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Material Type: Exam; Professor: Perrault; Class: BIOCHEM,CELL&MOLEC BIO II; Subject: Biological Sciences; University: San Diego State University; Term: Fall 2014;
Typology: Exams
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1. Which of the following RNA molecules is expected to display base-paired stem regions that involve 11 hydrogen bonds? a. 5โ-GCCGAAAACGGC-3โ b. 5โ-GCUGAAAACGGC-3โ c. 5โ-GGGGAAAACCCC-3โ d. 5โ-CGGAAAACCGCG-3โ e. 5โ-GUUGAAAACGGC-3โ 2. If a B-form duplex DNA molecule is 34 cm long, what is the approximate number of base pairs in this molecule? a. 105, b. 1,050, c. 10,500, d. 105,000, e. 1,050,000, 3. Which of the following ribonucleotide features is responsible for cleavage of phosphodiester bonds in RNA molecules under alkaline conditions? a. presence of uridine base b. single-stranded nature of RNA c. hydroxyl groups on both the 2โ and 3โ positions on the ribose sugar d. ability to form pseudoknots e. phosphodiester bond is more exposed to solvent 4. Which of the following is a feature of RNA synthesis but not DNA synthesis? a. release of pyrophosphate when a phosphodiester bond is formed b. newly synthesized chains grow in the 5โ to 3โ direction c. primer is not required to initiate chain synthesis d. unwinding of the duplex DNA template is required e. requires a multiple subunit enzyme 5. Which of the following correctly describes differences between prokaryotic and eukaryotic mRNAs? a. the 5โ end of eukaryotic mRNAs has a cap structure b. some prokaryotic mRNAs are polycistronic c. prokaryotic mRNAs have 3โ poly(A) tails d. eukaryotic mRNA lack a 5โ untranslated sequence (5โ UTR) e. a and b
6. Which of the following reactions is carried out by aminoacyl-tRNA synthetases? a. synthesis of tRNA molecules b. processes precursor tRNAs into mature tRNAs c. peptide bond formation d. addition of CCA bases at the 3โ end of tRNA molecules e. covalent linkage of amino acids to the 3โ end of cognate tRNAs 7. Which of the following steps involved in translation of eukaryotic mRNAs takes place subsequent to scanning of mRNA 5โ end sequence? a. peptide bond formation b. joining of 40S and 60S ribosomal subunits c. ternary complex formation d. circularization of mRNA e. a and b 8. Which of the following roles does the 5โ to 3โ exonuclease associated with a replicating DNA polymerase play in DNA synthesis? a. unwinds the DNA duplex b. removes DNA from the 5โ ends of Okazaki fragments c. repairs gaps in the lagging strand d. removes RNA primers e. prevents re-annealing of separated strands 9. The base-excision DNA repair system differs from the mismatch repair and nucleotide excision repair systems in which of the following ways? a. specialized proteins recognize the damage b. DNA ligase is required c. only a single nucleotide is removed d. a stretch of DNA 20 to 30 bp long is removed e. the intact homologous chromosome is used for repair 10. Loss-of-function mutations are generally recessive mutations but not so for dominant-negative mutations. Which of the following accounts for this? a. product from defective allele inhibits functioning of the wild-type allele product b. the wild-type allele does not produce sufficient amounts of the gene product c. dominant-negative mutations always cause a frameshift d. dominant-negative mutations prevent synthesis of the wild-type allele product e. dominant-negative mutations occur when the defective gene product is made in excess
16. Which of the following steps comes first when constructing a cDNA library from mRNAs? a. addition of EcoR1 linkers b. hybridization to oligo-dT primer c. exposure to alkaline conditions d. methylation of EcoR1 sites e. addition of G residues by terminal transferase 17. Why is a gene-specific oligonucleotide sequence 20 nt-long sufficient for detecting the corresponding human gene insert in bacterial colonies derived from a cDNA library? a. anything shorter than 20 nt does not form a stable hybrid b. anything longer than 20 nt does not penetrate bacterial cells c. nitrocellulose filters cannot bind single-stranded DNA longer than 20 nt d. probability of that sequence being present more than one gene is virtually nil e. larger oligonucleotides of a specific sequence are very difficult to synthesize chemically 18. Which of the following distinguishes expression plasmid libraries used for functional complementation in yeast from plasmids used for cloning in E. coli? a. presence of promoter sequences for transcription of gene inserts b. presence of a selection gene c. presence of a viral origin of replication d. absence of restriction enzyme sites e. coding sequence for RNA polymerase
19. Why is a PCR (polymerase chain reaction) step used in next-generation DNA sequencing methodologies? a. to determine the sequence of each individual array of molecules b. to allow the sequencing reaction to occur at high temperatures c. to determine sequences by hybridization d. to make sure the sequences do not overlap each other e. to produce attached localized arrays of millions of DNA molecules of identical sequence 20. Linkage mapping of inherited human disease genes relies on thousands of genetic markers at known positions on human chromosomes. Which of the following properties do these markers have that make them useful for this purpose? a. they correspond to sequence variations between individuals (polymorphisms) b. they are found within the coding regions of important genes c. they correspond to dominant mutations d. they always include a change in restriction enzyme sites e. they increase recombination frequency
21. Why does one make sure that yeast gene disruption constructs contain short sequences identical to those flanking the target gene? a. these serve as sites for homologous recombination when the construct is introduced in cells b. these contain the essential promoter elements required for expression c. they prevent cells from becoming diploid d. they serve as restriction sites for cutting by host cell enzymes e. they allow gene disruption in hapoid cells 22. Which of the following is a property of the human ฮฒ - globin gene family but not the human rDNA gene family? a. the sequence of each member is identical or nearly so b. intron and exon sequences are present in each member c. all members are transcribed into RNA d. non-transcribed spacer sequence between members is identical e. all members are transcribed at all stages of development 23. Which of the following characteristics of human minisatelllite DNA is responsible for individuals displaying different size bands of DNA when amplified by PCR? a. minisatellite DNA differs in sequence for each individual b. location of minisatellite DNA sequences differs for each individual c. total amount of minisatellite DNA differs between individuals d. number of repeat units in minisatellite DNA sequences varies between individuals e. minisatellite DNA contains restriction enzyme sites that differ between individuals 24. Which of the following sequence features are always found in bacterial DNA transposons? a. short inverted repeat sequences (5- 11 bp) directly flanking a protein-coding sequence b. long terminal repeat sequences (250-600 bp) flanking a protein coding sequence c. short target-site direct repeat sequences (5-11 bp) flanking the entire transposon d. restriction enzyme sites flanking the transposon e. a coding sequence for reverse transcriptase
25. Which of the following eukaryotic mobile elements most closely resemble retroviruses? a. SINES (short interspersed nuclear elements) b. LINES (long interspersed nuclear elements) c. DNA transposons d. LTR (long terminal repeat) retrotransposons e. L1 sequence