instructions 1. a brief cover letter (1-2 pages) explaining how you addressed ALL of the concerns of your reviewers’ in your final manuscript, make sure you describe where you made each change in the final manuscript (e.g., I changed figure 1 as the reviewer requested by altering the font and adding additional details to make the figure more descriptive)  Word Document (.doc or .docx)  2. author 3. author affiliation 4. title 5. article preview/teaser 6. full article text (1,000 - 1,250 words) 7. search/glossary words 8. figure captions 9. references 10. glossary 11. figures (4-6 total figures/tables/maps/diagrams) review from other student reviewer1 A. 1. This article clearly explains the effects of crude oil spills on phytoplankton.  The language is not cluttered thus easy to follow. 2. This article seems to be scientifically accurate.  3. This article flows very well and is organized in a reasonable way that is conducive to learning.   B. 1. This article functions well as a teaching piece.  It states many facts that show the author did sufficient research on the topic.  2. The author seemed to include all the necessary components to successfully tell the story. Although, it could have been more focused on just phytoplankton as the teaser suggests.  C.  1. Yes, the article includes ten references. 2. The author did include 4 figures that successfully add to the telling of the story.  These 4 figures each have their own description.  3. The author did cite their references throughout the article using the authors last name.  4. The article is over 1,000 words.  D.  2.  The article is very good but I would suggest making the article more pointed at the phytoplankton. 2016年3月25日 下午12:09 reviewer 2 A 1. The Article has a good point of view for us to understand Crude oil spillage are and how they affect use as americans. 2.This is an article that is scientifically accurate 3.if people read this article and they dont understand Crude oil spillage  this article encourages them to learn learn about it . B. 1.this article function as a piece of teaching us what . Crude oil spillage  it is and the affects on whart its doing to us in America and how we can resolve it this article tells a story in my reading this article i learned that our own Ohio stadium zero waste pretty interesting. 2.this article is ready to tell a story. about what Crude oil spillage is and why its a part of our life today In my reading I don’t see anything that needs to be added to this article expect maybe talk  about what can we do to slove this problem  C  1. yes this article has at least 10 references 2. Yes this author included at least 4 high-quality figures and/or tables. Each one has a description describing the figure  3.no they did not display figures properly thought the article D.  looking over this article I can make a final say is that this author did a good job on this article well thought out . great point need to be impoved  ...

1. instructions
1. a brief cover letter (1-2 pages) explaining how you addressed
ALL of the concerns of your reviewers’ in your final
manuscript, make sure you describe where you made each
change in the final manuscript (e.g., I changed figure 1 as the
reviewer requested by altering the font and adding additional
details to make the figure more descriptive) Word Document
(.doc or .docx)
2. author
3. author affiliation
4. title
5. article preview/teaser
6. full article text (1,000 - 1,250 words)
7. search/glossary words
8. figure captions
9. references
10. glossary
11. figures (4-6 total figures/tables/maps/diagrams)
review from other student
reviewer1
A.
1. This article clearly explains the effects of crude oil spills on
phytoplankton. The language is not cluttered thus easy to
follow.
2. This article seems to be scientifically accurate.
3. This article flows very well and is organized in a reasonable
way that is conducive to learning.
B.
1. This article functions well as a teaching piece. It states many
facts that show the author did sufficient research on the topic.
2. The author seemed to include all the necessary components to

2. successfully tell the story. Although, it could have been more
focused on just phytoplankton as the teaser suggests.
C.
1. Yes, the article includes ten references.
2. The author did include 4 figures that successfully add to the
telling of the story. These 4 figures each have their own
description.
3. The author did cite their references throughout the article
using the authors last name.
4. The article is over 1,000 words.
D.
2. The article is very good but I would suggest making the
article more pointed at the phytoplankton.
2016年3月25日 下午12:09
reviewer 2
A
1. The Article has a good point of view for us to understand
Crude oil spillage are and how they affect use as americans.
2.This is an article that is scientifically accurate
3.if people read this article and they dont understand Crude oil
spillage this article encourages them to learn learn about it .
B.
1.this article function as a piece of teaching us what . Crude oil
spillage it is and the affects on whart its doing to us in America
and how we can resolve it
this article tells a story in my reading this article i learned that
our own Ohio stadium zero waste pretty interesting.
2.this article is ready to tell a story. about what Crude oil
spillage is and why its a part of our life today In my reading I
don’t see anything that needs to be added to this article expect
maybe talk about what can we do to slove this problem
C
1. yes this article has at least 10 references

3. 2. Yes this author included at least 4 high-quality figures and/or
tables. Each one has a description describing the figure
3.no they did not display figures properly thought the article
D.
looking over this article I can make a final say is that this
author did a good job on this article well thought out . great
point need to be impoved in some areas but others it look good
like properly describle your figures alittle more in your article .
Author (Arial, Bold, 10
point)
Author Affiliation (Arial,
Bold, 10 point) University,
Department, Building, City,
State, Country)
Article Title (Arial, Bold,
10 point, 10 word limit.
Crude oil spillages affects aquatic organisms
Article Preview/ “ Teaser” ( 10- 15 words, Arial, 10 point, the
teaser is NOT the same as an Abstract)
Crude oil spillage is one of the most ecological disasters. How
does it affect phytoplankton?
Crude oil is responsible for the suffocation and death of
phytoplankton thus interfering with the aquatic
life
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4. Full Article Text (1000-1250 words, Use Arial and 10 pt.font
size)
There is enough evidence that despite taking adequate measures
to minimize their occurrences,
oil spillages still happen around the globe. Crude oil spillages
in water bodies such as oceans pose
significant implications to aquatic life, given that toxic
impacts traverse across trophic lines, thereby
affecting planktons especially the zooplankton and
phytoplankton (Juhasz, 2011).
On April 20, 2010, the Gulf of Mexico witnessed a devastating
explosion, which led to spillages
from oil wells totaling approximately 780 000 m3. It spread
widely causing a lot of damage to marine
habitats, the fishing as well as the tourism industry (Trannum &
Bakke, 2012). The huge spill of oil oozing
along the Gulf Coastline posed a lot of threat to several wildlife
species with some in their breeding
seasons. It is not only the birds that feel the impact of oil
spillage; however, they are normally the first
among all animals to feel the impact. This is because they are
just right there at the water surface,
where they swallow the oil and cover themselves in it, causing

5. kidney as well as liver problems. The
other affected species are planktons on which organisms feed on
all the way along the food web. Crabs,
oysters and mussels as well as shrimp eat plankton. The oil
affects plankton; hence they have nothing to
feed on. Long term exposure to oil can also affect the mammals
skins and lung problems leading to
deaths when they breathe it (Hayes, 2010).
Robertson (2010) noted that according to available data the
United States has a long history of
oil spillages. For example, the Toxics Targeting data show that
the country has since 1964 experienced
more than 324 oil spillages as a result of offshore drilling,
spilling over 500, 000 barrels of crude oil and
other related substances. Roberts posits that four of the
spillages occurred as a result of equipment
breakages and failures as well as accidents on the deepwater
areas. In addition, the thousands of liters
of produced water, a byproduct which includes grease, oil as
well as heavy metals, are dumped into the
sea annually. However, the 2010 British Petroleum oil spill that
affected the Gulf of Mexico shifted the
world attention on the United States third coast with many
questioning the country’s ability to fully

6. recover from the effects of the spill (see fig 1).
Crude oil contains compounds of hydrocarbon as well as
non hydrocarbon with the mixture
varying among various types of crude oil (see fig 2), resulting
in several chemical properties. Monocyclic
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aromatic hydrocarbons such as benzenes and toluene and
phenols are the most toxic elements of crude
oil, however, they pose minimal toxic impact on aquatic life
given that they are highly volatile. Polycyclic
aromatic hydrocarbon component of weathered crude oil is,
on the other hand, the main source of
toxicity at oil spill sites (Perhar & Arhonditsis, 2013). The
weathered oil adversely affects aquatic life
(figure 2).
There are several studies on the effect of crude oil on aquatic
life; however, many researchers
have concentrated with organisms located in higher trophic
regions neglecting those at the center of the
marine food chain, like the phytoplankton. Phytoplankton
performs a significant role in the ecological

7. condition of marine ecosystems and the atmospheric
regulation of carbon; thus any change in their
distribution pattern and abundance can affect the whole
ecosystem (Ozhan, Michael & Bargu, 2014).
Ozhan et al. (2014) indicate that crude oil spillages interferes
with water’s chemical composition and the
interaction of food webs, thereby, not only boosting
phytoplankton growth but also increasing its mass.
However, Perhar and Arhonditisis, (2014) suggest that some
classes of phytoplankton in collaboration
with microbial groups can play active functions in altering the
compounds of crude oil.
Trannum and Bakke (2012) suggest that oil spillages adversely
affect plankton, especially the
phytoplankton and the zooplanktons through inhibition of
gaseous exchange, light penetration, toxic
responses and hypoxia which occur due to high
degradation. In their support Jaiswar et al. (2013)
posited that crude oil contains highly concentrated
petroleum hydrocarbons which interfere with the
growth of chlorophyll (figure 4) thereby reducing its level,
while on the other hand, increasing the level of
phaeophytin. This, according to Jaiswar et al results in
lower levels of chlorophyll compared to

8. phaeophytin which is an unhealthy condition for the
growth of phytoplankton. The reduction in the
population of phytoplankton occurs because of inhibited
photosynthesis closely linked to decreased
pigmentation, cell membrane disruptions and unhealthy
phytoplankton cells.
Phytoplankton response to crude oil spillages depends on
the level of dosage and the type of
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phytoplankton specie involved. For example, short term oil
spillages are only associated with
photosynthesis defects, whereas long term exposure cause
massive destruction of phytoplankton cells.
However, some micro phytoplanktons contain toxic resistant
cells, enabling them to survive in mild
conditions and depend on their mutation capabilities to
survive in harsh conditions. Hydrocarbon
pollution is also known to interfere with the phytoplankton cell
size (Perhar & Arhonditisis, 2014). Perez
et al. (2010) noted an increase in the diameter as well as a
growth rate decline in isochrysis galbana

9. after the oil spill. They suggested that oil exposure interferes
with cell division mechanism, rather than
the production process of a new cell. They also posited that
reduction in growth rate may be as a result
of the prolongation of the cell cycle, instead of high mortality.
In studying the effects of oil spillages on
assemblages of phytoplankton, Perhar and Arhonditisis, (2014)
arrived at similar conclusions, pointing
out that decreased growth rates as well as increased cell size
occurred due to perturbations of the cell
cycle.
The Gulf of Mexico oil spillage changed the community
structure of phytoplankton and an
increase in biomass because of its damaging effect as well as
beneficial impacts of reduced predation
(Trannum & Bakke, 2012). In their support Miller, Roberts
and LaPoe (2014) reveal that crude oil
spillages also interfere with Phytoplankton communities.
However, they note that it is very complex to
understand the interplay between the components of crude oil
and phytoplankton, given that it varies
amongst different compounds, phytoplankton as well as
concentrations. In addition, other environmental
factors such as temperature, nutrient level and light play a

10. significant role. Thirdly, different
phytoplankton members, respond differently due to oil spillage;
with some taxa being stimulated, while
others hindered, and sensitivity differences causing a reduction
in species biomass in various levels.
With grazers such as fish affected, some phytoplankton species
may not be under intense grazing. This
may result in phytoplankton imbalance and shifts due to oil
spills.
Search Words (minimum of three, maximum of six, use Arial
and 10 pt font size)
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Chlorophyll
Monocyclic aromatic hydrocarbons
Phaeophytin
Phytoplankton
Polycyclic aromatic hydrocarbon
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11. Figure Legends for accompanying illustrations, tables, graphs,
and photographs (Use Arial and
10 pt. font size)
Fig 1. A view of the 2010 oil spill along the Gulf of Mexico
Figure 2. Chemical composition of oil spillage at Batroun in
Lebanon
(Source: Based on Khalaf et al., 2006)
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Fig 3 A diagram showing physical and ecological impacts of oil
spillage in the ocean
(Source: Based on Parhar & Arhonditisis, 2014)
Figure 4 Image of an affected plankton
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References (Use Arial and 10 pt. font size)
Hayes, Ashley. (2010). Oil spill could be disaster for
animals, experts say. Retrieved from.
http://edition.cnn.com/2010/US/04/29/oil.spill.wildlife/

12. JiyalalRam, M. J., Ram, A., Rokade, M. A., Karangutkar, S. H.,
Yengal, B., Dalvi, S., ... & Gajbhiye, S. N.
(2013). Phytoplankton dynamic responses to oil spill in Mumbai
Harbour. International Journal of
Innovative Biological Research, 2(1), 30-50.
Juhasz, A. (2011). Black tide: the devastating impact of the
Gulf oil spill. John Wiley & Sons.
Khalaf, G., Nakhlé, K., Abboud-Abi Saab, M., Tronczynski, J.,
& Mouawad, R. (2006). Preliminary results
of the oil spill impact on Lebanese coastal waters. Lebanese
Science Journal, 7(2), 135.
Miller, A., Roberts, S., & LaPoe, V. (2014). Oil and Water:
Media Lessons from Hurricane Katrina and
the Deepwater Horizon Disaster. Mississipi, MS: Univ. Press of
Mississippi.
Özhan, K., Miles, S. M., Gao, H., & Bargu, S. (2014).
Relative Phytoplankton growth responses to
physically and chemically dispersed South Louisiana sweet
crude oil. Environmental monitoring
and assessment, 186(6), 3941-3956.
Ozhan, K., Parsons, M. L., & Bargu, S. (2014). How were
phytoplankton affected by the Deepwater
Horizon oil spill?. BioScience, 64(9), 829-836.

13. Pérez, P., Fernández, E., & Beiras, R. (2010). Fuel
toxicity on Isochrysis galbana and a coastal
phytoplankton assemblage: Growth rate vs. variable
fluorescence. Ecotoxicology and
environmental safety, 73(3), 254-261.
Perhar, G., & Arhonditsis, G. B. (2014). Aquatic ecosystem
dynamics following petroleum hydrocarbon
perturbations: A review of the current state of knowledge.
Journal of Great Lakes
Research, 40(3), 56-72.
Robertson, C. (2010). Gulf of Mexico Has Long Been Dumping
Site. New York Times. Retrieved from.
http://www.nytimes.com/2010/07/30/us/30gulf.html
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http://edition.cnn.com/2010/US/04/29/oil.spill.wildlife/
April 1, 2016
Prof. Brian H. Lower
Editor, ScienceBites
The Ohio State University
School of Environment & Natural Resources
210 Kottman Hall

14. 2021 Coffey Road
Columbus, Ohio 43210 (USA)
Re: Revised Manuscript Version 2
Dear Dr. Lower,
Thank you for considering my revised manuscript for
publication in ScienceBites, I am pleased
that you have requested minor modification of our manuscript.
Below is a detailed point-by-point
explanation of how we addressed ALL of the reviewers’
comments in our revised
manuscript. To address these concerns we:
1. Modified and/or added additional text to the manuscript.
2. Modified Figure 1.
3. Added 9 new references.
4. Added 1 new co-author who performed additional work to
address the concerns of
Reviewer #2 regarding the specificity of the polyclonal
antibodies used in our
experiments.
We have also indicated the page and line number where new
text can be found in our revised
manuscript. While these modifications increased the length of
our manuscript, we attempted to
make text additions as brief as possible, while still addressing
the concerns of both reviewers.
In addition, we moved our figure captions to a separate “Figure
Legends” page in our manuscript

15. as you requested.
Should our revised manuscript be accepted for publication we
request that our article appear the
environmental section of ScienceBites.
We appreciate the comments and suggestions of the two
anonymous reviewers and the time and
effort of the editor. The input that we received from these
people has definitely improved the
quality of our manuscript.
Best regards,
Susie A. Student
Reviewer 1 Comments:
1. The authors need to explain why the performed the AFM
measurements in growth medium?
The use of growth medium adds complexity to the
measurements as it contains a lot of proteins
and can increase the non-specificity interactions.
We agree with Reviewer #1’s comment that having proteins in
the imaging fluid can add
complexity to the measurements. We regret that we mistakenly
listed our imaging buffer as
“growth medium” in our original manuscript when we actually
performed our AFM measurements
in phosphate buffered saline (PBS) at pH 7.4. We thank the
reviewer for her/his careful attention

16. to detail and we have corrected our mistake in the revised
manuscript. These changes can be
found on page 4, lines 11-13. The sentence now reads: “We
performed Ig-RFM in phosphate
buffered saline (PBS), pH 7.4, on living S. oneidensis MR-1
cells that were deposited on a
hydrophobic glass cover slip using an Asylum Research MFP-
3D-BIO AFM or a Digital
Instruments Bioscope AFM (15, 16).
2. The authors need to comment on the stability of the bacteria
during AFM measurements.
Bacteria were only deposited on glass and that allows the cell to
move under liquid.
We apologize for not making this point clear in the original
manuscript. For the experiments
shown in Figures 1 and 2, the bacteria were actually deposited
on OTS-functionalized glass and
not plain glass slides. OTS-glass is an ideal substrate for
immobilizing Gram-negative bacteria
like S. oneidensis MR-1 and we have used these substrates for
imaging S. oneidensis MR-1 in a
number of previous studies. This work has been published in
the Journal of Bacteriology,
Langmuir, and Science. To address this concern we state on
page 4, lines 14-19 of our revised
manuscript the following: “The hydrophobic glass cover slips
were made as described previously
(16) using a self-assembling silane compound called
octadecyltrichlorosilane (OTS; Sigma-
Aldrich). S. oneidensis MR-1 cells readily adsorbed onto OTS-
glass cover slips and remained
attached to the cover slips during the entire experiment. No
lateral cell movement was observed

17. during the experiment, as was the case for a number of previous
studies in which we used OTS-
glass to immobilize bacteria for AFM experiments (14, 16, 17,
23).
3. Please mention the type and the spring constant of the
cantilevers used? How were the
cantilevers were calibrated?
This information is provided in our revised manuscript on page
3, lines 17-23. It reads: “In this
study, we covalently coupled AntiMtrC or AntiOmcA to silicon
nitride (Si3N4) cantilevers (Veeco or
Olympus) via a flexible, heterofunctional polyethylene glycol
(PEG)-linker molecule, which
consisted of a NHS (N-hydroxysuccinimide) group at one end
and an aldehyde group at the other
end (i.e., NHS-PEG-aldehyde). The cantilevers had spring
constant values between 0.06 and
0.07 N/m as determined by the thermal method of Hutter and
Bechhoefer (11) and the z-
piezoelectric scanner was calibrated as described previously
(16).”
Reviewer 2 Comments:
1. Please provide some additional information about the
experiments done to verify the specificity
of the polyclonal antibodies (Page 4; L. 15-18).
We did as Reviewer 2 requested and added additional
information (including adding one
additional reference) regarding these experiments to our revised
manuscript. These changes
can be found on Page 4, line 23 – page 5, line 8. It now reads:
“Prior to conducting the Ig-RFM

18. experiments, the specificity of each polyclonal antibody (i.e.,
AntiOmcA and AntiMtrC) for OmcA
or MtrC was verified by Western blot analysis (22) of proteins
resolved by both denaturing and
nondenaturing polyacrylamide gel electrophoresis (PAGE; data
not shown). Briefly, 2.5 µg of
purified OmcA or MtrC was resolved by SDS-PAGE or native-
PAGE, transferred to PVDF
membrane, incubated with either AntiOmcA or AntiMtrC, and
then visualized using the Amersham
ECL Plus Western Blotting Detection kit. When the PVDF
membrane was incubated with
AntiOmcA, OmcA was the only polypeptide detected and when
incubated with AntiMtrC, MtrC
was the only cytochrome observed on the membrane.”
2. Please do not use the term significant if significance was not
tested statistically (Page 5; L. 11).
We did statistical analysis on our data because the other
reviewer also requested this. It can be
found on page 8, lines 15-18.
Author David A. Smith
Author Affiliation The Ohio State University, School of
Environment &
Natural Resources, Columbus, Ohio (USA).
Article Title Origin of Life in the Universe
Article Preview/“Teaser”
Earth is the only planet in our universe known to harbor life.

19. How did life come to
exist on Earth? What did Earth’s earliest inhabitants look like?
Does life exist
elsewhere in our universe?
Full Article Text
Earth is a unique planet within our solar system because it is
positioned within the
system’s habitable zone and as such has all the properties
needed to sustain carbon-
based life. These include a constant source of energy (i.e., the
sun), surface
temperatures that allow for the formation of liquid water and a
mass that generates
gravitational forces sufficient to hold an atmosphere.1 Earth’s
atmosphere in turn
shields organisms from the sun’s harmful radiation, helps to
maintain constant
surface temperatures, sustains the production of energy (e.g.,
cellular respiration)
and promotes the synthesis of organic molecules (e.g.,
photosynthesis).1,2,3
Scientists from the fields of biology, chemistry, geology and
physics have undertaken
the 4-billion year old quest for Earth’s first inhabitants. These
scientists interpret
Earth’s fossil record to search from telltale “bio-signatures”
that provide clues about
where, when and how life originated. They rely on

20. biochemical, genetic and
proteomic information to retrace evolutionary steps back to
life’s last common
ancestor.3,4 They study chemical reactions that occur between
simple organic
molecules (e.g., amino acid) and inorganic compounds (e.g.,
minerals) to predict
how diverse biomolecules may have originated and organized
into complex organic
molecules. And finally, they examine extraterrestrial matter
(e.g., meteorites) and
planets (e.g., Mars) for evidence of past or present life that may
provide clues for
how life originated on Earth.
In order to understand how life originated we must first
consider what it means to be
alive. Life can be difficult to define and different scientists
have different meanings
for the word. However, if we consider life on the most
fundamental level we can
define it based on several essential characteristics that are
required for all organisms
living on Earth. These include a need for liquid water, the
ability to be self-
sustaining and capable of evolution, dependence upon an
external energy source to
survive, and use of organic molecules to produce structures with
inherent function
and organization. When exploring the possibility of
extracellular life, NASA searches
the universe for habitable planets (or moons) that, in theory,
could support life.

21. NASA defines a habitable planet as one that can maintain liquid
water on its surface,
has a source of energy (e.g., star) that can be used to maintain
metabolism, and
possesses environmental conditions that are favorable for the
formation of complex
organic molecules.4
By calculating the amount of radiogenic lead generated by the
decay of uranium
since the Earth was formed, geologists estimate Earth’s age to
be approximately
4.55-billion years.5 During this time, the composition of gases
contained within the
atmosphere has changed. The early atmosphere is believed to
have originated from
outgassing of the Earth’s crust and mantle. These gases were
probably similar to
those released by modern-day volcanoes, which consist
primarily of CO2, H2O and
SO2 as well as CH4, CO, H2, H2S, NH3 and N2. Large
deposits of limestone and other
carbonates suggest that carbon dioxide (CO2) was an important
component of the
Earth’s atmosphere for much of its existence (Figure 1). It is
also likely that as
Earth’s surface temperature cooled, the H2O vapor that was
released from its
volcanoes and deposited on its surface by colliding comets
began to exist as liquid
and coalesce into pools, lakes and ultimately oceans sometime
between 4.4 and 3.5-
billion years ago.1,4,5
In 1953 Stanley Miller and Harold Urey conducted the first
experiment to create

22. simple organic molecules from a mixture of gases that were
thought to resemble
Earth’s primitive atmosphere.6 In their famous experiment,
Miller and Urey were
able to produce amino acids when an electric discharge (e.g.,
those produced by
electrical storms believed to be prevalent on early Earth) was
passed through a
gaseous mixture of ammonia (NH3), hydrogen (H2), methane
(CH4), and water (H2O)
vapor at 100oC (Figure 2).6 Among the new substances
produced in their
experiments were formaldehyde (H2CO) and hydrogen cyanide
(HCN), which then
reacted with one another via the Strecker reaction to produce
amino acids like
glycine and alanine. The formaldehyde also reacted with the
liquid water via the
Formose reaction to produce sugars like ribose (Figure 3).
Experiments by other
scientists showed that hundreds of organic molecules could be
formed under these
conditions, including all 20 naturally occurring amino acids and
the 5 nucleotides
required to construct RNA and DNA.5,7,8
Regardless of how the first life forms evolved, it is widely
accepted that Earth has
been inhabited by single-celled prokaryotes (Figure 4) for most
of its existence. The
oldest purported prokaryotic fossils discovered on Earth are
approximately 3.5 billion
years old.9,10 These microfossils are micrometer-scale
structures that have been
preserved in mineral deposits for billions of years (Figure 5).
Because primitive

23. Earth was surrounded by an atmosphere that lacked oxygen, the
earliest forms of
life were most likely anaerobic prokaryotes.11,12
Photosynthetic microorganisms
evolved and began releasing O2 into the atmosphere about 3.5-
billion years ago. As
atmospheric concentration of free O2 increased, aerobic
respiration evolved to meet
the metabolic needs of the first aerobic prokaryotes (2-billion
years ago) and then
the first eukaryotes, 1.4-billion years ago (Figure 1).13
Search words
Evolution, hydrothermal vent, microfossil, origin of life,
prebiotic, prokaryote,
protocell.
Figure Legends
Figure 1. Major milestones in the evolution of life on Earth.
The abstract clock
shows some of the major events in Earth’s history. Dates are
approximated based
on evolutionary, geological, or paleontological evidence. Ma is
equal to one-million
(106) years before present. Ga is equal to one-billion (109)
years before present.
Figure 2. The Miller-Urey experiment. The apparatus consisted
of a closed glass
tube connecting two glass chambers. The upper chamber
contained a mixture of
gases thought to resemble the atmosphere of primitive Earth.

24. The lower chamber
contained heated water, to resemble the ocean of early Earth.
Electrodes in the
upper chamber provided electrical sparks, simulating lightning.
As the gases passed
through the apparatus, they were cooled by condensers causing
water drops to form.
These drops contained dissolved organic molecules that had
formed in the upper
chamber. Sample probes allowed liquid samples to be removed
from the apparatus
for analysis. This figure was modified slightly from Yassine
Mrabet’s original figure
with permission by a Creative Commons Attribution-ShareAlike
license (CC-BY-SA).
Figure 3. Deep ocean hydrothermal vent. This vent is part of
the Brimstone Pit
located on the side of a large submarine volcano approximately
50 miles north of the
Island of Rota, in the Mariana Islands of the Pacific Ocean.
The pit is approximately
550 meters deep. The bubbles are likely CO2 being released
from the volcano. Also
note the yellow sulfur that is coating some of the pieces of
solidified lava. This photo
is in the public domain and was provided by the National
Oceanic and Atmospheric
Administration (NOAA).
Figure 4. A fragment of the Murchison meteorite and particle
sample (contained in
glass test tube) extracted from the meteorite for examination by
scientists at
Argonne National Laboratory. This photo is in the public
domain and was provided by

25. the U.S. Department of Energy (DOE).
Figure 5. A condensation reaction between two amino acid
molecules. Two amino
acid monomers alanine and glycine join together to form the
biopolymer
alanylglycine. Water (shown in blue) is released during the
reaction, hence the
name dehydration reaction. The opposite reaction (hydrolysis)
occurs when a water
molecule breaks the peptide bond (shown in red) of the
biopolymer releasing alanine
and glycine.
References
1. McMurran, M., & Christopher, G. (2009). Legal &
Criminological
Psychology, 14(1):101-107.
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3:REVIEWS1010.
http://genomebiology.com/2002/3/4/reviews/1010.
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collection, transport, and
processing: virology, p 1227-1241. Murray, P.R., et al. (Eds.),
Manual of
clinical microbiology, 8th ed, Washington, D.C.: Penguin Press.
5. Odell, J.C. (1970, April). Process for batch culturing. U.S.
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more of them.
New York: Jeremy P. Tarcher/Penguin.
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Retrieved from http://www.rollingstone.com.
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Consumer Reports,
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Most
Americans aren't getting enough sleep. And for both adults and
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there are health consequences. Star Tribune. Retrieved from
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Stanley taps new
boss. The Wall Street Journal, pp. A1, A16.
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podcast]. Retrieved
November 5, 2009, from
http://www.nature.com/nature/podcast/index-2009-
07-16.html.
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27. Corporation.
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Glossary
Habitable Zone – orbital region around a star in which a planet
with sufficient
atmosphere can support liquid water at its surface.
Hydrolysis – XXX.
Prokaryote – XXX.

28. Hadean
Archean
Proterozoic
C
enozoic
4 Ga
3 Ga
2 Ga
1 Ga
3800 Ma: First
prokaryotes
3500 Ma: First
photosynthetic
prokaryotes
2100 Ma: Fully

29. oxidizing atmosphere
530 Ma: Cambrian
explosion
250-65 Ma: Age of Dinosaurs
2.3 Ma: First Homo species
1400 Ma: First
eukaryotes
4200 Ma: First self-
reproducing biomolecules
2000 Ma: First
aerobic prokaryotes
1000 Ma: First
multicellular
organisms
200 Ma: First mammals 4300 Ma: Liquid water on
Earth's surface
4550 Ma: Formation of Earth
Time
Figure 1.
Mixture of gases

30. (primitive atmosphere)
Sample Probe
Sample Probe
Sample Probe
Water
(primitive ocean)
HeatCondensed liquid containing
organic molecules
Cold water inlet
Out D
ire
ct
io
n
of
w
at
er
v
ap
or
Electrodes +-

31. Condenser
Figure 2.
Tuesday, December 6, 11
Figure 3.
Tuesday, December 6, 11
Figure 4.
H CH3
C
N
H
H
C
O

32. O
H + C
C
O
O
H
H
H
HH
OC
C
C
C
N
O
H
N
H
H
H
H

33. HH
CH3
O
O
+
Dehydration
Reaction
Hydrolysis
Reaction
Water
N
H
H
Alanine
(Ala)
Glycine
(Gly)
Alanylglycine
(Ala-Gly)
Tuesday, December 6, 11

34. Figure 5.