The building blocks of life

What is DNA? deoxyribonucleic acid An extremely long macromolecule that is the main component of chromosomes The material that transfers genetic characteristics in all life forms

Structure of DNA 2 long chains of nucleotides that intertwine forming a double helix that winds around a central axis (think spiral staircase) Nucleotides have 3 parts: 1. 5-carbon sugar 2. Phosphate group 3. Nitrogen-containing base (Adenine, Thymine, Guanine, Cytosine)

How does it all stick together? (Backbone) Nucleotides on each chain are connected between their sugar groups by phosphate groups This occurs through covalent bonds (They share an oxygen) Known as the sugar phosphate backbone

How does it all stick together? (2 sides of the ladder)  The two chains are connected by hydrogen bonds between the two bases.  Complimentary base pairing rules:  Adenine pairs with Thymine  Cytosine pairs with Guanine

Make 2 nucleotides with clay (3 minutes!)

Who discovered it?  Many scientists communicated their discoveries and theories to help solve the structure of DNA!  Griffith  Oswald Avery  Hershey and Chase  Chargaff  Rosalind Franklin  Watson and Crick

Griffith’s experiment (1928) Discovers bacteria contain a molecule that can transfer genetic information from cell to cell.

Shows the substance that Griffith discovered is DNA

Hershey-Chase Experiment (1952) Confirm that the genetic material of viruses is DNA, not protein.

Chargaff’s Rule (1950) Analyzes the base composition of DNA in cells and discovers that the amounts of thymine and adenine are equal, and the amounts of guanine and cytosine are equal.

Rosalind Franklin (1952) Records an extremely important x-ray diffraction ‘photo’ that demonstrates DNA is in the shape of a helix. PHOTO 51

Watson and Crick (1953) proposed a model for the structure of the DNA double-helix structure of model made possible by Franklin’s work (photo 51) Watson, Crick and Wilkins shared the Nobel Prize in 1962 (Rosalind got left out!)

Craig Venter and Francis Collins (2000) Announce the draft DNA sequence of the human genome at a White House ceremony in D.C. Final version is published in 2003.

The Central Dogma Through the production of mRNA (transcription) and the synthesis of proteins (translation), the information contained in the DNA is expressed.

RNA RNA vs. DNA RNA, like DNA, is a nucleic acid. However, RNA differs from DNA in several ways. In addition to being smaller than DNA, RNA also  consists of one nucleotide chain instead of two,  contains the nitrogen base uracil (U) instead of thymine,  contains the sugar ribose instead of deoxyribose. RNA vs. DNA RNA, like DNA, is a nucleic acid. However, RNA differs from DNA in several ways. In addition to being smaller than DNA, RNA also  consists of one nucleotide chain instead of two,  contains the nitrogen base uracil (U) instead of thymine,  contains the sugar ribose instead of deoxyribose.

3 types of RNA