Chemistry of Leaf Slugs

Chemistry Connections

Episode #26

Welcome to Chemistry Connections, my name is Anushka Agarwal and I’m Nick Bailey, and we are your hosts for episode #26 called the chemistry of photosynthesis in leaf slugs. Today we will be discussing how leaf slugs use photosynthesis

Segment 1: Introduction to Chloroplasts and the Leaf Slug

Leaf slugs are a sea creature that is able to use photosynthesis. This is uncommon because animal cells generally do not contain chloroplasts.

Chloroplasts are the organelle commonly found in plant cells where the photosynthesis reactions occur. Both the light-dependent and light-independent reactions take place here.

Photosynthesis is the process where chloroplasts turn carbon dioxide into glucose. Water is also needed for the reactions to occur and oxygen is produced in addition to the glucose.

Segment 2: The Chemistry Behind Photosynthesis

There are two main parts to photosynthesis, the light-dependent and light-independent reactions.

Light Dependent: Chloroplasts require light energy in order to reduce NADP+ and ADP to create NADPH and ATP. We can see that this specific reaction is endothermic because the energy from the light was required to break the bonds in the reactants.

Light Independent: The light-independent reactions make the process of photosynthesis occur properly. The main reaction that takes place is referred to as the Calvin Cycle. This is the process where the plants use the CO2 to create glucose. The process starts with 3 Carbon-5 molecules(RUBP) and 3 Carbon- molecules(CO2). These combine to create 3 Carbon-6 molecules (mention stability) and will, almost instantaneously, turn into 6 Carbon-3 molecules. Then, in a process called reduction, 6 ATP and 6 NADPH, both of which donate electrons, will be oxidized and the carbons will be reduced, or will gain electrons. We will then have 6 Carbon-3 molecules(3G3P). One G3P molecule is “set aside” to later become glucose. The remaining 5 G3Ps go towards the process of regeneration where they will further reduce by 3 additional ATP molecules(go from 5 Carbon-3 molecules to 3 Carbon-5 molecules [same RUBP we started with]). In order to successfully create a single glucose molecule this process must occur twice because glucose is C6H12O6(only produce one Carbon-3 molecule in the first full rotation of the Calvin cycle)

Segment 3: Personal Connections

Nick: I found this topic particularly fascinating because it is one of the rare exceptions where animals use photosynthesis. As we had stated earlier, photosynthesis is commonly used in plants. The leaf slug can photosynthesize because it eats so much algae and is able to extract the chloroplasts from those plant cells, making it able to photosynthesize.

Anushka: I personally wanted to do this project on the leaf slug because I find them extremely interesting and cute. As I’d said earlier, please look up a picture of the leaf slug if you can, I promise you will not regret it. Not only are they amazing to look at, the leaf slug is also such an anomaly in nature. Their ability to photosynthesize because they eat too many greens never fails to peak my interest and wonder what else the world has hidden under the sea.

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