 5 elapsed. Calculated by dividing Time elapsed for currentstop (column 3) by estimated age of Earth (4.5 billion years).

fYear - day of 365-day year. Calculated by multiplying 365 days by %of current stop.


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Calendar Template - One Year

Su M T W Th F Sa Su M T W Th F Sa Su M T W Th F SaJanuary February March

1

1

2

3

4

5

1

2

3

4

2 3 4 5 6 7 8 6 7 8 9 10 11 12 5 6 7 8 9 10 119 10 11 12 13 14 15 13 14 15 16 17 18 19 12 13 14 15 16 17 18

16 17 18 19 20 21 22 20 21 22 23 24 25 26 19 20 21 22 23 24 2523 24 25 26 27 28 29 27 28 26 27 28 29 30 31 30 31

April May June1 1 2 3 4 5 6 1 2 3

2

3

4

5

6

7

8

7

8

9

10 11 12 13 4

5

6

7

8

9

109 10 11 12 13 14 15 14 15 16 17 18 19 20 11 12 13 14 15 16 17

16 17 18 19 20 21 22 21 22 23 24 25 26 27 18 19 20 21 22 23 2423 24 25 26 27 28 29 28 29 30 31 25 26 27 28 29 30 30

July August September1 1 2 3 4 5 1 2

2 3 4 5 6 7 8 6 7 8 9 10 11 12 3 4 5 6 7 8 99 10 11 12 13 14 15 13 14 15 16 17 18 19 10 11 12 13 14 15 16

16 17 18 19 20 21 22 20 21 22 23 24 25 26 17 18 19 20 21 22 2323 24 25 26 27 28 29 27 28 29 30 31 24 25 26 27 28 29 3030 31

October November December1 2 3 4 5 6 7 1 2 3 4 1 28 9 10 11 12 13 14 5 6 7 8 9 10 11 3 4 5 6 7 8 9

15 16 17 18 19 20 21 12 13 14 15 16 17 18 10 11 12 13 14 15 1622 23 24 25 26 27 28 19 20 21 22 23 24 25 17 18 19 20 21 22 2329 30 31 26 27 28 29 30 24 25 26 27 28 29 30

31


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Correlation of Events with Modern CalendarsAnswer Key


Timeelapsedb

Unitsc(%)

Calendar location (365 dayyear)

1 4.5 BYA 0 0 Day 1 (Jan 1)

2 4.2 BYA 0.3 BYR 6.7 Day 24 (Jan 24)

3 4 BYA 1.8 BYR 13.3 Day 49 (Feb 18)

4 2.5 BYA 2.5 BYR 44.4 Day 162 (June 10)

5 1.5 BYA3.05BYR

66.7 Day 243 (Aug 30)

6 1.0 BYA 3.5 BYR 77.8 Day 284 (Oct 12)

7 438 MYA3,910

MYR

90.3 Day 330 (Nov 22)

8 248 MYA3,995MYR

94.5 Day 345 (Dec 7)

9 225 MYA4,062MYR

95 Day 347 (Dec 9)

10 2 MYA4,140MYR

99.95 Day 365 (Dec 31)

aTime frame - length of time before present. BYA = billion years ago;MYA = million years ago.

b

Time elapsed - length of time since formation of planet. Byr = billionyears; Myr = million years.

cUnits - 5 elapsed. Calculated by dividing Time elapsed for currentstop (column 3) by estimated age of Earth (4.5 billion years).

fYear - day of 365-day year. Calculated by multiplying 365 days by %of current stop.


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SSStttuuudddeeennnttt HHHaaannndddooouuutttEarth History: Time Flies, No Matter What the

Scale

IntroductionThis exercise provides a timeline of the evolution of life through the major events in the development

oflife on the planet Earth. Nine cartoon illustrations are provided, each corresponding to a major

event in evolution. You and the other members in your group be challenged to mathematically relate

the geologic time scale of Earth's history to a yearly calendar, and to organize the cartoon in a

historical sequence.

Vocabulary:

Cyanobacteria - Bacteria likely responsible for the creation of earth's oxygen atmosphere. They werethe dominant lifeform on Earth for over 2 billion years. Today they are nearly extinct, living a

precarious existence in only a few localities worldwide.

Photosynthesis - The process by which plants, some bacteria, and some protistans use the energy

from the sun to produce sugar, which respiration in the cells converts intoATP, the "fuel" used by all

living things. The conversion of unusable sunlight energy into usable chemical energy, is associated

with the actions of the green pigment chlorophyll

Stromatolites - Communities of microorganisms growing in rock-like buildups of microbial mats that

form in limestone- forming environments. These communities include the oldest known fossils,

dating back some 3.5 billion years ago. They are prokaryotes(primitive organisms lacking a cellular

nucleus) that were abundant in warm aquatic environments and built reefs similarly to the way

coral does it today.

Materials check list (per group)1. One set of cartoon illustrations2. Paperclips or clothes pins3. Calculator4. Correlation of events worksheet5. Calendar template6. Pencil and eraser

Procedure

Organizing the Earth's History Time-line1. As a group, review the cartoon illustrations and deduce the scenario. What event is being

depicted in the illustration? How long ago do you think it happened?

2. Using paperclips, affix the cartoons on the ribbon where you think they might belong. Oneend refers to the present; the other end refers to 5 Billion Years Ago (BYA).


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3. Return to your seat. Now you will convert the historical date assigned to great events inmicrobial history into a date within a more familiar time scale to aid you in viewing

evolution in its proper scale.

Mathematically relate a geologic time scale to a yearly calendar

1. Your team should receive instructions, a worksheet for recording your calculations, a blankcalendar covering one year, and a list of events in evolution.

2. Begin by recording the names of your team members on the worksheet.3. Your team will be assigned events from evolutionary (and geological) history.4. Perform the calculations and record the results on the worksheet.5. Once you complete each conversion from historical time to the appropriate time scale, mark

the position of that event on the calendar.

a. First, identify this "Event" on the worksheet.b. Enter the "Historical date" currently assigned to this event.c. Subtract the historical date from the age of the Earth (4.5 billion years = 4,500 million

years). This "Time elapsed" value represents the length of time that passed between the

formation of Earth and the occurrence of this event.

d. Divide the time elapsed value by the total age of the Earth, and multiply by 100%. This"Percent elapsed" value is the proportion of Earths history that passed before this event.

e. Identify the total time on the calendar (365 days).f. Multiply the percent time elapsed by the total time on the calendar.g. Find and mark this point on the calendar.h. Repeat these steps for each of the events assigned to your team.i. When completed, review your results.

j. Submit this assignment as directed by your instructor.An example: Event first cell.

Historical date: 3.5 BYA

Time elapsed: 4.5 BY 3.5 BY = 1.0 BY

Percent elapsed: (1.0 / 4.5 ) x 100% = 22%

Length of current calendar: 365 days

Location on current calendar: 365 x .22 = 80.3

ANSWER: 1/3rd through the 81st day (March 23rd).

6. How did you do with the placement of the cartoons on the timeline?7. Return to the timeline and reposition the cartoons if necessary.


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Time Flies, No Matter What the Scale

Worksheet (Scale = Year)

Team Members:

Correlation of Events with Modern Calendars


Timeelapsedb

Unitsc(%)

Calendar location (365 day year)

1

2

3

4

5

6

7

8

9

10

aTime frame - length of time before present. BYA = billion years ago; MYA = millionyears ago.

bTime elapsed - length of time since formation of planet. Byr = billion years; Myr =million years.

cUnits - 5 elapsed. Calculated by dividing Time elapsed for current stop (column 3)by estimated age of Earth (4.5 billion years).

fYear - day of 365-day year. Calculated by multiplying 365 days by % of current stop.

microbial evolution activity

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