AP Biology class blog for discussing current research in Biology

Author: charbonknioxide

The Effect of Ethylene Gas on Plant Growth

Researcher Brad Binder, Professor of Biochemistry & Cellular and Molecular Biology, University of Tennessee, and his team, through their study, accidentally discovered that treating seeds with ethylene gas (C2H4) can enhance the plant’s growth and stress tolerance. This discovery can be a potential breakthrough for improving crop yields and improving plant’s resilience to environmental stress. Where in most cases one gets traded for the other, this revealed that by exposing germinating seeds to ethylene in darkness it is possible to increase growth and stress tolerance.

Plants produce ethylene as a hormone to regulate growth and stress responses. The accidental discovery occurred during an experiment where seeds were exposed to ethylene gas during germination in darkness. The plants exposed had larger leaves, longer root systems, and sustained faster growth throughout their lifespan compared to non-ethylene-exposed plants. The researchers extended their investigation to various crop species, such as tomatoes, cucumbers, wheat, and arugula, and all of them increased growth and stress tolerance after their short-term ethylene treatment.


The observed effects indicated that brief exposure to ethylene during seed germination can lead to long-lasting growth and stress tolerance benefits. The researchers proposed that ethylene priming enhances photosynthesis, particularly carbon fixation, leading to increased CO₂ absorption and higher levels of carbohydrates like starch, sucrose, and glucose. These molecules contribute to both increased growth and improved stress resilience in plants.

In AP Biology we learned all about the Calvin Cycle! The Calvin Cycle is a series of biochemical reactions that occur in the stroma of chloroplasts during photosynthesis. The cycle starts when the enzyme RuBisCO captures carbon dioxide from the atmosphere, which is then attached to RuBP, forming a six-carbon compound. This compound splits into two molecules of 3-PGA, each containing three carbon atoms. Then ATP and NADPH are reduced, which generates light-dependent reactions that are used to convert 3-PGA into G3P, a three-carbon molecule. Some G3P then continues to cycle and is reused to regenerate RuBP, while the rest contributes to glucose production for cellular respiration. The Calvin Cycle is vital in converting carbon dioxide into glucose for plant growth and sustenance.

I chose this topic because I really loved the photosynthesis unit, and my favorite part about it was memorizing the Calvin cycle, and comparing it to the Citric Acid Cycle.

What specifically about the ethylene gas causes an increased efficiency in Carbon Fixation?

What Impact Can Covid-19 Have on You? How Long Will It Last?

The University of Melbourne conducted a study, from January 2020 to October 2022 that involved over 12,000 participants. The study examined long COVID’s ability to last, and its correlation with different SARS-CoV-2 variants. The results showed a clear trend, where nearly 40% of individuals who had contracted COVID-19 had reported persisting symptoms associated with long COVID. The study observed a lessoning likelihood of COVID-19 causing lasting symptoms as the pandemic advanced. It was also revealed that individuals infected by the more recent Omicron variant were less prone to developing long COVID, with only 12% reporting persisting symptoms.


The study also revealed some demographic factors that influenced long COVID risk. Notably, women, individuals aged 40-49, and those with a history of chronic illness, anxiety, depression, or severe COVID-19 were identified as being at a higher risk for long COVID. In addition, the decrease in long COVID with newer strains did not appear to be solely attributed to vaccination rates, suggesting the involvement of other contributing factors. This new understanding of long COVID could pave the way for further exploration, offering insights into immunological and autoimmune mechanisms, and potentially shaping broader health research. Furthermore, the impact of long COVID, has caused 36 million people to still feel unwell up to weeks, months, and even years after contracting COVID-19.

Overall, the study underscores the widespread impact of long COVID, emphasizing the need for refined strategies in prevention, treatment, and support for individuals grappling with lasting symptoms after a COVID-19 infection. The evolving nature of the virus and its varying impact on different demographic groups highlight the importance of ongoing research to enhance our understanding and response to the long-term effects of COVID-19.

In AP Bio, we recently learned about the body’s immune system. The immune system is a complex network of cells that work together to protect the body from harmful pathogens. When a virus enters the body, phagocytic cells, like macrophages and dendritic cells, engulf the virus particles through phagocytosis.
Then, the virus is broken down into small peices. These pieces are presented on the cell surface as antigens. Those viral antigens are then presented to the helper T cells and once the helper T cells bind to the viral antigen, they become activated. Then the activated helper T cells release cytokines which starts the immune response and activated the other cells. The newly activated cells are helper B cells, cytotoxic T cells, and Memory B and T cells. The helper B cells have receptors that are specific to the viral antigens so they can directly recognize the virus. These cells begin to multiply. The cytotoxic T cells are able to directly kill the already infected cells, stopping the spread of the virus. They do this by releasing perforin into the cell, which tells the cell’s lysosomes to burst so the cell gets destroyed from the inside out. In addition there are plasma B cells which prevent the virus from infecting anymore cells. Then the memory cells remember the virus’ specific antigens so if the same virus infects again in the future, a faster response can be launched.

The immune system’s ability to recognise, combat, and remember viruses is what allows us to survive.

I chose this topic because one of my math teachers said he had long COVID and it was absolutely miserable so I wanted to learn more about it.

What is changing in the immune system that allows COVID-19 systems to persist in some and not others?


Missing Ribosomal DNA in Fruit Flies

This research was conducted by Yukiko Yamashita and her team on fruit fly germline stem cells and highlights the cells’ ability to retain their ribosomal DNA and continue to reproduce endlessly, giving immortality to these cells. 

Ribosomal DNA contains genes for ribosomes, which create the cell’s protein. In this case, it has a flaw because some of these genes will form a loop and pop out of the genome during cell division. If too much rDNA is lost in each generation, it would hinder their ability to build proteins, leading to extinction. However, the research showed that this is not happening, and germline stem cells are able to maintain their rDNA.

The research team used microscopy techniques to visualize rDNA in fruit fly testes and observed that their stem cells have a built-in mechanism to retain these essential genes. This mechanism involves a skewed swap of genomic sequences between two identical chromosomes, leading to one chromosome having extra rDNA, which is then passed to daughter stem cells. Fruit Flies that lack ribosomal DNA have different appearances such as unusual abdomen patterns.

The implications of this research go beyond fruit flies. Understanding how rDNA repeats are maintained in various species, including humans, is crucial, and the process is expected to be conserved across different organisms, even if the specific molecules involved are not. This research provides valuable insights into the mechanisms of immortality in germline stem cells and has the potential to inform our understanding of similar processes in other species. 

Drosophila melanogaster Female

In AP Bio we learned about the production of proteins and their transport system. The endomembrane system consists of the nucleus, the nuclear membrane, ribosomes, the rough ER, vesicles, the Golgi body, and the cell membrane. The proteins are made by ribosomes, some of which rest on the rough ER and others that float in the cytoplasm. Then they are transported by vesicles to the Golgi body, where they are packaged with a lipid label, and transported to the cell membrane, through which they exit the cell. In the case of fruit fly testes, essential genes are preserved becasue along the protein’s formation and transportation, some of its proteins exit the genome allowing the cell to preserve them. 

I chose this topic because the endomembrane system was my favorite thing to learn about, and I find genetic mutations interesting.

Where does the lost RNA go and what are the implications of it being in the cytoplasm?


Powered by WordPress & Theme by Anders Norén

Skip to toolbar