Discussion Questions April 5

Zimmer 2009a, Origin of Life


1. What hook does the author use to captor your attention? Carl Zimmer begins with Charles Darwin’s short perspective on how life begin. As a tool to capture the audience, I think this is effective by drawing on historical data to present day theories. But it also begins with a discussion that most people ponder: the origin of life.
2. How could you adapt this hook in your own case study? Introducing the case study with a question that is controversial and widespread will be a hook.
3. What is RNA (specifically mRNA, for those of you who have some background in this area)? Why is it essential for using the genetic code? RNA is ribonucleic acid is a single-strand molecule similar to DNA. MRNA is a messenger ribonucleic acid molecule that acts as a template for protein synthesis. The genetic code of transporting the DNA into proteins is identical to RNA.
4. What is the RNA world hypothesis? The hypothesis is that the origin of life may have started with RNA which can be traced with the present day RNA.
5. Why was lightening so essential to the origin of life? Zimmer uses Cleaves’ interpretations in which lightening was a potent source in the development of organic compounds in the beginning of earth. Sparks may have created more amino acids, for instance.
6. What ideas does Zimmer present on how cells may have originated? Zimmer suggests that protocells in temperatures in the 100 degrees C range assisted them to obtain nucleotides and develop RNA in lower temps, and this pattern of heat allowed RNA to replicate fast.
7. Do we have any conclusive evidence to support hypotheses on how life originated? The evidence of the experiments suggests many possibilities to the origin of life, but I do not think they are conclusive. As Zimmer mentions, cells are ever-evolving which suggests that we may not be certain about how cells developed and functioned in the beginning of earth. Experiments will always discover new possibilities.





Zimmer 2010, What the rock say

1. What hook does the author use to captor your attention? It starts with a story of Abigail and her hike to observe rocks. The rocks may appear to readers as insignificant but they are fossil records that can be used to determine the age of earth. The author also uses pictures and graphs throughout the reading keeps my attention going.
2. How could you adapt this hook in your own case study? Visuals will be effective in getting the readers attention, so using images to go along with the reading I think will be a good hook.
3. Why was Lord Kelvin’s estimate of the age of the Earth wrong? It was discovered that radioactivity (energy from unstable atoms) is what warms the earth, and this process can determine the ages of fossils and rocks.
4. Use figure 3.3 to explain the most common way fossils form. When an organism dies, its body gets covered by layers of sediment overtime. As the sediments accumulate, the bones fossilize. Many centuries later the fossils can be exposed from erosion, or discovered in other ways such as digging.
5. How does coal form? Plant remains metamorphose into hard rocks (coal) when are they are exposed to intense heat and pressure then compacted.
6. What are 12C and 13C? Why does the ration of 12C to 13C differ between plants and air? How do we use this difference to infer details about fossils ecosystem? Carbon-12 is a stable isotope of carbon and is plentiful, and-carbon 13 is a stable isotope of carbon. Carbon-13 is more difficult for plants to take in as opposed to carbon-12 which is lighter. So the levels of carbon-12 in plants is higher, and the levels of carbon-13 in the air is higher. When organisms die, they can preserve the levels of carbon, which can be detected in their fossils. The measurements can provide evidence of what organisms ate and the environment they lived in.
7. Find some images of Ediacaran fossils and post them in your blogs. Be sure to indicate where you found the images!

http://universe-review.ca/I10-77-Ediacara.jpg
http://www.fas.org/irp/imint/docs/rst/Sect20/vendintro.jpg

8. Why do plants colonize land before animals? According to the article, it appears that fungi and worked together to get on land. This made their expansion faster, compared to the colonization of animals.

9. How does this reading tie to the learning goals for this course? I think this article provides a great overview of the theory of fossils and the origin of life, which pertains to the course. This step-by-step reading can serve as a guideline of where science is today with fossilization and the evolution of earth.