The Molecular Basis of Inheritance
Reece et al., Campbell Biology. 9th ed., Chapter 16
Study hint: The animations in the activities of your CD ROM (and on the
website) are very helpful if you are a visual learner and want to understand the
concepts of this chapter better. Do them all!
0. Application
1. Hannelore Kohl, the spouse of former German chancellor Kohl, committed
suicide in 2001. The official reason was that she suffered from
Xeroderma pigmentosum. What are symptoms and causes of this
disease?
I. The big picture
2. In chapter 5 we briefly discussed the structure of DNA (Fig. 5.27). In
chapter 12 we looked at genetic material of eukaryotes during
_________. Chapter 14 acquainted us with patterns of inheritance and
what can go wrong when genetic information is mutated (in chapter 5 we
already encountered an example: if a genetic change leads to the change
of just one ________ of a polypeptide, the _______ is altered, which
determines the shape of the resulting ______. This can lead to severe
disease such as _________ (Figure 5.21).
3. Key concept I: Life poses challenges. It is clear that the health of
organisms depends on faithful replication of the genetic material, and the
inheritance of proven alleles fine-tuned by millions of years of _________.
In this chapter, we will discuss
a. how DNA’s structure fits its function (key strategy 5)
b. what safety net has evolved to ensure faithful replication and
c. how DNA is actually replicated fast and specifically (key concept 4), a
process that happens in ____ phase of _______ the meiotic or mitotic
cell cycle.
II. DNA as the Genetic Material
4. What (4) properties must the carrier molecule of heritable information
possess?
5. Explain why researchers originally thought protein was the genetic
material.
6. Summarize the experiments performed by the following scientists that
provided evidence that DNA is the genetic material:
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a. Frederick Griffith (Fig. 16.2)
b. Oswald Avery, Maclyn McCarty, and Colin MacLeod
c. Alfred Hershey and Martha Chase (Fig. 16.4)
7. Explain how Watson and Crick deduced the structure of DNA and
describe the evidence they used. Explain the significance of the
research of Rosalind Franklin (16.6).
8. Describe the structure of DNA. Explain the base-pairing rule and
describe its significance. Use the terms major and minor groove, 5’
and 3’, and antiparallel. (Fig. 16.7).
9. How did the newly deduced structure of DNA explain Chargaff’s rule
(concept check 16.1.2)?
DNA Replication and Repair
10. How can such a “simple” molecule as DNA fulfill the four tasks of a
genetic information carrier (question 4)?
11. Describe the semiconservative model of replication (Fig. 16.9) and
the significance of the experiments of Matthew Meselson and Franklin
Stahl (Fig. 16.10 and 16.11). Note that there is a tutorial on this on
Mastering Biology.
12. Distinguish between denaturing in proteins and in DNA.
13. Describe the process of DNA replication initiation in eukaryotes,
including the role of the origins of replication and replication forks,
topoisomerase, helicase, single-strand binding proteins, and RNA
primers(Fig. 16.12 – 16.13),
14. Draw the overview figure above Fig 16.15 and describe the synthesis
of a) the leading, and b) the lagging strand (Fig. 16.15-16.17). Please
watch the bioflix tutorial for this part. There are also good animated
tutorials.
15. Draw two sequential Okazaki fragments and describe how they are
made into one continuous DNA strand.
16. How do mutations arise? Distinguish between external and internal
factors.
17. Explain what happens in four common types of DNA damage.
18. Explain the roles of DNA polymerase, mismatch repair enzymes, and
nuclease in DNA proofreading and repair.
19. Describe the structure and function of telomeres (Fig. 16.19 and
16.20).
20. How does telomere shortening affect mitosis?
21. Why has evolution not selected for telomere maintenance into old age?
Think of the key concept “Solutions involve trade-offs”.
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22. How does telomerase work (see Figure 2 below)?\
Figure 2: Telomerase action
23. What is the consequence of telomerase activity in germ line and
cancer cells?
24. Describe function and mechanism of chromatin packing in eukaryotic
chromosomes (Fig. 16.21) and distinguish between hetero- and
euchromatin.
Essay question
1. Write an essay on DNA repair. Your essay should include a discussion of
the following points: causes of damage to DNA, consequences of DNA
damage, types of DNA damage, mechanisms of eukaryotes to repair DNA
damage. You should also hypothesize why eukaryotes invest a
considerable amount of energy in DNA repair while bacteria seem to be
able to succeed without extensive DNA repair.
2. Discuss the end-replication problem. Address the following points: why
and where does this problem occur? What are its consequences? How
do different cells deal with this problem? What does this have to do with
cancer? Why do recent findings give us hope for cancer therapy with less
side effects?
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