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DNA
Discovery
Structure
40 questions
Replication
1. Describe the two strains of bacteria
Griffith used in his experiment with mice.
• S strain (deadly)
-produced a protective slime coating that
helped it evade the mouse immune system.
-caused pneumonia (a deadly lung disease) in
mice.
• R strain (harmless)
-did not produce a protective slime coating
and therefore was easily defeated by the
mouse immune system.
2. What happened to the mice when Griffith
injected them with the heat-killed S strain?
The mice lived.
3. What happened to the mice when Griffith
injected them with a mixture of heat-killed S
strain and live R strain?
+
The mice died of pneumonia.
4. A process in which one strain of bacteria
is changed by a gene or genes from another
strain of bacteria.
a.
b.
c.
d.
Transcription
Replication
Transformation
duplication
5. Oswald Avery used ____ to degrade
(break down) various molecules taken
form heat-killed bacteria.
a.
b.
c.
d.
sulfur
enzymes
toxins
x-rays
6. What types of macromolecules did Avery
use enzymes on.
Carbohydrates
Proteins
Lipids
RNA
DNA
7. What kind of enzyme did Avery use to
degrade bacterial proteins?
a.
b.
c.
d.
carbohydrases
lipases
proteases
DNAses
Membrane protein
8. How did Avery ensure the validity of the
results of his experiment with bacteria and
mice?
a.
b.
c.
d.
He degraded only one type of molecule at a time.
He used all the enzymes at the same time.
He decided not to degrade proteins and DNA.
He injected a mixture of degraded molecules into
mice at the same time.
9. Bacteriophages are
a.
b.
c.
d.
a form of bacteria
enzymes
coils of DNA
viruses
10. What two organisms did Hershey and
Chase work with in their study of DNA?
a.
b.
c.
d.
Bacteriophages and mice
E. coli bacteria and mice
Bacteriophages and E. coli bacteria
Bacteriophages and viruses
Bacteriophages
E. coli bacterium
11. Interpret this micrograph.
Bacteriophages
Lysed
Bacterium
Phages
emerging
Bacteriophages breaking out of a
bacterium that has been infected.
12. What radioactive element did Hershey
and Chase use to “tag” DNA?
32P
(phosphorus)
DNA
13. What radioactive element did Hershey and
Chase use to “tag” the protein coat?
35S
(sulfur)
The amino acid methionine
14. Why can’t Hershey and Chase use to 35S to
tag phage DNA?
DNA does not contain sulfur.
15. What results did Hershey and Chase observe?
a. The protein coats were injected into the
bacterial cells causing transformation.
b. Protein coats do not contain phosphorus.
c. Radioactivity detected inside bacterial cells
came from 32P and not 32S.
d. Bacteriophages are good at infecting bacteria.
16. What can be concluded from the Avery and
Hershey & Chase experiments?
a.
b.
c.
d.
DNA is the transforming molecule.
Proteins are larger than nucleic acids.
Enzymes are good at breaking down molecules.
The S-strain is more deadly than the R-strain.
17. Before DNA could be shown to be the
genetic material in cells, scientists had to
show that it could
a. tolerate high temperatures
b. carry, make copies of, and transmit information
c. be modified in response to environmental
conditions.
d. be broken down into small subunits.
18. A nucleotide does NOT contain a
a.
b.
c.
d.
5-carbon sugar.
nitrogen base
protein
phosphate group
Phosphate
group
Nitrogenous
base
Sugar
(deoxyribose)
19. According to Chargaff’s rule
of base pairing, which of the
following is true about DNA?
a.
b.
c.
d.
A = T, and C = G
A = C, and T = G
A = G, and T = C
A=T=C=G
Erwin Chargaff
(1905 – 2002)
=
A
C
=
T
G
20. Name the missing nitrogenous base.
Thymine
Guanine
Adenine
_____________
Cytosine
21. Use Chargaff’s rule to complete the table below.
Organism
% Adenine
Human
30
% Cytosine
% Guanine
% Thymine
30
+ ?
60
100
21. Use Chargaff’s rule to complete the table below.
Organism
% Adenine
% Cytosine
% Guanine
% Thymine
Human
30
20
20
30
+ 40
60
100
22. The bonds that hold the two strands of
DNA together come from
a. The attraction of phosphate
groups for each other.
b. Strong bonds between
nitrogenous bases and the sugarphosphate backbone.
c. Hydrogen bonds between
nitrogenous bases.
d. Carbon-to-carbon bonds in the
sugar portion of the nucleotides.
T
A
G
C
23. What is the term that describes how
the two strands in DNA run in opposite
directions?
Antiparallel
C
G
T
A
T
A
G
C
24. Who took this photo?
Rosalind Franklin
Photo 51
(1920 – 1958)
25. What is this a photo of
and what technique was
used to make it?
•
•
The photo shows the
structure of DNA
Rosalind used X-ray
diffraction to take the
picture
Photo 51
26. List two things this
Rosalind Franklin learned
from her photo?
• DNA has a double
helix shape
• DNA is made of two
strands.
• The nitrogenous bases
are near the center.
Photo 51
27. Who are these two
men and what are
they famous for?
•
•
James Watson and
Francis Crick.
They won the Nobel
prize for building the
first accurate model of
DNA.
James Watson
(1928 - )
Francis Crick
(1916 - 2004 )
28. Name the three parts of the nucleotide
shown below?
A
C
B
A. phosphate group
B. sugar (deoxyribose)
C. nitrogenous base
29. The process of copying DNA prior to cell division
is called
a.
b.
c.
d.
cytokinesis
Interphase
Base pairing
replication
30. The diagram below shows the process
of DNA
a.
b.
c.
d.
replication
digestion
transformation
transpiration
31. The enzyme that “unzips” DNA during
replication is called
a.
b.
c.
d.
DNA polymerase
carbohydrase
helicase
replicase
32. The enzyme that “fastens” new nucleotides
to the original DNA strand is called.
a.
b.
c.
d.
carbohydrase
DNA polymerase
helicase
replicase
33. In which direction is the circled DNA
polymerase moving?
Right to left
34. From left to right, identify the missing bases.
T
G
A
C
35. Is the chromosome shown below from a
prokaryote or eukaryote? How do you know?
•
•
It is from a prokaryote
The DNA forms a loop or ring like this one
36. The micrograph below shows DNA in fruit
flies. What are the “bubbles” (as indicated by
the arrows) caused by?
The bubbles are where DNA replication is taking place.
37. Interpret the following sequence of
diagrams?
Replication
bubble
Replication
in two
directions
Replication
nearly
complete
Two
identical
chromosomes
result
The diagrams demonstrate prokaryote replication, which
involves only one replication bubble. Replication
proceeds within the bubble in opposite directions.
38. How many replication forks are shown
in this micrograph?
There are two forks. One at each
end of the bubble.
Replication
forks
39. Is this a prokaryotic or eukaryotic
chromosome? How can you tell?
Human
chromatids
• Eukaryotic
• The chromosome is rod shaped
instead of circular.
40. What are the tips of chromosomes
called and what enzyme replicates them.
Telomeres
Telomeres
• The tips are called telomeres
• The enzyme is telomerase