12–1 DNA - Biology Junction

Biology
Slide
1 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Slide
2 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Griffith and Transformation
Griffith and Transformation
In 1928, British scientist Fredrick Griffith was
trying to learn how certain types of bacteria caused
pneumonia.
He isolated two different strains of pneumonia
bacteria from mice and grew them in his lab.
Slide
3 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Griffith and Transformation
Griffith made two observations:
(1) The disease-causing strain of bacteria grew
into smooth colonies on culture plates.
(2) The harmless strain grew into colonies with
rough edges.
Slide
4 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Griffith and Transformation
Griffith's Experiments
Griffith set up four
individual experiments.
Experiment 1: Mice
were injected with the
disease-causing strain
of bacteria. The mice
developed pneumonia
and died.
Slide
5 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Griffith and Transformation
Experiment 2: Mice were
injected with the harmless
strain of bacteria. These
mice didn’t get sick.
Harmless bacteria
(rough colonies)
Lives
Copyright Pearson Prentice Hall
Slide
6 of 37
End Show
12–1 DNA
Griffith and Transformation
Experiment 3: Griffith
heated the diseasecausing bacteria. He then
injected the heat-killed
bacteria into the mice.
The mice survived.
Heat-killed diseasecausing bacteria (smooth
colonies)
Lives
Copyright Pearson Prentice Hall
Slide
7 of 37
End Show
12–1 DNA
Griffith and Transformation
Experiment 4: Griffith
mixed his heat-killed,
disease-causing bacteria
with live, harmless
bacteria and injected the
mixture into the mice.
The mice developed
pneumonia and died.
Heat-killed diseasecausing bacteria
(smooth colonies)
Harmless bacteria
(rough colonies)
Live diseasecausing bacteria
(smooth colonies)
Dies of pneumonia
Copyright Pearson Prentice Hall
Slide
8 of 37
End Show
12–1 DNA
Griffith and Transformation
Griffith concluded that
the heat-killed bacteria
passed their diseasecausing ability to the
harmless strain.
Heat-killed diseasecausing bacteria
(smooth colonies)
Harmless bacteria
(rough colonies)
Live diseasecausing bacteria
(smooth colonies)
Dies of pneumonia
Copyright Pearson Prentice Hall
Slide
9 of 37
End Show
12–1 DNA
Griffith and Transformation
Transformation
Griffith called this process transformation
because one strain of bacteria (the harmless strain)
had changed permanently into another (the
disease-causing strain).
Griffith hypothesized that a factor must contain
information that could change harmless bacteria
into disease-causing ones.
Slide
10 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Avery and DNA
Avery and DNA
Oswald Avery repeated Griffith’s work to determine
which molecule was most important for
transformation.
Avery and his colleagues made an extract from the
heat-killed bacteria that they treated with enzymes.
Slide
11 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Avery and DNA
The enzymes destroyed proteins, lipids,
carbohydrates, and other molecules, including the
nucleic acid RNA.
Transformation still occurred.
Slide
12 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Avery and DNA
Avery and other scientists repeated the experiment
using enzymes that would break down DNA.
When DNA was destroyed, transformation did not
occur. Therefore, they concluded that DNA was the
transforming factor.
Slide
13 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
Avery and DNA
Avery and other scientists discovered
that the nucleic acid DNA stores and
transmits the genetic information from
one generation of an organism to the
next.
Slide
14 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Hershey-Chase Experiment
The Hershey-Chase Experiment
Alfred Hershey and Martha Chase studied
viruses—nonliving particles smaller than a cell that
can infect living organisms.
Slide
15 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Hershey-Chase Experiment
Bacteriophages
A virus that infects bacteria is known as a
bacteriophage.
Bacteriophages are composed of a DNA or RNA
core and a protein coat.
Slide
16 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Hershey-Chase Experiment
They grew viruses in cultures containing
radioactive isotopes of phosphorus-32 (32P) and
sulfur-35 (35S).
Slide
17 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Hershey-Chase Experiment
If 35S was found in the bacteria, it would mean that
the viruses’ protein had been injected into the
bacteria.
Bacteriophage with
suffur-35 in protein coat
Phage infects
bacterium
No radioactivity
inside bacterium
Slide
18 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Hershey-Chase Experiment
If 32P was found in the bacteria, then it was the DNA
that had been injected.
Bacteriophage with
phosphorus-32 in DNA
Phage infects
bacterium
Radioactivity
inside bacterium
Slide
19 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Hershey-Chase Experiment
Nearly all the radioactivity in the bacteria
was from phosphorus (32P).
Hershey and Chase concluded that the
genetic material of the bacteriophage
was DNA, not protein.
Slide
20 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of DNA
The Components and Structure of DNA
DNA is made up of nucleotides.
A nucleotide is a monomer of nucleic acids made
up of:
•Deoxyribose – 5-carbon Sugar
•Phosphate Group
•Nitrogenous Base
Slide
21 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of DNA
There are four
kinds of bases in
in DNA:
• adenine
• guanine
• cytosine
• thymine
Slide
22 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of DNA
Chargaff's Rules
Erwin Chargaff discovered that:
• The percentages of guanine [G] and cytosine
[C] bases are almost equal in any sample of
DNA.
• The percentages of adenine [A] and thymine
[T] bases are almost equal in any sample of
DNA.
Slide
23 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of DNA
X-Ray Evidence
Rosalind Franklin used X-ray
diffraction to get information
about the structure of DNA.
She aimed an X-ray beam at
concentrated DNA samples
and recorded the scattering
pattern of the X-rays on film.
Slide
24 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of DNA
The Double Helix
Using clues from Franklin’s pattern, James
Watson and Francis Crick built a model that
explained how DNA carried information and
could be copied.
Watson and Crick's model of DNA was a
double helix, in which two strands were
wound around each other.
Slide
25 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of
DNA
DNA Double Helix
Slide
26 of 37
Copyright Pearson Prentice Hall
End Show
12–1 DNA
The Components and Structure of
DNA
Watson and Crick discovered that hydrogen bonds
can form only between certain base pairs—adenine
and thymine, and guanine and cytosine.
This principle is called base pairing.
Slide
27 of 37
Copyright Pearson Prentice Hall
End Show
12–1
Click to Launch:
Continue to:
- or -
Slide
28 of 37
End Show
Copyright Pearson Prentice Hall
12–1
Avery and other scientists discovered that
a. DNA is found in a protein coat.
b. DNA stores and transmits genetic
information from one generation to the next.
c. transformation does not affect bacteria.
d. proteins transmit genetic information from
one generation to the next.
Slide
29 of 37
End Show
Copyright Pearson Prentice Hall
12–1
The Hershey-Chase experiment was based on
the fact that
a. DNA has both sulfur and phosphorus in its
structure.
b. protein has both sulfur and phosphorus in
its structure.
c. both DNA and protein have no phosphorus
or sulfur in their structure.
d. DNA has only phosphorus, while protein
has only sulfur in its structure.
Slide
30 of 37
End Show
Copyright Pearson Prentice Hall
12–1
DNA is a long molecule made of monomers
called
a. nucleotides.
b. purines.
c. pyrimidines.
d. sugars.
Slide
31 of 37
End Show
Copyright Pearson Prentice Hall
12–1
Chargaff's rules state that the number of
guanine nucleotides must equal the number of
a. cytosine nucleotides.
b. adenine nucleotides.
c. thymine nucleotides.
d. thymine plus adenine nucleotides.
Slide
32 of 37
End Show
Copyright Pearson Prentice Hall
12–1
In DNA, the following base pairs occur:
a. A with C, and G with T.
b. A with T, and C with G.
c. A with G, and C with T.
d. A with T, and C with T.
Slide
33 of 37
End Show
Copyright Pearson Prentice Hall
END OF SECTION