Biology Notes - Understanding the Central Dogma of Biology

DNA is the genetic code of life. DNA and RNA are both nucleic acids. Remember the 4 macromolecules are lipids, carbs, proteins, and nucleic acid. Macromolecules are simply large molecules. They’re giants. These are also called polymers. They are made up of monomers. These giant macromolecules are made up thousands or hundreds of thousands of monomers. The monomers are the smaller “building blocks” that make up the polymer.
 
Polymer – lipids (commonly called fats)
monomer – none
This is unique to have no monomer.  
 
Polymer – carbs
monomer – monosaccharides.
Think of how a carb like a piece of bread has sugar in it. The individual units of sugar are the monomers.
 
Polymer – protein
monomer – amino acids
There are 20 different types of amino acids. Some are non-essential meaning we can synthesize (create) it ourselves. Other amino acids are essential meaning we need to get them from our diet.
 
Polymer – nucleic acid (DNA and RNA)
monomer – nucleotides 
Think about a macaroni necklace. They come in different sizes and colors. You can make a short strand or a super long one. In this 'necklace' are codes. The code is instruction for what the cell is supposed to do. The sequence determines the code. We have 26 letters in our alphabet. With those 26 letters we make thousands of words. What a word means all depends on how you put those letters together. It’s the same with DNA except there are only 4 'letters', but these words can be hundreds of thousands of 'letters' long. How these letters are put together determines what it means and what instructions it gives.
 
 
To understand DNA, it is helpful to understand the central dogma of biology.
 
DNA becomes RNA becomes protein.
The process of DNA becoming RNA is called transcription.
The process of RNA becoming protein is called translation.
The way I remember that is you have a foreign script and then you translate it. It’s easy to get transcription and translation backwards. So just remember if you’re going to translate a book (script), you have to first have the script. The script comes first.
 
Now let’s talk about nucleotides. Nucleotides are building blocks. Think about teeny tiny legos. They are so small, but you put thousands of them together and you can build something huge.
 
DNA has 4 types of nucleotides: Adenine, Guanine, Cytosine, and Thymine. It’s not necessary to memorize the names from the start. We use the first letter to represent each nucleotide. A, T, C, and G. To build DNA these nucleotides or tiny building blocks will pair up. A&T go together. C&G go together. To remember the letters of the nucleotides I say I’m AT CG’s house. A woman in my class would say G-Cat. Or remember that you are hanging out with two couples Adam and Tammy plus Cora and Gabriel or whatever you want to name your couples. Remember A&T are a couple. C&G are a couple. Unfortunately, Adam and Tammy get divorced. When DNA becomes RNA through the process of translation Adam leaves Tammy and pairs up with Ursela.
 
RNA has 4 nucleotides: Adenine, Uracil, Guanine, and Cytosine. RNA is made up of A, U, G, and C nucleotides. Now Cora and Gabriel stay together. They are always going to be a pair. However, Adam has divorced Tammy. Tammy (Thymine) is no longer in the picture. He has remarried Ursela.
 
A little memory tip to remember that RNA becomes protein is to think about RNs (nurses) drinking protein shakes.
 
There are 3 main differences between DNA and RNA - Sugar, structure, and nucleotides. We talked about the different nucleotides. DNA is made up of A&T, C&G. RNA is made up of A&U, C&G. The structural difference is DNA has a double helix. RNA has a single helix. A helix is like a spiral staircase. DNA remember D for double spiral. The other difference between the two is the sugar. DNA stands for deoxyribose nucleic acid. RNA is ribose nucleic acid. The sugar in DNA is deoxyribose. The sugar in RNA is ribose.
 
The strands of the helix (spiral staircase) are joined together by the nucleotides (letters).
 
To remember how DNA is put together we can use candy. This is a fun science project. You will need twizzlers, toothpicks, small marshmallows, and gum drops or you can use gummy bears. You’ll need 5 different colors of gum drops or gummy bears.
 
Twizzlers are the deoxyribose sugar.
The gum drops or gummy bears will be the nucleotides.
The marshmallows represent the hydrogen bond “gluing” the nucleotides as a pair.
The toothpicks are what you will put the gummy bears and marshmallows on to connect everything.
 
This is the color code I use for the nucleotides
A = green
T = white
C = purple
G = yellow
 
When you translate the DNA to RNA, you’ll drop the white gumdrops (thymine) and swap it out for U (uracil) red gum drops.
 
So this is how you build DNA using candy. You need a code to follow. This is what my biology teacher gave us.
G – C
G – C
T – A
G – C
A – T
A – T
G – C
A – T
A – T
A – T
 
Lay your twizzlers out. Use your toothpicks to string together the nucleotides following the color code to represent each nucleotide. Make sure you put a marshmallow in between. The marshmallow represents the hydrogen bond. Once you have it all connected, you will twist the twizzlers to represent your double helix. Remember a helix is like a spiral staircase. Your project should look like the picture shown. Have fun building “DNA”. Then you can eat it :)