Molecular Biology and Genetics, Exams of Biology

Download Molecular Biology and Genetics and more Exams Biology in PDF only on Docsity! Bio 340 Final Exam With 100% Correct Answers 2024 Success Assured How many chromatids (total) are in a cell with diploid number of 4 (2n = 4) if it is in G2? A. 4 B. 2 C. 6 D. 8 E. 16 - correct answer✔✔ D. 8 At which points in the cell cycle do you not see chromosomes, but only uncondensed DNA? A. During Gap 1 when proteins for cell growth are being manufactured B. During Synthesis when DNA is replicated C. During Gap 2 when protein microtubules for the spindle fibers are being made D. During G0 when the cell is quiescent E. During all of the above - correct answer✔✔ E. During all of the above In a 2n = 6 organism, how many chromatids are present in each individual cell immediately at the end of meiosis? A. 1 B. 2 C. 3 D. 4 E. 6 - correct answer✔✔ C. 3 In a 2n = 6 organism, how many chromatids are present in each individual cell at prophase II? A. 1 B. 2 C. 3 D. 4 E. 6 - correct answer✔✔ E. 6 In a 2n = 6 organism, are the cells haploid or diploid at prophase II? A. Haploid B. Diploid - correct answer✔✔ A. Haploid What strategies were helpful when Gregor Mendel studied patterns of inheritance? I. Study an organism with a long generation time II. Study an organism with few offspring per generation III. Focus on many traits at a time IV. Look at discontinuous traits A. Only I B. Only III C. Only IV D. All of these E. None of these - correct answer✔✔ C. Only IV In guinea pigs coat color is determined by a single gene with two alleles. A guinea pig from a true- breeding black strain is mated with a guinea pig from a true-breeding white strain. The F1 progeny are all black. Two of the F1 progeny are mated with each other. What proportion of the F2 progeny is expected to be white? D. 3/4 E. 9/16 - correct answer✔✔ D. 3/4 In a dihybrid cross (yellow, round x yellow, round), what proportion of the F2 offspring will be both heterozygous for the color gene and homozygous dominant for the shape gene? A. 1/8 B. 3/16 C. 1/4 D. 3/4 E. 9/16 - correct answer✔✔ A. 1/8 In a tetrahybrid cross, a plant of the genotype AaBbCcDd is crossed to itself. What is the probability of obtaining the phenotype "AbcD" in the offspring? A. 1/8 B. 1/32 C. 9/256 D. 3/64 E. 1/64 - correct answer✔✔ C. 9/256 In a tetrahybrid cross, a plant of the genotype AaBbCcDd is crossed to itself. What is the probability of obtaining the genotype AaBbCCDd in the offspring? A. 1/8 B. 1/32 C. 1/4 D. 3/16 E. 1/64 - correct answer✔✔ B/ 1/32 In a tetrahybrid cross, a plant of the genotype AaBbCcDd is crossed to itself. What is the probability of obtaining the genotype AABbCcdd in the offspring? A. 1/8 B. 1/32 C. 1/4 D. 3/16 E. 1/64 - correct answer✔✔ E. 1/64 How many autosomes do humans have? A. 22 pairs B. 16 C. 46 D. 23 pairs E. Depends on gender - correct answer✔✔ A. 22 pairs A geneticist is studying flower-color mutations in petunias. He finds two recessive mutants that have white flowers, rather than the wildtype purple. He crosses a homozygote for the first mutation with a homozygote for the second mutation. All the offspring have white flowers. Which of the following offspring is the best way to write the genotype of these offspring? A. Aa B. aa C. a1a1 D. a1a2 E. Aa1Bb1 - correct answer✔✔ D. a1a2 Snapdragons show incomplete dominance of red and white flower coloration, demonstrated by crossing an R1/R1 red flowered plant and an R2/R2 white flowered plant, producing pink offspring. Suppose the gene interaction was instead codominance, what could be a possible offspring phenotype in this cross? A. All red flowers B. Red and white flowers in a 3:1 ratio C. All red flowers with white spots D. All pink flowers - correct answer✔✔ C. All red flowers with white spots A portion of one strand of DNA has the sequence 5' AATGGCTTA 3' What is the sequence of the other strand? A. 3' TTACCGAAT 5' B. 5' TAAGCCATT 3' C. 3' AATGGCTTA 5' D. 5' AATGGCTTA 3' - correct answer✔✔ A. 3' TTACCGAAT 5' and B. 5' TAAGCCATT 3' Each of the four DNA molecules below is gradually heated. Which molecule will melt (denature) last? A. 5' ATATCGATTA 3' 3' TATAGCTAAT 5' B. 5' ACGGATGCAC 3' 3' TGCCTACGTG 5' C. 5' GCGCCCGGCG 3' 3' CGCGGGCCGC 5' D. 5' CGCCGGATGC 3' 3' GCGGCCTACG 5' - correct answer✔✔ C. 5'GCGCCCGGCG3' 3'CGCGGGCCGC5' Which of the following describes the second transesterification reaction in nuclear mRNA splicing? A. Joining the 3' end of exon 1 to the 5' end of exon 2 B. Joining the 3' end of exon 1 to the branch site A C. Joining the 3' end of the intron to the branch site A D. Joining the 5' end of the intron to the branch site A E. Joining the 5' end of exon 2 to the branch site A - correct answer✔✔ A. Joining the 3' end of exon 1 to the 5' end of exon 2 Which of the following types of RNA is found exclusively in eukaryotic cells? A. mRNA B. rRNA C. tRNA D. snRNA - correct answer✔✔ D. snRNA Which of the following statements is NOT true regarding transcription in prokaryotes vs eukaryotes? A. Transcription initiation requires a sigma factor in prokaryotes and general transcription factors in eukaryotes B. Transcription termination can involve a stem-loop structure in prokaryotes and an RNase enzyme in eukaryotes C. Transcription involves making an RNA copy of a DNA sequence in both prokaryotes and eukaryotes D. Transcription requires a promoter sequence in prokaryotes but not in eukaryotes - correct answer✔✔ D. Transcription requires a promoter sequence in prokaryotes but not in eukaryotes Which of the following functions are associated with the carboxy terminal domain (CTD) of eukaryotic RNA polymerase II? A. 5' capping B. Polyadenylation C. Splicing D. Termination E. All of the above - correct answer✔✔ E. All of the above In eukaryotes, which of the following is true about introns and exons? A. The mature mRNA transcript contains a mix of introns and exons B. The primary RNA transcript contains both introns and exons C. Exons are repeating sequences that are typically found at the ends of a chromosome D. The mature mRNA transcript only contains the introns because the exons have been spliced out - correct answer✔✔ B. The primary RNA transcript contains both introns and exons Which of the following statements regarding mRNA information and orientation is true? A. The amino terminus of a polypeptide is encoded toward the 5' end of the mRNA B. The carboxy terminus of a polypeptide is encoded toward the 5' end of the mRNA C. The amino terminus of a polypeptide is encoded toward the 3' end of the mRNA D. The amino terminus of a polypeptide is encoded in the 5' UTR E. The carboxy terminus of a polypeptide is encoded in the 5' UTR - correct answer✔✔ A. The amino terminus of a polypeptide is encoded toward the 5' end of the mRNA Given this section of an mRNA molecule 5' AUGUUACCA 3' (use the genetic code), determine the amino acid sequence of the translated polypeptide. A. His-Thr-Arg B. Met-Leu-Pro C. Ala-Gly-Asp D. Phe-Ile-Val - correct answer✔✔ B. Met-Leu-Pro What is the sequence of the mRNA molecule that encodes the following peptide (use genetic code): N - Met-Leu-Pro - C A. 5' AUGUUACCA 3' B. 5' AUGCUCCCG 3' C. 5' AUGUUGCCC 3' D. 5' AUGCUACCU 3' E. 5' AUGCUGCCA 3' - correct answer✔✔ All are correct possible answers A portion of mRNA attached to a ribosome reads: 5' GACCAUUUUUGA 3' In the polypeptide produced, what amino acid will be attached to the amino group of the histidine encoded by this mRNA (use genetic code)? A. Aspartic acid (Asp) B. Proline (Pro) C. Serine (Ser) D. Phenylalanine (Phe) E. Tyrosine (Tyr) - correct answer✔✔ A. Aspartic acid (Asp) What is the function of the Shine-Dalgarno sequence? A. Base-pairing with the mRNA to align the preinitiation complex at the start codon B. Specification of the transcription initiation site in bacteria C. Specification of the transcription initiation site in eukaryotes D. Specification of the authentic start codon in bacterial mRNA E. Specification of the authentic start codon in eukaryotic mRNA - correct answer✔✔ D. Specification of the authentic start codon in bacterial mRNA For a gene under positive control, which of the following would prevent transcription? A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor - correct answer✔✔ E. Inhibitor For a gene under negative control, which of the following would you expect to find bound to the repressor if there is active transcription? A. Repressor B. Corepressor C. Inducer D. Effector E. Inhibitor - correct answer✔✔ C. Inducer Which molecule serves as the inducer for the lac operon? A. cAMP B. Glucose C. Lactose D. Allolactose - correct answer✔✔ D. Allolactose Which of the following conditions will result in the greatest levels of transcription of the lac operon? A. Lactose absent, glucose absent B. Lactose absent, glucose present C. Lactose present, glucose present D. Lactose present, glucose absent - correct answer✔✔ D. Lactose present, glucose absent Which of the following mutations will result in the lowest level of transcription of the lac operon when lactose is present? A. An operator mutation that prevents binding of the lac repressor B. A mutation in the lac repressor that prevents it from binding to the operator C. A mutation in CAP that prevents it from binding to the CAP binding site D. A mutation in the lac repressor that prevents it from binding allolactose - correct answer✔✔ D. A mutation in the lac repressor that prevents it from binding allolactose The regulatory elements in the lac operon act to: A. Repress transcription when there is no lactose present B. Repress transcription when there is lactose present C. Activate transcription when there is no glucose present D. Activate transcription when there is glucose present E. A and C - correct answer✔✔ E. A and C The expression of a gene can be increased by: A. Knocking out its repressor B. Increasing the concentration of its corepressor C. Increasing the concentration of its inhibitor D. Decreasing the concentration of its effector E. Decreasing the concentration of its inducer - correct answer✔✔ A. Knocking out its repressor A bacterium is unable to transport lactose into the cell to be broken down. Which gene is likely mutated in this bacterium? A. lacZ B. lacY C. lacI D. lacP E. lacO - correct answer✔✔ B. lacY Under which conditions will E. coli make the least amount of beta-galactosidase? A. I+O+Z+, glucose absent, lactose present B. IsOcZ+, glucose present, lactose absent C. I-O+Z+, glucose absent, lactose present D. IsO+Z+, glucose absent, lactose present - correct answer✔✔ D. IsO+Z+, glucose absent, lactose present In terms of lac operon regulation, what happens when an I+,O+,P+,Z- mutant E. coli is grown in medium containing no glucose and high lactose? A. CAP is bound to the DNA but the lac repressor is not, E. coli grows B. CAP is bound to the DNA but the lac repressor is not, E. coli does not grow C. lac repressor is bound to the DNA but CAP is not, E. coli grows D. lac repressor is bound to the DNA but CAP is not, E. coli does not grow E. Both CAP and lac repressor are bound to DNA, E. coli does not grow - correct answer✔✔ E. Both CAP and lac repressor are bound to DNA, E. coli does not grow Which of the following tends to loosen the interaction between DNA and histones? A. Acetylation of histone tails B. Deacetylation of histone tails - correct answer✔✔ A. Acetylation of histone tails Which of the following repair pathways can fix a thymine dimer? A. Mismatch repair B. Base excision repair C. Nucleotide excision repair D. Photoreactivation - correct answer✔✔ C.Nucleotide excision repair and D.Photoreactivation Which of the following proteins would be recruited to repair a mismatch? A. Photolyase B. MutS, MutL, MutH C. UvrA, UvrB, UvrC, UvrD D. Glycosylase E. AP endonuclease - correct answer✔✔ B. MutS, MutL, MutH Which of the following statements is false about homologous recombination? A. It is a mechanism to repair double strand breaks B. It involves photolyase C. It involves MutSLH proteins D. Depending on the resolution of Holliday junctions, you can get recombinant or non- recombinant products E. It involves strand invasion by the 3' end of a broken DNA strand - correct answer✔✔ B. It involves photolyase and C. It involves MutSLH proteins Is heteroduplex DNA always an outcome of homologous recombination? A. Yes, heteroduplex DNA is always created during homologous recombination B. No, heteroduplex DNA is only created during homologous recombination when the homologs have different DNA sequences C. No, heteroduplex DNA is only created when Holliday junction crossovers have same sense resolution D. No, heteroduplex DNA is only created when Holliday junction crossovers have opposite sense resolution E. Heterotduplex DNA formation and homologous recombination are not related - correct answer✔✔ A. Yes, heteroduplex DNA is always created during homologous recombination DNA polymerase III adds nucleotides . A. To the 3' end of the RNA primer B. To the 5' end of the RNA primer C. In the place of the primer RNA after it is removed D. To both ends of the RNA primer E. To internal sites in the DNA template - correct answer✔✔ A. To the 3' end of the RNA primer In agarose gel electrophoresis, which way will the DNA move? A. Toward the positive electrode B. Toward the negative electrode - correct answer✔✔ A. Toward the positive electrode You have to use PCR to amplify three different regions of the strawberry genome. The product lengths are 200, 350, and 700 base pairs (nucleotides). After gel electrophoresis, which PCR product is closest to the wells? A. 200 B. 350 C. 700 - correct answer✔✔ C. 700 Which of the following statements about ddNTPs is true? A. DNA polymerase can add a new dNTP to a 3 ′ ddNTP B. ddNTPs have a hydroxyl group on the 2 ′ carbon C. ddNTPs have a hydroxyl group on the 3 ′ carbon D. ddNTPs have a hydrogen on the 3 ′ carbon - correct answer✔✔ D. ddNTPs have a hydrogen on the 3 ′ carbon Which of the following libraries would be expected to have the same set of sequences? A. cDNA libraries made from mouse liver and kidney cells B. DNA and cDNA libraries made from mouse liver cells C. DNA libraries made from mouse liver and chicken liver cells D. cDNA libraries made from mouse liver and chicken liver cells E. DNA libraries made from mouse liver and kidney cells - correct answer✔✔ E. DNA libraries made from mouse liver and kidney cells Molecular cloning involves cutting a gene from its normal location, inserting it into a circular piece of DNA, and then transferring the circle of DNA into a bacterial or yeast cell. Which of the following is used to cut the gene from its normal location? A. Restriction enzyme B. Plasmid C.Bacteriophage D.Vector E. Ligase - correct answer✔✔ A. Restriction enzyme What extra elements are required in expression vectors that are not found in typical cloning vectors? A. Sites for restriction nuclease cleavage Tall green 410 Short yellow 390 What is the distance between these genes? A. They are not linked B. 10.8 cM C. 12.5 cM D. 20 cM E. 75 cM - correct answer✔✔ D. 20 cM In a population of fish a scientist finds there are 11 different possible colors of eye. How many polygenes are involved in determining eye color in this species? A. 2 B. 11 C. 3 D. 5 E. 6 - correct answer✔✔ D. 5 Genes contributing to polygenic (quantitative) traits are inherited according to Mendelian rules. A. True B. False - correct answer✔✔ A. True Single Nucleotide Polymorphisms (SNPs) associated with phenotypes can be found in what regions of the genome? A. Introns B. Enhancers C. Exons D. Intergenic regions E. All of the above - correct answer✔✔ E. All of the above Two women who are the same height have the same genotypes at the strongest height-associated loci. A. True B. False - correct answer✔✔ B. False You find variation in yield per plant in a field of genetically uniform (clonal) corn. You take samples from corn with the largest yield and make crosses. What yield do you expect to find in the offspring of these crosses? A. Substantially more average yield compared to the average of the previous population B. A little improvement in the average yield compared to the average of the previous population C. The same average yield of the previous population D. I cannot tell - correct answer✔✔ C. The same average yield of the previous population A population of mice has two color morphs: white and agouti. The difference is due to a single gene with two alleles; agouti is dominant over white. In the population, the frequency of the agouti allele is 0.4 and that of the white allele is 0.6. In a population of 50 mice, how many are heterozygotes for this gene? A. 0.48 B. 48 C. 50 D. 24 E. None - correct answer✔✔ D. 24 A population of flies is polymorphic for gene A. The gene has two alleles, A and a. The population is made up of the following genotypes: AA(0.2), Aa(0.2), aa(0.6). Is this population in Hardy- Weinberg equilibrium? A. Yes B. No - correct answer✔✔ B. No In a population of vampire bats, the gene for bloodsucking (S) has two alleles with the following relative fitness values. This locus will be subject to . Genotype: S1S1 S1S2 S2S2 Relative fitness: 0.75 1 0.5 A. Directional selection towards the S1S1 allele B. Stabilizing selection C. Directional selection towards the S2S2 allele D. Directional selection towards the S1S2 allele E. Heterozygote advantage - correct answer✔✔ B. Stabilizing selection and E. Heterozygote advantage All cells in the human body are constantly replicating. A. True B. False - correct answer✔✔ B. False Which phase of the cell cycle includes DNA replication? A. Anaphase B. G1 phase C. S phase D. M phase - correct answer✔✔ C. S phase What type of cell division generates a cell with only half of the complete genome? If two people who are both carriers for a genetically inherited recessive disease decide to become parents, what will be the odds that their children will also be carriers? A. 0.25 B. 0.5 C. 0.75 D. 1 - correct answer✔✔ B. 0.5 If two parents are heterozygous for a genetically inherited dominant trait, what is the probability that they will have a child together who has this trait in his or her phenotype? A. 0.25 B. 0.5 C. 0.75 D. 1 - correct answer✔✔ C. 0.75 In a dihybrid cross, SsYy x SsYy, what fraction of the offspring will be homozygous for both traits? A. 1/16 B. 1/8 C. 3/16 D. 1/4 E. 3/4 - correct answer✔✔ D. 1/4 Which of the statements about inheritance of rare traits in pedigrees are true? A. An affected child must have at least one unaffected parent B. An unaffected child cannot have an affected parent C. It is assumed that unrelated individuals who join an affected family do not carry the trait D. Males and females are always equally affected by a rare trait - correct answer✔✔ C. It is assumed that unrelated individuals who join an affected family do not carry the trait Which of the following statements correctly describes the role of telomerase in eukaryotic cells? A. It synthesizes the Okazaki fragment needed to prevent loss of genetic information at the 5' end of the chromosome B. It synthesizes new DNA (using a RNA template) at the 3' end of the chromosome C. It synthesizes new DNA (using a DNA template) at the 3' end of the chromosome D. It synthesizes DNA on both the 5' and 3' ends of the chromosome - correct answer✔✔ B. It synthesizes new DNA (using a RNA template) at the 3' end of the chromosome Which of the following is true regarding the direction of new DNA synthesis during replication? A. The lagging strand DNA polymerase synthesizes DNA in the same direction that the replication fork is moving B. The leading strand DNA polymerase synthesizes DNA in the same direction that the replication fork is moving C. The leading and lagging strand DNA polymerases synthesize DNA in the 5' to 3' direction, which is in the same direction that the replication fork is moving for either strand D. The leading strand DNA polymerase synthesizes DNA in the 5' to 3' direction, while the lagging strand DNA polymerase synthesizes DNA in the 3' to 5' direction - correct answer✔✔ B. The leading strand DNA polymerase synthesizes DNA in the same direction that the replication fork is moving What enzyme(s) is/are responsible for removal of RNA primers and joining of Okazaki fragments? A. DNA polymerase I B. DNA polymerase III C. DNA ligase D. DNA polymerase I and DNA ligase E. DNA ligase and DNA gyrase - correct answer✔✔ D. DNA polymerase I and DNA ligase Which of the following is NOT consistent with the Chargaff rule? A. (A+G) = (C+T) B. (A+C) = (G+T) C. A = T D. (C+G) = (A+T) E. (A+G)/(C+T) = 1 - correct answer✔✔ D. (C+G) = (A+T) Which of the following is a true difference between ATP (adenosine triphosphate) molecules and the adenine ribonucleotides that make up a strand (polymer) of RNA? A. There is no structural difference B. ATP has three phosphate groups, while an adenine ribonucleotide in RNA only has one phosphate group C. An adenine ribonucleotide in RNA has two hydroxyl groups on the sugar molecule, while ATP only has one hydroxyl group on the sugar molecule D. An adenine ribonucleotide in RNA only has one hydroxyl group on the sugar molecule, while ATP has two hydroxyl groups on the sugar molecule. - correct answer✔✔ B. ATP has three phosphate groups, while an adenine ribonucleotide in RNA only has one phosphate group The template strand of the DNA will be to the RNA transcribed. A. Identical B. Identical except U is replaced with T in RNA C. Identical except T is replaced with U in RNA D. Complementary - correct answer✔✔ D. Complementary If the coding strand of DNA has the following sequence: 5' AGTCAGA 3', what will be the sequence of the transcribed RNA? A. Formation of the preinitiation complex B. Formation of the initiation complex C. Scanning for the initiator codon D. Ribosome assembly E. Binding of initiation factors - correct answer✔✔ C. Scanning for the initiator codon Which process occurs during translation initiation in prokaryotes? A. The ribosomal small subunit scans mRNA to find the first AUG codon B. mRNA binds to the ribosomal small subunit by the Kozak sequence C. RNA polymerase binds to the promoter D. TBP binds to the TATA-box E. mRNA binds to the small subunit ribosomal RNA by the Shine-Dalgarno sequence - correct answer✔✔ E. mRNA binds to the small subunit ribosomal RNA by the Shine-Dalgarno sequence During translation initiation in prokaryotes, the amino acid on the initiator tRNA is . A. methionine (Met) B. N-formylmethionine (fMet) C. acetylated D. IF-1 E. 7-methylguanosine - correct answer✔✔ B. N-formylmethionine (fMet) If an mRNA molecule has introns and exons in it, where is it? A. At a ribosome B. In the nucleus C. In a prokaryotic cell D. Could be in the nucleus or ribosome - correct answer✔✔ B. In the nucleus