CH 11-15

Which sequence of events CORRECTLY describes 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 Multiple Choice 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? Multiple Choice 1 3 4 6 9

3

DNA Polymerase uses what kind of enzymatic activity in the process of proofreading? Check All That Apply 5' -> 3' exonuclease activity to remove the mismatched bases. 3' -> 5' exonuclease activity to remove the mismatched bases. 5' -> 3' polymerase activity to replace the excised bases. 3' -> 5' polymerase activity to replace the excised bases. Helicase activity to open up the template DNA. Ligase activity to form a phosphodiester bond between the newly synthesized DNA and the DNA that was present before the mismatch occurred.

3' -> 5' exonuclease activity to remove the mismatched bases. 5' -> 3' polymerase activity to replace the excised bases.

DNA polymerases use their ________ activity to remove a mismatched base pair. Multiple Choice 3' -> 5' exonuclease. 5' -> 3' exonuclease. RNase. protease.

3' -> 5' exonuclease.

Reverse transcriptase is an enzyme that can synthesize DNA from an RNA template. What DNA sequence is produced from an RNA molecule with the sequence 5'AUUGACGGU3'? Multiple Choice 3'UAACUGCCA5'. 5'TTTCTGCCT3'. 3'TAACTGCCA5'. 5'ATTCAGCCT3'. 3'TUUCTGCCU5'.

3'TAACTGCCA5'.

What is the complementary DNA strand to 5′-ATTCGGTGA-3′? Multiple Choice 5′-TAAGCCACT-3′. 3′-CGGATTGTC-5′. 5′-CGGATTGTC-3′. 3′-TAAGCCACT-5′. 3′-ATTCGGTGA-5′.

3′-TAAGCCACT-5′.

An mRNA sequence is 5′-AUG GGC ACU CAU ACU UAA-3′, 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? Multiple Choice 2 3 4 5 6

4

Factors that can alter the level of expression of a gene include Check All That Apply an increase in environmental temperature. an increase in salinity. exposure to UV radiation. presence of a particular energy substrate.

All

Points of control in eukaryotic gene expression include Check All That Apply RNA processing. translation. transcription. post-translation.

All

Which of the following statements describe a reason ribosomal genes are useful for comparing evolutionary relationships among organisms? Multiple Choice There are many differences in these genes, even among closely related species. All organisms possess these genes and they can be compared with each other. These are the only genes that have been sequenced for every organism on Earth. Ribosomes of prokaryotes and eukaryotes are identical. It is possible to compare the large subunit genes with the small subunit genes.

All organisms possess these genes and they can be compared with each other.

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

Alternative splicing

Which of the following is FALSE when comparing RNA and DNA? Multiple Choice Both contain nucleotides connected by phosphodiester linkages. Both contain phosphate groups. Both are composed of nucleotides that contain sugars. Both are composed of identical nucleotides. Both are composed of nucleotides that contain a phosphate group, a pentose sugar, and a nitrogenous base. Both have a 5' end and a 3' end. Both are composed of purines and pyrimidines.

Both are composed of identical nucleotides.

Histone deacetylase inhibitors are a class of drugs used as mood stabilizers and anti-epileptics that are also being researched for their efficacy as anti-cancer agents. Histone deacetylase inhibitors block the action of histone deacetylases, which remove acetyl groups from lysine residues in histone tails. How will blocking histone deacetylases affect gene expression in the cell? Multiple Choice Chromatin will become more tightly compact, and gene expression will be reduced. Chromatin will become more tightly compact, and gene expression will be increased. Chromatin will become more open, and gene expression will be reduced. Chromatin will become more open, and gene expression will be increased. Chromatin will become more methylated, and gene expression will be decreased.

Chromatin will become more open, and gene expression will be increased.

During DNA replication, all of the following proteins are important for separating the DNA strands and allowing movement of the replication fork EXCEPT Multiple Choice DNA polymerase. helicase. topoisomerase. single-stranded binding proteins. both helicase and topoisomerase.

DNA polymerase.

The function(s) of DNA polymerase includes which of the following? Multiple Choice DNA synthesis. DNA proofreading. removal of RNA primers and filling in the gaps. DNA synthesis and proofreading. DNA synthesis, DNA proofreading, and removal of RNA primers and filling in the gaps.

DNA synthesis, DNA proofreading, and removal of RNA primers and filling in the gaps.

A single gene always encodes an enzyme. Answer True False

False

Different globin polypeptides are expressed at similar levels during the embryonic and fetal stages of mammalian development. Answer True False

False

Eukaryotic genes are almost always organized in groups, similar to operons in prokaryotes. Answer True False

False

MicroRNAs increase the rate of mRNA translation. Answer True False

False

Small effector molecules directly bind the DNA they regulate. Answer True False

False

Unmethylated CpG islands are correlated with inactive genes. Answer True False

False

If a cell's splicesomes were mutated so they no longer functioned normally, what consequences would result? Multiple Choice 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 best describes DNA polymerase? Multiple Choice It is an enzyme required to produce a primer needed for DNA replication. It is an enzyme that catalyzes the addition of nucleotides to the 5′ end of a growing DNA strand. It is an enzyme that catalyzes the addition of nucleotides to the 3′ end of a growing DNA strand. It is an enzyme required to glue pieces of DNA fragments together. It is an enzyme that polymerizes the DNA and keeps the replication fork open.

It is an enzyme that catalyzes the addition of nucleotides to the 3′ end of a growing DNA strand.

______________ are made in replicating the lagging strand of DNA, but are not made during leading strand DNA replication. Multiple Choice primers. nucleases. Okazaki fragments. pyrophosphates. DNA polymerases.

Okazaki fragments.

Which of the following statements about DNA is FALSE? Multiple Choice One chromosome is made up of many DNA molecules. A eukaryotic genome is made up of many DNA molecules. A DNA double helix contains both covalent bonds and hydrogen bonds. A strand of DNA is made up of many nucleotides. All of these are TRUE.

One chromosome is made up of many DNA molecules.

Which of the following is true concerning a somatic cell mutation? Multiple Choice A small fraction of the gametes carry the mutation. Half of the gametes carry the mutation. All of the gametes carry the mutation. Only a small group of cells within the organism is affected by the mutation. All cells within the organism are affected by the mutation.

Only a small group of cells within the organism is affected by the mutation.

Why would bacteria evolve so that the presence of tryptophan inhibits its own production? Multiple Choice Producing the enzymes that synthesize tryptophan is metabolically expensive, so it is wasteful to make them when tryptophan levels are high and its synthesis is not necessary. Producing high levels of tryptophan inhibits the production of other amino acids, so inhibiting its production allows all amino acids to be synthesized at equal concentrations. High levels of tryptophan causes cells to become unresponsive to external stimuli, so its production must be regulated. High levels of tryptophan inhibit cellular respiration and the synthesis of ATP, so its production must be regulated. All of these choices are TRUE

Producing the enzymes that synthesize tryptophan is metabolically expensive, so it is wasteful to make them when tryptophan levels are high and its synthesis is not necessary.

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

RNA polymerase; ribosomes

Which of the following statements about the 5′cap and mRNA processing is TRUE? Multiple Choice The addition of a 5′ cap to mRNA occurs while the pre-mRNA is being made. The 5' cap causes the mRNA to be rapidly degraded. The 5' cap prevents the exit of mRNA from the nucleus. 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.

What basic features of transcription is NOT shared by both prokaryotes and eukaryotes? Multiple Choice 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.

Which of the following statements about RNA processing in eukaryotes is INCORRECT? Multiple Choice The excision of introns from pre-mRNA is the only modification required to produce a 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. Modification occurs in the nucleus.

The excision of introns from pre-mRNA is the only modification required to produce a mature mRNA.

Which of the following is NOT a criterion for an organism's genetic material? Multiple Choice The genetic material must contain information necessary to construct a whole organism. The genetic material must be transmitted from parent to offspring. To transmit information the genetic material must be replicated. The genetic material must be dynamic, changing rapidly in response to changes in the environment. Genetic material must account for the known variation within each species and among different species.

The genetic material must be dynamic, changing rapidly in response to changes in the environment.

Which of the following is NOT true of small effector molecules? Multiple Choice They can cause a conformational change in a regulatory protein. They can prevent a repressor from binding a gene region. They can regulate gene transcription by binding to DNA. They can regulate gene transcription by binding a regulatory protein.

They can regulate gene transcription by binding to DNA.

Both eukaryotes and prokaryotes require a promoter region for gene transcription. Answer True False

True

Loosely packed chromatin is said to be in an open conformation. Answer True False

True

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

True

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

True

The progressive shortening of telomeres in DNA correlates with cell senescence. Answer True False

True

When considering the complexity of genetic material, multiple genes are found within a chromosome. Answer True False

True

When lactose becomes available the genes encoding b-galactosidase and lactose permease are upregulated in E. coli. Answer True False

True

Which of the following characteristics of genetic material accounts for the need to get a flu vaccine every year, but a polio vaccine once in a life time? Multiple Choice Information. Replication. Transmission. Replication and Transmission. Variation.

Variation.

Liver cells, mammary cells, and skin cells all contain the same genome; however, their respective proteomes vary drastically. This observation is best explained by what phenomenon? Multiple Choice gene splicing cell division cell differentiation crossing over evolution

cell differentiation

Which of the following is the highest (or most complex) level of structure for genetic material? Multiple Choice nucleotide. double helix. DNA. gene. chromosome.

chromosome

The lac operator site within the lac operon is an example of a Multiple Choice cis-acting element. para-acting element. trans-acting element. inter-acting element. contra-acting element.

cis-acting element.

A eukaryotic gene that is regulated by three activator proteins is said to be under Multiple Choice triplet regulation. individual control. self-regulation. combinatorial control. elastic control.

combinatorial control.

A genes expressed at a relatively constant level in tissues regardless of variations in the animal's condition is called a Multiple Choice transposable element. steady state gene. constitutive gene. recombinant gene. multifunctional gene.

constitutive gene.

Genes organized into an operon are beneficial to certain bacteria because the operon allows for Multiple Choice differential regulation of individual genes that encode proteins with a common function. coordinated regulation of a group of genes that encode proteins with a common function. separate regulation of individual genes that encode proteins with different functions. coordinated regulation of a group of genes that encode proteins with different functions. coordinated regulation of a group of proteins involved in numerous cellular activities.

coordinated regulation of a group of genes that encode proteins with a common function.

Eukaryotic DNA methylation occurs on which base? Multiple Choice guanine cytosine thymine adenine thymine and adenine

cytosine

The major difference in gene regulation between prokaryotes and eukaryotes is that... Multiple Choice eukaryotic and prokaryotic genes are usually grouped for common functions. eukaryotic genes regulation requires fewer signals that prokaryotic gene regulation. eukaryotic gene regulation is more simplistic than prokaryotic gene regulation. eukaryotic genes are arranged individually, while prokaryotic genes are grouped into operons. eukaryotic gene regulation tends to require less coordination and integration than prokaryotic gene regulation.

eukaryotic genes are arranged individually, while prokaryotic genes are grouped into operons.

Which of the following results in a spontaneous mutation? Multiple Choice free radicals produced by cellular metabolism exposure to ultraviolet light exposure to benzo (a)-pyrene, a chemical substance found in cigarette smoke exposure to ultraviolet light and benzo (a)-pyrene exposure to X-rays

free radicals produced by cellular metabolism

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 _______. Multiple Choice chromosome trait allele gene expression

gene

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

gene expression.

A cell's ability to control their level of gene expression is called Multiple Choice gene transformation. gene regulation. gene splicing. gene addition. gene correction.

gene regulation.

Protein(s) that play a role in initiating transcription in eukaryotes include Check All That Apply general transcription factors. transposase. RNA polymerase II. mediators. general transcription factors and RNA polymerase II.

general transcription factors. RNA polymerase II. mediators. general transcription factors and RNA polymerase II.

The proofreading function of DNA polymerase reduces the error rate from about one in a million base pairs to about one in a ________ base pairs. Multiple Choice hundred thousand. ten thousand. thousand. ten million. hundred million.

hundred million.

DNA methylation Multiple Choice increases transcription. inhibits transcription. increases crossover events. decreases crossover events. promotes post-translational modification of proteins

inhibits transcription.

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

introns.

Which molecule catalyzes covalent bond formation between fragments of DNA. Multiple Choice helicase. ligase. polymerase. primase. nuclease.

ligase.

Sickle-cell anemia is a human disease that occurs as a result of what type of mutation in the b-globin gene? Multiple Choice silent missense nonsense frameshift sense

missense

A researcher determined that a strain of E. coli is producing a shortened version of a protein required for glucose metabolism. What type of mutation could be responsible for this shorter than normal protein? Multiple Choice nonsense mutation missense mutation silent mutation sense mutation frameshift mutation

nonsense mutation

Beginning with the simplest level of structure, which order of organization of genetic material is CORRECT? Multiple Choice DNA, nucleotide, gene, genome, chromosome. nucleotide, DNA, gene, chromosome, genome. DNA, nucleotide, gene, chromosome, genome. nucleotide, DNA, gene, genome, chromosome. nucleotide, DNA, chromosome, gene, genome.

nucleotide, DNA, gene, chromosome, genome

___________ are the building blocks of DNA. Multiple Choice genes. double helices. amino acids. nucleotides. chromosomes.

nucleotides

The nucleotides within DNA are composed of a Multiple Choice phosphate group, ribose sugar, and nitrogenous base. sulfur group, ribose sugar, and nitrogenous base. phosphate group, deoxyribose sugar, and nitrogenous base. sulfur group, deoxyribose sugar, and nitrogenous base. phosphate group, hexose sugar, and nitrogenous base.

phosphate group, deoxyribose sugar, and nitrogenous base.

An mRNA that contains the coding sequence for two or more structural genes is called a Multiple Choice polyintronic mRNA. polyextronic mRNA. polycistronic mRNA. polyexpressive mRNA. polyrepressor mRNA.

polycistronic mRNA.

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

pre-mRNA

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

promoter

The general transcription factor TFIID Multiple Choice recognizes the enhancer. recognizes the TATA box. recognizes the silencer. transcribes mRNA. is a silencer.

recognizes the TATA box.

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

release factors

Which of the following is NOT a protein involved in DNA replication? Multiple Choice replication fork. single-stranded binding proteins. DNA ligase. topoisomerase. helicase.

replication fork.

A(n) ________ operon is one whose transcription is decreased by effector molecules. Multiple Choice activated repressible inducible coinducible compressible

repressible

An activator is to an enhancer as a(n) _____ is to a silencer. Multiple Choice transcription factor inducer repressor mediator RNA polymerase II

repressor

Alternative splicing Check All That Apply results in different proteins in the same family. is important for multicellular organisms with different cell types. results in proteins that can quickly be activated and deactivated. is a gene regulatory mechanism in eukaryotes but not prokaryotes. have pre-RNA that are the same as other genes.

results in different proteins in the same family. is important for multicellular organisms with different cell types. is a gene regulatory mechanism in eukaryotes but not prokaryotes. have pre-RNA that are the same as other genes.

Proofreading by DNA polymerase involves the removal of Multiple Choice only the mismatched base on the old strand of DNA. only the mismatched base on the newly synthesized strand of DNA. the mismatched base pair on both strands of DNA. several bases on the newly synthesized strand of DNA. several bases on the old strand of DNA.

several bases on the newly synthesized strand of DNA.

MicroRNAs (miRNAs) Multiple Choice are long RNA molecules. silence the expression of specific mRNAs. are found only in animals. are cut by an enzyme called transcriptase.

silence the expression of specific mRNAs.

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

tRNA

The lacP site within the lac operon is upstream of the genes that encode for lactose uptake and metabolism proteins. The lacP site is Multiple Choice the lac promoter site. where RNA polymerase binds. the site where genes are transcribed that encode proteins for metabolizing lactose. the lac promoter site where RNA polymerase binds. the lac promoter site, where genes are transcribed that encode proteins for metabolizing lactose.

the lac promoter site where RNA polymerase binds.

In E. coli cells when lactose is absent from the environment, Multiple Choice large amounts of b-galactosidase, lactose permease, and galactosidetransacetylase are made. trace amounts of b-galactosidase, lactose permease, and galactosidetransacetylase are made. no b-galactosidase, lactose permease, andgalactosidetransacetylas are made. the lac operon is induced. polycistronic mRNA levels would be very high.

trace amounts of b-galactosidase, lactose permease, and galactosidetransacetylase are made.

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

transcription factors

The event that occurs when allolactose levels increase in E. coli is Multiple Choice transcription of genes within the lac operon increases. transcription of genes within the lac operon decreases. transcription of genes within the lac operon does not change. E. coli cells replicate rapidly. the tryptophan operon becomes more active.

transcription of genes within the lac operon increases.

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

transcription.

The core promoter in eukaryotes is usually composed of which two features? Multiple Choice transcriptional start site and enhancer transcriptional start site and response elements transcriptional start site and TATA box enhancer and TATA box response elements and TATA box

transcriptional start site and TATA box

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

transfer RNA and ribosomal RNA

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

~20

How many replication forks are there at an origin of replication? Multiple Choice 1. 2. 3. 4. 5.

2

Complete the sentences about the process of DNA replication with the correct terms. New DNA is synthesized in the ____________ direction. The enzyme that removes tightened coils ahead of the replication fork is ____________ . The enzyme that catalyzes new DNA synthesis is ____________ . DNA synthesis occurs continuously on the ____________ . DNA synthesis occurs in small sections on the ____________ . Fragments of discontinuous DNA synthesis are called ____________ . Gaps in the sugar-phosphate backbone of DNA are closed by ____________ . topoisomerase * 5' phosphate * DNA-polymerase * 3' to 5' * leading strand * replication fork(s) * DNA ligase * DNA-helicase * ribosomes * primase * RNA primers * lagging-strands * hexokinase * single-stranded-protein * okazaki-fragments * 3' OH * transfer RNA

5' to 3' topoisomerase DNA polymerase leading strand lagging strand okazaki fragment DNA ligase

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

5′AUGUUACAUCGG3'

Which of the following statements in TRUE? Multiple Choice Many active genes are found in euchromatin, because proteins involved in transcription can easily access these regions of DNA. Euchromatin, found in interphase cells, is readily visible and easily viewed. A region of DNA is either heterochromatin or euchromatin, it cannot go back and forth between the two forms. When DNA is being replicated, the chromosomes are composed chiefly of heterochromatin. All choices are correct.

Many active genes are found in euchromatin, because proteins involved in transcription can easily access these regions of DNA.

Complete the sentences about the process of DNA replication with the correct terms. When replication starts, an origin of replication forms, consisting of two ____________ moving in opposite directions. DNA double helix is separated into single strands by the enzyme ____________ . Newly-exposed, unreplicated DNA is protected by ____________ . Short segments of RNA are synthesized, called ____________ . The enzyme that synthesizes the short segments of RNA is called a ____________ . The short RNA segments provide a free ____________ for replication. topoisomerase * 5' phosphate * DNA-polymerase * 3' to 5' * leading strand * replication fork(s) * DNA ligase * DNA-helicase * ribosomes * primase * RNA primers * lagging-strands * hexokinase * single-stranded-protein * okazaki-fragments * 3' OH * transfer RNA

Replication forks DNA helicase single strand binding protein RNA primers primase 3' OH

The enzyme that attaches DNA nucleotides at the ends of eukaryotic chromosomes in order to prevent chromosome shortening is called Multiple Choice Polymerase. Ligase. Telomerase. Topoisomerase. Primase.

Telomerase

Which of the following statements about telomeres is INCORRECT? Multiple Choice Telomeres are lengthened by telomerase. Telomeres are found at the ends of chromosomes. Telomeres are short repeat sequences. Telomeres would be longer in cells of older than younger individuals. Telomeres are crucial to the viability of a cell that replicates often.

Telomeres would be longer in cells of older than younger individuals.

If an organism had a DNA polymerase III that lost its ability to proofread, which of the following statements would be TRUE? Multiple Choice DNA could not be synthesized, and the organism would die. DNA polymerase III would randomly add new nucleotides, and the entire sequence of new DNA would be worthless. The organism would die. The mutation rate for the organism would increase, and more substitutions would be seen in its DNA than in an organism that had functional proofreading. The proofreading ability of RNA polymerase would restore the lost proofreading ability of the DNA polymerase III, and the organism would be normal. DNA Polymerase I would take over the function of DNA Polymerase III, and the organism would be normal.

The mutation rate for the organism would increase, and more substitutions would be seen in its DNA than in an organism that had functional proofreading.

What is the function of the poly A tail? Multiple Choice 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 would occur from a mutation in the gene's promoter region? Multiple Choice The sequence of the mature mRNA would change. The ability of pre-mRNA to be properly spliced would change. The ability of mRNA to be translationally regulated would change. The amino acid sequence of the translated protein would be altered. The rate of transcription may increase or decrease.

The rate of transcription may increase or decrease.

Which of the following statements about the mRNA start codon is INCORRECT? Multiple Choice 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.

Why is there a need to produce Okazaki fragments on the lagging strand, but not on the leading strand of DNA? Multiple Choice The two parental strands of DNA are antiparallel and DNA polymerase makes DNA in the 5′ to 3′ direction only. It is substantially more efficient to make several shorter strands rather than one longer strand of DNA. There is not enough cellular DNA ligase for bonding Okazaki fragments together if they were produced from both parental strands. By having one leading strand and one lagging strand the cell can limit the amount of DNA polymerase used for chromosomal replication. The leading strand opens first, and so Okazaki fragments are not needed. The lagging strand unwinds second resulting in the need to produce Okazaki fragments.

The two parental strands of DNA are antiparallel and DNA polymerase makes DNA in the 5′ to 3′ direction only.

Which of the following is NOT a mechanism that cells use to ensure their DNA is accurately replicated? Multiple Choice Hydrogen bonding across the double helix is more stable when nucleotides abide by Chargaff's rules. DNA polymerase is unlikely to catalyze the phosphodiester bond if a mismatched nucleotide enters the active site. When mismatched nucleotides are detected, DNA polymerase will begin to synthesize DNA in the 3' to 5' direction to correct the mistake. DNA polymerase can identify mismatched nucleotides and use its 3' to 5' exonuclease activity to remove a small section of DNA that includes the mutation. All of these are mechanisms that cells have to ensure the fidelity of DNA replication.

When mismatched nucleotides are detected, DNA polymerase will begin to synthesize DNA in the 3' to 5' direction to correct the mistake.

What would result from a single nucleotide deletion (point mutation) within the coding sequence of a structural gene? Multiple Choice a silent point mutation with no deleterious effects a missense point mutation resulting in the change of one amino acid a nonsense point mutation resulting in the generation of a premature stop codon a frameshift mutation, producing a different amino acid sequence altogether All of the choices are possible.

a frameshift mutation, producing a different amino acid sequence altogether

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

aminoacyl-tRNA synthetase

What type of regulatory transcription factor binds DNA and increases the transcription of a gene? Multiple Choice a repressor exerting negative control a repressor exerting positive control an activator exerting negative control an activator exerting positive control a combination of both a repressor and activator exerting negative control

an activator exerting positive control

The likely outcome from a mutation in the lacO site (lac Operator) of the lac operon would be Multiple Choice binding of RNA polymerase could be hindered. binding of a repressor protein could be hindered. binding of the activator protein could be hindered. duplication could be affected. the order in which the genes of the lac operon are transcribed could be altered.

binding of a repressor protein could be hindered.