DNA Chapter 10 02/04/13

1. Mr. Hunter
Biology 02/04/2013
• Objective(s)
• SWBAT
• Identify various experiments involving the discovery of
DNA.
• Analyze the structure of DNA in terms of nucleotides,
base pair rules and hydrogen bonding.
• Bell Ringer – What is the complementary (matching)
base sequence of the following strand of DNA:
GGGCATACCGGAT - Original strand
CCCGTATGGCCTA - Complementary
strand

2. A. Is the structure of DNA the
same for all the organisms in
the pictures on the left?
B. Why don’t you look like a
spider or an elephant? –
Explain
Answer: DNA has general similar
Answer
molecular structure. The arrangement
of the monomer units (nucleotides) are
different for each organism.

3. • Maury Polvich – Paternity Testing
The Popularity of DNA and beyond
• CSI – Forensic action series
• Forensic Files- Case studies of crimes
using the latest molecular biology
techniques (DNA)

4. DNA: Experimentation and
Discovery
Mr. Hunter
Biology Chapter 10
02/04/2013
mrhunterspage.blogspot.com
Kennedy High School

5. • Fredrick Griffith conducted
Experimental Discovery experiments in 1928 to try to
find a cure for pneumonia.
• He accidently found that one of
the two strains of bacteria that
he was studying was able to
transform the nonvirulent ( not
causing disease). form into a
virulent form (causing disease)
• He concluded that a hereditary
factor was released which
caused the transformation
• Question: What two forms of
bacteria did Griffith use in his
experiment?

6. • In the early 1940s, American
Experimental Discovery Scientist, Oswald Avery wanted
to test the results of Griffith’s
transformation experiment.
• Wanted to determine if
transforming agent was
proteins, RNA or DNA
• Determined using enzymes that
destroyed RNA, proteins and
DNA. Found that DNA was
responsible for the
transformation of the harmless
strain into the deadly strain.
• Question: What were the three
macromolecules tested in Avery’s
experiment?

7. • In 1928, Alfred Hershey and
Experimental Discovery
Martha Chase wanted to know if
proteins or DNA was passed from
viruses to bacterial cells (E-coli)
• Bacteriophages are viruses that
infect bacteria.
• Radioactive Sulfur was used to
label the protein coat of the virus.
Radioactive Phosphorus was used
to label the DNA of the virus.
• They found that DNA was
incorporated in the cells infected
by the virus.
• Question: Why were sulfur and
Phosphorus used in their
experiments?

8. 1. Briefly describe the experiments of
REVIEW
Griffith, Avery and Hershey / Chase
2. What are the monomer units of
DNA known as _________
3. Griffith used heat to kill the
virulent strain of bacteria in his
experiment. The hereditary
information was still passed on.
What can you can conclude about
the stability of DNA and proteins in
terms of temperature?
4. Compare / Contrast the
experiments of Griffith and Avery
5. What is a bacteriophage?
* You may use one of the above review
questions as an exit question for
today. 02/04/13

9. • Watson and Crick were
Experimental Discovery scientists in the early 1950s
who determined the double
helix structure of DNA.
• Series of sugar phosphates and
nitrogen bases are the
components of a nucleotide.
Pg. 197 text fig. 10-6

10. DNA
• Deoxyribonucleic acid
(DNA)
• Made of two long
chains of repeating
subunits called
nucleotides
• The long chains are
coiled to form a double
helix

11. The Structure of • By the 1950s most scientists
DNA were convinced that genes
were made of DNA (basic
functional structure of genetic
material deoxyribonucleic acid)
• Watson and Crick discovered
the double helix structure of
DNA
• Each strand of the double helix
is made of nucleotides
• Nucleotides are the subunits of
DNA

12. DNA has a double helix
structure
• DNA was discovered
to have a double helix
Structure
• The structure is held
in place by Hydrogen
Bonds joining
nucleotide bases.
•There are (2) H-bonds
between the bases A
and T. There are (3) H-
bonds between the
bases G and C

13. Nucleotide
Three Parts:
1.Phosphate Group
2.Five Carbon Sugar
Molecule
3.Nitrogen Containing
Base

14. Nucleotides • The 5 carbon sugar in the
nucleotide molecule of DNA is
Continued called deoxyribose
• Sugar molecules and
phosphate groups are the same
for nucleotide molecules in
DNA
• The nitrogen bases may be of 4
different kinds
• 2 Double Ring Purine bases:
• 2 Single Ring Pyrimidine bases

15. Nitrogen Bases
• Purines (Double Rings)
• 1. Adenine (A)
• 2. Guanine (G)
• Pyrimidines (Single Rings)
• 1. Thymine (T)
• 2. Cytosine (C)
• Erwin Chargaff Rules of Base
Pairing : A = T, C = G
• The % of A =T and % of G = C

16. Replication of DNA
• DNA is copied with the help of many enzymes
• Complementary structure of DNA is used to
make copies of the DNA when the cell divides
• Watson and Crick proposed that one strand of
DNA serves as a template (pattern) on which
the other strand is built
• The process of making a copy of DNA is called
DNA Replication

17. Steps of Replication
• 1. The enzyme Helicase separates the double
helix by breaking Hydrogen bonds between
the bases AT and CG. Other proteins hold the
strands apart so they won’t twist back
together.
• The points at which the strands separate are
called replication forks.
• 2. The enzyme, DNA polymerase travels along
the strands of DNA adding new nucleotides

18. • 3. DNA polymerase remains attached until all
of the DNA has been copied.
• This process produces 2 DNA molecules
composed of an old and new strand
• The nucleotide sequences of both of the DNA
molecules are identical

20. Review
1. What do the initials DNA stand for ________________
2. Name the two scientists responsible for the discovery of the double
helix structure of DNA___________________
3. Define Nucleotide_____________________________
4. List the three parts of a nucleotide.
5. Name the two groups of nitrogen bases in DNA (P)_______ and
(P) ________
6. The ________ have a double chemical ring structure and the _______
have a single chemical ring structure.
7. The four types of nitrogen bases found in DNA are:
8. The two bases that belong to the group of Purines are _________ and
_______. The two bases that belong to the Pyrimidines are ________
and __________.
9. What bases complement (match) the following DNA strand :
AATTGCCGA