BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: #eukaryotes

Exploring Multicellularity on Planet Earth

Billions of years ago, it is believed that some event—whether it be a meteor crash-landing on planet Earth, or a lightning strike creating amino acids and proteins—sparked the origin of life. From there, single celled organisms, like bacteria, made their home on our planet; and eventually, unicellularity became multicellularity. The reason behind this phenomenon, though, is what continues to be unknown. What really is the point of the majority of organisms being compiled of millions of cells, and not just one? 

Scientists at Lund University strive to answer this question. In order to do this, green algae from Swedish lakes were taken into their lab, as this specific botanic organism is extremely suitable for the goals of this experiment. For one, it is a eukaryote, which will allow researchers to gain insight on the evolution of all eukaryotes, in general. They are widely studied in the study of evolution because of their very apparent evolutionary process. There is a great amount of data to reveal that all eukaryotes have common ancestry, including the presence of double membranes, circular genomes, ribosomes, linear chromosomes, and more in all eukaryotic organisms. 

Another reason as to why green algae is such an appropriate fit for an experiment exploring the evolutionary characteristics of unicellular and multicellular organisms is that it is sometimes unicellular, other times starts off this way but then becomes multicellular, and the remaining types are always multicellular. This makes green algae the perfect candidate for an experiment such as this. Data from the environments of all these different cellularly-dense types of algae was collected and compared to one another. While doing this, scientists looked out for the adaptations promoted by the environments the algae were in, what conditions exactly promoted unicellularity or multicellularity, and why the form of life it encouraged was beneficial to the organism. 

Previously, it had been theorized by evolutionary biologists that multicellularity benefited organisms that utilized it, but the Lund University research team was shocked at the results they found from analyzing the environmental data of the algae: there were no benefits of living multicellularly for these organisms. A member of the study, Charlie Cornwallis, made the following comment on the experiment’s outcomes: “I was surprised that there were no benefits or costs to living in multicellular groups. The conditions that individual cells experience can be extremely different when swimming around on their own, to being stuck to other cells and having to coordinate activities. Imagine you were physically tied to your family members, I think it would have quite an effect on you.” 

At the conclusion of the study, Charlie Cornwallis made one final statement: “The results of this study contribute to our understanding of how complex life on Earth has evolved….The next time you walk along the shores of a lake rich in nitrogen just imagine that this fosters the evolution of multicellular life.”

Green algae under a microscope

Green algae under a microscope.

Potential Life On Venus?

In an article published on September 19th, 2020, Dennis Overbye speaks on a new discovery that has sparked conversation for the possibility of life on the planet venus. On September 14th, scientists announced the discovery of Phosphine gas on Venus. The significance of this discovery is that scientists don’t know what could potentially produce the gas except for microbes. According to the National Center for Biotechnological Information(NCBI), “Microbes are tiny living things that are found all around us and are too small to be seen by the naked eye. They live in water, soil, and in the air.” Overbye states that “on earth, anyway, the only natural source of phosphine is microbes; the gas is often associated with feces.” He quickly counters this by acknowledging that there is a large possibility that scientists don’t know everything about Phosphine gas.

Microbes, which are both eukaryotes and prokaryotes(or neither), consist of archaea, bacteria, fungi, viruses, protists, and other microscopic animals. Eukaryotes are cells that simply consist of DNA within a nucleus while prokaryotes are unicellular organisms that don’t consist of a nucleus nor organelles. As learned throughout the year, the difference in complexity and functions of eukaryotic and prokaryotic organisms widen the array of the potential situation in Venus. If both prokaryotes and eukaryotes can survive in the atmosphere of Venus, the potential answer to what enables this grows. Also, due to the microscopic nature of microbes, also known as microorganisms, it would be very hard to infer whether they are or aren’t present on Venus.

As the article continues, Overbye continues to speak on what was previously known about the planet. He references information from “Carl Sagan, then a doctoral student at the University of Chicago” who “provided an accurate explanation for Venus’s torrid temperature, in his 1960 Ph.D. thesis. The planet’s crushing carbon dioxide atmosphere had created a runaway greenhouse effect, he concluded. Venus was a lifeless desert, at least on the ground.”

With this, Sagan and Harold Morowitz, a biochemist at Yale, pointed out, in 1967, how the clouds of Venus seemed more suitable for life. ““If small amounts of minerals are stirred up to the clouds from the surface, it is by no means difficult to imagine an indigenous biology in the clouds of Venus,” they wrote in a paper in Nature.” These claims, which were not very popular, have become very relevant again due to new findings and open up many possibilities.

All in all, the search for life on other planets is very much up and running. Will we find it soon?

 

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