11/17 Daily Catalyst Page 47 Intro to DNA
 1. True or false, only eukaryotic cells contain DNA.
 2. How does the structure of protein allow proteins to
aid in transport?
 3. In your opinion, why was discovering the structure
of DNA more important than discovering DNA itself?
11/17 Class Business Pg. 47 Intro to
DNA
 DNA quiz on Thursday
 Structure, scientists, and function
 IC updated. Please check grades!
11/17 Agenda Page 47 Intro to DNA
 Daily Catalyst
 Class Business
 Intro to DNA
 Workbook Page 87
11/17 Objective Page 47 Intro to DNA
 We will be able to justify the selection of data
from historical investigations that support the
claim that DNA is the source of heritable
information.
Essential Questions:
 Who discovered the structure of DNA?
 What is the structure of DNA
 How does the structure of DNA relate to its function?
 How does the structure of DNA allow DNA to be the
source of heritable information?
 Brain Pop on DNA
 http://www.brainpop.com/health/freemovies/dna/
 We are silent and respectful during Brain Pop
 **Pay special attention to what is the function of DNA
and why is DNA important.**
What are we going to accomplish
today?
What?
Who/When?
How?
The “What”
Key Point #1: DNA
Deoxyribonucleic Acid
DNA History
 Early in the 1800’s, Darwin proposed there was a similarity
between organisms, but he did not know what that was. We
now know that is DNA!
 Gregor Mendel in 1859 observed characteristics of pea
plants and wanted to know why a red flower and a white
flower produced a pink flower.
 DNA was discovered in 1869 by a Swiss doctor.
 The science experiments that led to the
discovery of DNA and the discovery of the
structure of DNA.
DNAHow its structure was
discovered.
History of the DNA
1869- Friedrich Miescher-Swiss chemist showed that when pepsin
(an enzyme that digested) proteins was used on the nucleus of
cells a strange phosphorous-containing material remained. The
question arose are genes composed of DNA or proteins.
1914-Robert Feulgen German chemist found a staining technique
that stains more or less strongly based in the amount of DNA
present. He found that all cells in an organism had the same
amount of DNA except gametes, which had half the normal
amount.
1928-Fred Griffith performed an experiment with 2 different
strains of Pneumococcus. One was virulent and the other was not.
The virulent strain had a smooth polysaccharide capsule which
protected from the immune system. This allowed to caused
pneumonia in mice and killed them. The other strain did not have
the capsule and was "rough". This strain could not cause
pneumonia in mice. When Griffith injected the rough strain of bacteria in mice they
lived, and when the smooth strain of bacteria was injected into the mice they died. He
killed some of the smooth bacteria by heating them and then injecting them into the
mice. The mice lived. He then took some of the killed smooth bacteria and some of
the rough bacteria and mixed them together. This bacteria then had the ability to kill
mice. This is because the rough bacteria had been "transformed" by taking up some
of the DNA from the smooth bacteria.
The conclusion was that the bacteria had incorporated heredity from source and in
doing so expressed a new smooth trait.
1944-Avery, McLeod and McCarty tried mixing the rough strain with different chemical from
the S strain and it was found the DNA extracted from the smooth-strain and transform the
rough strain.
In his work with pneumonia-causing bacteria and mice, Griffith found
that
A)the protein coat from pathogenic cells was able to transform
nonpathogenic cells.
B)heat-killed pathogenic cells caused pneumonia.
C)some substance from pathogenic cells was transferred to
nonpathogenic cells, making them pathogenic.
D)the polysaccharide coat of bacteria caused pneumonia.
E)bacteriophages injected DNA into bacteria.
C
The above diagram outlines Griffith’s experiment. In his work with
pneumonia-causing bacteria and mice, Griffith found that some
substance from pathogenic cells was transferred to nonpathogenic cells,
making them pathogenic.
Alfred Hershey and Martha Chase demonstrated the genetic material is DNA by using
viruses that infect bacteria. These viruses only stay on the outside of the cell when
infecting. Also viruses are made of protein and DNA.
Which of the following scientists developed a stain for DNA and found
that gametes had half the amount of DNA found in somatic cells?
A)Feulgen
B)Griffith
C)Miescher
D)Avery, McCleod, and McCarty
A
Robert Feulgen was a German scientist that developed a stain for DNA.
The DNA in the cell, the more strongly it stained. It was found that all
somatic cells in a particular organism has stains the same amount except
for the gametes. They stain half as strongly.
It demonstrated that DNA is the material that genes are made of and not protein.
In trying to determine whether DNA or protein is the genetic material,
Hershey and Chase made use of which of the following facts?
A)DNA does not contain sulfur, whereas protein does.
B)DNA contains phosphorus, but protein does not.
C)DNA contains nitrogen, whereas protein does not.
D)A and B only
E)A, B, and C
D
Hershey and Chase used to radioactive sulfur to tag proteins and used
radioactive phosphorous to tag DNA in their experiment.
DNA History
 Up until the 1950’s, scientists were not sure how genetic
material was passed from parents to offspring.
 An experiment in 1952 confirmed that DNA is passed on
and DNA carries traits.
 On your notecard:
 With your table group, summarize the Hershey and
Chase experiment in words THAT YOU WILL
REMEMBER.
 Time: 8 minutes
 Noise: 2 (with group)
 Tape the notecard into your notes
Chargaff's Rule and that A+G=C+T=50%
A
T
G
C
Humans 30.9
29.4
19.9
19.5
Wheat
27.3
27.1
22.7
22.8
Yeast
31.3
32.9
18.7
17.1
Lutea
13.4
12.4
37.1
37.1
T7
26.3
26.0
24.0
24.0
Sarcina
In analyzing the number of different bases in a DNA sample, which
result would be consistent with the base-pairing rules?
A) A = G
B) A + G = C + T
C) A + T = G + T
D) A = C
E) G = T
B
A+G=C+T
This is because A base pairs with T and C base pairs with G. A and G
are both purines and T and C are both pyrimidines.
 Key Point #2: In 1953, scientists Watson, Crick, and
Franklin discovered the STRUCTURE of DNA.
 They used the technique x-ray crystallography to
uncover the structure of DNA.
 Watson and Crick were awarded the Nobel prize in
1962.
Double Helix
The “HOW”
 How does DNA do its job?
 Wait, what IS DNA’s job?
DNA’s Job
Key Point #3:
GENETIC information.
 DNA is the ________
Carries our traits.
 Like hair color, eye color, height, and diseases
 This makes DNA HERITABLE
Explain this quote
 “DNA
is the blueprint of the cell.”
 Like
a blueprint for a house, DNA is
the information that tells our body
what traits we will have.

For example: eye color and hair color
Where is DNA stored?
 Since DNA is SOOO important and give us our traits, we store it in a
very special place.
Key Point #4:
DNA is stored in the organelle, the
nucleus.
 WHY?
 The DNA NEVER leaves the nucleus.
Objective revisited
 We will be able to justify the selection
of data from historical investigations
that support the claim that DNA is the
source of heritable information.
Work Time
 Directions: Complete workbook page 87 -88 on a
separate sheet of paper and attach this paper into
your notes. You are welcome to use your textbook.

 Noise: 1 (partner)
 Time: till the end of class