How the Internet is Changing Your Brain

I was introduced to this video on Academic Earth in relation to my post about where science education should go, and it goes without saying that they harmonize each other very well. Please watch this 2 minute video, and it will open your eyes to what our technology is doing to our brains.

Created by AcademicEarth.org

Why do Onions Make You Cry?

Cutting onions is arguably the worst part of cooking, the burning irritation you get in your eye becomes unbearable so much as to take a break mid way through chopping.  So why is this? This is all to do with mixing molecules in the onion cells that aren't supposed to be together, an enzyme named Allilinase and a molecule called Allilin.  Think of this like the type of adhesive that has two parts that you need combine together to make the glue active.  When we cut onion we start the chain of reactions allowing the Allilin to come in contact with Allilinase to turn the Allilin into Sulfenic Acid and this Sulfenic Acid turns into syn-Propanethial-S-oxide though the enzyme Lachrymatory Factor Synthase.

This syn-Propanethial-S-oxide is what everyone hates because this is the irritant that when combined with the moisture in your eyes gives you that pain and your body tells your tear ducts to try and wash it out.

References:
Something about Science

Why Does Garlic Sometimes Turn Blue?

I've noticed sometimes when I cook garlic in butter that the garlic will turn blue after a while, and I had to ask myself why this happens.  After finding out that it is safe and poses no loss of taste, I sighed and continued reading.  It seems to be due to the presence of sulfates within the garlic, a component of what gives it such a pungent smell.  What happens is that the sulfates combine with the copper ions present in the butter, water, or cooking equipment to create something known as Copper (II) sulfate, or CuSO₄. This new compound is what gives off that bright blue colour.

So you may ask now if there are any precautions to be taken to avoid receiving this colour.  Luckily science has gained us much information about this process.  The main component of this phenomena is an enzyme present within the garlic that catalyzes this reaction, and can be deactivated simply by heating at high temperatures, or by letting the garlic age.

Hydrangeas and their Variety of Colour

Hydrangeas (Hydrangea macrophylla) have been known to form in a range of colours, from red, to purple, to blue, with having nothing to do with the genetics of the plant. So, if this colour difference isn't due to the genes, it must be due to certain environmental factors, and as it turns out, it is all to do with the pH and other properties of the soil. The more acidic the soil, and the greater [Al³⁺] in the soil, the more blue the sepals of the hydrangea will become. So why is this? Let's start with looking at the pigments which govern the colour of the sepals. The major pigment found in Hydrangeas (along with a number of other plants) is called Myrtillin, also known as delphinidin 3-glucoside, which is part of a group of molecules called anthocyanin.

But odly, this molecule assumes a red colour in acidic conditions and blue in basic conditions¹ (opposite to that of the soil conditions) and the pH within the sepals is usually slightly acidic, with little variation, so the blue colouring must have something to do with the Al³⁺. Through much research, Kondo et al. ², came up with a model proposing that the aluminum acts as a bridge to coordinate the Myrtillin to other copigments pigments known as acylquinic acids, which produces this blue colour.

While this is how the blue colour is formed, it can be safely assumed that the red colour is merely caused by Myrtillin by itself without any co-pigments or metal chelation.  A question which hasn't been answered yet is what the pH of the soil has to do with all of this.  The low pH allows there to be more free aluminum ions within the soil, to allow there to be more [Al³⁺] taken up into the plant.

References:
Second figure from 1.
1. K. Yoshida, M. Mori and T. Kondo, Nat. Prod. Rep., 2009, 26, 884–915.
2. T. Kondo, Y. Toyama-Kato and K. Yoshida, Tetrahedron Lett., 2005, 46, 6645–6649.