Download Ch11 Answers to Concept Check Questions

CHAPTER 11
Concept check questions (in figure legends)
FIGURE 11.1
Concept check: Explain why the mouse in part (d) died.
Answer: In this experiment, the type R bacteria had taken up genetic material from the
heat-killed type S bacteria, which converted the type R bacteria into type S. This enabled
them to proliferate within the mouse and kill it.
FIGURE 11.2
Concept check: What was the purpose of adding RNase and protease to a DNA extract?
Answer: RNase and protease were added to the DNA extract to rule out the possibility
that small amounts of contaminating RNA or protein was responsible for converting the
type R bacteria into type S.
FIGURE 11.5
Concept check: Why were two different radioisotopes used?
Answer: In this experiment 32P was used to label DNA and 35S was used to label protein.
FIGURE 11.7
Concept check: Which of these components are not found in DNA?
Answer: Ribose and uracil are not found in DNA.
FIGURE 11.10
Concept check: Which components of a nucleotide form the backbone of a DNA strand?
Answer: Deoxyribose and phosphate form the backbone of a DNA strand.
FIGURE 11.11
Concept check: Why is modeling useful?
Answer: Modeling is useful because it shows how molecules can fit together in a
complicated three-dimensional structure.
FIGURE 11.14
Concept check: What holds the DNA strands together?
Answer: Hydrogen bonding between base pairs and base stacking holds the DNA strands
together.
FIGURE 11.15
Concept check: Describe the major and minor grooves.
Answer: The major and minor grooves are the indentations where the bases make contact
with water. The major groove is wider than the minor groove.
FIGURE 11.16
Concept check: What are the structural differences between B DNA and Z DNA?
Answer: B DNA is a right-handed helix and the backbone is helical, whereas Z DNA is a
left-handed helix and the backbone appears to zigzag slightly. Z DNA has the bases tilted
relative to the central axis, whereas they are perpendicular in B DNA. There are also
minor differences in the number of bases pairs per turn.
FIGURE 11.17
Concept check: What types of bonds hold nucleotides together in an RNA strand?
Answer: Covalent bonds hold nucleotides together in an RNA strand.
FIGURE 11.18
Concept check: What are the base-pairing rules in RNA?
Answer: A bonds with U and G bonds with C.