Biol 3000 Exam 1 Diller

Avery and his colleagues purified various chemicals from pathogenic bacteria and showed that ____ was (were) the transforming agent. a. DNA c. RNA e. phage b. protein d. Carbohydrates

A

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately, what percentage of the nucleotides in this sample will be thymine? a. 12 b. 24 c. 31 d. 38 e. It cannot be determined from the information provided

A

During protein synthesis, ribosomes: a. attach to the mRNA molecule and travel along its length. b. attach to the DNA molecule and travel along its length to produce an mRNA molecule. c. translate mRNA into tRNA. d. transcribe mRNA to tRNA. e. translate mRNA into DNA.

A

In DNA replication, the lagging strand: a. is synthesized as a series of Okazaki fragments. b. is synthesized as a complementary copy of the leading strand. c. pairs with the leading strand by complementary base pairing. d. is made up entirely of RNA primers. e. is not synthesized until the synthesis of the leading strand is completed. (IMAGE ON STUDY GUIDE)

A

In all organisms, the AUG codon usually codes for: a. initiation of translation. b. termination of transcription. c. termination of chain elongation. d. formation of a peptide bond between adjacent amino acids. e. a termination tRNA molecule.

A

Initiation of transcription requires: a. a promoter sequence. d. a DNA primer. b. DNA polymerase. e. Okazaki fragments. c. an RNA primer. (IMAGE ON STUDY GUIDE)

A

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in its a. sequence of bases. d. side groups of nitrogenous bases. b. phosphate-sugar backbones. e. different five-carbon sugars. c. complementary pairing of bases.

A

Nucleosomes are best described as: a. eukaryotic DNA associated with histone proteins. b. prokaryotic DNA associated with nonhistone proteins. c. eukaryotic DNA associated with nonhistone proteins. d. prokaryotic DNA associated with histone proteins. e. eukaryotic DNA associated with scaffolding proteins

A

Refer to Figure 1. Which letter or a combination of letters would you expect to indicate a position(s) where a topoisomerase is required? a. (a) b. (b) c. (c) d. (d) e. (c) and (d)

A

Refer to Figure 5. The portion of the molecule labeled 5 is: a. the attached amino acid or peptide. d. the anti-codon. b. a double-stranded region. e. the codon. c. a single-stranded region

A

The DNA double helix has a uniform diameter because ____, which have two rings, always pair with ____, which have one ring. a. purines; pyrimidines d. ribose sugars; deoxyribose sugars b. pyrimidines; purines e. nucleotides; nucleoside triphosphates c. deoxyribose sugars; ribose sugars

A

The Y-shaped structure where the DNA double helix is actively unwound during DNA replication is called the a. replication fork. d. unwinding point. b. replication Y. e. Y junction. c. elongation junction.

A

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that a. the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. b. the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. c. ATP contains three high-energy bonds; the nucleoside triphosphates have two. d. ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. e. triphosphate monomers are active in the nucleoside triphosphates, but not in ATP.

A

Tobacco mosaic virus has RNA rather than DNA as its genetic material. In a hypothetical situation where RNA from a tobacco mosaic virus is mixed with proteins from a related DNA virus, the result could be a hybrid virus. If that virus were to infect a cell and reproduce, what would the resulting "offspring" viruses be like? a. tobacco mosaic virus b. the related DNA virus c. a hybrid: tobacco mosaic virus RNA and protein from the DNA virus d. a hybrid: tobacco mosaic virus protein and nucleic acid from the DNA virus e. a virus with a double helix made up of one strand of DNA complementary to a strand of RNA surrounded by viral protein

A

Uracil forms a complementary pair with ____________ in RNA and _____________ in DNA. a. adenine; adenine c. thymine; thymine e. adenine; uracil b. adenine; thymine d. uracil; adenine

A

What is the function of topoisomerase? a. relieving strain in the DNA ahead of the replication fork b. elongation of new DNA at a replication fork by addition of nucleotides to the existing chain c. the addition of methyl groups to bases of DNA d. unwinding of the double helix e. stabilizing single-stranded DNA at the replication fork

A

What kind of chemical bond is found between paired bases of the DNA double helix? a. hydrogen c. Covalent e. phosphate b. ionic d. Sulfhydryl

A

Which of the following is a characteristic of uracil? a. the ability to bond with adenine d. the ability to bond with cytosine b. the ability to bond with guanine e. contains two nitrogenous rings c. is a purine

A

Which of the following serves as an "adapter" in protein synthesis and bridges the gap between mRNA and proteins? a. tRNA c. rRNA e. DNA b. cDNA d. promoter sequences

A

Why does DNA synthesis only proceed in the 5' to 3' direction? a. Because DNA polymerases can only add nucleotides to the 3' end of a polynucleotide strand. b. Because the 3' end of the polynucleotide molecule is more electronegative than the 5' end. c. Because that is the direction in which the two strands of DNA unzip. d. Because that is the only direction that polymerases can be oriented. e. Because the chromosomes are always aligned in the 5' to 3' direction in the nucleus.

A

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent a. leading strands and Okazaki fragments. b. lagging strands and Okazaki fragments. c. Okazaki fragments and RNA primers. d. leading strands and RNA primers. e. RNA primers and mitochondrial DNA. Refer to the list of enzymes below to answer the following questions. The answers may be used once, more than once, or not at all. A. helicase B. nuclease C. ligase D. DNA polymerase I E. primase

A

separates the DNA strands during replication a. A b. B c. C d. D e. E

A

One of the mRNA codons specifying the amino acid leucine is 5'-CUA-3'. Its corresponding anticodon is: a. 5'-CUA-3'. c. 3'-GAU-5'. e. 5'-GAU-3'. b. 3'-AUC-5'. d. 3'-GAT-5'.

C

Refer to Figure 5. The process illustrated in the associated figure is: a. DNA synthesis. c. transcription. e. protein synthesis. b. translation. d. a frame shift mutation.

C

Refer to Figure 5. The process illustrated in the figure begins at the area labeled: a. A c. E e. None of the above b. D d. G

C

Refer to Figure 6. The portion of the molecule in the figure that contains the anticodon is: a. 1. b. 2. c. 3. d. 4. e. 5.

C

Statement A. An origin (e.g. oriC) is a cis -acting element that can support replication of any DNA sequence joint to it (in appropriate cell). Statement B. Most of the bacterial chromosomes (genomes) are single replicons because each of them contains only one origin. a. only A. is true c. both A. and B. are true b. only B. is true d. both A. and B. are false (IMAGE ON STUDY GUIDE)

C

Statement A. DNA replication is generally controlled at the initiation stage Statement B. DNA replication may be unidirectional or bidirectional depending on whether one or two replication forks advance from the origin of replication a. only A. is true c. both A. and B. are true b. only B. is true d. both A. and B. are false

C

What are ribosomes composed of? a. rRNA only d. mRNA, rRNA, and protein b. proteins only e. mRNA, tRNA, rRNA, and protein c. both rRNA and protein

C

What determines the nucleotide sequence of the newly synthesized strand during DNA replication? a. the particular DNA polymerase catalyzing the reaction b. the relative amounts of the four nucleoside triphosphates in the cell c. the nucleotide sequence of the template strand d. the primase used in the reaction e. both A and D

C

What is the effect of a nonsense mutation in a gene? a. It changes an amino acid in the encoded protein. b. It has no effect on the amino acid sequence of the encoded protein. c. It introduces a stop codon into the mRNA. d. It alters the reading frame of the mRNA. e. It prevents introns from being expressed. Each of the following is a modification of the sentence THECATATETHERAT. A.THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT

C

What is the function of DNA polymerase? a. to unwind the DNA helix during replication b. to seal together the broken ends of DNA strands c. to add nucleotides to the end of a growing DNA strand d. to degrade damaged DNA molecules e. to rejoin the two DNA strands (one new and one old) after replication

C

What is the most abundant type of RNA? a. mRNA c. rRNA e. hnRNA b. tRNA d. pre-mRNA

C

Which of the following numbered terms represents the correct order of sequences/structures in a eukaryotic mRNA molecule? 1. 3' UTR 2. ORF 3. G-cap 4. 5' UTR 5. Poly A a. 5 2 3 4 1 c. 3 4 2 1 5 e. 1 3 2 5 4 b. 3 2 4 1 5 d. 4 3 1 2 5

C

covalently connects segments of DNA a. A b. B c. C d. D e. E

C

A dividing eukaryotic cell lacking telomerase activity would a. have a high probability of becoming cancerous. b. produce Okazaki fragments. c. be unable to repair replication errors. d. undergo a reduction in chromosome length. e. be immortal.

D

All of the following may be functions of a DNA polymerase in DNA replication except a. covalently adding nucleotides to the new strands. b. proofreading each added nucleotide for correct base pairing. c. replacing RNA primers with DNA. d. initiating a polynucleotide strand. e. none of the above

D

During translation, chain elongation continues until what happens? a. No further amino acids are needed by the cell. b. All tRNAs are empty. c. The polypeptide is long enough. d. A stop codon is encountered. e. The ribosomes run off the end of mRNA.

D

For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. This is because a. proteins have a greater variety of three-dimensional forms than does DNA. b. proteins have two different levels of structural organization; DNA has four. c. proteins are made of 20 amino acids and DNA is made of four nucleotides. d. Only A and C are correct. e. A, B, and C are correct.

D

How does DNA polymerase discriminate between the insertion of correct and incorrect base pairs as DNA replication proceeds? a. Incorrect nucleotides repel each other because of their charges. b. Distances between atoms and bond angles give incorrect base pairs (A-T and G-C) the same geometry. c. Deviations from the normal base pairs result in the same geometry as normal base pairs. d. If the new base pair exhibits improper geometry, the polymerase active site cannot adopt the conformation required for catalysis and the incorrect nucleotide is not incorporated. e. b, c and d

D

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? a. DNA does not contain sulfur, whereas protein does. b. DNA contains phosphorus, but protein does not. c. DNA contains nitrogen, whereas protein does not. d. A and B only e. A, B, and C

D

RNA polymerase and DNA polymerase differ in that a. RNA polymerase uses RNA as a template, and DNA polymerase uses a DNA template. b. RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to double-stranded DNA. c. RNA polymerase is much more accurate than DNA polymerase. d. RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis. e. RNA polymerase does not need to separate the two strands of DNA in order to synthesize an RNA copy, whereas DNA polymerase must unwind the double helix before it can replicate the DNA

D

Refer to Figure 2. The segments labeled F are responsible for: a. linking short DNA segments. d. initiating DNA synthesis. b. synthesizing the leading strand. e. unwinding the DNA double helix. c. forming the replication fork.

D

Since one strand of DNA is synthesized continuously during replication and the other is made discontinuously, replication is said to be ___________. a. continuous c. discontinuous e. semicontinuous b. hemicontinuous d. semidiscontinuous

D

Suppose the following DNA sequence (on template strand) was mutated from 3' AGAGAGAGAGAGAGAGAG 5' to 3' AGAAGAGAGATCGAGAGA 5'. What amino acid sequence will be generated based on this mutated DNA? a. arg-glu-arg-glu-arg-glu d. ser-ser-leu b. glu-arg-glu-leu-leu-leu e. leu-phe-arg-glu-glu-glu c. ser-leu-ser-leu-ser-leu

D

The 5' end of each Okazaki fragment begins with: a. the same RNA primer that began synthesis on the leading strand. b. a DNA primer binding to the template DNA. c. DNA polymerase binding to the template DNA. d. a separate RNA primer. e. a small DNA primer.

D

The catalytic activity of peptidyl transferase, which catalyzes the transfer of the polypeptide chain attached to the tRNA in the ____________ site to the aminoacyl-tRNA in the ____________ site, is a(an) ____________ molecule located within the large ribosomal subunit. a. A; P; DNA c. A; P; mRNA e. P; A; protein b. P; A; tRNA d. P; A; rRNA

D

The final product of DNA replication is: a. mRNA, tRNA, and rRNA molecules. b. a wide variety of proteins. c. DNA fragments. d. two DNA molecules, each of which contains one new and one old DNA strand. e. the enzymes needed for further processes, such as DNA polymerase.

D

The total number of three-base combinations of the four nucleic acid bases is: a. 20. b. 35. c. 45. d. 64. e. 1.5 x 105 .

D

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5'AUG-UCU-UCG-UUA-UCC-UUG a. met-arg-glu-arg-glu-arg d. met-ser-ser-leu-ser-leu b. met-glu-arg-arg-gln-leu e. met-leu-phe-arg-glu-glu c. met-ser-leu-ser-leu-ser

D

Which of the above is analogous to a frameshift mutation? a. A b. B c. C d. D e. E Figure 1. Here is a sketch of an incomplete replication fork, as might be seen in E.coli. (IMAGE ON STUDY GUIDE)

D

Which of the following help to hold the DNA strands apart while they are being replicated? a. primase d. single-strand binding proteins b. ligase e. exonuclease c. DNA polymerase

D

Which of the following statements about telomerase is incorrect? a. It is a DNA Polymerase. b. It is a reverse transcriptase c. It carries its own template in the form of RNA. d. It does not require a primer. e. None, because they are all true

D

Which of the following statements does not apply to the Watson and Crick model of DNA? a. The two strands of the DNA form a double helix. b. The distance between the strands of the helix is uniform. c. The framework of the helix consists of sugar-phosphate units of the nucleotides. d. The two strands of the helix are held together by covalent bonds. e. The purines form hydrogen bonds with pyrimidines

D

Which of the following statements is false when comparing prokaryotes with eukaryotes? a. The prokaryotic chromosome is circular, whereas eukaryotic chromosomes are linear. b. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. c. The rate of elongation during DNA replication is higher in prokaryotes than in eukaryotes. d. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. e. Eukaryotes have telomeres, and prokaryotes do not.

D

Which of these mechanisms ensures that the DNA sequence in the genome remains accurate? a. proofreading during DNA replication b. mismatch repair c. complementary base pairing during DNA replication d. all of the above e. b. and c. only

D

removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments a. A b. B c. C d. D e. E

D

Refer to Figure 1. At which letter or letter combination would you expect to see a discontinuous synthesis of DNA (the lagging strand)? a. (a) b. (b) c. (c) or (a) d. (d) or (b) e. (c) and (d)

E

Refer to Figure 2. The correct designation for the DNA strand labeled C is: a. the leading strand. c. Okazaki fragments. e. None of the above b. 3'. d. polymerase.

E

Refer to Figure 3. Given the three DNA molecules (1, 2, 3), which would support the synthesis of additional DNA with DNA polymerase? a. 1 and 3 b. 1 and 2 c. 2 and 3 d. 2 only e. 3 only

E

Suppose one were provided with an actively dividing culture of E. coli bacteria to which radioactive thymine had been added. What would happen if a cell replicated once in the presence of this radioactive base? a. One of the daughter cells, but not the other, would have radioactive DNA. b. Neither of the two daughter cells would be radioactive. c. All four bases of the DNA would be radioactive. d. Radioactive thymine would pair with nonradioactive guanine. e. DNA in both daughter cells would be radioactive.

E

The leading and the lagging strands differ in that a. 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. b. 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. c. the leading strand is synthesized continuously, whereas the lagging strand is synthesized in short fragments that are ultimately stitched together. d. both A and B e. both A and C

E

Which of the following reasons explains why a single-stranded DNA circle cannot serve as a DNA polymerase template? a. DNA polymerase cannot initiate DNA strand formation. b. DNA polymerase can only add nucleotides to the 3'-hydroxyl end of an existing strand. c. DNA polymerase can only add nucleotides to the 5'-hydroxyl end of an existing strand. d. DNA polymerase requires a primer. e. a, b and d

E

Which of the following statements about human telomeres is correct? a. They contain multiple copies of a short RNA sequence. b. They are present at the ends of eukaryotic chromosomes. c. They can be extended by an enzyme called telomerase. d. both a. and b. e. both b. and c.

E

Why do eukaryotic cells have multiple initiation sites in their DNA unlike bacteria that usually have only one? a. Cells of higher organisms can have up to 1000 times the amount of DNA as bacteria. b. Eukaryotic cells incorporate nucleotides at much slower rates. c. Eukaryotic DNA sequences are much more complicated. d. Eukaryotic cells have too many DNA polymerases. e. a and b

E

synthesizes short segments of RNA a. A b. B c. C d. D e. E

E

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) are available. Two of them can correctly match the mRNA so that a dipeptide can form. (IMAGE ON STUDY GUIDE) The dipeptide that will form will be a. cysteine-alanine. d. alanine-alanine. b. proline-threonine. e. threonine-glycine. c. glycine-cysteine.

B

Choose the answer that has these events of protein synthesis in the proper sequence. 1. An aminoacyl-tRNA binds to the A site. 2. A peptide bond forms between the new amino acid and a polypeptide chain. 3. Release factor interacts with codon located within A site. 4. A small ribosomal subunit binds with mRNA. 5. tRNA translocates to the P site. a. 1, 3, 2, 4, 5 c. 5, 4, 3, 2, 1 e. 2, 4, 5, 1, 3 b. 4, 1, 2, 5, 3 d. 4, 1, 3, 2, 5

B

DNA-cutting enzymes used in the repair of DNA damage a. A b. B c. C d. D e. E

B

How is the four-letter language of nucleic acids converted into the 20-word language of amino acids? a. The 4 nucleic acid bases combine in two-letter combinations that define different amino acids. b. The 4 nucleic acid bases combine in three-letter sequences that define different amino acids. c. Triplets of the two-letter nucleic acid bases are translated into the 20 different amino acids. d. The 4 bases each specify one amino acid, which give rise to the remaining 16 amino acids. e. The 4 bases are first converted into tRNA molecules, which can each attach to 5 amino acids.

B

If proteins were composed of only 12 different kinds of amino acids, what would be the smallest possible codon size in a genetic system with four different nucleotides? a. 1 b. 2 c. 3 d. 4 e. 12

B

RNA polymerase moves along the template strand of DNA in the ____ direction, and adds nucleotides to the ____ end of the growing transcript. a. 3' to 5'; 5' d. 5' to 3'; 3' b. 3' to 5'; 3' e. b. or d. depending on the gene c. 5' to 3'; 5'

B

Refer to Figure 1. At which letter or letter combination would you expect to see the more continuous synthesis of DNA (the leading strand)? a. (a) b. (b) c. (c) d. (d) e. (c) and (d)

B

Which of the following best describes semiconservative replication? a. The translation of a DNA molecule into a complementary strand of RNA. b. A DNA molecule consists of one parental strand and one new strand. c. The number of DNA molecules is doubled with every other replication. d. The replication of DNA never takes place with 100% accuracy. e. The replication of DNA takes place at a defined period in the cell cycle.

B

Which of the following is analogous to telomeres? a. the pull tab on a soft drink can b. the two ends of a shoelace c. the central spindle that a CD fits around while in the case d. the mechanism of a zipper that allows the separated parts to be joined e. the correct letters used to replace errors in a document after they have been deleted in a word processor

B

Why is only one strand of DNA transcribed into mRNA? a. Because mRNA is only required in small quantities. b. Because transcribing both DNA strands would produce different amino acid sequences. c. Because the other strand would produce the same amino acid sequence in reverse order. d. Because all genes are located on the same DNA strand, while the other strand acts as protection. e. Because the other strand is transcribed directly into amino acids.

B

Following peptide bond formation between the amino acid in the A site on the ribosome and the growing polypeptide chain, the tRNA in the A site: a. releases the growing polypeptide chain. b. picks up another amino acid to add to the chain. c. moves to the P site of the ribosome. d. forms a peptide bond with A site of the ribosome. e. forms a covalent bond with the P site of the ribosome.

C

A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA codes for this peptide? 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

C

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs? a. The tRNA that was in the A site moves into the P site. b. The tRNA that was in the P site moves into the A site. c. The tRNA that was in the P site moves to the E site and is released. d. The tRNA that was in the A site departs from the ribosome. e. Both A and C are correct.

E

In order to participate in translation a tRNA: a. must be able to fit Into a ribosome. b. must have an anticodon. c. must have an attachment site for the amino acid. d. must be recognized by a specific aminoacyl-tRNA synthetase that adds the correct amino acid. e. All of the above

E