Chapter 7 Nucleic Acids: The Molecular Basis of Life • MHR 247CHAPTER 7 REVIEW
Summary of Expectations
Briefly explain each of the following points.- For many years, scientists believed that
proteins rather than DNA were the material of
heredity. (7.1) - The bonding of nucleotide base pairs proposed
by Watson and Crick accounts both for
Chargaff’s rule and for the observed structure
of the DNA molecule. (7.1) - The two strands in a DNA molecule are
complementary and antiparallel. (7.2) - Any fragment of a DNA strand has a constant
orientation or directionality. (7.2) - DNA is arranged in different ways in
prokaryotes and eukaryotes, but these different
arrangements serve some of the same needs. (7.2) - The base pairing properties of DNA provide a
way to replicate the molecule accurately. (7.2) - The accuracy of DNA replication is much
higher than that which could be attained
through base pairing mechanisms alone. (7.3) - DNA can only be synthesized in one direction,
but replication of DNA strands proceeds in
two directions at once. (7.3) - Organisms that have many similar genes may
physically appear to be very different. (7.4) - The mammalian genome contains a great deal
of DNA other than that contained in genes. (7.4)
Language of Biology
Write a sentence using each of the following words or
terms. Use any six terms in a concept map to show
your understanding of how they are related.- ribose nucleic acid • conservative theory
(ribonucleic acid or RNA) • semi-conservative - deoxyribose nucleic theory
acid (deoxyribonucleic • dispersive theory
acid or DNA) • replication origin - chromosome • DNA polymerase
- nucleotide • replication forks
- nitrogenous • helicases
- adenine • primer
- guanine • Okazaki fragments
- cytosine • leading strand
- thymine • DNA ligase
- uracil • lagging strand
- Chargaff’s rule • primase
- directionality • telomere
- purine • replication machine
- pyrimidine • gene
- complementary • genome
- antiparallel • regulatory sequence
- nucleoid • exon
- supercoiled • intron
- plasmid • multi-gene family
- histone • transposon
- chromatin • pseudogene
- nucleosome • repetitive sequence DNA
1.Identify and describe three experiments that
helped pave the way to the discovery of DNA
as the hereditary material.
2.What are the components of a single
nucleotide?
3.Using symbols to represent the four
nitrogenous bases, illustrate the molecular
structure of both strands of a portion of a DNA
molecule. Use each base at least twice.
4.What is the base sequence of the DNA strand
that is complementary to a strand with the
sequence ACGTTGCTA?
5.What contribution do hydrophilic and
hydrophobic reactions make to the stability
of a DNA molecule?
6.The following terms describe different
arrangements of DNA. Organize them by
distinguishing which are found in prokaryotic
versus eukaryotic cells, and by placing them in
order from least compact to most compact.
nucleosome plasmid
chromatin 30 nm array
supercoil
7.What role does histone play in arranging DNA
within eukaryotic cells? What properties of this
protein contribute to this role?
8.Do all your body tissues contain the same
amount of DNA? Explain.
9.The replication of DNA is said to be semi-
conservative. What does this mean?
10.What is the function of primase in DNA
replication?
11.Briefly compare the roles played by the
following:
(a)leading strand and lagging strandUNDERSTANDING CONCEPTS