Bio 2
Fall, 2009
UPDATED 10/21/09
Study Guide
For Exam 2
Exam 2 will cover section 6.7 of Chapter 6 and Chapters 7, 16, 17, 18 and the
portion of Ch. 21 that is covered on Tuesday, Oct. 27.
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Be sure to read all chapters and take the time to be sure that you understand the
material.
Hopefully, you are keeping up with Mastering Biology! All of those materials are
available for you to review after the due date. This is a very good way to study for
the exam.
This study guide is intended to help you focus your work, but be sure to accomplish
the steps listed above first.
Chapter 7:
Membrane Structure
1. Explain the meaning of the statement that phospholipids and most other
membrane constituents are amphipathic molecules.
2. Explain how the fluid mosaic model of membrane structure explains each
experimental finding:
a. Membranes with different functions may differ in type and number of
membrane proteins.
b. Membrane proteins are not very water-soluble.
c. EMs of freeze-fracture membrane preparations show protein particles
interspersed in a smooth matrix.
3. Describe the fluidity of the components of a cell membrane and explain how
membrane fluidity is influenced by temperature and membrane composition.
4. Explain how cholesterol resists changes in membrane fluidity as temperatures
change.
5. Distinguish between peripheral and integral membrane proteins.
6. List six major functions of membrane proteins.
7. Explain the role of membrane carbohydrates in cell-cell recognition.
Traffic across Membranes
8. Explain how hydrophobic molecules cross cell membranes.
9. Distinguish between channel proteins and carrier proteins.
10. Explain how aquaporins facilitate the passage of water through membranes.
11. Define diffusion. Explain why diffusion is a passive and spontaneous process.
12. Explain why a concentration gradient of a substance across a membrane
represents potential energy.
13. Distinguish between solutions that are hypertonic, hypotonic, and isotonic to cell
contents.
14. Define osmosis and predict the direction of water movement based on differences
in solute concentrations.
15. Describe how living cells with and without cell walls regulate water balance.
16. Explain how transport proteins facilitate diffusion.
Bio 2
Fall, 2009
UPDATED 10/21/09
17. Distinguish between osmosis, facilitated diffusion, and active transport.
18. Describe the two forces that combine to produce an electrochemical gradient.
19. Explain how an electrogenic pump creates voltage across a membrane. Name two
electrogenic pumps.
20. Describe the process of cotransport.
21. Explain how large molecules are transported across a cell membrane.
22. Distinguish between exocytosis and receptor-mediated endocytosis.
Chapter 16
DNA as the Genetic Material
1. Explain why researchers originally thought protein was the genetic material.
2. 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.
3. Describe the structure of DNA. Explain the base-pairing rule and describe its
significance.
DNA Replication and Repair—Key FigureFig. 16.17
4. Describe the semiconservative model of replication and the significance of the
experiments of Matthew Meselson and Franklin Stahl.
5. Describe the process of DNA replication, including the role of the origins of
replication and replication forks.
6. Explain the role of DNA polymerases in replication.
7. Explain what energy source drives the polymerization of DNA.
8. Distinguish between the leading strand and the lagging strand.
9. Explain how the lagging strand is synthesized even though DNA polymerase can add
nucleotides only to the 3’ end. Describe the significance of Okazaki fragments.
10. Explain the roles of DNA ligase, primer, primase, helicase, topoisomerase, and
single-strand binding proteins.
11. Define “antiparallel” and explain why continuous synthesis of both DNA strands is
not possible.
12. Briefly explain the roles of DNA polymerase, mismatch repair enzymes, and
nuclease in DNA proofreading and repair.
13. Describe the function of telomeres.
14. Explain the possible significance of telomerase in germ cells and cancerous cells.
Bacterial and Eukaryotic Chromosomes
15. Compare a bacterial chromosome and a eukaryotic chromosome.
16. Describe how the packing of chromatin changes during the course of the cell cycle.
17. Distinguish between heterochromatin and euchromatin.
Chapter 18
The Connection between Genes and Proteins
Bio 2
Fall, 2009
UPDATED 10/21/09
1. Explain the reasoning that led Archibald Garrod to suggest that genes dictate
phenotypes through enzymes.
2. Distinguish between the “one gene-one enzyme” hypothesis and the “one geneone polypeptide” hypothesis and explain why the original hypothesis was
changed.
3. Explain how RNA differs from DNA.
4. Briefly explain how information flows from gene to protein. Is the central dogma
ever violated?
5. Distinguish between transcription and translation.
6. Compare where transcription and translation occur in bacteria and in eukaryotes.
7. Define “codon” and explain the relationship between the linear sequence of
codons on mRNA and the linear sequence of amino acids in a polypeptide.
8. Explain why polypeptides begin with methionine when they are synthesized.
9. Explain what it means to say that the genetic code is redundant and unambiguous.
10. Explain the significance of the reading frame during translation.
11. Explain the evolutionary significance of a nearly universal genetic code.
The Synthesis and Processing of RNA: Key Figures  17.3, 17.10
12. Explain how RNA polymerase recognizes where transcription should begin.
Describe the role of the promoter, the terminator, and the transcription unit.
13. Explain the general process of transcription, including the three major steps of
initiation, elongation, and termination.
14. Explain how RNA is modified after transcription in eukaryotic cells.
15. Define and explain the role of ribozymes. What three properties allow some RNA
molecules to function as ribozymes?
16. Describe the functional and evolutionary significance of introns.
17. Explain why, due to alternative RNA splicing, the number of different protein
products an organism can produce is much greater than its number of genes.
The Synthesis of Protein: Key Figures17.17, 17.18, 17.19, 17.21
18. Describe the structure and function of tRNA.
19. Explain the significance of wobble.
20. Explain how tRNA is joined to the appropriate amino acid.
21. Describe the structure and functions of ribosomes.
22. Explain the statement, “A ribosome can be regarded as one colossal ribozyme.”
23. Describe the process of translation (including initiation, elongation, and
termination) and explain which enzymes, protein factors, and energy sources are
needed for each stage.
24. Describe the significance of polyribosomes.
25. Explain what determines the primary structure of a protein and describe how a
polypeptide must be modified before it becomes fully functional.
26. Describe what determines whether a ribosome will be free in the cytosol or
attached to the rough endoplasmic reticulum.
27. Define “point mutations”. Distinguish between base-pair substitutions and basepair insertions. Give an example of each and note the significance of such
changes.
Bio 2
Fall, 2009
UPDATED 10/21/09
28. Distinguish between a missense and a nonsense mutation.
29. Why is an insertion or deletion more likely to be deleterious than a substitution?
30. Define the term ‘mutation’. Give an example of a physical and a chemical agent
of mutation.
31. Briefly compare gene expression in bacteria, archaea and eukarya. In general, is
archaeal gene expression more similar to bacterial or eukaryotic gene expression?
32. Describe the historical evolution of the concept of a gene.
Chapter 18 (Skim section 18.4)
KEY FIGURE  18.6
Bacterial Regulation of Transcription
1. Briefly describe two main strategies that cells use to control metabolism.
2. Explain the adaptive advantage of bacterial genes grouped into an operon.
3. Explain how an inducible operon differs from a repressible operon.
Regulation of Eukaryotic Gene Expression
4. Define differential gene expression. At what level is gene expression generally
controlled?
5. Distinguish between heterochromatin and euchromatin.
6. Explain how DNA methylation and histone acetylation affects chromatin structure
and the regulation of transcription.
7. Define epigenetic inheritance.
8. Describe the role of the transcription initiation complex.
9. Define control elements and explain how they influence transcription.
10. Distinguish between general and specific transcription factors.
11. Explain the role of promoters, enhancers, activators, and repressors in
transcriptional control.
12. Explain how eukaryotic genes can be coordinately expressed. Describe an
example of coordinate gene expression in eukaryotes.
13. Describe the process and significance of alternative RNA splicing.
14. Describe the processing of pre-mRNA in eukaryotes.
15. Describe factors that influence the lifespan of mRNA in the cytoplasm. Compare
the longevity of mRNA in prokaryotes and eukaryotes.
16. Explain how gene expression may be controlled at the translational and posttranslational level.
The Roles of Noncoding RNAs
17. Describe two ways in which microRNAs (miRNAs) and small interfering RNAs
(siRNAs) contribute to the control of gene expression.
Molecular Biology of Cancer
18. Distinguish between proto-oncogenes and oncogenes. Describe three genetic
changes that can convert a proto-oncogene to an oncogene.
Bio 2
Fall, 2009
UPDATED 10/21/09
19. Explain how mutations in tumor-suppressor genes can contribute to cancer.
20. Explain how excessive cell division can result from mutations in the ras protooncogene.
21. Explain why a mutation knocking out the p53 tumor suppressor gene can lead to
excessive cell growth and cancer.
22. Explain how inherited cancer alleles can lead to a predisposition to certain
cancers.
CHAPTER 21: GENOMES AND THEIR EVOLUTION
The Human Genome Project
1. Describe the goals of the Human Genome Project. What important questions do
we still need to answer about the human genome?
DNA Analysis and Genomics
2. Explain how researchers recognize protein-coding genes within DNA sequences.
3. Define and compare the fields of proteomics and genomics.
4. Describe the trends that have been identified across major taxa with respect to
genome size and gene density.
5. Describe the surprising findings of the Human Genome Project with respect to the
size of the human genome.
6. Compare the basic structure of prokaryotic and eukaryotic genomes.
7. Distinguish between transposons and retrotransposons.
Genomic Clues to Evolutionary History
8. Describe in general terms the events that may have led to evolution of the globin
superfamily.
9. How does exon shuffling lead to new proteins with novel combinations of
functions?
10. In broad terms, describe how chimp and humans genomes differ.
11. What genetic similarities led a researcher to call fruit flies “little people with
wings”?