Chapter 11 Lecture Notes

Chapter 11-1
Genes are made of DNA

Define Key Terms:

  • Virus
  • Bacteriophage

Genes are made of DNA- (Griffith)

  • Griffith was a British Biologist studying two strains (forms) of bacterial species.
  • One strain caused Pneumonia, which was deadly to the mice that he used in his experiments, and the other was harmless. (See Figure 11-1)
  • When he injected heat-treated bacteria into the mice, the mice remained healthy.
  • The heat killed the deadly strain of the bacteria making it harmless.

Avery shows DNA is the transforming factor

  • American scientist, Avery took Griffith’s work as step further.
  • Avery wanted to test whether protein was the transforming factor, he treated Griffith mixture of heat-treated deadly strain and live harmless strain with protein destroying enzymes.
  • From his results, Avery concluded that protein could not be the transforming factor.
  • Next they treated the bacteria with DNA destroying enzymes, this time the colonies failed to transform.
  • From this, Avery concluded that DNA is the genetic material of cells.
  • See Figure 11-2

Virus experiments provide more evidence

  • Read pg. 227
  • Summary of Hersey & Chase’s work

Stage 1

  • Protein coats of phages are radioactively labeled.
  • Phages infect bacteria
  • No radioactivity enters cell

Stage 2

  • DNA of phages is radioactively labeled
  • Phages infect bacteria with genetic material
  • Radioactivity enters the cell.


  • Complete Concept Check 11-1
  • Answer question in a complete sentences
  • You may use the same paper as your notes.
  • We will go over answers together in class


Chapter 11-2

Nucleic Acids store information in their sequences of chemical units

Define Key Terms

  • Deoxyribonucleic acid (DNA)
  • Nucleotide
  • Nitrogen base
  • Pyrimidine
  • Purine
  • Double Helix

The Building blocks of DNA

  • DNA is a kind of nucleic acid, a polymer built from monomers called peptides.
  • Another group of nucleic acids is called Ribonucleic acid (RNA) also plays a key role in cells.
  • Nucleotides are the building blocks of nucleic acid polymers.
  •  Only 4 types of Nucleic acids make up DNA (They are?) See page 230 Figure 11-6
  • Each nucleotide has 3 parts: (See Figure 11-5) Draw and label this figure in your notes
  • A ringed shaped sugar called deoxyribose
  • A phosphate group
  • A Nitrogenous base

 Nitrogen Bases

  • The four nucleotide bases found in DNA differ from one another only in their Nitrogen bases.
  • Thymine & Cytosine are made of single ringed structures called pyrimidines.
  • Adenine & Guanine are larger double ringed structures called purines. Read DNA Strands on p. 230
  • Read DNA’S structure on p. 230
  • Read The Double Helix on p. 231
  • Review Complimentary base pairs on p. 231
  • See Fig. 11-7 and 11-8


  • Complete  11-2 Concept Check
  • Answer questions in complete sentences
  • You may answer on the same page as your class notes.
  • We will go over answers together in class.