Biological+Polymers

Biological polymers These include DNA, RNA, Proteins and Polysaccharides. More from AnnMarie & Nathan

// DNA: // The double helix we all have learned about throughout our schooling. DNA is made up of 4 repeating units. These units can vary and create endless patterns of this polymer. This is how we get the variation in all species of life! To look at the structure of a DNA molecule, go check out this website: [|DNA]

Can you see the different monomers that make up the DNA strand?


 * Cool Fact: ** DNA and RNA is the longest known polymer! It can reach several inches in length! As the order of the mammal gets higher, one can see the DNA under an ordinary light microsope!

Ever wonder if you could extract DNA on your own? Well it is not as hard as you may think. All you need is a piece of fruit and some patience! See below and try it sometime!
 * __ Try at Home:  __**


 * DNA Extraction at Home (or at school) **

Fruit: strawberry, banana, or kiwi Sandwich bags: the “Ziploc” ones Coffee filters or tissue paper: if you use tissue paper, be sure to use 3 papers together. Funnel: this makes it easier, but can do without. The funnel can be purchased from AutoZone or any auto parts store. Buffer solution: To make 100 ml of buffer: add 90 ml of distilled water, ¼ tsp on table salt and about 10 ml of shampoo. Stir it all together until the salt is dissolved.
 * Materials: **

1. Make the buffer solution as defined above. 2. Place some fruit in a sandwich bag. It should be about 1 med strawberry, or ½ a kiwi, or 1.5 inches of banana. 3. Smash the fruit in the bag. Be sure to get it really juicy and pulverized! 4. Place about 2-3 ml of the buffer in the plastic bag with the fruit. Keep mixing for about 2 minutes. 5. Filter the contents of the plastic bag into a small container using a coffee filter or tissue paper. Keep the liquid, and discard the solid and the filter into the trash. 6. Pour about 25-30 ml of cold alcohol carefully down the side of the container. The alcohol must be cold! You will see two layers. The alcohol should be the top layer. Cover and wait 2-3 minutes. 7. At the interface between the two layers you should be begin to see the DNA collecting. It appears as a white cloudy layer. You can gently pull the DNA strand out using a paperclip that you have bent into a hook. 8. Clean up.
 * Procedure: **

// PROTEINS: // So we have all heard of proteins, but did you know they were polymers? Proteins are polymers that can be made of 20 different types of monomers and these can vary from proteins. Each monomer has its own name, but the class of these monomers are called amino acids. To see some proteins in 3D, go check out this JavaApplet: [|Proteins] ** Cool Fact: ** Did you know that silk and wool are proteins? These are also considered industrial products and are used in many fabrics!

// POLYSACCARIDES: // These polymers are made from sugar molecules. So essentially a small sugar molecule, called a monosaccharide, is the monomer!

So one example is cellulose. Cellulose is made of the monomer glucose. Glucose is a 6 carbon chain monomer. Cellulose is made of hundreds of these monomers. To see the basic structure, go check out: [|Polysaccarides]

Did you know? Humans can not digest cellulose, but there is another polysaccharide that has the same number of monomers and has the same exact structure just has a different chirality (see below for what this is if you are not sure) that we can digest! Do you know what it is? The answer is //Starch!//
 * Cool Fact: ** Cellulose is found in cotton and wood. It is insoluble in water.

//What is chirality?// An easy way to define it: Hold up your two hands, see how they are exactly the same? They have the same number of fingers and are put together in the same order? Keeping your hands open, try to put your left hand on your right hand so the backs are facing the same direction. We call this “super imposing” the image. Do they fit? No! This means they are non super imposable mirror images and therefore are chiral. Just like cellulose and starch!

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