Introduction to DNA课件.pptVIP

Go thru central dogma Include gene in DNA Appllies universally to all living organisms Yet so malleable we have diverse life living in almost every available niche on our planet In our workshop, we will focus on content and techniques that will take us through this central dogma Today we’ll start with an introduction to the structure of DNA and how it replicates This slide shows the chemical structure of DNA. It is fairly complicated but elegant and I am going to work you through it DNA is built from a series of nucleotides which are strung together. One nucleotide consists of a phosphate, sugar, and nitrogenous base Point out in diagram as purple circle, yellow diamond, and colored squares The nucleotides are paired left to right and then strung top to bottom to form what looks like a ladder The phosphate and sugar groups are purely structural and make up the sides of the ladder and are called the sugar-phosphate backbone. Let’s look at the phosphate group in the middle. It has a central P and four Os and is negatively charged. Let’s look at the sugar. The sugar is made of five carbons which are numbered 1 – 5 as you can see in this diagram. The sugar is called deoxyribose because it doesn’t have an oxygen at carbon 2 Let’s look at how the sugar and phosphate connect in this bottom left diagram: You can see that one of the oxygens in the Phosphate group binds to the 5 carbon below it and the other binds to the 3 carbon above it. This connection is called a phosphodiester bond. Let’s look at how the phosphodiester bonds are formed in the two sides of the ladder. On one side we start with an unattached phosphate group, which then attaches to the carbon 3 etc. while the other one goes in the opposite direction so we say one sside of the ladder goes 3 to 5 prime while the other is antiparrallel and goes 5 to 3 prime. The nitrogenous bases are in the middle and they carrry the information in genes which we will talk about tomorrow. There are four bases cytosine, guan