DNA

DNA DNA is often called the blueprint of life. In simple terms, DNA contains the instructions for making proteins within the cell. Why is DNA called the blueprint of life?

Why do we study DNA? We study DNA for many reasons, e.g., its central importance to all life on Earth, medical benefits such as cures for diseases, better food crops. About better food crops, this area is controversial. There is a Dr. Charles Arntzen who is working on bioengineering foods with vaccines in them. People in poor countries could be immunized against diseases just by eating a banana, for instance.

DNA by the Numbers Each cell has about 2 m of DNA. The average human has 75 trillion cells. The average human has enough DNA to go from the earth to the sun more than 400 times. DNA has a diameter of only 0.000000002 m. The earth is 150 billion m or 93 million miles from the sun. If you unravel all the DNA in the chromosomes of one of your cells, it would stretch out 2 meters. If you did this to the DNA in all your cells, it would stretch from here to sun more than 400 hundred times!

(Deoxyribonucleic Acid) DNA double helix DNA (Deoxyribonucleic Acid) is the substance that makes up the genes and chromosomes of all living things.

DNA Double Helix 1. Two strands of nucleotides wound about each other in a twisting shape. 2. Sugar – phosphate backbones on the outside of the double helix and the nitrogen bases are on the inside.

DNA Double Helix Models

Building block of DNA is the nucleotide Building block of DNA is the nucleotide. A nucleotide consists of a sugar, phosphate and nitrogen base.

DNA Structure 1.The sugar in DNA is deoxyribose. 2. DNA contains four different nitrogenous bases. Thymine and cytosine have single-ring structures (pyrimidines). 3.Adenine and guanine have double-ring structures (purines)

Nitrogen Bases of DNA

Chargaff’s Rule: 1. Adenine and Thymine always join together A T 2. Cytosine and Guanine always join together C G

The purine bases are adenine and guanine. (LARGE and in charge) The pyrimidine bases are cytosine and thymine. (U is for uracil found in RNA) (CUT a piece of pie).

The nitrogen bases of DNA A = T G = C

DNA structure

Replication - DNA is copied 1st step - two chains separate at replication fork 2nd step - helicase enzymes break hydrogen bonds between base pairs 3rd step - DNA polymerase binds new nucleotides to existing chains -G-C- -A-T- -C-G- -T-A- -G -A -C -T -C- -T- -G- -A- -G- -A- -C- -T- C- T- G- A-