Molecular Genetics - Chapter 6 Review Questions
1. What is a genome?
2. What was Friedrich Miescher’s important contribution to our knowledge of DNA?
3. In Frederick Griffith’s experiments, what was “transformed”? (Be specific about the cell types.)
4. Oswald Avery, Colin McLeod, and Maclyn McCarty treated the heat-killed S-strain bacteria with
3 different enzymes before adding the live R-strain. Addition of which enzyme resulted in no
transformation?
5. What type of virus did Martha Chase and Alfred Hershey work with? What important conclusion
did they make from their experiments?
6. What are the 3 components of a DNA nucleotide?
7. Which of the 2 nitrogenous bases are purines? Do they have a single or double-ring structure?
8. What are 3 differences between DNA and RNA?
9. What is the name of the bond that attaches 2 adjacent nucleotides in a single strand of
nucleotides?
10. What does it mean that the 2 strands of DNA are "antiparallel"?
11. What important contribution did Erwin Chargaff make to knowledge of the structure of DNA?
12. What type of images did Rosalind Franklin generate? What important conclusion about the
structure of DNA was made from these images?
13. What organism did Matthew Meselson and Franklin Stahl use in their experiments? What did
they conclude from their experiments?
14. What proteins are responsible for unwinding DNA and for preventing its reannealing in DNA
replication?
15. Why does DNA polymerase build new DNA using nucleoside triphosphates?
16. What are 2 functions of DNA polymerase I?
17. Why are Okazaki fragments formed on the lagging strand?
18. What are 2 differences between DNA replication in eukaryotic cells and prokaryotic cells?
19. Describe how eukaryotic DNA is "packed" into chromosomes.
20. Why do chromosomes shorten during every round of replication?
21. What is the effect of high levels of telomerase in cancer cells?
Molecular Genetics - Chapter 6 Review Questions - Answers
1. the complete set of an organism's hereditary information
2. he isolated a “phosphorus-rich substance” in the nuclei of cells and called it nuclein
3. the Streptococcus pneumoniae R (rough) cells were transformed into S (smooth) cells
4. deoxyribonucleases (enzymes that digest DNA)
5. they worked with a type of bacteriophage; they concluded that the hereditary material was the
DNA, not protein
6. a deoxyribose sugar, a phosphate group (on the 5’ C) and a nitrogenous base (on the 1’ C)
7. adenine and guanine, double-ring (thymine, uracil and cytosine are all pyrimidines)
8. Any 3 of...DNA contains deoxyribose sugar/RNA contains ribose sugar; thymine/uracil; double-stranded/single-stranded; found in the nucleus/found in the nucleus & the cytoplasm. etc.
9. phosphodiester bond
10. the 2 strands have opposite orientation; the 5' end of one strand is complementary to the 3'
end of the other
11. Chargaff collected DNA samples from various organisms and isolated the 4 nitrogenous bases.
He found that the amount of A = amount of T and the amount of C = amount of G for all samples
12. she generated X-ray crystallographs of DNA, which suggested the double helix shape, and a
constant diameter of 2 nm
13. they used Escherichia coli (E. coli); they concluded that DNA replicated semi-conservatively
14. DNA helicase and single-stranded binding proteins
15. the extra phosphate groups provide energy needed to attach the nucleotide to the DNA molecule
16. it removes RNA primers and replaces them with DNA; it acts as an exonuclease, correcting any
errors in the newly replicated DNA strands
17. because the lagging strand is synthesized away from the origin of replication, so it is
synthesized discontinuously (in pieces or fragments)
18. -there are only 3 DNA polymerase enzymes in prokaryotes (more than 3 in eukaryotes)
-only 1 replication origin in prokaryotes, multiple replication origins in eukaryotes
19. DNA coils around histones, forming nucleosomes. which are coiled into solenoids, which are
supercoiled into chromosomes.
20. because the RNA primer at the 5' end of the newly synthesized strands of DNA is not replaced
with DNA
21. it replaces the telomeres lost during replication, allowing the cancer cells to continue dividing
indefinitely