Page 87 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Science

What is keratin? Alpha keratin
How this protein makes up your hair

The secret behind some of nature’s Alpha helix
Keratin is made of coils of
toughest materials amino acids held together
by peptide bonds to form
polypeptide chains.
eratin is a protein found in humans and
animals alike. There are two main
Ktypes and each has a slightly different Protofibril
Three alpha helices twist
structure. Alpha keratin, which is the main
together to form a protofi bril,
structural component of hair, skin, nails, hooves the first step towards creating

and the wool of animals has a coiled shape, a hair fi bre.
whereas the tougher beta keratin, found in bird
beaks and reptile scales, consists of parallel
sheets. Both are composed of amino acids – Microfibril
the building blocks of all proteins that make up An 11-stranded cable is formed
a large proportion of our cells, muscles and by nine protofi bril joining
together in a circle around two
other tissues.
more protofi bril strands.
The flexibility of the keratin depends on the

proportion of different amino acids present.
One particular amino acid, called cysteine, is Macrofibril
Hundreds of microfi brils
responsible for forming disulphide bridges that bundle together in an irregular
bond the keratin together and give it its structure to create a
strength. The more cysteine the keratin macrofi bril.
contains, the stronger the bonds will be, so more
can be found in rigid nails and hooves than in Curly hair has more bonds Hair cell
These macrofi brils join

soft, flexible hair. Incidentally, it’s the sulphur between amino acids in together within hair cells,
within cysteine that creates the strong odour the protein chain that making up the main body of
makes up keratin

of burning hair and nails. the hair fibre called the cortex.
What’s inside dust?
From skin cells to space rocks, there’s a long
list of particles lying around your home

t’s a myth that dust in our homes
is only made up of dead skin. In
Ifact, it contains an average of
9,000 different species of microbes,
alongside a powdery potion of animal
hairs, pollen, decomposing insects,
fabric fibres and much more. The

majority actually comes from outside,
having been blown in through © SPL; Thinkstock; Corbis
windows and doors or carried in on
your clothes or shoes. The rest comes
directly from the people, animals or
objects inside the house.
Thousands of different species of
bacteria and fungi are commonly
found in dust, as well as tiny
creatures called dust mites, which
produce allergens. However, among
all of these disgusting things, you
might also find something to

treasure. Dust has been found to
contain tiny particles of space dust
called micrometeorites, which were
once part of comets and asteroids, A coloured scanning electron Household dust is mostly
and you should be able to pick them micrograph of household dust harmless and 80 per cent of
containing pet hair, insect
out using a very strong magnet. remains and pollen it can be removed by
cleaning regularly

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