C) Segment 1 would denature at a lower temperature than segment 2 D) Segment 2 would denature at a lower temperature than segment 1

Transcription

1 Bio Final: 1. Which option best describes transformation in bacteria? A) the ability to be lethal to mice or other animals B) the ability to mutate its DNA sequences to adapt to a new environment C) the infection of cells by a phage DNA molecule D) changes in the gene expression of the bacteria to adapt to a new environment E) assimilation of external DNA into a cell 2. Cytosine makes up 19% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? A) 31% B) 62% C) 19% D) 25% E) It cannot be determined from the information provided. 3. Which of the following best describe the arrangement of an Okazaki fragment? A) primase, polymerase, ligase B) 3' RNA nucleotides, DNA nucleotides 5' C) DNA polymerase I, DNA polymerase III D) 5' DNA to 3' E) 5' RNA nucleotides, DNA nucleotides 3' 4. At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence? A) 5' G C C T A G G 3' B) 3' G C C T A G G 5' C) 5' A C G T T A G G 3' D) 5' A C G U U A G G 3' E) 5' G C C U A G G 3' 5. Which of the following can be directly determined from X-ray diffraction photographs of crystallized DNA? A) the length of the gene B) the sequence of nucleotides C) the diameter of the helix D) the bond angles of the subunits E) the frequency of A vs. T nucleotides

2 6. In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of 14N? A) A B) B C) C D) D E) E 7. 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) 3' UGA 5'. C) 5' TCA 3'. D) 3' ACU 5'. 8. A scientist induces a mutation in the gene encoding DNA Polymerase III making it non- functional. What will be the result when the cell tries to replicate? A) the DNA will not unwind properly B) RNA nucleotides will not be matched up correctly to the DNA template strand C) DNA nucleotides will not be properly matched up to the template strand D) RNA primers will remain in the DNA sequence between Okazaki fragments. Segment 1: 5` - ATATGAGTAGT 3` 3` - TATACTCATCA 5` Segment 2: 5` - GCGCAGACGAC 3` 3` - CGCGTCTGCTG 5` 9. Refer to the 2 sequences of DNA shown above. Which of the following is one way that the two fragments would differ? A) Segment 1 would not code for mrna as both strands contain T, a base not found in RNA B) Segment 1 would be more soluble in water than segment 2, as it has more phosphate groups

3 C) Segment 1 would denature at a lower temperature than segment 2 D) Segment 2 would denature at a lower temperature than segment The leading and the lagging strands differ in that A) the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. B) the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. C) the leading strand is synthesized at twice the rate of the lagging strand. D) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. 11. Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells: A) cannot replicate DNA. B) lack the enzyme telomerase. C) have shortened telomeres. D) cannot repair thymine dimers. 12. Which of the following does not occur in prokaryotic eukaryotic gene expression, but does in eukaryotic gene expression? A) mrna, trna, and rrna are transcribed. B) A poly-a tail is added to the 3' end of an mrna and a cap is added to the 5' end. C) RNA polymerase binds to the promoter. D) Transcription can begin as soon as translation has begun. E) RNA polymerase requires a primer to elongate the molecule. 13. The coding region of an mrna molecule is 900 bases long, yet only codes for a protein of 300 amino acids. Why is this? A) many noncoding stretches of nucleotides are present in mrna. B) the genetic code uses a triplet code to signal each amino acid. C) sections of the mrna are used as untranslated regions and regulate the stability of the molecule. D) nucleotides break off and are lost during the transcription process. E) there are termination exons near the beginning of mrna. 14. Which of the following is the first event to take place in translation in eukaryotes? A) elongation of the polypeptide B) the small subunit of the ribosome recognizes and attaches to the 5' cap of mrna C) base pairing of activated methionine-trna to AUG of the messenger RNA D) binding of the larger ribosomal subunit to smaller ribosomal subunits

4 E) covalent bonding between the first two amino acids 15. Which of the following DNA mutations is the most likely to be damaging to the protein it specifies? A) a base-pair deletion B) a codon substitution C) a substitution in the last base of a codon D) a codon deletion E) a point mutation The following questions refer to this table of codons. 16. Which of the following sequences of nucleotides in the template strand of DNA could code for the polypeptide sequence cys-trp-pro-asp would be A) 5' TTG-CTA-CAG-TAG 3'. B) 3' AAC-GAC-GUC-AUA 5'. C) 3' ACA-ACC-GGT-CTA 5'. D) 5' AUG-CTG-CAG-TAT 3'. E) 3' AAA-AAT-ATA-ACA 5'.

5 17. Which of the following sequences in the coding strand of DNA could code for the peptide NH2-phe-pro-lys-gly-phe-pro-COOH? A) 3' UUU-CCC-AAA-GGG-UUU-CCC B) 3' AUG-AAA-GGG-TTT-CCC-AAA-GGG C) 5' TTT-CCC-AAA-GGG-TTT-CCC D) 5' GGG-AAA-TTT-AAA-CCC-ACT-GGG E) 5' ACT-TAC-CAT-AAA-CAT-TAC-UGA 18. Which type of bond is responsible for maintaining the shape of the trna molecule? A) covalent bonding between sulfur atoms B) ionic bonding between phosphates C) van der Waals interactions between hydrogen atoms D) peptide bonding between amino acids E) hydrogen bonding between base pairs 19. Consider this anti-codon sequence of trna - 3`-GUA -5`. Which is the codon sequence on the mrna strand? A) UGG B) GUG C) GUA D) UUC E) CAU 20. Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double-stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA. A) 2, 1, 4 B) 1, 3, 2, 4 C) 3, 4, 1, 2 D) 3, 4, 2 E) 2, 3, In 1997, Dolly the sheep was cloned. Which of the following processes was used? A) use of mitochondrial DNA from adult female cells of another ewe B) replication and dedifferentiation of adult stem cells from sheep bone marrow C) separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe

6 D) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate E) isolation of stem cells from a lamb embryo and production of a zygote equivalent 22. The segment of DNA shown above has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments? A) B) C) D) E) 23. In a developing frog embryo, most of the yolk is A) located near the animal pole. B) found within the cleavage furrow. C) found within the blastocoels. D) located near the vegetal pole. E) distributed equally throughout the embryo. 24. The outer-to-inner sequence of tissue layers in a post-gastrulation vertebrate embryo is A) ectoderm mesoderm endoderm. B) endoderm ectoderm mesoderm.

7 C) mesoderm endoderm ectoderm. D) ectoderm endoderm mesoderm. E) endoderm mesoderm ectoderm. 25. Scientists develop a drug that they find is able to block gastrulation. What effect would you expect to happen? A) cleavage would not occur in the zygote. B) embryonic germ layers would not form. C) fertilization would be blocked. D) the blastula would not be formed. E) the blastopore would form above the gray crescent in the animal pole. 26. The developing frog contains an open space within the gastrula what is this space called? A) ectoderm. B) mesoderm. C) endoderm. D) archenteron. E) notocord. 27. ATP hydrolysis directly powers the movement of A) K+ out of cells. B) Na+ into cells. C) Ca++ into cells. D) Na+ out of cells. E) Cl- into cells. 28. The primary means by which a neuron can communicate to a second neuron is by A) the frequency of its action potentials. B) the peak of the depolarization phase of an action potential. C) the peak of the undershoot/hyperpolarization of an action potential. D) varying how much neurotransmitter it releases for a given action potential. E) remaining in the depolarization phase of the action potential for an extended interval. 29. The release of neurotransmitters from the terminal of a sensory neuron is most directly linked to A) the entry of potassium into the axon terminal. B) the exit of potassium from the axon terminal. C) the entry of sodium into the axon terminal. D) the exit of sodium from the axon terminal. E) the entry of calcium into the axon terminal. 30. Several EPSPs arrive at the axon hillock from different dendritic locations, depolarizing the postsynaptic cell to threshold for an action potential. This is

8 known as: A) temporal summation. B) spatial summation. C) tetanus. D) the refractory state. E) a post-synaptic potential. 31. Action potentials are normally carried in only one direction: from the axon hillock toward the axon terminals. If you experimentally depolarize the middle of the axon to threshold, using an electronic probe, then A) no action potential will be initiated. B) an action potential will be initiated and proceed only in the normal direction toward the axon terminal. C) an action potential will be initiated and proceed only back toward the axon hillock. D) two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock. E) an action potential will be initiated, but it will die out before it reaches the axon terminal.