Although it weighs 1500g in air, the human brain only weighs 50g when suspended in cerebrospinal fluid due to the conferring of buoyancy.
Mitochondria (singular, mitochondrion), are rod-shaped organelles that can be considered the power generators of the cell, converting oxygen and nutrients into adenosine triphosphate (ATP). ATP is the chemical energy “currency” of the cell that powers the cell’s metabolic activities. This process is called aerobic respiration and is the reason animals breathe oxygen. Without mitochondria, higher animals would likely not exist because their cells would only be able to obtain energy from anaerobic respiration, a process much less efficient than aerobic respiration. In fact, mitochondria enable cells to produce 15 times more ATP than they could otherwise, and complex animals, like humans, need large amounts of energy in order to survive.
I have made the mistake of looking at all the awesome Biology summer placements and studentships different institutions offer and now I want to do all of them!
A collaboration of Dutch chemists and microbiologists at Radboud University Nijmegen has confirmed the existence of a uniquely shaped enzyme. CS₂ hydrolase, in a form known as a catenane, consists of two (one single- and one double-ringed) interlocked macrocycles, maintained via weak non-covalent interactions in a manner never before seen in biology.
Verification by size exclusion chromatography, multi-angle laser light scattering and native mass spectrometric analyes has established that the enzyme structure, from thermophilic archaeon Acidianus A1-3 is indeed entwined.
In an earlier paper, the regulatory role this odd conformation plays in catalysis is described by microbiologist Mike Jetten, who first found the primal archaeon in the mudpots of Italian volcanic solfataras, where they had been obtaining their energy by converting CS₂ into H₂S and CO₂ using CS₂ hydrolase.
“The enzyme monomer displays a typical β-carbonic anhydrase fold and active site, yet CO₂ is not one of its substrates. Owing to large carboxy- and amino-terminal arms, an unusual hexadecameric catenane oligomer has evolved. This structure results in the blocking of the entrance to the active site that is found in canonical β-carbonic anhydrases and the formation of a single 15-Å-long, highly hydrophobic tunnel that functions as a specificity filter.
The tunnel determines the enzyme’s substrate specificity for CS₂, which is hydrophobic.”
Van Eldijk et al., “Evidence that the catenane form of CS₂ hydrolase is not an artefact”. Chemical Communications, advance article, doi: 10.1039/c3cc43219j (2013).
I am forever amazed that everything that we think, feel, do, or seem is nothing more than sodium and potassium moving in and out of ion gated channels as a result of an action potential. Where are memories stored? Images? Thoughts? It all comes down to these tiny chemical elements and I don’t understand why. The brain is such a complex and fascinating thing.
The human Y chromosome, vital for the determination of the male sex, evolved from the X chromosome.