dna
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DNA. DiscoveryStructure Replication. 40 questions. 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 - PowerPoint PPT PresentationTRANSCRIPT
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DNA Discovery Structure Replication
40 questions
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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.
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2. What happened to the mice when Griffith injected them with the heat-killed S strain?
The mice lived.
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The mice died of pneumonia.
+
3. What happened to the mice when Griffith injected them with a mixture of heat-killed S strain and live R strain?
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4. A process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria.
a. Transcriptionb. Replicationc. Transformationd. duplication
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5. Oswald Avery used ____ to degrade (break down) various molecules taken form heat-killed bacteria.
a. sulfurb. enzymesc. toxinsd. x-rays
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6. What types of macromolecules did Avery use enzymes on.
CarbohydratesProteins
LipidsRNADNA
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7. What kind of enzyme did Avery use to degrade bacterial proteins?
a. carbohydrasesb. lipasesc. proteasesd. DNAses
Membrane protein
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8. How did Avery ensure the validity of the results of his experiment with bacteria and mice?
a. He degraded only one type of molecule at a time. b. He used all the enzymes at the same time.c. He decided not to degrade proteins and DNA.d. He injected a mixture of degraded molecules into
mice at the same time.
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9. Bacteriophages are
a. a form of bacteriab. enzymesc. coils of DNAd. viruses
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10. What two organisms did Hershey and Chase work with in their study of DNA?
a. Bacteriophages and miceb. E. coli bacteria and micec. Bacteriophages and E. coli bacteriad. Bacteriophages and viruses
Bacteriophages
E. coli bacterium
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11. Interpret this micrograph.
Bacteriophages breaking out of a bacterium that has been infected.
BacteriophagesLysed Bacterium
Phages emerging
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12. What radioactive element did Hershey and Chase use to “tag” DNA?
32P (phosphorus)
DNA
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13. What radioactive element did Hershey and Chase use to “tag” the protein coat?
35S (sulfur)
The amino acid methionine
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14. Why can’t Hershey and Chase use to 35S to tag phage DNA?
DNA does not contain sulfur.
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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.
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16. What can be concluded from the Avery and Hershey & Chase experiments?
a. DNA is the transforming molecule.b. Proteins are larger than nucleic acids.c. Enzymes are good at breaking down molecules.d. The S-strain is more deadly than the R-strain.
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17. Before DNA could be shown to be the genetic material in cells, scientists had to show that it coulda. tolerate high temperaturesb. carry, make copies of, and transmit informationc. be modified in response to environmental
conditions.d. be broken down into small subunits.
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18. A nucleotide does NOT contain a
a. 5-carbon sugar.b. nitrogen basec. proteind. phosphate group
Phosphate group
Sugar (deoxyribose)
Nitrogenous base
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19. According to Chargaff’s rule of base pairing, which of the following is true about DNA?
a. A = T, and C = Gb. A = C, and T = Gc. A = G, and T = Cd. A = T = C = G
Erwin Chargaff (1905 – 2002)
A
C
T
G
=
=
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Thymine Guanine_____________ Cytosine
20. Name the missing nitrogenous base.
Adenine
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21. Use Chargaff’s rule to complete the table below.
Organism % Adenine % Cytosine % Guanine % Thymine
Human 30 30
60100
+ ?
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21. Use Chargaff’s rule to complete the table below.
Organism % Adenine % Cytosine % Guanine % Thymine
Human 30 3020 20
60100
+40
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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 sugar-phosphate backbone.
c. Hydrogen bonds between nitrogenous bases.
d. Carbon-to-carbon bonds in the sugar portion of the nucleotides.
T GA C
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23. What is the term that describes how the two strands in DNA run in opposite directions?
AntiparallelC A T G
T AG C
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24. Who took this photo?
Rosalind Franklin
Photo 51
(1920 – 1958)
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25. What is this a photo ofand what technique was used to make it?
Photo 51
• The photo shows the structure of DNA
• Rosalind used X-ray diffraction to take the picture
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26. List two things this Rosalind Franklin learnedfrom her photo?
• DNA has a double helix shape
• DNA is made of two strands.
• The nitrogenous bases are near the center.
Photo 51
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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 )
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28. Name the three parts of the nucleotide shown below?
C
B
A
A. phosphate groupB. sugar (deoxyribose)C. nitrogenous base
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29. The process of copying DNA prior to cell division is called
a. cytokinesisb. Interphasec. Base pairingd. replication
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30. The diagram below shows the process of DNA
a. replicationb. digestionc. transformationd. transpiration
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31. The enzyme that “unzips” DNA during replication is called
a. DNA polymeraseb. carbohydrasec. helicased. replicase
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32. The enzyme that “fastens” new nucleotides to the original DNA strand is called.
a. carbohydraseb. DNA polymerasec. helicased. replicase
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33. In which direction is the circled DNA polymerase moving?
Right to left
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34. From left to right, identify the missing bases.
TG
AC
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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
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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.
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37. Interpret the following sequence of diagrams?
The diagrams demonstrate prokaryote replication, which involves only one replication bubble. Replication
proceeds within the bubble in opposite directions.
Replication bubble
Replication nearly
complete
Two identical
chromosomes result
Replication in two
directions
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38. How many replication forks are shown in this micrograph?
There are two forks. One at each end of the bubble.
Replication forks
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39. Is this a prokaryotic or eukaryotic chromosome? How can you tell?
• Eukaryotic• The chromosome is rod shaped
instead of circular.
Human chromatids
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40. What are the tips of chromosomes called and what enzyme replicates them.
• The tips are called telomeres• The enzyme is telomerase
TelomeresTelomeres