10 Points on Photosynthesis

• Photosynthesis converts light energy (carried by photons) into ATP, which is a molecule which can store energy in a form that is usable by the plant.
• Chloroplasts are transparent organelles which contain grana, which are stacks of thylakoids which in turn contain a green pigment called chlorophyll. This is where photosynthesis takes place.
• Chlorophyll absorbs all wavelengths of light except for green (and yellow), which they reflect to our eyes.
• An electron transfer chain is used to synthesize ATP
• Oxidation occurs when electrons are lost. Reduction occurs when electrons are gained.
• PS2 (Photosystem 2) is simulated by light of wavelength 680 nm and takes two electrons from a water molecule, breaking the covalent bond which holds it together. Oxygen and H2 are separated.
• The electrons travel through the transport chain using oxidation and reduction reactions. It goes from PS2 to PQ to B6F. B6F pumps hydrogen ions into the chloroplast when it gets the electron, and then passes it on to PC.
• The next link in the chain is PS1 (Photosystem 1). It gets simulated by light of wavelength 700 nm and is then reduced. The electron then goes to Fd (ferrodoxin) and FNR.
• NADP is the end of the chain, and a positive hydrogen ion (proton) neutralizes it.
• ATP is formed by ATP synthase. It spins ADP around. (when this combines to one phosphate it becomes ATP). The hydrogen ions 'slow' the spinning down and the last phosphate attaches to the combination and becomes ATP.

Fetal Pig Dissection

Day 1 — Abdominal Cavity & reproductive system

This week, we had the opportunity to perform a fetal pig dissection. I, along with my group members (Benn, Amriya, Amir and Jianan), performed the dissection on a pig fetus to see the various organs and organ systems as they appeared in real life. We began the lab by gathering all the required materials; including scissors, pins, a scalpel, latex gloves, and goggles.

Our pig was female because of the urogenital papilla near the anus. We started by going through the lower body; the first day of the two-day lab would be devoted to exploring the abdominal cavity. Following our handout, we first made an incision along the stomach, followed by an incision laterally across it and around the umbilical cord to expose the abdominal cavity.

The umbilical vein was visible at this point, and we had to cut it to get to the organs underneath.

The umbilical vein is the elastic-looking cord ending at the liver.

The first organ we encountered was the liver. The umbilical vein led to the liver. It was a large structure which surrounded the stomach and parts of the small intestine.

After removing the liver, most of the other parts of the cavity were visible. The stomach is visible in the following pictures, as well as the large & small intestine and one of the kidneys. The structure running along the stomach is the spleen, where blood cells mature. The pancreas is right under the stomach.

Inside the abdominal cavity	The liver
Stomach, small & large intestines, spleen  and pancreas	Kidney (Located at the back and to the sides - we left the other one inside).

The stomach wasn’t empty. Inside were small dark objects inside a fluid. [below, left]

The uterus was then removed. The urinary bladder is the sac in between the two reddish tubes. The ovaries are located behind it. [above, right]

Day 2 — Thoracic cavity and head

On the second day of the dissection, we moved up to the thoracic cavity. Inside we were able to locate the heart, lungs, and thyroid glands. The heart was the first organ we encountered, surrounded by the aorta and various other veins and arteries. This is the center of the circulatory system, so there were larger blood vessels (to hold a larger amount of blood from the rest of the body) and the heart was very muscular, to be able to pump blood non-stop all around the body.

Heart, surrounded by ribcage and lungs

Heart with lungs

Moving further up the chest and into the neck area, we were able to isolate the thyroid gland. We found it near the esophagus and the various muscles and blood vessels which were going to the head. The thyroid gland is responsible for controlling the growth of the pig, and would have released the growth hormones necessary for the development of the pig. The parathyroid glands are supposed to be located on the thyroid gland, but we were unable to isolate them.

Thyroid gland

Our next step was to proceed to the head; isolating the brain (and hopefully, the brainstem). We had to exercise extra caution during this part because we had to cut through cartilage (the bone hadn’t developer yet) in the skull, all while trying not to damage the brain. Below are a few pictures of this process. In the end, while we could see the brainstem, we weren’t able to extract it along with the brain. 

The last part of our process was isolating the eye. Located close to the brain, this is one of the most developed organs we had examined so far. Inside, we could see a small yellowish sphere — which was the lens.