If you are a university student, especially a STEM major, ESPECIALLY AN ORGANIC CHEMISTRY STUDENT, you need a whiteboard.
You can revise all the notes in your respective hemisphere but without active repetition it means nothing. Write your mechanism/structure/wedding vows. Erase part of it. Write it again. Erase more of it. Repeat.
Get a big one so that you can sit on the floor/bed/table without straining your back from looking down. I have no attention span but I can white-board for hours.
CRISPR gene-editing technology is now starting to be used in human trials to treat several diseases in the U.S.
The first clinical trials using CRISPR-edited cells have begun in the US, with researchers at the University of Pennsylvania treating cancer patients with an experimental therapy, according to a report by NPR.
CRISPR works by targeting certain genes responsible for certain functions or traits. When found, an enzyme called Cas9 binds to the DNA, “cuts” it, and shuts off that targeted gene. The study from the University of Pennsylvania, run by Dr. Edward Stadtmauer, will remove immune system cells from patients. Then, scientists will attempt to genetically alter them in a lab. Afterward, the cells will be reintroduced to each patient’s body. If all goes according to plan, the cells will target and eliminate the cancerous cells. The study features 18 patients.
“To date, two patients with relapsed cancers – one with multiple myeloma and one with sarcoma – have been treated as part of this trial,” wrote Penn Medicine spokesperson said. “Findings from this research study will be shared at an appropriate time via a medical meeting presentation or peer-reviewed publication.”
If successful, the trial is one of many that could revolutionize how diseases are prevented and treated.
Haemoglobin is a macromolecule that comprises 96% of red blood cells’ dry weight, and is responsible for the transport of oxygen in our blood. It is a tetramer that consists of 4 protein subunits - 2 alpha-globin and 2 beta-globin molecules - which are each associated with a heme group.
Haemoglobin transports oxygen by allowing O2 molecules to reversibly bind to the iron centre of the heme group, assisted by a histidine residue in each globin subunit.
O2 and the histidine residue act as ligands that reversibly form coordinate bonds with the Fe2+ ion in the heme group. This causes the degenerate d orbitals of the Fe2+ ion to split into different energy levels, as the donated electrons from the ligands cause different levels of repulsion in the ion’s orbitals due to the difference in their proximity to the ligand.
Our perception of colour for transition metal complexes is due to the absorption of light corresponding to the energy gap between the energy levels when lower energy d electrons are excited to a higher energy level. As a result, the change in splitting of the orbitals due to the addition of the O2 ligand causes the perceived colour to change as well, which is why we perceive oxygenated blood as a brighter red than deoxygenated blood.
Haemoglobin also exhibits an interesting property called the cooperative binding of oxygen. When a molecule of oxygen binds to a subunit of haemoglobin, it undergoes a change in structure such that the other 3 subunits can bind to oxygen more easily. Similarly, when a molecule of oxygen detaches from a subunit, the haemoglobin molecule changes its conformation such that the other 3 molecules of oxygen are released more easily.
This allows the rapid loading and unloading of oxygen molecules in the lungs and tissues respectively to occur.
In people with the condition sickle cell anaemia, a mutated form of haemoglobin called HbS is produced instead. This form of haemoglobin has a point mutation in which a glutamic acid residue is replaced by a valine residue. As a result, in low-oxygen conditions, such as in capillaries, HbS undergoes a change in shape and sticks together to form long, brittle rod-like structures. This causes the red blood cells to elongate and form a sickle-like shape. These red blood cells can clog up capillaries easily, increasing the possibility of stroke.
These sickle-shaped red blood cells are also prone to haemolysis, causing them to be destroyed at a much faster rate than red blood cells; a normal red blood cell usually lasts for 90-120 days, as opposed to 10-20 for sickled red blood cells. Consequently, the body is unable to replenish the supply of red blood cells sufficiently, resulting in shortness of breath, dizziness, and high heart rate.
Electroactive bacteria were running current through “wires” long before humans learned the trick.
At three o’clock in the afternoon on September 4, 1882, the electrical age began. The Edison Illuminating Company switched on its Pearl Street power plant, and a network of copper wires came alive, delivering current to a few dozen buildings in the surrounding neighborhood.
One of those buildings housed this newspaper. As night fell, reporters at The New York Times gloried in the steady illumination thrown off by Thomas Edison’s electric lamps. “The light was soft, mellow, and grateful to the eye, and it seemed almost like writing by daylight,” they reported in an article the following day.
But nature invented the electrical grid first, it turns out. Even in 1882, thousands of miles of wires were already installed in the ground in the New York region — in meadows, in salt marshes, in muddy river bottoms. They were built by microbes, which used them to shuttle electricity.
Electroactive bacteria were unknown to science until a couple of decades ago. But now that scientists know what to look for, they’re finding this natural electricity across much of the world, even on the ocean floor. It alters entire ecosystems, and may help control the chemistry of the Earth.