Transcript Homer`s Hair
Homer’s Hair Arrggh! Where’s my hair gone? Ohhh! Why won’t it grow faster? What is this hair stuff anyway? Homer’s Hair Structure The main component of hair is keratin. Keratins are proteins made of long chains (polymers) of amino acids. They account for approximately 85% of Homer’s hair with the remainder comprising water, fats, vitamins and trace elements. Homer’s hair seen under an electron microscope. Homer’s hair structure. Homer’s Amino acids Amino what? Where are they? Will they hurt me? Homer’s Amino Acids Amino-acids are small biomolecules. There are 16 different amino acids found in keratin. Hydrogen Carboxyl group Amino group ‘R’ group Homer’s Amino Acids So, how many do I need? Can I eat them? Mmmmmm amino acids. How many amino acids does it take for 1 hair to grow for 1 second? Let’s do the Calculation What shape is your hair Homer? Cubic Cylindrical OK we agree it is a cylinder. So we can work out a volume of hair grown per month using пr2h For this we need to know the length of hair grown per month and the radius of a hair Choose a length (mm) 1 10 100 Choose a radius (mm) 1 0.05 0.0001 Volume of Hair per month You grow about 10 mm of hair per month and the radius of one hair is about 0.05 mm (it takes about the width of 10 hairs is about 1 mm. Therefore the Volume of hair grown per month is = П x (0.05)2 x 10 = 0.0785 mm3 Mass of Hair We now need to transform this volume into a mass. What relates mass and volume? Refractive index Density Body Fat Index So we need to know the density of hair – does it float or sink in water? Well it does a bit of both (surface tension is a problem) which suggests the density of hair is about the same as water which is 1 g/cm3 – careful of the units Homer, convert it into g/mm3 1 g/cm3 = 0.001 g/mm3 So the mass of hair grown per month is Mass = density x volume = 0.001 g/mm3 x 0.0785 mm3 = 0.000 0785 g Mass per second OK so we know how much mass each hair puts on per month, but we need to know how much mass per second. How many seconds in a month Homer? About 30 days, 24 hrs per day, 60 minutes per hour, 60 seconds per minute 30 x 24 x 60 x 60 = 2592000 seconds per month Therefore Mass of hair per sec = 0.000 0758 / 2592000 = 0.000 000 000 0302 g Moles So now we have a mass of hair per second we need to work out the number of molecules. To work out the number of molecules we first need to work out the number of moles. number of moles = mass of hair / RMM As you know Homer hair is made of keratin which is a protein made up of amino acids. To work out the number of moles of amino acids per second we need to know the relative molecular mass (RMM) of amino acids. As this is a rough calculation we will use the average RMM of 135 g/mole. Moles to Molecules OK Homer are you ready for this. Number of moles of amino acids = 0. 000 000 000 0302 g 135 g/mole = 0.000 000 000 000 224 moles Not much Hey? Now to convert it into molecules Moles to Molecules Avogadro was the first to work out how many molecules were in a mole. He found that in one mole there are 603 000 000 000 000 000 000 000 Molecules We now call this Avogadro’s Number = 0.000 000 000 000 224 x 603 000 000 000 000 000 000 000 The Answer = 135 000 000 000 amino acids per second That’s 135 Billion Homer’s donut tower Which is a very large number Homer! If each amino acid was a donut! Arrrrgggghhhh!Then you could make a donut tower 4,375,000 km tall. Enough to reach the moon 11 times! Ok amino acids do your thing!