The Facebook classic How many times can you click in 30 seconds, is now on Scratch.
Homocysteine is an amino acid. Amino acids are the building blocks of proteins. When proteins break down, elevated levels of amino acids like homocysteine may be found in the bloodstream. Having elevated levels of homocysteine in the blood (hyperhomocysteinemia) is associated with atherosclerosis and blood clots. It is not possible to get homocysteine from the diet. It must be made from methionine, another amino acid that is found in meat, fish, and dairy products.
Proteins come in all shapes and sizes, and proteins can be made to do almost anything. The most important protein contributor to blood pH is hemoglobin. Hemoglobin binds oxygen to its heme groups to form oxyhemoglobin, and it bonds carbon dioxide to its heme groups to form carboxyhemoglobin. Dissolved carbon dioxide in the blood naturally forms carbonic acid, an acid (obviously) which lowers the pH of the blood.