DNA RNA MUTATION GENE REGULATION HW
AP BIOLOGY
DR WEINER
Multiple Choice (1.5 pts)
1. After mixing a heat-killed, phosphorescent strain of bacteria with a living non-phosphorescent strain,
you discover that some of the living cells are now phosphorescent. Which observations would provide
the best evidence that the ability to fluoresce is a heritable trait?
a. DNA passed from the heat-killed strain to the living strain.
b. Protein passed from the heat-killed strain to the living strain.
c. The phosphorescence in the living strain is especially bright.
d. Descendants of the living cells are also phosphorescent.
2.
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with
modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They
reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the
nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment
work?
a. There is no radioactive isotope of nitrogen.
b. Avery et al. have already concluded that this experiment showed inconclusive results.
c. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra
neutrons; therefore, they are more radioactive.
d. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not
distinguish between DNA and proteins.
3. Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately
what percentage of the nucleotides in this sample will be thymine?
a. 12
b. 24
c. 31
d. 38
4.
Chargaff's analysis of the relative base composition of DNA was significant because he was able
to show that
a. the relative proportion of each of the four bases differs within individuals of a species.
b. the amount of A is always equivalent to T, and C to G.
c. the amount of ribose is always equivalent to deoxyribose.
d. transformation causes protein to be brought into the cell.
5. Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive
thymine has been added. What would happen if a cell replicates once in the presence of this
radioactive base?
a. One of the daughter cells, but not the other, would have radioactive DNA.
b. Neither of the two daughter cells would be radioactive.
c. All four bases of the DNA would be radioactive.
d. DNA in both daughter cells would be radioactive.
6. A new DNA strand elongates only in the 5' to 3' direction because
a. DNA polymerase begins adding nucleotides at the 5' end of the template.
b. Okazaki fragments prevent elongation in the 3' to 5' direction.
c. replication must progress toward the replication fork.
d. DNA polymerase can only add nucleotides to the free 3' end.
7. Which would you expect of a eukaryotic cell lacking telomerase
a. a high probability of becoming cancerous
b. production of Okazaki fragments
c. inability to repair thymine dimers
d. a reduction in chromosome length
8. A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon
for the mRNA transcribed is
a. 3' UCA 5'.
b. 5' TCA 3'.
c. 3'ACU 5'.
d. either UCA or TCA, depending on wobble in the first base.
9. A possible sequence of nucleotides in the template strand of DNA that would code for the
polypeptide sequence phe-leu-ile-val would be
a. 5' TTG-CTA-CAG-TAG 3'.
b. 3' AAC-GAC-GUC-AUA 5'.
c. 5' AUG-CTG-CAG-TAT 3'.
d. 3' AAA-AAT-ATA-ACA 5'.
e. 3' AAA-GAA-TAA-CAA 5'.
10. Which of the following is NOT a potential control mechanism for gene regulation in eukaryotes?
a. Degradation of mRNA
b. Transcription initiation
c. Operon regulation
d. Gene amplification
11. The sequence of nucleotides in DNA codes for the production of proteins, and that code is carried
to the ribosome for translation as an mRNA molecule. Which of the following represents the
longest strand of nucleotide bases?
a. The gene for hemoglogin, a protein of 20 amino acids
b. The normal chloride channel protein gene associated with cystic fibrosis, which consists of 63
nucleotide bases
c. The mutated sickle cell form of the hemoglobin gene which has a single nucleotide base
substitution
d. The mutated cystic fibrosis mRNA which has a base insertion
12. The genetic code is essentially the same for all organisms. From this, one can logically assume
which of the following?
a. A gene from one organism can theoretically be expressed in another organism
b. All organisms have experienced convergent evolution
c. DNA was the first genetic material
d. Different organisms have different types of amino acids
13. A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of
the following might this illustrate?
a. The sequence does not mutate
b. Any mutation in the sequence has been selected against
c. The sequence is found in many, but not all, promoters
d. The sequence evolves very rapidly
Use the following model of a primary transcript to answer the following question:
5’UTR E1 I1 E2 I2 E3 I3 E4 UTR3’
14. What will be the structure of the mRNA found in the cytoplasm?
a. 5’UTR I1 I2 I3 UTR3’
b. 5’ E1 E2 E3 E4 3’
c. 5’UTR E1 E2 E3 E4 UTR3’
d. 51 I1 I2 I3 3’
15. a mutant bacterial strain has a defective aminoacyl tRNA synthetase that attaches a lysine to the
tRNA with the anticodon AAA, instead of the normal phenylalanine. The consequence of this for
the cell would be
a. none of the proteins in the cell would contain phenylalanine
b. proteins in the cell will include lysine instead of phenylalanine at amino acid positions
specified by the UUU codon
c. the ribosome will skip the UUU codon
d. the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysinespecifying codons
16. Suppose that a mutation alters a single tRNA such that it still attaches to the same amino acid (phe)
but its anticodon loop has the sequence AAU that binds the mRNA codon UUA which specifies
leucine (leu).
a. The modified tRNA will cause this mRNA to make a nonfunctioning product
b. The modified tRNA will be unable to enter the ribosome to bind to the UUA codon
c. One mutated tRNA will be inconsequential because there will many “normal” ones competing
d. Every leucine in the protein will have been replaced with a phenylalanine
17. Altering the patterns of gene expression in prokaryotes would most likely serve the organism’s
survival in which of the following ways?
a. Organizing gene expression so that the genes are expressed in a given order
b. Allowing each gene to be expressed an equal amount of time
c. Allowing the organisms to adjust to changes in environmental conditions
d. Allowing environmental changes to alter the prokaryote’s genome
18. If you were to observe the activity of methylated DNA, you would expect it to
a. Be replicating continuously
b. Be unwinding in preparation for transcription
c. Have turned off or slowed down the process of transcription
d. Be very actively transcribed and translated
19. Steroid hormones produce their effects in cells by
a. Activating key enzymes in metabolic pathways
b. Activating translation of certain mRNAs
c. Binding to intracellular receptors and promoting transcription of certain genes
d. Binding to cell surface receptors, inducing an amplification event, and promoting the
transcription of certain genes
20. Transcription factors in eukaryote usually have DNA binding domains as well as other domains
that are also specific for binding. In general, which of the following would you expect many of
these transcription factors to be able to bind?
a. Repressors
b. Protein-based hormones
c. Other transcription factors
d. ATP
21. At the beginning of the century there was a general announcement regarding the sequencing of the
human genome and the genomes of many other multicellular eukaryotes. There was surprise
expressed by many that the number of protein-coding sequences was much smaller than they had
expected. Which of the following could account for most of the rest?
a. Junk DNA that serves no purpose
b. rRNA and tRNA coding sequences
c. non-protein-coding DNA that is transcribed into several kinds of small RNAs with
biological function
d. DNA that is not transcribed or translated
22. One way scientists hope to use the recent knowledge gained about noncoding RNAs lies with the
possibilities for their use in medicine. Of the following scenarios for future research, which would you
expect to gain most from RNAs?
a. Exploring ways to turn on expression of pseudogenes
b. Targeting siRNAs to disable the expression of an allele associated with an
autosomal recessive disease
c. Targeting siRNAs to disable the expression of an allele associated with an
autosomal dominant disease
d. Creating knock-out organisms that can be useful in pharmaceutical drug design
23. The place on the mRNA that allows for the binding of the ribosome and the initiation of
translation, but is not translated, is called the
a. coding region
b. 5’ noncoding region
c. 3’ noncoding region
d. intron
Questions 24 and 25 refer to an experiment of lactose metabolizing bacteria. Changes in the amount of
lactose metabolizing enzymes and their corresponding mRNA and lactose were recorded
Lactose added
lactose removed
90
80
70
Amount
60
lactose
50
mRNA
40
lactase enzyme
30
20
10
0
0
20
40
60
80
100
Time
24. Which of the following is a correct inference based on the observed data in the experiment?
a. Proteins and mRNA have similar life spans in the cell
b. The mRNA is degraded slower than the lactase enzyme
c. Translation rate is not related to lactose concentration
d. Transcription precedes translation
25. Which of the following is the best hypothesis about the above experiment?
a. The control of enzyme production occurred at the translational level
b. Lactose was hydrolyzed into glucose and galactose in bacteria
c. mRNA production changed with the amount of lactose present
d. A repressor protein controls enzyme production
VERY SHORT SHORT ANSWERS (3 pts)
1. Briefly describe how the Hershey Chase experiment proved that DNA was the hereditary
molecule
2. Briefly describe how the Meselson Stahl experiment proved semiconservative replication
3. Briefly explain why DNA replication is continuous on the leading strand and discontinuous on
the lagging strand
4. Briefly describe the functions of the following in DNA replication:
a. Helicase
b. Single stranded binding proteins
c. Primase
d. DNA polymerase
e. Ligase
5. How do we know that gene expression is fundamentally the same in prokaryotes and
eukaryotes?
6. What is a codon? What is an anticodon? What is the relationship between them what is their
role in translation?
7. Briefly describe the 3 stages of transcription
8. Briefly describe how introns are removed
9. Briefly describe base substitution mutations and insertion /deletion mutations. Which group of
mutations is more deleterious?
10. Contrast the lac and trp operons
11. How can chromatin structure be changed in order to activate or silence genes?
12. What role do transcription factors play in eukaryotic gene transcription?
13. What os RNA interference and how does it affect gene expression?
14. If all diploid cells in an organism contain the same genome, what makes them behave
differently?
15. Explain the role of cytoplasmic determinants and induction in differentiation
16. What are proto-oncogenes?
17. What are the ways proto-oncogenes become mutated to oncogenes?
18. What happens to the cell cycle when a proto-oncogene becomes an oncogene?
19. Briefly describe the function of the normal Ras protein and its mutant.
20. What are tumor suppressor genes and what happens when they are mutated?
21. Briefly describe the function of normal p53 and its mutant