Every human being has something in their body called cells. A cell is within us and gives us structure. The cells are able to take any food we eat it and turn into energy for us to use. (What is A cell?: MedlinePlus Genetics, 2021). Within a cell are organelles. An organelle is a subcellular structure that we need to carry out certain tasks. There are 3 major organelles in the cell, pyrenoid, chloroplast, and the nucleus. Sometimes the cells also go through apoptosis, which is basically cell suicide. It will remove any of the harmful cells and keeps balance within the body. (Apoptosis (article) | developmental biology). All cells must undergo mitosis to remove things like an infection or something that can cause our DNA damage. Pyrenoid is found in chloroplast of things like algae. They are a form of carbon dioxide fixation in the algae. (Pyrenoid 2021). Its role in apoptosis is shown when a plant may be in the dark. For example Metazoans. Biochemical assays of the activities of cell death-associated proteases, caspases, are measured through fluorogenic substrates (Segovia, Haramaty, Berges, & Falkowski, 2003). Next is the nucleus. The chromatin will have condensation come during its phase of apoptosis. It will go from a heterogenous to an inert, which is highly condensed. (Nuclear condensation, 2021). Lastly to look at is the chloroplast. Cell death is crucial in chloroplast. Through the process they create reactive oxygen species also known as ROS and even contribute through cytochrome f release. (Aken & Breusegem, 2015).
Within this article they did a testing on whether or not the presence of oxic and anoxic have an effect on microbial activity. They wanted to see if doing the test with these two controls would show some type of decay to the algae. When doing the test, the data showed that there was no difference in the pattern of decay. They took each of the alages and put them into the 2 different groups. For the “oxic” group, within its tube it had no sealed lid. Without the lid they were able to top it with water to prevent desiccation (removal of moisture). For the “anoxic” group the lid remained on until they looked at the results.Since water was only added to the “oxic” group, it could’ve had effects on the algae’s chemical gradients. Which caused damage. But the results still show that there was little to no difference between the “oxic” and “anoxic” groups There was no pattern of algae decay and these appear to have had negligible effects on the decay of the algae. (Science Advances)
In the fossils, there were many features that I wasn’t expecting to see. I find it so amusing that something can stay inside of something for so long and still stay intact. I also found it interesting that things could be pretty clear visuals. Within the Zelkova leaf there were visible grana stacks in the chloroplast. A grana stack is a stack of thylakoid discs. In a fern found in the Jurassic period the nuclei was still able to be found. In the megasphaera there was a tomographic virtual section and a nuclei was found. Now in the holotype R. chitrakootensis it is believed to be seen as pyrenoids but it is unlikely. Which is within the chloroplast and deals with carbon fixation. The oldest crown eukaryote is said to be Bangiomorpha pubescens.
Caryosphoeroides and Glenobtrydian are early eukaryotes and Leptoteichos are said to have a putative nucleus or chloroplast. Lastly Shutyosphoeridium and Dictyosphoera are also putative ear;y eukaryotes and have intracellular structures that suggest nuclei or collapsed cellular contents.
Within the cells, 6 different types of changes occur when there is something trying to affect it. You have the nucleus, chloroplast, starch grain ring, pyrenoid, Y-shaped junction, and thinning- or holes in the chloroplast. In one example a way to show it is in the decay of V. aureus.When this algae was decaying, over the span of 31 days you could see all 6 of these changes happening. For the loving colonies they went from having cell boundaries and structure to nothing- no order. The chloroplast shape changed and became irregular. Causing it to become thin and have patches. Pyrenoids soon become nonexistent and leave holes ringed by starch grains. The only thing that held its structure was the nucleus. After weeks od decay it was still able to be visible and have no deformation.
References
What is A cell?: MedlinePlus Genetics. (2021, February 22). Retrieved April 05, 2021, from https://medlineplus.gov/genetics/understanding/basics/cell/
Apoptosis (article) | developmental biology. (n.d.). Retrieved April 05, 2021, from https://www.khanacademy.org/science/biology/developmental-biology/apoptosis-in-development/a/ apoptosis
Pyrenoid. (2021, February 26). Retrieved April 05, 2021, from https://en.wikipedia.org/wiki/Pyrenoid
Segovia, M., Haramaty, L., Berges, J., & Falkowski, P. (2003, May 01). Cell death in the UNICELLULAR chlorophyte Dunaliella tertiolecta. a hypothesis on the evolution of apoptosis in higher plants and Metazoans. Retrieved April 05, 2021, from http://www.plantphysiol.org/content/132/1/99.short
Nuclear condensation, dna fragmentation and membrane disruption during apoptosis. (2021, March 23). Retrieved April 05, 2021, from https://www.abcam.com/kits/nuclear-condensation-dna-fragmentation-and-membrane-disruption-du ring-apoptosis
Aken, O., & Breusegem, F. (2015, October 03). Licensed to KILL: Mitochondria, Chloroplasts, and cell death. Retrieved April 05, 2021, from https://www.sciencedirect.com/science/article/abs/pii/S1360138515002034
Carlisle, E. M., Jobbins, M., Pankhania, V., Cunningham, J. A., & Donoghue, P. C. (2021). Experimental taphonomy of organelles and the fossil record of early eukaryote evolution. Science Advances, 7(5). doi:10.1126/sciadv.abe9487