Name ____________________________________________ Date __________ Period ______

Guided Notes: Chapter 9 - DNA: The Genetic Material

Section 1 Identifying the Genetic Material

Objectives

Relate Griffith’s conclusions to the observations he made during the transformation experiments.

Summarize the steps involved in Avery’s transformation experiments, and state the results.

Evaluate the results of the Hershey and Chase experiment.

Transformation : Griffith’s Experiments

1928, Frederick Griffith, a bacteriologist, tried to find a vaccine for _________________

Vaccine

o Prepared from –

o Purpose –

Virulent –

Transformation –

Griffith’s Experiments:

o R bacteria – rough bacteria that did not have an outer capsule

o S bacteria – smooth bacteria had an outer capsule that protected the bacteria

from the body’s defenses.

Injected mice with: Result:

S bacteria

R bacteria

Heat-killed S bacteria

Heat-killed S bacteria & R bacteria

What useful application is there for humans in regards to bacterial transformation?

Transformation: Avery’s Experiments – He wanted to determine what molecule was responsible for transformation.

Enzyme used Result:

Protein destroying enzyme

DNA destroying enzyme

Conclusion:

Viral Genes and DNA: DNA’s Role Revealed

Hershey’s and Chase’s Experiments: They wanted to prove that DNA carried genetic

material.

Bacteriophage or phage –

Radioactive isotopes can be used to tag a molecule so that you can determine where it goes by tracing the radioactive isotope.

They tagged the protein coat of the bacteriophage with radioactive sulfur (35S) because proteins contain sulfur, but DNA does not.

They tagged the DNA of the bacteriophage with radioactive phosphorous (32P) because DNA contains phosphorous, but protein does not.

They carried out 2 separate experiments.

Virus’s protein coat labeled with (35S) Virus’s protein coat labeled with (32P)

Phage infects E. coli bacteria Phage infects E. coli bacteria

Bacterial cells were spun to remove the virus’s protein coats.

Bacterial cells were spun to remove the virus’s protein coats.

Result: Result:

Conclusion: Section 2 The Structure of DNA

Objectives

Describe the three components of a nucleotide.

Develop a model of the structure of a DNA molecule.

Evaluate the contributions of Chargaff, Franklin, and Wilkins in helping Watson and Crick determine the double-helical structure of DNA.

Relate the role of the base-pairing rules to the structure of DNA.

DNA Overview (Video Clip) DNA is made up of subunits called ____________________, each made of 3 parts: a _______,

a ______________ group, and a ______________base. In DNA, the sugar is _____________.

Watson and Crick determined that a DNA molecule is a ____________________ — two

strands twisted around each other, like a winding staircase.

_______________________ are the subunits that make up DNA. Each nucleotide is

made of three parts: a phosphate group, a five-carbon sugar molecule, and a nitrogen-

containing base.

The five-carbon sugar in DNA nucleotides is called _______________________.

Nucleotides (Video clip) What portion of the ladder do the sugars and phosphate groups of

a nucleotide form? ____________ The nitrogen bases face each other and bond to form

what portion of the ladder? __________________

The nitrogen base in a nucleotide can be either a bulky, _________________________,

or a smaller, _______________________________.

Discovering DNA’s Structure:

Chargaff’s Observations What is Chargaff’s rule, based on his observations? _______________________________

Wilkins and Franklin’s Photographs What did the X-ray diffraction photographs suggest about the structure of DNA? ____________

____________________________________________________________________________

Watson and Crick’s DNA Model Whose ideas did Watson & Crick incorporate into their model of DNA? ____________________

____________________________________________________________________________

Pairing Between Bases

The strictness of base-pairing results in two strands that contain ___________________

____________________________________________

3 things that determine why the bases pair:

1.

2.

3.

Section 3 The Replication of DNA

Objectives

Summarize the process of DNA replication.

Describe how errors are corrected during DNA replication.

Compare the number of replication forks in prokaryotic and eukaryotic DNA.

Roles of Enzymes in DNA Replication

The process of making a copy of DNA is called ________________________________.

It occurs during the ________________ (S) phase of the cell cycle, before a cell divides.

DNA replication occurs in three steps: See page 198 Figure 9.

o Step 1 _____________________________________________________________

that link the complementary nitrogen bases between the two strands. The ________

where the double helix separates are called _______________________________.

o Step 2 At the replication fork, ___________________________________________

_______________________. __________________________________________

to the exposed nitrogen bases, __________________________________________.

o Step 3 ________________________ that are __________________________ DNA

molecule.

(Video clip) DNA Replication

What is the end result of DNA replication? ___________________________________________

______________________________________________________________________________

Checking for Errors

An important feature of DNA replication is that _________________________________

______________________________________________________________________

This proofreading ____________________ in DNA replication to about _____________

______________________________________________________________________

The Rate of Replication See page 200 Figure 10.

The _____________________ molecules found in __________________ usually have

______________________________________________________________________.

The __________________________________________________________________

_______________________of the DNA circle.

In ______________ cells, each chromosome contains __________________________.

Each human chromosome is ______________________________________________

_____________________________________________________________________.

With multiple replication forks working in concert, _______________________________

___________________________________________________.

Video Clip: Multiple replication forks in eukaryotes reduce the replication time from?