Chapter 12 Biology

When an aminoacyl-tRNA synthetase charges a tRNA it results in the release of which molecule? mRNA ATP AMP pyrophosphate AMP and pyrophosphate

AMP and pyrophosphate

What molecule indirectly provides the energy for translation? ADP ATP GMP GDP GTP

ATP

Evaluate the reasons ribosomal genes are useful for comparing evolutionary relationships among organisms? Because there are many differences in these genes, even among closely related species Because all organisms possess these genes and they can be compared with each other Because these are the only genes that have been sequenced for every organism on Earth Because ribosomes of prokaryotes and eukaryotes are identical Because it is possible to compare the large subunit genes with the small subunit genes

Because all organisms possess these genes and they can be compared with each other

A single gene always encodes for an enzyme. True False

False

The cells of every organism make only a few different tRNA molecules encoded by the same gene.

False

Which of the following statements about RNA processing in eukaryotes is INCORRECT? Introns are simply excised out of pre-mRNA to produce the mature mRNA. A protein/RNA complex is used to remove introns from the pre-mRNA. A poly A tail is added on to the 3′ end of the mRNA. A 7-methylguanosine cap is added on to the 5′end of the mRNA. Processing occurs in the nucleus.

Introns are simply excised out of pre-mRNA to produce the mature mRNA.

If a cell's splicesomes were mutated so they no longer functioned normally, what consequences would result? Introns would remain in the mature mRNA. Exons would be missing in the mature mRNA. Transcription would cease. A functional protein would still be produced. RNA processing would remain intact.

Introns would remain in the mature mRNA.

Which of the following statements about RNA polymerase in bacteria is INCORRECT? It binds the promoter region of a gene. It is bound to a sigma factor during initiation of transcription. It synthesizes RNA. It catalyzes the addition of nucleotides to the 5′end of a growing RNA strand. It dissociates from the DNA at the terminator.

It catalyzes the addition of nucleotides to the 5′end of a growing RNA strand.

When does the small ribosomal subunit bind to the translational complex in eukaryotic cells? It is the first component to bind to the mRNA After the initiator tRNA binds, but before the start codon has been found After the large ribosomal subunit binds, but before the initiator tRNA binds After the start codon has been found by initiator tRNA The small ribosomal subunit binds the initiator tRNA and this complex is the first to bind to the mRNA

It is the first component to bind to the mRNA

The following mRNA transcript would result in what polypeptide sequence? 5′ ACU-UUC-ACU-AUG-UUU-UUA-UCC-UCC-ACU-CCU-UGA 3′ Use the following codons and the amino acids they encode. AUG = Start or Met; UUU, UUC = Phe; UUA, UUG = Leu; UCU, UCC = Ser; CCU, CCC = Pro; ACU, ACC = Thr; UGA = Stop. Thr-Phe-Thr Phe-Leu-Ser-Ser-Thr-Pro Met-Phe-Leu-Ser-Ser-Thr-Pro Thr-Phe-Thr-Phe-Leu-Ser-Ser-Thr-Pro Met-Phe-Leu-Ser-Ser

Met-Phe-Leu-Ser-Ser-Thr-Pro

Which of the following statements about the 5′cap and mRNA processing is TRUE? The addition of a 5′ cap to mRNA occurs while the pre-mRNA is being made. The 5′ cap helps stabilize the mature mRNA. The 5′ cap prevents the degradation of mature mRNA. The 5′ cap is added to the pre-mRNA by splicesomes. The 5′ cap is a group of adenosine molecules.

The addition of a 5′ cap to mRNA occurs while the pre-mRNA is being made.

An mRNA sequence is 5′AUG-GGC-ACU-CAU-ACU-UAA3′, where AUG is the start codon and UAA is the stop codon. How many distinct aminoacyl-tRNA synthetases are required to translate the mRNA sequence? 2 3 4 5 6

4

If a DNA template strand has a sequence of 3′ TACAATGTAGCC 5′, then the RNA produced from it will be which sequence? 3′TACAATGTAGCC5′ 5′ATGTTACATCGG3′ 5′AUGUUACAUCGG3' 3′AUGUUACAUCGG5′ 3′ATGTTACATCGG5′

5′AUGUUACAUCGG3'

The amino acids of a growing polypeptide chain are held together by what kind of bond during the elongation stage of translation? hydrogen peptide glycosidic noncovalent lactose

peptide

The transcription process in a eukaryotic gene directly produces _________. rRNA pre-mRNA mRNA DNA Protein

pre-mRNA

Transcription begins near a site in the DNA called the ______. promoter enhancer response element transcription unit regulatory sequence

promoter

What is NOT a component of the translation machinery? mRNA tRNA translation factors ribosomes protein polymerase

protein polymerase

What molecule(s) exhibits self-splicing? rRNA tRNA mRNA rRNA and tRNA rRNA and mRNA

rRNA and tRNA

What factors are recognized by the cell in order to recognize the stop codon and disassemble the translation machinery? elongation factors release factors transcription factors initiation factors mRNA factors

release factors

Which of the following serves as the "translator" or intermediary between an mRNA codon and an amino acid? rRNA snRNA tRNA siRNA snRNPs

tRNA

The process that produces mRNA from DNA is called transcription. translation. replication. processing. post-translational modification.

transcription.

What products of nonstructural genes are never translated? transfer RNA ribosomal RNA messenger RNA transfer RNA and ribosomal RNA ribosomal RNA and messenger RNA

transfer RNA and ribosomal RNA

A defective ribosome would have the MOST detrimental effect on what processes would a defective ribosome have the most detrimental effect? translation replication transcription replication and transcription replication and translation

translation

More than one codon can specify the same amino acid. True False

true

RNA polymerase II of eukaryotes always requires more than one general transcription factor to initiate transcription. True False

true

How many distinct aminoacyl-tRNA synthetases does each cell make? ~1 ~20 ~60 ~120 ~180

~20

What basic features of transcription is NOT shared by both prokaryotes and eukaryotes? Both prokaryotic and eukaryotic genes have a promoter site. RNA polymerase transcribes genes in both prokaryotes and eukaryotes. Gene transcription involves initiation, elongation, and termination in both prokaryotes and eukaryotes. The complexity of protein components involved in transcription is similar for both prokaryotes and eukaryotes. The initiation of transcription in both prokaryotes and eukaryotes involves the interactions of more than one protein.

The complexity of protein components involved in transcription is similar for both prokaryotes and eukaryotes.

What is the function of the poly A tail? The poly A tail is required for the termination of translation, it is recognized by the release factor proteins The poly A tail is required for the mRNA to resume its double helical structure The poly A tail increases mRNA stability in eukaryotes. The poly A tail increases mRNA stability in prokaryotes. The poly A tail serves as a termination sequence for RNA polymerase III.

The poly A tail increases mRNA stability in eukaryotes.

Which of the following statements about the mRNA start codon is INCORRECT? The start codon is only a few nucleotides from the ribosomal binding site. The start codon is usually GGA. The start codon is usually AUG. The start codon specifies the amino acid, methionine. The start codon defines the reading frame.

The start codon is usually GGA.

The term N-terminus refers to the presence of a(n) ________ at one of the ends of a polypeptide. oxygen atom carboxyl group amino group carbonyl group sulfate group

amino group

What enzyme catalyzes the attachment of amino acids to tRNA molecules? helicase topoisomerase aminoacyl-tRNA synthetase ribosome translation factor

aminoacyl-tRNA synthetase

The most common eukaryotic ribosome carries out its function in the Golgi apparatus. nucleus. cytosol. mitochondria. chloroplast.

cytosol.

Because more than one codon can specify the same amino acid, the genetic code is said to be repetitive. redundant. reverse. degenerate. wobbly.

degenerate.

An organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product is called a _______. chromosome trait allele gene expression

gene

The processes of transcription and translation are collectively known as RNA processing. gene duplication. protein synthesis. DNA synthesis. gene expression.

gene expression.

Intervening sequences that are transcribed, but not translated into protein are called exons. introns. spliceosomes. transposons. transcription factors.

introns.

The molecule mRNA, which contains the information to make a polypeptide, is constructed from a DNA template. True False

True

The termination of translation occurs when a release factor recognizes the stop codon. True False

True

________ is to transcription as ________ are to translation. RNA spliceosome; ribosomes RNA polymerase; ribosomes RNA polymerase; RNA spliceosomes DNA polymerase; RNA polymerase DNA polymerase; ribosomes

RNA polymerase; ribosomes

tRNA contains the genetic code for producing a polypeptide. True False

false

Which of the following statements about tRNA is FALSE? tRNAs of both eukaryotes and prokaryotes share common features. The two-dimensional structure of tRNAs exhibits a cloverleaf pattern. tRNAs are produced in the nucleus. functional tRNAs have been spliced by splicesomes. tRNAs possess an anticodon complementary to the codon.

functional tRNAs have been spliced by splicesomes.

Which region of a structural gene contains the information that specifies an amino acid sequence? promoter region transcribed region terminator regulatory sequence enhancer region

transcribed region

What protein influences the ability of RNA polymerase to transcribe genes? DNA polymerases DNA helicases transcription factors snRNPs tRNA

transcription factors

Identify the anticodon sequence for an mRNA sequence that is 5′AUG-GGC-ACU-CAU3′. 3′AUG-GGC-ACU-CAU5′ 3′UAC-CCG-UGA-GUA5′ 5′AUG-GGC-ACU-CAU3′ 5′UAC-CCG-UGA-GUA3′ 3′TAC-CCG-TGA-GTA3′

3′UAC-CCG-UGA-GUA5′

Decide which sequence of events is most CORRECT for the initiation and elongation steps of translation in prokaryotic cells? (1) initiator tRNA binds start codon on mRNA (2) small ribosomal subunit binds to mRNA (3) large ribosomal subunit binds (4) tRNA entry and peptidyl transfer reaction (5) translocation of ribosome and release of tRNA 1, 2, 3, 4, 5 1, 2, 3, 5, 4 1, 3, 2, 4, 5 2, 3, 1, 5, 4 2, 1, 3, 4, 5

2, 1, 3, 4, 5

How many nucleotides are contained in a single codon? 1 3 4 6 9

3

What process enables a single gene to encode two or more polypeptides that are different in their amino acid sequence. Reverse transcription Self-splicing Capping Alternative splicing Regulatory splicing

Alternative splicing

If Nirenberg and Leder had the technology, what would be a better substitute to using radiolabeled amino acids? Radiolabeled proteins Radiolabeled tRNAs Ribosomes acids labeled with a fluorescent dye Amino acids labeled with a fluorescent dye All of the above

Amino acids labeled with a fluorescent dye

Which amino acid would Nirenberg and Leder have found when they used the triplet UAG? Isoleucine Proline Lysine Threonine None of these

None of these

What protein is involved in synthesizing messenger RNA in eukaryotes? RNA polymerase I RNA polymerase II RNA polymerase III sigma factor both RNA polymerase I and III

RNA polymerase II

All enzymes are proteins. True False

false

As part of the transcriptional unit, regulatory sequences are the sites where RNA polymerase and transcription factors bind to regulate transcription. True False

false

Because of the abundance of ribosomes, translation is NOT an energy costly process for the cell. True False

false

In eukaryotes, 40S and 60S combine to form a 100S ribosome. True False

false

Translation is a relatively slow process. true false

false