Biology 121 – Molecular Cell Biology
Fall 2011 - Exam 1
Version 2
Name: _______________________________
1. In order for mRNA synthesis to take place, which of the following is absolutely essential?
a. A promoter
b. An RNA polymerase
c. General transcription factors (or TFII’s)
d. Both b and c
e. All of the above
2. How does a cell deal with misfolded proteins?
a. They’re ubiquitinated and taken to the proteosome to be digested.
b. They get refolded, but only in the endoplasmic reticulum.
c. Chaperones ensure that misfolding never occurs; except when it is done intentionally for a number of
reasons.
d. The misfolded domain of the protein is truncated, but the rest is usable.
e. None of the above
3. Why are viruses not considered alive by many scientists?
a. They do not possess genes
b. They do not evolve by natural selection
c. They do no metabolize
d. They are not organized
e. All of the above
4. Where does protein synthesis take place?
a. In the cytosol
b. In the mitochondrial lumen
c. In the endoplasmic reticulum lumen
d. Both a and b
e. All of the above
5. What determines the total cell mass of an organism?
a. The size and total of number of their cells
b. The complexity of the genome
c. The complexity of the organ system
d. The complexity of the signaling system
e. The complexity of the extracellular matrix
6. What does not lead to the formation of new genes in a genome?
a. Synthesis of new genes by the organism
b. Accidents or mistakes in the sequence followed by non-random survival
c. Gene duplication
d. DNA Shuffling
e. Transposable elements
7. Currently, how are living organisms classified?
a. By Kingdoms: Archaea, Protista, Animalia, Plantae, Fungi
b. By Kingdoms: Archaea, Prokaryotes, Animalia, Plantae, Fungi
c. By Kingdoms: Archaea, Bacteria, Animalia, Plantae, Fungi
d. By Domains: Archaea, Bacteria, Eukaryotes
e. By Domains: Archaea, Fungi, Eukaryotes
8. Which of the following statements is true?
a. Most of the cellular species on Earth have been identified and named.
b. Most of the cellular species that have been identified and named are vertebrates.
c. Bacteria constitute a very small fraction of the total cellular species on Earth.
d. Only a small fraction of cellular species on Earth has been identified and named.
e. Only a small fraction of cellular species on Earth remains unidentified.
9. What is the function of an Internal Ribosome Entry Sequence?
a. To allow the ribosome to enter the cytosol from the nucleus
b. To allow the ribosome to enter the cytosol from the endoplasmic reticulum
c. To alter the initiation of translation when the cell encounters the lack of nutrients and/or oxygen
d. To allow a cell an alternative place for the initiation of translation to occur
10. What is the difference between the exoskeleton of a lobster and that of caterpillar?
a. One is made up of chitin and the other is not.
b. Both are made up of chitin, but one is modified by being encrusted in calcium carbonate.
c. One is made up of chitin and the other is made up of keratin encrusted in calcium carbonate.
d. One is an extracellular matrix and the other is an intracellular matrix.
e. There is no difference because both are made up of the exact same material.
11. How does the formation of heterochromatin affect the expression of a gene?
a. The dense packing of heterochromatin makes it difficult to express genetic information coded in
these regions.
b. The loose packing of heterochromatin makes it difficult to express genetic information coded in these
regions.
c. The TATA box is typically not found in DNA segments found within a heterochromatin.
d. Heterochromatin is degraded so that the cell can reduce the number of errors it makes in expression
e. Very few genes within heterochromatin are inactive, most are expressed normally.
12. Which of the following statements about transcription is true?
a. The RNA template strand is read from 5’ to 3’ so that RNA synthesis can occur in the 5’ to 3’ direction.
b. The DNA template strand is read from 5’ to 3’ so that RNA synthesis can occur in the 5’ to 3’
direction.
c. The RNA template strand is read from 3’ to 5’ so that RNA synthesis can occur in the 5’ to 3’ direction.
d. The DNA template strand is read from 3’ to 5’ so that RNA synthesis can occur in the 5’ to 3’
direction
e. The RNA template strand is read from 3’ to 5’ so that protein synthesis can occur in the 5’ to 3’
direction.
13. Which of the following is not a basic feature of all cells?
a. Possessing more than one type of cell membrane
b. Ability to sense and respond to the environment
c. Double-stranded DNA, RNA, and proteins
d. Carrying out metabolic processes
e. Possessing a cytosol
14. Which of the following is not involved in alternative RNA splicing?
a. More than one protein may be expressed from the same gene.
b. More than one mRNA molecule may be expressed from the same gene.
c. May involve the use of alternative (or cryptic) splice sites.
d. A portion of some exons may be removed, but never the whole exon.
e. Both a and d
15. Which of the following statements about TF II’s and tissue-specific transcription factors is
true?
a. They’re both uniquely specific to the cell type that expresses them.
b. They perform their function in the cytosol.
c. Both are involved in positive feedback regulation of their own expression
d. Both must bind to consensus sequences found in the DNA to regulate the initiation of transcription.
e. Both c and d
16. Which of the following may result if polyadenylation does not occur?
a. Transport of the mature mRNA to the cytosol may still occur only if the Cap at the 5’-end is present.
b. An mRNA molecule corresponding to only one gene will be synthesized.
c. Termination of transcription occurs where the gene ends.
d. RNA polymerase II can continue to catalyze RNA synthesis indefinitely or until the end of the DNA
is reached.
e. The half-life of the mRNA molecule is increased.
17. Which of the following is not a feature found in the 5’-UTR of an mRNA molecule?
a. A cap
b. A promoter
c. An internal ribosomal entry sequence
d. A binding site for the small ribosomal subunit
e. None of the above
18. Which of the following allows a eukaryotic cell to regulate which of the genes in its genome it
will express?
a. Regulation of protein methylation allows RNA remodeling
b. Glycosylation of the DNA allows promoter accessibility.
c. Transcription factors regulate promoter activation.
d. The spliceosome regulates protein folding.
e. Eukaryotes regulate gene expression through repressors and activators.
19. Which of the following contributes to the complexity of the human genome (compared to lower
order animals)?
a. Higher amount of regulatory regions
b. Higher total number of genes
c. Larger genome
d. The amount of coding region in the exons
e. The amount of noncoding region in the exons
20. What is the most common source of DNA mutation?
a. DNA replication
b. UV radiation from the sun, especially for sunbathers
c. Smoking
d. Reactive oxygen species
e. Point mutation
21. Which of the following statement is true about polypeptide synthesis?
a. The mRNA template is read from 5’ to 3’ so that polypeptide synthesis can occur 3’ to 5’
b. The mRNA template is read from 3’ to 5’ so that polypeptide synthesis can occur 5’ to 3’
c. The mRNA template is read from 5’ to 3’ so that polypeptide synthesis can occur in the amino- to
carboxy-terminus direction.
d. The mRNA template is read from 3’ to 5’ so that polypeptide synthesis can occur in the amino- to
carboxy-terminus direction.
e. The mRNA template is read from 3’ to 5’ so that polypeptide synthesis can occur in the carboxy- to
amino-terminus direction.
22. Which of the following is not involved in cell to cell communication?
a. Histone proteins
b. Membrane receptors
c. Ligands
d. The bloodstream
e. None of the above
23. What molecules that are part of the spliceosome allow it to choose the appropriate cell specific
exons?
a. Splicing enhancers
b. Small nuclear riboproteins
c. Alternative splice sites
d. Micro RNAs
e. All of the above are possible depending on the type of cell.
24. Name the parenchymal cell from the list below.
a. Endothelial cell in the liver
b. Fibroblast in the heart
c. Epithelial cell in the skin
d. All of the above
e. None of the above
25. What must occur during standard initiation of translation?
a. Initiation factors must bind to the 5’ Cap of mRNA.
b. Initiation factors must bind to the Poly-A tail of mRNA.
c. The small ribosomal RNA must scan the 5'-UTR of mRNA for UAG.
d. The whole ribosome must scan the 5'-UTR of mRNA for UAG.
e. Both a and b
26. Which of the following is not a co-translational event?
a. Transport of the polypeptide strand into the ER lumen
b. Addition of a lipid residue
c. Protein folding
d. Isomerization of disulfide linkages
e. None of the above
27. Which of the following is true about the primary structure of protein?
a. The primary structure is determined by inherited genetic information.
b. The primary structure determines the repetitive folding of the secondary structure.
c. The primary structure directly determines the quaternary structure of protein.
d. Both a and b
e. All of the above
28. Which of the following is true about the maintenance of the extracellular matrix (ECM)?
a. The cell secretes ECM proteins only as the result of an injury to the connective tissue.
b. The density of the ECM depends solely on the space that is occupied by the cell itself.
c. In many organisms, the ECM is based on sugars supported by proteins and inorganic molecules
d. Secretion and degradation of ECM materials are not regulated.
e. All of the above
29. Which of the following are functions of the covalent modification of histones?
a. Telling the cell to condense the DNA into the heterochromatin structure
b. Telling the cell to express this stretch of DNA
c. Telling the cell that the DNA is undamaged and normal
d. Both a and b
e. Both b and c
30. Which of the following is not a post-translational event?
a. Transport of the polypeptide strand into the ER lumen
b. Acetylation
c. Truncation (or proteolytic modification)
d. Formation of a polymer protein
e. None of the above
31. Which of the following statements about the evolution of organisms is most true?
a. Environmental changes directly affect the evolution of a species.
b. DNA replication is error-prone and, therefore, is the major contributor to the evolution of organisms.
c. A species chooses to evolve a certain way to accommodate environmental changes.
d. DNA repair reduces the amount of DNA mutations, therefore, contributes to the evolution of
organisms.
e. None of the above
32. Which of the following statements is not true about transposons?
a. “Parasitic” DNA sequences that are known to have arisen from viruses
b. Can disrupt gene function
c. Can create new genes by integration within and fusion with host gene segments
d. Half of all human DNA has homology to known transposons
e. 10% of currently occurring mouse mutations are transposon-driven
33. The least common cause(s) of variation in human genetics is?
a. Independent assortment of chromosomes
b. Random gamete contribution to fertilization
c. Cross over of chromosomes during meiosis
d. Environmental mutation
e. None of the above
34. Which of the following could not contribute to the production of gene families?
a. Transposable element movement
b. Gene duplication
c. Horizontal transfer of genes
d. DNA shuffling
e. All are capable of contributing
35. A function of a spliceosome is to __________.
a. Remove introns from the DNA template in the nucleus
b. Remove some exons from the nuclear RNA molecule in the nucleus
c. Remove introns from the mature mRNA molecule in the cytosol
d. Remove some exons from the mature mRNA molecule in the cytosol
e. Remove some exons from the nuclear RNA molecule in the cytosol
36. What is the function of selective degradation of RNA?
a. To prevent the translation of damaged RNA in the cytosol
b. To prevent the export of mRNAs that contain intronic RNA from the nucleus
c. To prevent the export of incompletely synthesized RNA from the nucleus
d. To prevent the translation of unwanted RNA in the cytosol
e. All of the above
Use the figure above to answer the following two questions (37 and 38).
37. In order for endocrine cell A to communicate with target cell C’, what must occur?
a. Target cell C’ must synthesize a receptor that can specifically recognize a signaling molecule from
cell A.
b. Endocrine cell A must be a different kind of cell than target cell C’.
c. Endocrine cell A must be a neuron.
d. Both a and b
e. Both b and c
38. Which of the following statements is true?
a. Endocrine cell B and target cell B’ must possess a similar pattern of gene expression for them to
communicate.
b. All cells that receive the same signal from endocrine cell A will respond in the same way
c. An intercellular communication system may be considered to be both endocrine signaling and paracrine
signaling if the signaling cell and target cell are in the same vicinity within a tissue.
d. This communication system cannot occur without the bloodstream.
e. All of the above
39. Why is the rate of DNA mutation so low when DNA replication is so error-prone (i.e. makes a
lot of mistakes)?
a. Proofreading mechanisms can reduce the amount of mutations produced during DNA replication.
b. Organisms cannot survive errors in replication and any errors are removed from the genome
c. DNA repair systems can greatly reduce the amount of mutations produced during DNA replication.
d. Both a and c
e. All of the above
40. Which of the following is not a function of RNA polymerase II?
a. Unwinding DNA
b. Matching nucleic acid bases
c. Polymerizing nucleic acid bases
d. Synthesizing mRNA
e. Synthesizing tRNA
The figure above represents one strand of DNA. Use it to answer the following three questions (41-43).
41. Which of the following statements is true about transcription?
a. Tissue specific transcription factors may only bind the upstream promoter region
b. The mRNA 3’-UTR extends to the transcription termination sequence of the DNA template
c. The TATA box is bound by a TF (II) to recruit RNA polymerase II.
d. Tissue-specific transcription factor binding to upstream promoter regions recruits RNA polymerase II.
e. Both a and d
42. Which of the following statements is true about translation of the mRNA encoded by this
DNA?
a. If present in this particular mRNA, the IRES will be found in exon 1.
b. Amino acid 1 will be a tryptophan
c. The mRNA encoded for is able to make a polypeptide that contains more than 146 amino acids
d. The entire exon 3 region is used to express the carboxy-terminus of the polypeptide.
e. None of the above
43. Which of the following statements is true about transcriptional and translational processing?
a. The nuclear RNA sequence contains only exon 1, exon 2, and exon 3 without introns 1 or 2.
b. The spliceosome can produce an mRNA containing all three exons.
c. To transport the mRNA into the cytosol, a Cap must be added to the 5’-end during splicing.
d. In the mature mRNA, the promoter sequence is found upstream from the 5’-UTR.
e. All of the above
44. Which of the following statements supports the concept of gene conservation?
a. If the function is essential and unchanged, then the structure must be unchanged.
b. High sequence homology between genes in two organisms means that the genes perform the same
function using the same mechanism.
c. All cells from bacteria to humans have extremely high sequence homology in the small ribosomal subunit because they use the same mechanism to express DNA.
d. Both a and c
e. All of the above
45. List the four primary components of all signaling systems in multicellular organisms, in order
of activity?
a. Ligand, receptor, second messenger cascade, target mechanisms
b. Ligand, plasma membrane, second messenger cascade, target mechanisms
c. Signaling cell, bloodstream, membrane receptor, target cell
d. Contact-dependent signaling, paracrine signaling, endocrine signaling, synaptic signaling
e. Ligand, receptor, second messenger cascade, signal transduction pathway
46. Which of the following directly causes DNA mutation?
a. Ionizing radiation
b. Smoking
c. Reactive oxygen species (ROS)
d. Erroneous repair
47. Which of the following is true about proteins expressed from the nuclear genome?
a. Translation may occur either in the nucleus or the cytosol
b. Modification of a protein must occur after the termination of translation.
c. Proper folding is a post-translational modification.
d. All proteins must undergo post-translational modification.
48. Eukaryotic DNA differs from prokaryotic in which of the following ways?
a. Prokaryotic chromosomes are linear DNA molecules
b. Eukaryotes have more than one location for DNA
c. Prokaryotic chromosomes are 50% protein
d. Eukaryotic chromosome number is constant across species
e. All of the above
49. Which of the following is not programmed cell death?
a. Necrosis
b. Autophagy
c. Apoptosis
d. Cornification
e. Anoikis
50. How come all of a cell’s mitotic descendents don’t have to repeat its process of selecting which
genes to express from its genome?
a. Trithorax proteins bind to open nucleosomes and keep them open.
b. Polycomb proteins methylate uneeded nucleosomes and then bind to them to keep them tight.
c. Perpetuating methyltransferase copies parent strand methylation patterns
d. Positive feedback loops from transcription factors on their own expression
e. All of the above