Unit 1
Part complete In a DNA nucleotide, to which carbon on deoxyribose is the nitrogenous base attached? See Section 7.2. 1′ 2′ 3′ 5′
1'
What normally binds to an open A site on the ribosome? See Section 9.1. A tRNA that carries the next amino acid to be added to the polypeptide chain The 3' UTR (untranslated region) of the mRNA The initiator tRNA that carries the first amino acid in the polypeptide chain An empty tRNA after its amino acid has been added to the polypeptide chain
A tRNA that carries the next amino acid to be added to the polypeptide chain
In the process of eukaryotic pre-mRNA splicing, how is the lariat intermediate formed? See Section 8.4. By joining the 3' end of exon 1 to the 2'carbon of the branch site By joining the 3' end of the intron to the 2' carbon of the branch site By joining the 5' end of the intron to the 2' carbon of the branch site By joining the 5' end of exon 2 to the 2' carbon of the branch site
By joining the 5' end of the intron to the 2' carbon of the branch site
Which enzyme in E. coli is responsible for the removal of RNA primers from DNA? See Section 7.4. DNA ligase DNA polymerase III 3′-5′ exonuclease DNA polymerase I
DNA polymerase I
In 1944, Avery, MacLeod, and McCarty provided direct evidence that DNA was the hereditary molecule. They treated heat-killed extracts from lethal SIII (smooth) bacteria with various enzymes and found that transformation was prevented only upon treatment with __________. DNase Protease RNase Lipase
DNase
Which of the following reagents is NOT required for the polymerase chain reaction? See Section 7.5. Dideoxynucleotide triphosphates A heat-stable DNA polymerase. A pair of DNA primers. Deoxynucleotide triphosphates
Dideoxynucleotide triphosphates
Which of the following types of cells typically displays little or NO telomerase activity? See Section 7.4. Male germ-line cells (spermatocytes). Stem cells Female germ-line cells (oocytes). Differentiated somatic cells.
Differentiated somatic cells.
Which protein is responsible for initial denaturation of oriC in E. coli? See Section 7.4. Primase DnaA Single-stranded binding protein (SSB). DnaB
DnaA
Ribosomal subunits are large complexes composed of numerous polypeptides and at least one rRNA molecule. Which subunits include three rRNA molecules? See Section 9.1. Bacterial large subunits Eukaryotic large subunits Eukaryotic small subunits Prokaryotic small subunits
Eukaryotic large subunits
Intrinsic termination of transcription in bacteria requires which of the following? See Section 8.2. Formation of a hairpin in the nascent RNA followed by a rut site Formation of a hairpin in the nascent RNA and the activity of rho protein Formation of a hairpin in the nascent RNA followed by a stop codon Formation of a hairpin in the nascent RNA followed by a string of uracil nucleotides
Formation of a hairpin in the nascent RNA followed by a string of uracil nucleotides
Which of the following is an example of the phenomenon termed "RNA editing"? See Section 8.4. Posttranscriptional addition of a poly-A tail to the 3' end of mRNA Co-transcriptional addition of a modified guanosine nucleoside to the 5'end of mRNA Posttranscriptional insertion of uracil nucleotides facilitated by a guide RNA Co-transcriptional splicing of mRNA to remove introns
Posttranscriptional insertion of uracil nucleotides facilitated by a guide RNA
Which of the following statements best describes the structure of RNA molecules in general? See Section 8.1. RNA molecules form a double helix modeled after the DNA from which they are encoded. RNA molecules are single-stranded, but they commonly form localized secondary structures by forming covalent bonds between regions of the molecule. RNA molecules are single-stranded, but they commonly form localized secondary structures (such as stems and loops) by base pairing between regions of the molecule. RNA molecules are single-stranded, and they do not commonly form localized secondary structures.
RNA molecules are single-stranded, but they commonly form localized secondary structures (such as stems and loops) by base pairing between regions of the molecule.
Which eukaryotic promoters display a high degree of variability in the type, number, and location of consensus sequence elements? See Section 8.3.. RNA pol I promoters for rRNA RNA pol III promoters for snRNA RNA pol II promoters for mRNA RNA pol III promoters for tRNA
RNA pol II promoters for mRNA
Which of the following statements about DNA replication in E. coli is true? See Section 7.3. Replication proceeds in both directions from multiple origins of replication. Replication proceeds in one direction from multiple origins of replication. Replication proceeds in both directions from a single origin of replication. See Figure 7.10 for more information. Replication proceeds in one direction from a single origin of replication.
Replication proceeds in both directions from a single origin of replication. See Figure 7.10 for more information.
Which of the following is NOT one of the four processes of evolution that leads to changes in the frequency of alleles in a population over time? See Section 1.5. Natural selection Sexual reproduction Mutation Genetic drift
Sexual reproduction
What does the phrase "central dogma of molecular biology" describe? The fact that hereditary information flows from DNA through mRNA to create proteins, the functional products of most genes The fact that all living things are made of cells The fact that DNA constitutes the genome in all living things The fact that the structure of DNA is a double helix
The fact that hereditary information flows from DNA through mRNA to create proteins, the functional products of most genes
In the early 1960s, a number of investigators conducted a series of elegant experiments that helped to decipher the genetic code. Which of the following describes a bona fide property of the genetic code? See Section 9.5. The genetic code is a doublet code comprising two nucleotides per codon. The genetic code consists of non-overlapping codons. Spacers or markers separate codons from one another. The genetic code consists of overlapping codons.
The genetic code consists of non-overlapping codons.
What is the function of the sigma subunit in bacterial RNA polymerase? See Section 8.2. Elongation of the RNA during synthesis The sigma subunit induces a conformational change in the RNA polymerase core enzyme that switches it to its active form. Binding to the template DNA strand Recognition of the transcriptional termination sequence
The sigma subunit induces a conformational change in the RNA polymerase core enzyme that switches it to its active form.
The RNA transcribed from a gene will be complementary and antiparallel to which of the following? See Section 8.2. Both strands of the DNA. The template strand of the DNA The non-template strand of the DNA The coding strand of the DNA
The template strand of the DNA
In the process of translational initiation in bacteria, where does the initiator tRNA first bind to the ribosome? See Section 9.2. To the partial A site on the small ribosomal subunit To the partial P site on the small ribosomal subunit To the partial P site on the large ribosomal subunit To the partial A site on the large ribosomal subunit
To the partial P site on the small ribosomal subunit
No. Primase synthesizes short RNA primers that provide the 3′-OH to which DNA polymerase can add new nucleotides. Which enzyme is responsible for relieving the torsional stress caused by DNA unwinding in the process of DNA replication? See Section 7.4. DNA ligase Topoisomerase DNA polymerase Helicase
Topoisomerase
What is the final step of translational initiation in both bacteria and eukaryotes? See Section 9.2. Binding of the intact ribosome to the 5' cap on the mRNA Binding of the initiator tRNA to the AUG start codon Union of the large subunit with the small subunit to form the intact ribosome Binding of GTP to the intact ribosome
Union of the large subunit with the small subunit to form the intact ribosome
In the early 1900s, scientists noted that chromosome movements during cell division in reproductive cells mirrored the patterns of inheritance described by Mendel. These results and others confirmed that Mendel's hereditary units (genes) were located on chromosomes. The sum total of chromosomes in an organism and the alleles they carry constitute its __________, whereas the organism's observable traits constitute its __________. genotype; phenotype mitosis; meiosis genes; genome homologous pairs; alleles
genotype, phenotype
What type of bond holds the two strands of DNA together through the formation of complementary base pairs? Hydrogen bonds Phosphodiester bonds Covalent bonds Ionic bonds
hydrogen bonds
What is polycistronic mRNA? See Section 9.3. mRNA that encodes multiple different polypeptide products mRNA that is present in many copies in the cell mRNA that includes multiple coding segments (exons) interrupted by intervening sequences (introns) mRNA that is being translated by multiple ribosomes simultaneously
mRNA that encodes multiple different polypeptide products
Which of the following are classified as functional or structural RNAs? See Section 8.1. Only mRNAs mRNAs, tRNAs, and rRNAs mRNAs and tRNAs tRNAs, rRNAs, and snRNAs
tRNAs, rRNAs, and snRNAs
What is the Shine-Dalgarno sequence? See Section 9.2. A short conserved nucleotide sequence upstream of the AUG start codon that binds initiator tRNA A conserved nucleotide sequence that identifies a transcriptional start site A short conserved nucleotide sequence upstream of the AUG start codon that serves to align the mRNA on the bacterial small ribosomal subunit A short conserved nucleotide sequence downstream of the stop codon that signals termination of translation
A short conserved nucleotide sequence upstream of the AUG start codon that serves to align the mRNA on the bacterial small ribosomal subunit
What is a charged tRNA? See Section 9.2. A tRNA that is bound to the small ribosomal subunit An ionic form of a tRNA A tRNA that carries a specific amino acid A tRNA that is bound to an initiation factor (IF)
A tRNA that carries a specific amino acid
Which domain(s) of life include(s) multicellular organisms? Eukarya Bacteria Archaea and Eukarya Archaea
eukarya
In a hypothetical strand f DNA, the [A + G] / [C + T] or purine / pyrimidine ratio for one strand of a double-stranded DNA molecule is 0.6 What is the purine / pyrimidine ratio in the complementary strand? See Section 7.2 0.33 1.67 0.6 3.33
1.67
Aminoacyl-tRNA synthetases are the enzymes responsible for attaching the correct amino acid to the corresponding tRNA molecule. How many different tRNA synthetase enzymes are typically required to accomplish this task in the cell? See Section 9.4. 1 20 61 64
20
How large is an origin of replication (oriC) in E. coli? See Section 7.4. 9 base pairs. 13 base pairs. 245 base pairs. 1000 base pairs.
245 base pairs.
How many different RNA polymerase enzymes are required to transcribe the various classes of RNA in eukaryotic cells? See Section 8.3. 1 2 3 4 or more
3
The genetic code consists of a total of how many different codons? See Section 1.3. 16 20 61 64
64
In 1928, Frederick Griffith conducted a series of experiments that demonstrated which of the following? See Section 7.1. A "transformation factor" could be released from one cell and picked up by another cell, thus changing the genetic identity of the recipient cell. DNA was a polymer composed of four repeating nucleotides. Nuclei of white blood cells contain a weakly acidic substance, termed nuclein. DNA was localized to chromosomes.
A "transformation factor" could be released from one cell and picked up by another cell, thus changing the genetic identity of the recipient cell.
What is a promoter region as it relates to transcription and translation? See Section 1.3. A DNA sequence that specifies where RNA polymerase will bind to the DNA to initiate transcription A DNA sequence that specifies the start site for DNA replication A DNA sequence that specifies the start site for translation An mRNA sequence that specifies the start site for transcription
A DNA sequence that specifies where RNA polymerase will bind to the DNA to initiate transcription
Which of the following statements about DNA replication is false? New nucleotides are added to a growing DNA strand by phosphodiester bonds. A new DNA strand is synthesized with the same polarity (5' and 3' ends) as the template strand. DNA polymerase enzymes synthesize new DNA by adding nucleotides exclusively to the 3' end of the newly synthesized strand. DNA replication produces a DNA duplex that consists of one new strand of DNA and one old strand of DNA.
A new DNA strand is synthesized with the same polarity (5' and 3' ends) as the template strand.
Which of the following forms the backbone of a polynucleotide chain? See Section 7.2. Alternating nitrogenous bases and phosphate groups. Alternating sugars and nitrogenous bases. Alternating sugar and phosphate groups. Base pairs
Alternating sugar and phosphate groups.
Which of the following steps in translation is NOT facilitated by elongation factors? See Section 9.2. Recruitment of charged tRNAs to the A site Binding of initiator tRNA to the AUG start codon Formation of peptide bonds between sequential amino acids Translocation of the ribosome along the mRNA
Binding of initiator tRNA to the AUG start codon
How is the cap attached to the 5' end of eukaryotic mRNAs? See Section 8.4. By a 5'-5' phosphodiester bond By a 5'-3' phosphodiester bond By an unusual 5'-5' triphosphate linkage By an unusual 5'-3' triphosphate linkage
By an unusual 5'-5' triphosphate linkage
Watson and Crick derived their model of DNA structure not from their own laboratory research but rather through the analysis and interpretation of experimental data generated by others, such as Erwin Chargaff, Rosalind Franklin, and Maurice Wilkins. Which of the following provides evidence that DNA nucleotides are arranged as complementary base pairs? See Section 1.2. DNA nucleotides contain a five-carbon deoxyribose sugar, a phosphate group, and one of four possible nitrogenous bases. Complementary strands of DNA are antiparallel. The nucleotides forming a single strand of DNA are linked together by covalent phosphodiester bonds. Percentages of adenine and thymine are approximately equal to one another, and the percentages of cytosine and guanine are approximately equal to one another.
Percentages of adenine and thymine are approximately equal to one another, and the percentages of cytosine and guanine are approximately equal to one another.
