Chemistry and Fall: Why Leaves Change Colors

Autumn. It’s the season where we break out our sweaters and flannels, drink hot cocoa and apple cider, carve pumpkins, go apple picking, and enjoy the chillier weather. But, in my opinion, the best part about autumn is the changing colors of the leaves. They change from their normal green color to varying shades of yellow, orange, red, and brown. Fall foliage is beautiful and breathtaking. But how and why do the leaves change their colors during this season?

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First, we need to understand what makes leaves green in the first place and why this coloring disappears. Leaves contain structures in their cells called chloroplasts, which is where photosynthesis takes place. Photosynthesis is the process where light energy from the sun is captured and is used to convert carbon dioxide and water into oxygen and sugars. The light from the sun is absorbed by chlorophyll found in the chloroplasts. Chlorophyll is also responsible for the green in leaves because it acts a dominant pigment, overshadowing the others. As the hours of sunlight decrease in autumn, the chlorophyll present struggle to keep the photosynthesis process going and the trees stop producing new chlorophyll. Eventually there are no chlorophyll left and the green color of leaves goes away.

Photosynthesis Chemical Reaction

This allows the other pigments to show themselves. Carotene and xanthophyll are responsible for the yellow and orange colors in leaves. The vivid and scarlet red colorings come from anthocyanins. These are produced in the fall from built up sugars in the leaf. They can combine with the leftover green pigments of chlorophyll to create varying shades of red.

Beta-carotene

 

Xanthophyll

Anthocyanin

According to the United States National Arboretum, the quality of the leaf colors seen in autumn depend on the sunlight, weather, and soil moisture. To get the brightest colors, a sufficient amount of moisture is needed in the growing season, followed by a dry, cool, and sunny autumn that has warm days and cool nights, but no frost. Wind and heavy rain can cause leaves to fall before they fully show all their colors, while a lack of rain and wind will cause the autumnal color display to flourish.

Tannin

Leaves eventually turn brown from the tannin pigment as the sunlight available continues to decrease, the temperature drops, and the frost kills the leaves. In spring the process begins anew!

Sources:

https://www.pbs.org/newshour/science/why-do-leaves-change-color

https://www.washingtonpost.com/lifestyle/kidspost/ever-wondered-why-leaves-change-colors/2017/09/22/6a7b8cfa-9d6b-11e7-8ea1-ed975285475e_story.html?noredirect=on&utm_term=.433e9b094384

The New Stoned Age

CBD, cannabidiol, is a derivative of cannabis and has spread in popularity in the past few months. It’s been seen in oils, infused into coffee beans, bath bombs, ice cream and even dog treats. CBD, unlike THC, does not give off the same type of high, but you also do not feel normal after you take it. CBD causes a body high rather than a mental one. The effects are comparable to taking a long warm bath or completing a intense mediation session. As anxiety has been on the high for our times, CBD seems like the magic cure all. CBD helps relieve people of pain, inflammation, anxiety, lethargy, and more. It makes people feel relaxed without any mental fog.

CBD has different effects than THC due to receptors. THC interacts with CBS and CB2 receptors found in the nervous system. CB1 receptors are fond in the part of the brain that is concerned with emotion, memory and cognition. The attachment of THC to these receptors alters concentration, thinking, perception, and pleasure. CBD doesn’t bind to CB1 or CB2 receptors. CBD interacts with a variety different receptors to create different effects within the body. First, it targets the serotonin 1A receptor, which controls the release of certain hormones that affect stress reactions and social behavior. The interaction with this receptor is what causes the elimination of anxiety, pain, and depression. Another receptor that CBD interacts with to help alleviate pain is the TRPV1 receptor, which is a vanilloid receptor. CBD also has an affinity for nuclear receptors called PPARs (peroxisome proliferator activated receptors) to cause an anticancer effect. These effects have been shown to regress lung cancer cell lines. The final benefit of CBD is the inhibition of anandamide re-uptake. CBD competitively binds to fatty acid binding protein (FABP) with anandaminde in order to cross the cell membrane. Since anandamide cannot enter the cell without FABPs, it cannot be metabolized. Overall, CBD is a beneficial legal derivative of cannabis.

Sources:

https://www.nytimes.com/2018/10/27/style/cbd-benefits.html?rref=collection%2Fsectioncollection%2Fhealth&action=click&contentCollection=health&region=stream&module=stream_unit&version=latest&contentPlacement=1&pgtype=sectionfront

https://ministryofhemp.com/blog/cbd-in-the-brain/

Chemistry - Now Streaming on all Virtual Reality Devices

Have you ever gotten frustrated with your reactions in lab and wished you could see with your naked eye what was happening with the molecules? This might seem an impossible dream, but now you can. Researchers have developed a virtual reality environment that allows molecules to obey the laws of molecular physics while being visualized and manipulated by the virtual reality user. This virtual reality technology has so far been used to observe protein interactions on a molecular level, thread methane through a carbon nanotube, and unwind a helical molecule and wind it up in the opposite direction. As these are 3D molecules that obey the laws of molecular physics, once can manipulate these molecules to see how they fold, how positively and negatively charged particles interact, and allows researchers to collaborate and visualize these molecules simultaneously even if they are countries apart.

Figure 1: Virtual Reality Allows Manipulation of Molecules in Space

            Being able to visualize a molecule is incredibly important in order to be able to study the molecule. Before the technology that we are so used to today existed, scientists would build models using metal, wood, and rods to replicate what exists on the microscopic level. Michael Levitt, recipient of the Nobel Prize in Chemistry in 2013, shows how vital this process is to researchers as he shares that building molecules is “slow work, but at the end you really know the molecule” (The Nobel Lecture). These stick models might have helped visualize the molecule; however, it came at the expense of the molecule’s movement. The physical models do not have the natural movement or interactions that molecules exhibit and experience in space. As technology developed, 2D simulations of molecules became the widely accepted method for modeling. Again, these had a significant drawback as they existed on a 2D level and did not accurately portray the size of atoms and molecular structures. Whereas physical models had too little movement, 2D models had unlimited movement and do not accurately reflect repulsive or steric forces that impede real molecules.

Figure 2: 17-Alanine Tied in a Knot Using Virtual Reality

Clearly, this technology proves to be an all-around advantage. It makes molecular activity and structures more available to scientists, and makes chemistry more available to the general public. This is not an elite system or technology that is exclusive to big pharma companies or high-end researchers. Anybody who owns a virtual reality device will be able to share in the wealth of chemistry knowledge that this application provides. This visualization method is currently in pilot testing and its use in research labs is being monitored and refined. The pilot models already tested showed that this operating system has another significant advantage as well. The virtual reality imaging performs tasks with more than ten times the speed of traditional 2D models.

            In a world dominated by technology, bringing chemistry into mainstream technology will help change the public’s perspective of chemistry, and hopefully reduce chemophobia. People tend to need to see to believe, and being able to see the molecules, move them around, and understand their structure will allow people to feel a direction connection with chemistry instead of thinking of it as a dangerous, abstract concept. Also, as technology is so prominent in society, by increasing the applications of technology in the chemistry field it could expose more people to the world of chemistry.

Sources:

Article: It's Time for a Chemistry Lesson. Put on Your Virtual Reality Goggles. 

Author: Veronique Greenwood 

Source: New York Times 

https://www.nobelprize.org/prizes/chemistry/2013/levitt/lecture/
https://www.nytimes.com/2018/07/03/science/chemistry-virtual-reality.html?rref=collection%2Ftimestopic%2FChemistry&action=click&contentCollection=science&region=stream&module=stream_unit&version=latest&contentPlacement=7&pgtype=collection