Deck 14: From Dna to Protein: Gene Expression

Question 1

Which statement about RNA is not true?

A) Transfer RNA functions in translation.
B) Ribosomal RNA functions in translation.
C) RNAs are produced by transcription.
D) Messenger RNAs are produced on ribosomes.
E) DNA codes for mRNA, tRNA, and rRNA.

Answer 1

D

Question 2

Which statement about RNA splicing is not true?

A) It removes introns.
B) It is performed by small nuclear ribonucleoprotein particles (snRNPs).
C) It removes the introns at the ribosome.
D) It is usually directed by consensus sequences.
E) It shortens the RNA molecule.

Answer 2

C

Question 3

Transcription

A) produces only mRNA.
B) requires ribosomes.
C) requires tRNAs.
D) produces RNA growing from the 5´ end to the 3´ end.
E) takes place only in eukaryotes.

Answer 3

D

Question 4

Tuberculosis is a world health issue, killing over a million people annually. Several antibiotics have been developed to treat Mycobacterium tuberculosis, the bacterium that causes the disease. Essentially the antibiotics

A) kill the bacteria directly.
B) inhibit bacterial protein synthesis.
C) alleviate the bloody cough, fever, and chills so the patient can recover comfortably.
D) produce a lethal toxin that destroys the bacteria.
E) breaks peptide bonds preventing gene expression.

Question 5

The study of Neurospora mutants grown on various supplemented media led to

A) a determination of the steps in biological pathways.
B) the one-gene, one-enzyme hypothesis.
C) the idea that genes are "on" chromosomes.
D) Both a and b
E) Both a and c

Question 6

Within a group of mutants with the same growth requirement (i.e., the same overt phenotype), mapping studies determined that individual mutations were on different chromosomes. This indicates that

A) the same gene governs all the steps in a particular biological pathway.
B) different genes can govern different individual steps in the same biological pathway.
C) different genes govern the same step in a particular biological pathway.
D) all biological pathways are governed by different genes.
E) genes do not govern steps in biological pathways.

Question 7

Which statement about translation is not true?

A) Translation is RNA-directed polypeptide synthesis.
B) An mRNA molecule can be translated by only one ribosome at a time.
C) The same genetic code operates in almost all organisms and organelles.
D) Any ribosome can be used in the translation of any mRNA.
E) There are both start and stop codons.

Question 8

The classic work of Beadle and Tatum, later refined by others, provided evidence for the

A) one-gene, one-enzyme hypothesis.
B) one-gene, one-polypeptide hypothesis.
C) mechanism by which information in genes is translated into traits.
D) effects of some mutations on organisms.
E) All of the above

Question 9

The major phenotypic expression of genotype is in

A) proteins.
B) tRNA.
C) mRNA.
D) nucleic acids.
E) rRNA.

Question 10

The adapters that allow translation of the four-letter nucleic acid language into the 20-letter protein language are called

A) aminoacyl-tRNA synthetases.
B) transfer RNAs.
C) ribosomal RNAs.
D) messenger RNAs.
E) ribosomes.

Question 11

Which of the following is not a difference between RNA and DNA?

A) RNA has uracil; DNA has thymine.
B) RNA has ribose; DNA has deoxyribose.
C) RNA has five bases; DNA has four.
D) RNA is a single polynucleotide strand; DNA is a double strand.
E) RNA molecules are smaller than human chromosomal DNA molecules.

Question 12

An mRNA has the sequence 5´-AUGAAAUCCUAG-3´. What is the template DNA strand for this sequence?

A) 5´-TACTTTAGGATC-3´
B) 5´-ATGAAATCCTAG-3´
C) 5´-GATCCTAAAGTA-3´
D) 5´-TACAAATCCTAG-3´
E) 5´-CTAGGATTTCAT-3´

Question 13

The genetic code

A) is different for prokaryotes and eukaryotes.
B) has changed during the course of recent evolution.
C) has 64 codons that code for amino acids.
D) has more than one codon for many amino acids
E) is ambiguous.

Question 14

Which of the following are model organisms used in biological research?

A) Pea plants
B) Fruit flies
C) E. coli
D) Bread mold
E) All of the above

Question 15

Genes code for

A) enzymes.
B) polypeptides.
C) RNA.
D) All of the above
E) None of the above

Question 16

After irradiating Neurospora, Beadle and Tatum collected mutants that would

A) not grow on a minimal medium but would grow on a minimal medium with arginine.
B) grow on any minimal medium.
C) not grow on any minimal medium.
D) grow on a minimal medium but would not grow on a minimal medium with arginine.
E) None of the above

Question 17

Which of the following does not occur after eukaryotic mRNA is transcribed?

A) Binding of RNA polymerase to the promoter
B) Capping of the 5´ end
C) Addition of a poly A tail to the 3´ end
D) Splicing out of the introns
E) Transport to the cytosol

Question 18

How does RNA differ from DNA?

A) RNA contains uracil instead of thymine and it is usually single-stranded.
B) RNA contains uracil instead of thymine and it is usually double-stranded.
C) RNA contains thymine instead of uracil and it is usually single-stranded.
D) RNA contains uracil instead of cytosine.
E) None of the above

Question 19

Genetic material is composed of

A) DNA.
B) amino acids.
C) ribose.
D) carbohydrates.
E) lipids.

Question 20

Normally, Neurospora can synthesize all 20 amino acids. A certain strain of this mold cannot grow 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 affecting a biochemical pathway leading to the synthesis of carbohydrates.
C) has a mutation affecting the biochemical pathways leading to the synthesis of all 20 amino acids.
D) has a mutation affecting the biochemical pathway leading to the synthesis of leucine.
E) has a mutation affecting the biochemical pathways leading to the syntheses of 19 of the 20 amino acids.

Question 21

Which of the following does (do) not follow the "central dogma"?

A) Yeast
B) Onion cells
C) Bread mold
D) Skin cells
E) Retroviruses

Question 22

The process of transcription synthesizes

A) transfer RNA.
B) messenger RNA.
C) ribosomal RNA.
D) proteins.
E) a, b, and c

Question 23

Gene expression can be regulated

A) before transcription.
B) during transcription and before translation.
C) during translation.
D) after translation.
E) All of the above

Question 24

RNA polymerase is

A) an RNA-directed DNA polymerase.
B) an RNA-directed RNA polymerase.
C) a DNA-directed RNA polymerase.
D) a typical enzyme.
E) a form of RNA.

Question 25

Promoters are made of

A) proteins.
B) carbohydrates.
C) lipids.
D) nucleic acids.
E) amino acids.

Question 26

Viruses that violate the "central dogma" through the use of an enzyme that makes DNA copies of an RNA molecule are called

A) bacteriophage.
B) retroviruses.
C) RNA viruses.
D) DNA viruses.
E) enveloped viruses.

Question 27

Which of the following molecules transfers information from mRNA to protein?

A) DNA
B) mRNA
C) tRNA
D) Proteins
E) Lipids

Question 28

The "central dogma" of molecular biology states that

A) information flow between DNA, RNA, and protein is reversible.
B) information flow in the cell is unidirectional, from protein to RNA to DNA.
C) information flow in the cell is unidirectional, from DNA to RNA to protein.
D) the DNA sequence of a gene can be predicted if we know the amino acid sequence of the protein it encodes.
E) the genetic code is ambiguous but not degenerate.

Question 29

A transcription start signal is called a(n)

A) initiation codon.
B) promoter.
C) origin.
D) operator.
E) nonsense codon.

Question 30

The adapters that allow translation of the four-letter nucleic acid language into the 20-letter protein language are called

A) aminoacyl tRNA synthetases.
B) transfer RNAs.
C) ribosomal RNAs.
D) messenger RNAs.
E) ribosomes.

Question 31

Transcription is the process of

A) synthesizing a DNA molecule from an RNA template.
B) assembling ribonucleoside triphosphates into an RNA molecule without a template.
C) synthesizing an RNA molecule using a DNA template.
D) synthesizing a protein using information from a messenger RNA.
E) replicating a single-stranded DNA molecule.

Question 32

Which of the following statements about the flow of genetic information is true?

A) Proteins encode information that is used to produce other proteins of the same amino acid sequence.
B) RNA encodes information that is translated into DNA, and DNA encodes information that is translated into proteins.
C) Proteins encode information that can be translated into RNA, and RNA encodes information that can be transcribed into DNA.
D) DNA encodes information that is translated into RNA, and RNA encodes information that is translated into proteins.
E) None of the above

Question 33

DNA is composed of two strands, only one of which typically is used as a template for RNA synthesis. By what mechanism is the correct strand chosen?

A) Both strands are tried, and the one that works is remembered.
B) Only one strand has the start codon.
C) The promoter acts to aim the RNA polymerase.
D) A start factor informs the system.
E) It is chosen randomly.

Question 34

The region of DNA in prokaryotes to which RNA polymerase binds most tightly is the

A) promoter.
B) poly C center.
C) enhancer.
D) operator site.
E) minor groove.

Question 35

RNA polymerase uses the _______ DNA template to synthesize a _______ mRNA.

A) 5´ to 3´; 5´ to 3´
B) 3´ to 5´; 3´ to 5´
C) 5´ to 3´; 3´ to 5´
D) 3´ to 5´; 5´ to 3´
E) Examples of all of the above have been found.

Question 36

In bacteria, there is/are _______ RNA polymerase(s) that catalyze the synthesis of RNA from DNA.

A) one
B) three
C) four
D) five
E) six

Question 37

Which of the following molecules transfers information from the nucleus to the cytoplasm?

A) DNA
B) mRNA
C) tRNA
D) Proteins
E) Lipids

Question 38

Single-stranded RNA replicates by

A) making an RNA strand that is complementary to the original RNA strand.
B) using an adapter molecule.
C) the process of transcription.
D) the process of translation.
E) the process of reverse transcription.

Question 39

Retroviruses do not follow the "central dogma" of DNA $\to$ RNA $\to$ protein because they

A) contain RNA that is used to make DNA.
B) contain DNA that is used to make more RNA.
C) contain DNA that is used to make tRNA.
D) contain only DNA as the genetic material.
E) do not contain either DNA or RNA as the genetic material.

Question 40

The link between mRNA and a protein is

A) tRNA.
B) a promoter.
C) RNA polymerase.
D) DNA polymerase.
E) a start codon.

Question 41

The termination of transcription is signaled by

A) the stop codon.
B) a sequence of nitrogenous bases.
C) a protein bound to a certain region of DNA.
D) rRNA.
E) tRNA.

Question 42

Exons are

A) spliced out of the original transcript.
B) spliced together from the original transcript.
C) spliced to introns to form the final transcript.
D) much larger than introns.
E) larger than the original coding region.

Question 43

The process of transcription requires

A) a temporary stopping of DNA replication.
B) a temporary separation of the strands in the DNA template.
C) destruction of one of the strands of the DNA template.
D) relaxation of positive supercoils in the DNA template.
E) induction of positive supercoils in the DNA template.

Question 44

The genetic code is best described as

A) redundant but not ambiguous.
B) ambiguous but not redundant.
C) both ambiguous and redundant.
D) neither ambiguous nor redundant.
E) nonsense.

Question 45

Errors in transcription are not as potentially harmful as errors in DNA replication because

A) many copies of RNA are made.
B) RNA strands have a relatively short life span.
C) RNA polymerases proofread and correct the errors.
D) a and b are correct
E) a, b, and c are correct

Question 46

The direction of synthesis for a new mRNA molecule is _______ from a _______ template strand.

A) 5´ to 3´; 5´ to 3´
B) 5´ to 3´; 3´ to 5´
C) 3´ to 5´; 5´ to 3´
D) 3´ to 5´; 3´ to 5´
E) 5´ to 5´; 3´ to 3´

Question 47

A template DNA strand has the following base sequence: 3´-GUC, CCA-5´. What would be the corresponding mRNA sequence?

A) 3´-GUC, CCA-5´
B) 5´-GUC, CCA-5´
C) 3´-CAG, GGU-5´
D) 5´-CAG, GGU-3´
E) 5´-CAG, GGT-3´

Question 48

Imagine that a novel life-form is found deep within Earth's crust. Evaluation of its DNA yields no surprises. However, it is found that a codon for this life-form is just two bases in length. How many different amino acids could this organism be composed of?

A) 4
B) 8
C) 16
D) 32
E) 64

Question 49

How can DNA, which is made up of only four different bases, encode the information necessary to specify the workings of an entire organism?

A) DNA molecules are extremely long.
B) DNA molecules form codons of three bases that code for amino acids.
C) The genetic code is redundant but not ambiguous.
D) DNA can be replicated with low error rates.
E) All of the above

Question 50

Exons are

A) translated.
B) found in most prokaryotic genes.
C) removed during RNA processing.
D) Both a and b
E) Both a and c

Question 51

There are _______ different RNA polymerases in eukaryotes.

A) two
B) three
C) four
D) five
E) six

Question 52

Poly uracil codes for

A) three different amino acids.
B) poly tryptophan.
C) mRNA.
D) a fatty acid.
E) phenylalanine.

Question 53

Termination of transcription involves a

A) stop codon.
B) terminator sequence.
C) termiproteator.
D) hairline slip.
E) series of As.

Question 54

When eukaryotic DNA is hybridized with mRNA, the hybrid molecules contain loops of double-stranded DNA, which are

A) retroviruses.
B) introns.
C) exons.
D) transcripts.
E) puffs.

Question 55

The three codons in the genetic code that do not specify amino acids are called

A) missense codons.
B) start codons.
C) stop codons.
D) promoters.
E) initiator codons.

Question 56

The stop codons code for

A) no amino acid.
B) methionine.
C) glycine.
D) halt enzyme.
E) DNA binding protein.

Question 57

There are differences in the amount of transcription that takes place for different genes. One reason for these differences is that

A) some promoters are more effective at transcription initiation.
B) longer genes take longer to transcribe.
C) the outcome is influenced by random chance.
D) ribosomes tend to attach to transcripts even before transcription is completed.
E) None of the above

Question 58

The regions of DNA in a eukaryotic gene that contain noncoding base sequences are called

A) enhancers.
B) mRNAs.
C) hnRNAs.
D) introns.
E) leader sequences.

Question 59

How many codons specify amino acids?

A) 20
B) 23
C) 45
D) 60
E) 61

Question 60

Nucleic acid hybridization

A) is used to study the relationship between eukaryotic genes and their transcripts.
B) requires that the original DNA molecule be denatured.
C) involves the use of a probe to form a double-stranded molecule.
D) originally revealed the existence of introns.
E) All of the above

Question 61

Which of the following statements about codons and anticodons is true?

A) The codon bonds covalently with the anticodon.
B) The base sequences are the same.
C) There are 64 codons and 61 anticodons.
D) Activating enzymes link codons and anticodons.
E) At contact, the codon and the anticodon are antiparallel to each other.

Question 62

What events must take place to ensure that the protein made is the one specified by mRNA?

A) tRNA must read mRNA correctly.
B) tRNA must carry the amino acid that is correct for its reading of the mRNA.
C) Covalent bonding between the base pairs must occur.
D) Both a and b
E) All of the above

Question 63

Fewer different tRNA molecules exist than might have been expected for the complexity of its function. This is possible because

A) the third position of the codon does not have to pair conventionally.
B) the second position of the codon does not have to pair conventionally.
C) the anticodon does not have the conventional bases.
D) there are fewer amino acids than there are possible codons.
E) the code is degenerating.

Question 64

How is it possible for single-stranded RNA to fold into complex shapes?

A) Phosphodiester linkages form between the phosphate and the sugar ribose.
B) Internal base pairings make this possible: adenine with uracil and cytosine with guanine.
C) Uracil's methyl group binds to adenine, spiraling the molecule.
D) The single strand "twists" around itself.
E) The RNA binds to proteins, creating a conformation (three-dimensional shape).

Question 65

What are the three processes that must be completed before transcripts can be translated in eukaryotes?

A) Binding of snRNPs, addition of a poly A tail, splicing of introns
B) Binding of snRNPs, transporting, synthesizing of ribose
C) Capping, transporting, synthesizing of ribose
D) Binding of snRNPs, capping, splicing
E) Splicing, capping, addition of a poly A tail

Question 66

snRNPs are

A) exon-intron boundary regions.
B) small nuclear ribonucleoprotein particles.
C) protein fragments removed from snRNA molecules.
D) signal ribosomal nuclear proteins.
E) glucose-conjugated trapezoids.

Question 67

The modified G cap on eukaryotic mRNAs is found

A) at the 5´ end.
B) at the 3´ end.
C) in the consensus sequence.
D) in the poly A tail.
E) in snRNA.

Question 68

The conformation of tRNA is maintained by

A) peptide bonds.
B) hydrogen bonds.
C) disulfide bridges.
D) phosphodiester bonds.
E) glycosidic linkages.

Question 69

The enzyme that charges the tRNA molecules with appropriate amino acids is

A) tRNA chargeatase.
B) amino tRNA chargeatase.
C) transcriptase.
D) aminoacyl-tRNA synthetase.
E) None of the above

Question 70

Poly A tails

A) are added after transcription.
B) are encoded by a sequence of thymines in the DNA.
C) are found in all mRNAs.
D) have no function.
E) are removed during RNA processing.

Question 71

Which of the following is not part of RNA processing in eukaryotes?

A) Splicing of exons
B) Reverse transcription
C) Addition of a 5´ cap
D) Addition of a poly A tail
E) Intron removal

Question 72

Consensus sequences (short segments of DNA) appear in the boundaries between introns and exons of various genes. These sequences appear to be involved in

A) directing the polymerases to the appropriate place on the DNA for transcription to begin.
B) the splicing of introns out of the DNA.
C) allowing the transcription to stop at the appropriate spot.
D) catalyzing the synthesis of a protein.
E) None of the above

Question 73

The tail added to pre-mRNA is

A) coded for by DNA.
B) composed of poly T.
C) important for mRNA stability.
D) attached to its 5´ end.
E) All of the above

Question 74

RNA processing in eukaryotes involves the

A) addition of a G cap.
B) addition of a poly A tail.
C) removal of introns.
D) splicing of exons.
E) All of the above

Question 75

The difference between mRNA and tRNA is that

A) tRNA has a more elaborate three-dimensional structure.
B) tRNAs are usually much smaller than mRNAs.
C) mRNA carries amino acids.
D) Both a and b
E) None of the above

Question 76

The guanosine triphosphate (GTP) cap that is added to the 5´ end of primary mRNA

A) contains all the coding and noncoding sequences of the DNA template.
B) provides the mRNA molecule with a poly A tail.
C) facilitates the binding of mRNA to ribosomes.
D) forms hydrogen bonds.
E) helps transfer amino acids to the ribosomes.

Question 77

The binding of snRNPs to consensus sequences is necessary for

A) gene duplication.
B) the addition of a poly A tail.
C) capping an hnRNA.
D) RNA splicing.
E) transcription.

Question 78

Chromosomes of eukaryotic DNA must have

A) DNA sequences that make up telomeres and centromeres.
B) proteins that are centromeres and DNA that form telomeres.
C) a 5´ G cap.
D) an inactivation center.
E) None of the above

Question 79

A sequence of three RNA bases can function as

A) a codon.
B) an anticodon.
C) a gene.
D) Both a and b
E) Both a and c

Question 80

Activating enzymes

A) are sometimes referred to as the second genetic code.
B) link the right tRNAs and amino acids.
C) are also known as aminoacyl-tRNA synthetases.
D) are specific for one amino acid.
E) All of the above