Hair Type – Keratin

Last week, we talked about the three major types of bonds that keratin molecules can make: disulfide bonds (strongest), salt bonds, and hydrogen bonds  (weakest). This week, we’ll see how keratin molecules can interact to make hair curly or straight.

Disulfide Bonds

In natural hair types, these disulfide bonds are the major players in terms of protein-interactions for creating straight or curly hair. In curly hair, the disulfide bonds are generally formed perpendicularly between sulfur atoms on the neighbouring keratin chains.  This makes the strand more tightly coiled.

Also, the distribution of these bonds is important; if they are evenly distributed, then the hair is straight. If the bonds are more heavily distributed on one side that the other, this will lead to a kink or a curl to form. Finally, curly hair is found to have more sulfur atoms participating in disulfide bonds with neighbouring strands than straight hair.

Hook of the Follicle

Remember when we were talking about how the follicle plays a part in the type of hair you have? I mentioned that the follicle can sometimes have a hook, which leads to curly hair. A reason why this is true is that the hook forces the keratin molecules on the hair shaft to be brought closer to other keratin chains, inducing more disulfide bonds which leads to curlier hair.

Hooks lead to curly hair, partly because the disulfide bonds would now be angled instead of horizontal.

If you imagine a line that traces the shape of the hairs in the image above and then draw multiple lines that are perpendicular, or at a right angle, to the lines representing the hair, you can see that the sulfurs (represented by the multiple lines) seem closer together. This allows the hair to form more disulfide bonds at a shorter length than the straight hair with its neighbours, thus creating curly or wavy hair.

Salt (Ionic) Bonds

This bond offers weak interactions between neighbouring keratin chains. These bonds are actually more important in terms of elasticity as well as cosmetic purposes.

Hydrogen Bonds

These bonds are even weaker than the salt/ionic bonds, but they do form between neighbouring keratin chains too! These bonds, like the ionic bonds, contribute to our hairs’ elasticity. They can form temporary bonds, but these can be broken very easily or will break on their own after some time.

So, you can see that the disulfide bonds contribute a lot to our hair types. Hydrogen bonds have the ability to form temporary bonds, which are helpful for short-term curls or waves, but nothing permanent!

Thanks for reading! If you have a suggestion for a topic, you should definitely request it here!

Eye Discharge

Ever wake up from a nice nap or a great sleep to find little white crusties in the corner of your eyes? Sometimes, they might even be slimy! But what are those things and why do we find them?

What are Eye Crusties aka Dream dust aka Rheum aka Sleep?

When I was little, one of my friends told me that those little white/yellowish crusties were called ‘dream dust’ and we got them because the Sandman wanted us to have nice dreams. So for years, that’s what I’ve been referring to them as, though I was almost 100% sure the reasoning wasn’t on par.

When I started looking into this,  I found that the real name for the eye crusties actually is Sleep, but the scientific umbrella term for it is Rheum. Sleep is a type of Rheum, which in turn is simply discharged mucous. You might remember seeing the term rheum on Benylin bottles, or other cough and cold syrups, for the French translation. The term sleep just refers to the rheum that is discharged when one is sleeping. Fitting, I’d say.

But sleep does include the discharge from your nose and mouth while you’re sleeping as well. There is a specific term for the mucous that is discharged from our eyes while we sleep: goundGound is mainly composed of an oil produced by a sebaceous gland that line our eyelids, mucous, and some other particles like dust and skin cells. We actually produce gound during the day, but we blink it away which doesn’t give it the chance to clump.

Main point: eye crusties = mucous discharge.

Why does it happen?

Mucous likes to help our bodies protect themselves against infectious diseases.  So the discharge of mucous from our eyes while we sleep might just be our eyes protecting themselves from infections; the mucous usually carries away the harmful agents, be it makeup or bacteria, towards the corners of our eyes (known as the inner canthi and the outer canthi).

If you have a cold or the flu, you are more likely to produce gound to excrete the bacteria that are making you sick. If you don’t take off your makeup before you go to bed, you’re likely to produce a lot of gound too.


On its own, these discharges of mucous shouldn’t be too alarming. But if they are coupled with other symptoms involving the eye, such as inflammation or visual changes, they can indicate more worrying conditions such as Conjunctivitis or a corneal ulcer. Consult with your physician if there are multiple symptoms.

Sometimes, the excessive production of gound can lead to your eyes being glued shut. In this case, it is best to place a warm washcloth on your eyes to loosen them. Just make sure to dispose or wash the washcloth thoroughly, since reusing it can just bring those harmful agents back into your eyes!


And that’s really all there is to say about eye crusties. Now you’ll know that they’re proof that your body wants you to stay healthy!

Have a suggestion? Why not place it here?


Hiskey, D. 2011. What the ‘sleep’ in your eyes is. <>. August 27, 2013.

IMG Health Publications. 2013. Eye discharge. <>. August 27, 2013.



Background Info

You might have guessed already that melanin is one of the pigments that causes the colour of your hair, skin and eyes. But did you know that there are several types of melanin?

That’s right, the pigment we thought we knew so well is actually a family of pigments. Melanin is produced by melanocytes and is formed by aggregating several different component molecules together. The variability in the combinations of molecules results in the different types of melanin. The exact composition and structures of these melanin molecules are still being researched. But it is known that the metabolism of an amino acid, tyrosine, is required to produce melanin.

Everyone seems to have a relatively similar concentration of melanocytes in their bodies; however, the frequency at which the melanocytes are induced to produce melanin varies with different ethnicities and individuals due to an increase or decrease in the expression of the melanin-producing genes.

Benefits to having a lot of melanin

This dark pigment allows for the absorption of UV radiation, which prevents our cells from dying or becoming cancerous. Melanin helps protect our DNA from being damaged by UV rays. This aspect is extremely important as DNA encodes almost all of the parts of our body, with the exception of the bacteria that exist inside and our mitochondria (which we inherit from our moms). If even a single mutation were introduced into our genome, there’s a chance that it will result in a malfunctioning protein which can lead to the breakdown of different biological processes.

For cold-blooded animals, melanin also provides a way to absorb heat from sunlight.

Disadvantages to producing a lot of melanin

Having too much melanin can mean that even the smallest of stimuli, like a scratch, can induce the production of more melanin. This results in the formation of dark patches of skin at those areas.

Two types of melanin molecules will be involved in next week’s post about Hair Colour, so stay tuned!

Simon, J.D. 2013. John D. Simon. <>. August 22, 2013.

Taylor, S.C. 2003. The Advantages and Disadvantages of Having More Melanin in Your Skin. <>. August 22, 2013.