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1) Normally, the mold Neurospora can synthesize all 20 amino acids. A certain strain of this mold cannot gro in minimal nutritional medium but grows only when the amino acid leucine is added to the medium. This strain
A) is dependent on leucine for energy
B) has a mutation in the gene that encodes the enzyme that charges the leucine tRNA
C) has a mutation affecting the biochemical pathway leading to the synthesis of leucine
D) has a mutation in the gene that encodes the leucine tRNA
C) has a mutation affecting the biochemical pathway leading to the synthesis of leucine
2) Which statement exemplifies the (i) unambiguity and (ii) redundancy of the genetic code?
A) (i) UUU and UUC both code for Phe; (ii) UUU codes only for Phe.
B) (i) UUU codes only for Phe; (ii) UUU and UUC both code for Phe.
C) (i) UUU codes for both Phe and Ser; (ii) UUU and UUC both code for Phe and Ser.
D) (i) UUU and UUC both code for Phe and Ser; (ii) UUU codes for both Phe and Ser.
B) (i) UUU codes only for Phe; (ii) UUU and UUC both code for Phe.
3) In comparing DNA replication with RNA transcription in the same eukaryotic cell, only DNA replication ________.
A) uses RNA polymerase
B) makes a new molecule from its 5' end to its 3' end
C) occurs in the nucleus of the cell
D) incorporates the entire template molecule in the product
D) incorporates the entire template molecule in the product
4) Which of the following help(s) to stabilize mRNA by inhibiting its degradation?
A) 5' cap and poly (A) tail
B) introns
C) snRNPs
D) RNA polymerase
E) TATA box
A) 5' cap and poly (A) tail
5) A particular triplet of bases in the template strand of DNA is 5' GAT 3'. The corresponding codon in the RNA transcript is
A) 5' AUC 3'.
B) 5' CTA 3'.
C) 3' AUC 5'.
D) 5' UTA 3'.
A) 5' AUC 3'.
6) What molecules are responsible for the catalytic activity in the spliceosomes that are involved in removal of introns?
A) RNA polymerases
B) ribonucleases
C) invertases
D) ribozymes
E) ligases
D) ribozymes
7) Which of the following statements regarding translation is false?
A) During codon recognition, the incoming tRNA anticodon base-pairs with the mRNA codon in the A site.
B) During peptide bond formation, the amino acids attached to the tRNA in the P site are covalently joined to the A-site amino acid.
C) When a stop codon enters the A site, release factors disconnect the newly synthesized polypeptide from the tRNA, and translation is terminated.
D) After translocation, the tRNA containing the growing peptide is in the E site.
D) After translocation, the tRNA containing the growing peptide is in the E site.
8) A ribosome has made a tri-peptide, MET-ARG-SER, which is attached to the tRNA in the P site. The codon in the E site is ____________ and the codon in the A site _______________
A) AUG..........CGU
B) CGU.........can not be determined
C) UCA..........AUG
D) UGA..........CGU
B) CGU.........can not be determined
9) A charged tRNA is really the link between the mRNA and the newly synthesized protein. Which of the following statements best describes a charged tRNA?
A) The charged tRNA contains the amino acid that is complementary to the codon, once the amino acid is matched to the codon it is added to the growing peptide chain.
B) The charged tRNA contains the anticodon that is complementary to the codon and once it is matched to the codon, it recruits aminoacyl tRNA synthetase to add the correct amino acid to the growing peptide chain
C) The charged tRNA contains the anticodon that is complementary to the codon and it carries the appropriate amino acid, once the tRNA is matched with the codon the entire tRNA is added to the growing peptide chain.
D) The charged tRNA contains the anticodon that is complementary to the codon and it carries the appropriate amino acid, once the tRNA is matched with the codon the amino acid is added to the growing peptide chain.
D) The charged tRNA contains the anticodon that is complementary to the codon and it carries the appropriate amino acid, once the tRNA is matched with the codon the amino acid is added to the growing peptide chain.
10) Cells are able to distinguish proteins destined for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because __________.
A) some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER
B) there are two types of ribosomes: one group that synthesizes cytoplasmic proteins only, and another type that synthesizes secreted or compartment-specific proteins only
C) each compartment in the cell (the nucleus, lysosome, and so forth) has its own set of ribosomes that synthesize proteins unique to that compartment
D) proteins destined for secretion or for a specific compartment are all synthesized in the nucleus, whereas cytoplasmic proteins are all synthesized in the cytoplasm
A) some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER
11) A gene known as BRCA-1 is associated with an inherited susceptibility to breast and ovarian cancer. In 75% of the families, the mutant BRCA-1 allele produces a protein that is shorter (fewer amino acids) than the protein product of the normal BRCA-1 allele. This is most likely the result of
A) translocation
B) recombination
C) nondisjunction
D) a missense mutation
E) a nonsense mutation
F) a silent mutation
E) a nonsense mutation
12) A mistake is made during DNA replication, so there is incorrect base pairing in the DNA. Depending on how the replication repair mechanism fixes this problem, a point mutation may or may not result. What might the replication repair mechanism do, and would it result in a point mutation?
A) The repair mechanism might replace the T with a C, which would result in a point mutation.
B) The repair mechanism might replace the G with an A, which would result in a point mutation.
C) The repair mechanism might replace the G with a C, which would result in a point mutation.
D) The repair mechanism might replace the T with a G, which would not result in a point mutation.
B) The repair mechanism might replace the G with an A, which would result in a point mutation.
13) A student was asked the following question:
“The following DNA sequence occurs near the middle of the coding region of a gene.
DNA: 5' A A T G A A T G G* G A G C C T G A A G G A 3'
There is a G to A base change at the position marked with an asterisk. Consequently, a codon
normally encoding an amino acid becomes a stop codon. How will this alteration influence
Transcription?” The student responded with the following: “When the transcription process reaches a stop codon, transcription will end, causing a shorter mRNA” How would you re-word this statement to more accurately describe the effect of this mutation?
A) When the RNA polymerase reaches the nucleotides that code for a stop codon, it will not be affected by the base pair change and transcription will proceed normally.
B) When the transcription machinery reaches that stop codon, transcription will end, causing a shorter mRNA and protein.
C) When the transcription process reaches that stop codon, transcription will terminate early, resulting in a shorter protein.
D) This statement is accurate as written.
A) When the RNA polymerase reaches the nucleotides that code for a stop codon, it will not be affected by the base pair change and transcription will proceed normally.
14) Below are two different mutations of a DNA sequence in a eukaryotic organism.
First mutation: Original DNA sequence (coding strand), starting at the beginning of the coding region of the gene:
Normal: ATGATCTTCCTAAAGTAA
Mutation: TTGATCTTCCTAAAGTAA
Second mutation: Original DNA sequence (coding strand), starting at the beginning of the coding region of the gene:
Normal: ATGATCTTCCTAAAGTAA
Mutation: ATGATCTTCCTATAGTAA
In the sequences above (that show mutations in underline), which mutation would stop DNA replication?
A) Only the first mutation
B) Only the second mutation
C) Both
D) Neither
D) Neither
15) Extracellular glucose inhibits transcription of the lac operon by ________.
A) inhibiting RNA polymerase from opening the strands of DNA to initiate transcription.
B) strengthening the binding of the repressor to the operator.
C) reducing the levels of intracellular cAMP.
D) activating adenylyl cyclase.
E) weakening the binding of the repressor to the operator.
C) reducing the levels of intracellular cAMP.
16) Although the expression of most bacterial genes is tightly regulated, some genes are expressed at roughly constant rates (i.e., constitutively). Which of the following genes would you predict to be constitutively expressed?
A) genes that code for ribosomal RNAs
B) genes involved in the degradation of tryptophan
C) genes involved in the biosynthesis of the amino acid tryptophan
D) genes involved in the transport of the sugar maltose
E) genes involved in the degradation of arabinose, a sugar
A) genes that code for ribosomal RNAs
17) The tryptophan operator
A) binds to the tryptophan repressor when the repressor is bound to tryptophan
B) is an allosteric protein
C) is required for production of the mRNA encoded by the tryptophan operon
D) is important for the production of the tryptophan repressor
A) binds to the tryptophan repressor when the repressor is bound to tryptophan
18) You have inserted the gene for human growth factor into the E. coli lactose operon, replacing the structural genes with the gene for human growth factor. What substance must you add to your culture of bacteria to cause them to produce human growth factor for you?
A) allolactose
B) human growth factor
C) lac repressor protein
D) lac operator protein
A) allolactose
19) Typically, acetylation of histone tails leads to ________.
A) the repressor protein detaching from the operator
B) relaxed packaging of the chromatin and increased transcription
C) tighter packaging of the chromatin and reduced transcription
D) activation of origins of replication
E) activation of topoisomerase
B) relaxed packaging of the chromatin and increased transcription
20) In the structural organization of many eukaryotic genes, individual exons may be related to which of the following?
A) the various domains of the polypeptide product
B) the number of single nucleotide polymorphisms in the gene.
C) the number of polypeptides making up the functional protein
D) the number of start sites for transcription
E) the sequence of the intron that immediately precedes each exon
A) the various domains of the polypeptide product
21) During an experiment assessing the development of a fly embryo, a scientist artificially turns on a homeotic gene that controls eye development in somatic cells that develop into the wings. Which of the following is the most likely outcome of this experiment?
A) A normal adult fly will develop.
B) A mutant adult fly will develop that has eyes on its wings.
C) A mutant adult fly will develop that has legs on its head.
D) A mutant adult fly will develop that has no eyes on its head but has eyes on its wings.
B) A mutant adult fly will develop that has eyes on its wings.
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 noncoding RNAs?
A) targeting siRNAs to disable the expression of an allele associated with autosomal recessive disease
B) targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease
C) creating knock-out organisms that can be useful for pharmaceutical drug design
D) looking for a way to prevent viral DNA from replicating
B) targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease
23) A protein that can stimulate transcription by binding to a DNA sequence that is located far away from the promoter is called a(n)
A) operator
B) modifier
C) enhancer
D) activator
E) inducer
E) inducer
24) Proteasomes..
A) degrade proteins that have been ubiquitylated.
B) bring secretory proteins to the endoplasmic reticulum.
C) are required for newly synthesized proteins to assume their proper conformation (three dimensional
shape).
D) guide mRNAs to the ribosome.
E) are required for RNA processing.
A) degrade proteins that have been ubiquitylated.
25) Communication within and between cells of an embryo can include all of the following except ________.
A) changes in gene transcription.
B) increased concentration of signaling molecules.
C) changes in binding to regulatory sequences.
D) alterations in DNA sequences
D) alterations in DNA sequences
26) In Drosophila, the protein bicoid
A) increases the metabolic activity of the embryo.
B) is required for the fusion of sperm and egg nuclei.
C) determines the sex of the embryo.
D) determines the anterior-posterior axis of the embryo.
E) is required for the onset of gastrulation in the embryo.
D) determines the anterior-posterior axis of the embryo.
27) Which of the following viruses would be the most likely to have reverse transcriptase?
A) an RNA-based lysogenic virus
B) a DNA-based lysogenic virus
C) an RNA-based lytic virus
D) a DNA-based lytic virus
A) an RNA-based lysogenic virus
28) Regarding COVID, which is false?
A) All of the structural proteins arise from an mRNA transcript which is cleaved by nucleases.
B) The COVID genome encodes non-structural proteins such as enzymes, structural proteins such as the spike protein, and accessory proteins that make viral replication easier
C) The viral spike protein binds to the human receptor protein ACE2
D) Some of the COVID vaccines contain the mRNA that encodes the viral spike protein.
A) All of the structural proteins arise from an mRNA transcript which is cleaved by nucleases.
29) Which of the following statements is false?
A) All viruses contain a protein coat called a capsid
B) The capsid proteins are encoded for in the viral genome
C) The protein subunits that spontaneously assemble to form the capsid are called capsomeres.
D) Some viruses contain an envelope composed of a phospholipid bilayer containing viral proteins and glycoproteins.
E) The envelope is wrapped around the viral genome, and the capsid is wrapped around the envelope.
E) The envelope is wrapped around the viral genome, and the capsid is wrapped around the envelope.
30) In a single PCR cycle consisting of 30 seconds at 95°C, 30 seconds at 55°C, and 30 seconds at 72°C, what is happening during the 55°C step?
A) DNA polymerase is being inactivated.
B) Primers are being denatured.
C) The DNA to be amplified is being denatured.
D) Primers are annealing to the DNA
E) DNA polymerase is extending new DNA from the primers.
D) Primers are annealing to the DNA
31) The fact that plants can be cloned from adult somatic cells suggests that
A) differentiated cells retain all of the genes that were present in the zygote
B) differentiation does not occur in plants
C) genes are lost during differentiation
D) differentiated cells contain cytoplasmic determinants
E) the differentiated state is normally very stable
A) differentiated cells retain all of the genes that were present in the zygote
32) Genetic engineering has been used to create plants that are
A) resistant to insects
B) resistant to herbicides
C) resistant to frost or salinity
D) all of the above
D) all of the above
33) Determining the genomic sequence of a lower eukaryotic multicellular organism, such as a roundworm or a fruit fly, is most important because
A) it allows researchers to use the sequence to build a "better" roundworm or fruit fly, resistant to disease.
B) It allows research on a group of organisms we do not usually care much about.
C) a sequence that is found to have a particular function in the roundworm or fruit fly is likely to have a closely related function in vertebrates (humans).
D) the roundworm and the fruit fly are good animal models for trying out cures for viral illness.
C) a sequence that is found to have a particular function in the roundworm or fruit fly is likely to have a closely related function in vertebrates (humans).
34) A current view of how the human and chimpanzee can share most of their nucleotide sequence yet exhibit significant phenotypic differences is that some of the most rapidly evolving sequences encode
A) regulatory RNAs and regulatory proteins.
B) tRNAs
C) repeat sequences.
D) structural proteins
E) transposable elements
A) regulatory RNAs and regulatory proteins.
35) Cholera is an intestinal disease that causes rapid dehydration and death if not treated. Potatoes have been engineered to produce proteins from the bacteria that causes cholera. This is an example of using genetic engineering to
A) produce vaccines
B) produce dangerous organisms.
C) produce cholera-resistant potatoes.
D) enhance economically important species.
A) produce vaccines
36) Regarding CRISPR-Cas9, and gene editing, which of the following is true?
A) The function of the Cas 9 enzyme is to cut DNA molecules
B) The function of the guide RNA is to direct the Cas 9 enzyme to its target DNA
C) CRISPR-Cas9 is naturally occurring anti-viral defense mechanism in prokaryotes
D) The CRISPR-Cas9 technology can now be used to "edit" a gene, such that a mutant sequence is removed and replaced with the wild type sequence.
E) all of the above are true.
E) all of the above are true.
