DNA Structure

Hershey & Chase

• Used a bacteriophage (virus) to infect a bacterial cell

• Wanted to see if the protein or DNA was responsible for infection of the bacteria (and subsequent viral reproduction)

• Labelled viral proteins with 35S and viral DNA with 32P (radioactive isotopes – easy to see)

• Observations: The protein coat stayed outside of the cell, DNA was injected into the cell, and virus reproduction followed

• Concentration: DNA is the hereditary material

DNA Structure

• Nucleic acids include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)

• Nucleic acids are composed of nucleotide monomers

• A nucleotide is composed of 3 parts: a phosphate group, a 5-carbon sugar (pentose), and a nitrogenous base

Overview:

• The nucleotides in DNA contain the sugar deoxyribose, while the nucleotides in RNA contain the sugar ribose

• There are 4 types of nitrogenous bases in DNA: adenine (A), thymine (T), guanine (G), and cytosine (C)

• RNA contains the same nitrogenous bases except it has uracil (U) instead of thymine (T)