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Biology Ch. 9 Test
Question | Answer |
---|---|
What is a vaccine? | a substance that is prepared from killed or weakened disease-causing agents, including certain bacteria |
Define virulent. | able to cause disease |
Define transformation. | a change in genotype caused when cells take up foreign genetic material |
Define bacteriophage. | a virus that infects bacteria |
What is a double helix? | two strands of nucleotides twisted around each other |
What is a nucleotide? | subunits that make up DNA |
Define deoxyribose. | the five-carbon sugar found in DNA nucleotides |
What are base-pairing rules? | the rules stating that cytosine pairs with guanine and adenine pairs with thymine in DNA, and that adenine pairs with uracil in RNA |
What are complementary base pairs? | a characteristic of nucleic acids in which the sequence of bases on one strand is paired to the sequence of bases on the other |
What is DNA replication? | the process of making a copy of DNA |
What are DNA helicases? | enzymes which open the double helix by breaking the hydrogen bonds that link the complementary nitrogen bases between the two strands before DNA replication can begin |
What are replication forks? | the Y-shaped areas where the double helix separates |
What are DNA polymerases? | enzymes at the replication fork which move along each of the DNA strands adding nucleotides to the exposed nitrogen bases |
What kind of bond holds the double helix together? | hydrogen bond |
What is a nitrogen base made of? | one or two rings of carbon and nitrogen atoms |
What does DNA stand for? | deoxyribonucleic acid |
What is cytosine? | one of two pyrimidines used as a nitrogen base in nucleotides |
What is adenine? | one of two purines used as a nitrogen base in nucleotides |
Who found that the capsule that enclosed on strain of Streptococcus pneumoniae cause the microorganism's virulence? | Frederick Griffith |
Avery's experiments demonstrated that DNA is what kind of material? | genetic |
Where did Hershey and Chase find that most of the radioactive substance is found after tracing the 32P? | in the lower layer |
What did Watson and Crick use to build their model of DNA? | Wilkins' and Franklin's X-ray diffraction photographs |
Where in the cell cycle does DNA replication take place? | the synthesis phase |
Eukaryotic DNA contains many replication forks working together, whereas PROKARYOTIC DNA contains how many replication forks during replication? | two |
Who developed high quality X-ray diffraction photographs of DNA? | Wilkins and Franklin |
Who demonstrated that DNA is the material responsible for transformation? | Avery |
Who discovered transformation in bacterial cells? | Griffith |
Who discovered the three-dimensional structure of DNA with the help of other scientists? | Watson and Crick |
What role do base-pairing rules play in the structure of DNA? | They hold the double helix together. |
What is a nucleotide made up of? | a phosphate group, a five-carbon sugar molecule, and a nitrogen containing base |
Why did Hershey and Chase use radioactive elements in their experiments? | They release particles that can be detected by machines and be followed in a biological process |
How does DNA polymerase "proofread" a new DNA strand? | Nucleotides are only added to a growing strand if the previous nucleotides is correctly paired. |