Unit 9/Ch. 17: Gene Expression

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. 5' ACU 3'

A

In any given species, there are at least how many types of aminoacyl tRNA synthetases? A. 20 B. 40 C. 100 D. 200

A

Once a peptide has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what occurs next? A. translocation B. reading of the next codon of mRNA C. initiation D. the polypeptide leaves through the exit tunnel

A

The RNA world hypothesis proposes that the first complex molecule was RNA and it preceded protein formation. Which major function of the ribosomal RNA supports the hypothesis? A. rRNA has catalytic properties in the large subunit and it assembles proteins. B. rRNA is a protein molecule that helps in the synthesis of other proteins. C. rRNA is essential for the transcription process. D. rRNA plays a major role in post-translational processes.

A

The anticodon loop of the tRNA that will complement the mRNA codon 5' CCG 3' is A. 3' GGC 5' B. 5' GGC 3' C. 5' UGC 3' D. 3' UGC 5'

A

What does it mean when we say the genetic code is not ambiguous? A. A single codon can only specify the addition of one amino acid. B. The genetic code is different for different domains of organisms. C. The genetic code is universal (the same for all organisms). D. More than one codon can specify the addition of the same amino acid.

A

What would happen if the 5' GTP cap was not added to an mRNA? A. The transcript would degrade when the mRNA moves out of the nucleus to the cytoplasm. B. The mRNA molecule would stabilize and start the process of translation within the nucleus of the cell. C. The mRNA molecule would move out of the nucleus and create more copies of the mRNA molecule. D. The mRNA molecule would not be able to add the poly-A tail on its strand at the 5' end.

A

3.Which one of the following best describes the cap modification of eukaryotic mRNA? A. Modified guanine nucleotide added to the 3' end of the transcript B. Modified guanine nucleotide added to the 5' end of the transcript C. String of adenine nucleotides added to the 3' end of the transcript D. String of adenine nucleotides added to the 5' end of the transcript

B

A nonsense mutation in a gene _____. A. changes an amino acid in the encoded protein B. introduces a premature stop codon into the mRNA C. has no effect on the amino acid sequence of the encoded protein D. alters the reading frame of the mRNA

B

A poly-A sequence is added at the: A. 5' end of a transcript in the nucleus B. 3'-end of a transcript in the nucleus C. 5' end of a transcript in the cytoplasm D. 3'-end of a transcript in the cytoplasm

B

Codons are part of the molecular structure of _____. A. a protein B. mRNA C. tRNA D. rRNA

B

In his transformation experiments, what did Griffith observe? A. Mutant mice were resistant to bacterial infections. B. Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form. C. Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic. D. Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains.

B

Refer to the metabolic pathway illustrated below. If A, B, and C are all required for growth, a strain that is mutant for the gene-encoding enzyme A would be able to grow on medium supplemented with _____. A --enzyme A--> B --enzyme B--> C A. nutrient A only B. nutrient B only C. nutrient C only D. nutrients A and C

B

The location of transcription and RNA processing in a eukaryotic cell is the ______________, whereas the location of translation in a eukaryotic cell is the _______________. A. cytoplasm; ribosomes B. nucleus; cytoplasm C. ribosomes; nucleus D. cytoplasm; nucleus

B

The one gene, one enzyme hypothesis is the idea that each gene encodes a single enzyme. The hypothesis has been updated based on modern discoveries. Which of the following is the main reason why the initial hypothesis was updated? A. Genes code only for RNA molecules, not for enzymes. B. Some genes encode proteins that are not enzymes. C. Genes only code for structural proteins. D. Genes code for other molecules besides proteins.

B

The process by which a portion of DNA is copied into a strand of RNA is called A. replication. B. transcription. C. translation. D. translocation.

B

There are sixty-one mRNA codons that specify an amino acid, but only forty-five tRNAs. This is best explained by the fact that _____. A. some tRNAs have anticodons that recognize four or more different codons B. the rules for base pairing between the third base of a codon and tRNA are flexible (wobble) C. many codons are never used, so the tRNAs that recognize them are dispensable D. the DNA codes for all sixty-one tRNAs, but some are then destroyed

B

What must occur before a newly made polypeptide is secreted from a cell? A. It must be translated by a ribosome that remains free within the cytosol. B. Its signal sequence must target it to the ER, after which it goes to the Golgi. C. Its signal sequence must be cleaved off before the polypeptide can enter the ER. D. Its signal sequence must target it to the plasma membrane, where it causes exocytosis.

B

What specific component of a spliceosome recognizes the splice sites and catalyzes the splicing reactions during RNA processing in a eukaryotic cell? A. snRNP B. snRNA C. protein D. UTR

B

A peptide has the sequence 5'-phe-pro-lys-gly-phe-pro-3'. Which of the following sequences in the mRNA strand could code for this polypeptide? A. 5' ACT-TAC-CAT-AAA-CAT-TAC-UGA 3' B. 3' UUU-CCC-AAA-GGG-UUU-CCC 5' C. 5' UUU-CCC-AAA-GGG-UUU-CCC 3' D. 3' AUG-AAA-GGG-TTT-CCC-AAA 5'

C

During elongation, which site in the ribosome represents the location where a codon is being read? A. E site B. P site C. A site D. The small ribosomal subunit

C

How many stop codons are there in the genetic code? A. 1 B. 2 C. 3 D. 4

C

Of the following, which is the most current description of a gene? A. a unit of heredity that causes formation of a phenotypic characteristic B. a DNA subunit that codes for a single complete protein C. a DNA sequence that is expressed to form a functional product: either RNA or polypeptide D. a discrete unit of hereditary information that consists of a sequence of amino acids

C

RNA molecules that act as enzyme are called A. spliceosomes. B. proteins. C. ribozymes. D. RNA polymerases.

C

The main enzyme involved in transcription is ________________. A. DNA polymerase B. helicase C. RNA polymerase D. transcription factors

C

The process by which mRNA is decoded by a ribosome, thereby producing a polypeptide (or protein) is called A. replication. B. transcription. C. translation. D. translocation.

C

Transcription in eukaryotes requires which of the following in addition to RNA polymerase? A. start and stop codons B. ribosomes and tRNA C. several transcription factors D. aminoacyl-tRNA synthetase

C

Use this model of a eukaryotic transcript to answer the following question(s). E = exon and I = intron UTR E1 I1 E2 I2 E3 I3 E4 UTR Which components of the previous molecule will also be found in mRNA in the cytosol? A. 5' UTR I1 I2 I3 UTR 3' B. 5' E1 E2 E3 E4 3' C. 5' UTR E1 E2 E3 E4 UTR 3' D. 5' E1 I1 E2 I2 E3 I3 E4 3'

C

What characteristic of the genetic code points to a common ancestry for all organisms? A. The code is degenerate. B. The code contains 64 codons. C. The genetic code is almost universal. D. The code contains stop codons

C

What is the first amino acid added to a polypeptide chain? A. adenine B. leucine C. methionine D. thymine

C

What is the main function of t-RNA? A. Proof reading B. Inhibits protein synthesis C. Transports amino acids to ribosomes D. None of the above

C

What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure above? A. ionic bonding between phosphates B. van der Waals interactions between hydrogen atoms C. hydrogen bonding between base pairs D. peptide bonding between amino acids

C

Which of the following demonstrates the proper relationship between genes and proteins? A. RNA → DNA → proteins B. proteins → RNA → DNA C. DNA → RNA → proteins D. DNA → proteins → RNA

C

Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression? A. mRNA, tRNA, and rRNA are transcribed. B. RNA polymerase binds to the promoter. C. A cap is added to the 5' end of the mRNA. D. RNA polymerase requires a primer to elongate the molecule.

C

Which of the following is the most abundant type of RNA in a cell? A. mRNA B. tRNA C. rRNA D. snRNA

C

Which of the following occurs in prokaryotes but not in eukaryotes? A. post-transcriptional splicing B. translation in the absence of a ribosome C. concurrent transcription and translation D. gene regulation

C

2.Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the _____. A. binding of ribosomes to mRNA B. binding of the anticodon to small subunit of the ribosome C. attachment of amino acids to rRNAs D. binding of the anticodon to the codon and the attachment of amino acids to tRNAs

D

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is _____. A. TTT B. UUA C. UUU D. AAA

D

A segment of DNA that codes for a particular protein, or polypeptide, is the definition of a A. chromosome. B. chromatid. C. nucleosome. D. gene.

D

Alternative RNA splicing _____. A. is a mechanism for increasing the rate of translation B. can allow the production of similar proteins from different RNAs C. increases the rate of transcription D. can allow the production of proteins of different sizes and functions from a single mRNA

D

An original section of DNA has the base sequence AGCGTTACCGT. A mutation in this DNA strand results in the base sequence AGGCGTTACCGT. This change represents _____. A. a missense mutation B. a point mutation C. a silent mutation D. frameshift mutation

D

Garrod hypothesized that "inborn errors of metabolism" such as alkaptonuria occur because _____. A. metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies B. enzymes are made of DNA, and affected individuals lack DNA polymerase C. certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors D. genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes

D

Many antibiotics interfere with the transfer of genetic information from RNA to protein, preventing bacteria from growing. Which of the following processes is affected by antibiotics? A. Replication B. Transcription C. Transmission D. Translation

D

The peptide bond synthesis in translation is catalyzed by A. a ribosomal protein B. a cytoplasmic protein C. mRNA D. rRNA

D

The sequence that signals the end of transcription is called the A. promoter B. stop codon C. TATA box D. terminator

D

What are introns? A. DNA sequences to which polymerases bind B. the processed mRNA C. translated DNA sequences in a gene D. untranslated DNA sequences in a gene

D

What step(s) of translation require energy, which is provided by GTP (guanosine triphosphate, found at the 5' cap of mRNA)? A. Initiation only B. Elongation only C. Initiation and elongation D. All of them

D