Section Practice Final
The process in which DNA is transferred from one bacterium to another by a virus is called a. transduction b. transposition c. translation d. transformation e. conjugation
d
Acetylation of lysines on the amino terminal tails of core histones in a region of a chromosome a. helps to loosen the packaging of the chromatin to promote transcription. b. leads to tighter packaging of chromatin, preventing transcription. c. prevents promoters in the region from binding transcription factors. d. allows the cell to prepare for mitosis. e. none of the above.
a
Cellulose is a carbohydrate and is also a polymer. What best describes its structure? a. a chain of covalently linked glucose residues b. a chain of glucose residues linked by hydrogen bonds c. a chain of amino acids d. a complex of fatty acids e. a helix made of nucleotides
a
In many cells splicing is an important part of transcription. What happens in "splicing"? a. some regions of the newly formed RNA, which do not code for protein, are cut out b. some regions of the DNA that do not code for protein are cut out c. the introns are connected to the exons d. the upstream and downstream regions are connected to the protein coding region e. a poly A tail is added to the mRNA
a
The Messelson-Stahl experiment showed that DNA replication is "semi-conservative." This means: a. that newly synthesized DNA contains one old strand and one new strand b. that DNA gets heavier as it is synthesized c. that part, but not all, of the DNA sequence is saved during replication d. that replication is dispersive e. that some mistakes are made in the sequence during replication
a
The human genome has a surprisingly small number of genes, but many different forms of a protein can be made from a single gene. How is this done? a. by alternative splicing of the mRNA b. by alternative splicing of the amino acid chain c. by increasing the mutation rate d. by using different promoter sites e. by codon skipping on the ribosome
a
The lac repressor protein has two binding sites. They are specific for: a. inducer and operator b. beta-galactosidase and lactose permease c. inducer and promoter d. promoter and operator e. lactose and tryptophan
a
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.
a
What are polysomes? a. groups of ribosomes reading the same mRNA simultaneously b. ribosomes containing more than two subunits c. multiple copies of ribosomes found associated with giant chromosomes d. aggregations of vesicles containing ribosomal RNA e. ribosomes associated with more than one tRNA
a
What is the function of an aminoacyl tRNA synthetase? a. It attaches amino acids to tRNA's. b. It combines amino acids. c. It synthesizes tRNA. d. It removes introns from genes. e. It carries tRNAs to the ribosome.
a
What is the major protein in microfilaments? a. actin b. dynein c. kinesin d. keratin e. tubulin
a
When comparing the structure of genes in procaryotes versus eucaryotes: a. Eucaryotic genes are bigger, in part because of large introns. b. Eucaryotic genes are bigger because they have more genes per operon. c. Eucaryotic genes have promoters, but procaryotic genes don't. d. Both eucaryotic and procaryotic genes are folded in a "beads on a string" structure. e. Eucaryotic genes are larger because they encode much bigger proteins.
a
When the cell synthesizes a protein that is to be secreted into the medium, which pathway is followed? a. synthesis starts on the ribosome, then -> ER -> Golgi -> plasma membrane b. synthesis starts in the ER, then -> ribosome ->. Golgi -> plasma membrane c. synthesis starts on the ribosome, then -> nucleus -> ER -> Golgi -> plasma membrane d. synthesis starts in the nucleus -> ER -> Golgi -> plasma membrane e. synthesis starts on the ribosome, then -> Golgi -> ER -> plasma membrane
a
Which of the following does not occur after mRNA is transcribed a. Binding of RNA polymerase II to the promoter b. Capping of the 5' end c. Addition of a poly A tail d. Splicing out of the introns e. Movement to cytosol.
a
Which of the following is TRUE in eukaryotic cells? a. Transcription occurs in the nucleus and translation in the cytoplasm. b. Both transcription and translation occur in the cytoplasm. c. Both transcription and translation occur in the nucleus. d. Transcription occurs in the cytoplasm and translation in the nucleus. e. Translation may occur in either the cytoplasm or in the nucleus.
a
Which part of the mitotic apparatus generates a force that causes chromosomes to move to the poles of the cell? a. kinetochore b. centrosome c. actin and myosin d. centromere e. metaphase plate
a
An operon that encodes proteins to be used in synthesis of an amino acid will likely a. contain introns d. always be turned ON b. be repressible by the amino acid c. be inducible by the amino acid e. none of the above
b
Assume that the A and B genes are 6 map units apart on a chromosome. Parents with genotypes AABB are crossed with aabb to yield AaBb progeny (A and B are dominant to a and b). If these AaBb progeny are crossed with aabb what percent of the progeny are likely to have the Ab phenotype? a. none b. 3% c. 25% d. 50% e. 97%
b
Choose the answer that has these events of protein synthesis in the proper sequence. 1. An aminoacyl-tRNA binds to the A site; 2. A peptide bond forms; 3. tRNA leaves the P site and the P site remains vacant; 4. Small ribosomal subunit associates with mRNA; 5. Translocation of the tRNA to the P site. a. 1, 3, 2, 4, 5 b. 4, 1, 2, 5, 3 c. 5, 4, 3, 2, 1 d. 4, 1, 3, 2, 5 e. 2, 4, 5, 1, 3
b
During DNA replication, DNA polymerase adds nucleotides to the: a. 3ʼ end of the newly synthesized strand as it moves toward the 3ʼ end of the template strand b. 3ʼ end of the newly synthesized strand as it moves toward the 5ʼ end of the template strand c. 5ʼ end of the newly synthesized strand as it moves toward the 5ʼ end of the template strand d. 5ʼ end of the newly synthesized strand as it moves toward the 3ʼ end of the template strand e. none of the above
b
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.
b
Human cells have an electrochemical gradient across the plasma membrane. What is the nature of this gradient? a. high Na+ outside the cell, positively charged inside the cell b. high Na+ outside the cell, negatively charged inside the cell c. high K+ outside the cell, positively charged inside the cell d. high K+ outside the cell, negatively charged inside the cell e. high Na+ inside the cell, positively charged inside the cell
b
If no lactose is present in the medium the genes in the lac operon will not be transcribed at a significant rate. Why? a. they will be tightly folded into chromatin b. the lac repressor protein will bind the operator and block transcription c. the absence of lactose means the CAP protein cannot be activated d. the CAP protein will bind the lac repressor e. no cAMP will be made
b
In DNA replication, - the leading strand is different from the lagging strand because: a. in the leading strand new nucleotides are added to the 5' end. b. synthesis of the leading strand does not produce Okasaki fragments. c. the leading strand starts with the synthesis of RNA but the lagging strand does not. d. synthesis of only the leading strand is semiconservative. e. synthesis of only the lagging strand is semiconservative.
b
In E. coli, when the concentration of glucose is high, the concentration of _______ is low. a. CRP b. cAMP c. repressors d. inducers e. None of the above
b
In eukaryotic genes, the regions that code for the amino acid sequence of a protein gene product are a. introns b. exons c. anticodons d. replicons e. transposons
b
In the Hershey-Chase experiment viruses were labeled with either P-32 or S-35. What was the biological question they were trying to solve? They wanted to determine: a. if the genetic information is in DNA or RNA b. if the genetic information is in DNA or protein c. if proteins contain phosphorous d. if DNA contains sulfur e. if viruses contain genes
b
Messelson and Stahl used light and heavy isotopes of nitrogen to investigate the way that DNA is replicated. Starting with DNA that contained only heavy nitrogen they found that after one round of replication using light nitrogen - a. the new DNA strands, like the old strands contained only heavy nitrogen. b. the new DNA contained heavy nitrogen in one strand and light nitrogen in the other. c. the new DNA contained only light nitrogen, in both strands. d. both strands of the DNA contained the same mix of light and heavy nitrogen. e. some double helices contained all heavy nitrogen and the others contained all light nitrogen.
b
One of the key components of transcription is: a. DNA polymerase b. RNA polymerase c. Primase d. tRNA e. ribosomes
b
What are the most abundant lipid molecules in cell membranes? a. free fatty acids b. phospholipids c. cholesterol d. fats e. amino acid helices
b
When does recombination (crossing over) occur in meiosis? a. in interphase before meiosis I b. in prophase of meiosis I c. in telophase of meiosis I d. in the period between meiosis I and II e. in prophase of meiosis II
b
Which of the following is not true of plasmids? a. They often contain a gene for antibiotic resistance. b. They are usually packaged in a protein coat. c. They contain an origin of replication. d. Although they are normally found in bacterial cells they can carry human genes. e. They can be taken up by bacterial cells and duplicated within the cells.
b
A DNA sequence, which can be distant from the gene, stimulates transcription when bound by a protein. This sequence is called a(n) a. TATA box. b. operon. c. enhancer. d. promoter. e. consensus sequence.
c
A protein is synthesized from its _______ as the ribosome moves toward the ______ end of the mRNA. a. N to C terminus; 5ʼ b. C to N terminus; 5ʼ c. N to C terminus; 3ʼ d. C to N terminus; 3ʼ e. none of the above
c
An alpha helix is an example of a. structure of a DNA molecule b. primary structure of a protein c. secondary structure of a protein d. quaternary structure of a protein e. RNA secondary structure
c
Consider the mRNA codon 5' CCU 3'. Which of the following is an appropriate anticodon sequence (for a tRNA anticodon loop) that would decode this codon during translation? a. 3' CCU 5' b. 3' UCC 5' c. 3' GGA 5' d. 5' UCC 3' e. 3' TCC 5'
c
Procaryotic cells are different from eukaryotic cells because a. Only procaryotes have chloroplasts. b. Only eukaryotes have ribosomes. c. Only eukaryotes have nucleosomes. d. Only procaryotes have cell walls. e. Only procaryotes have lysosomes.
c
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
c
Transcription usually starts a. at the ATG start codon. b. at a TAA, TAG, or TGA codon. c. several hundred bases upstream of the protein coding region. d. several hundred bases downstream of the protein coding region. e. in the intron.
c
What are the elements of a completed mRNA? a. promoter, 5' untranslated region, open reading frame, polyA tail b. 5' untranslated region, exons plus introns, polyA tail c. CAP, 5' untranslated region, protein coding region, 3' untranslated region, polyA tail d. CAP, protein coding region, polyA tail e. 5' untranslated region, introns, polyA tail
c
What is the function of an aminoacyl-tRNA synthetase? a. synthesize tRNA b. form covalent bond between an acetyl group and tRNA c. connect an amino acid with tRNA d. synthesize an aminoacyl bond on the ribosome e. convert amino acids into tRNA molecules
c
What is the role of the primase enzyme in DNA replication? a. it unwinds the DNA to start replication b. it synthesizes a small DNA that binds to the priming site c. it synthesizes a small RNA to make a DNA/RNA double stranded region d. it synthesizes DNA on the leading strand e. it fills in the gaps in DNA
c
Which of the following seals the sticky ends of restriction fragments to make recombinant DNA. a. restriction enzymes b. gene cloning c. DNA ligase d. gel electrophoresis e. reverse transcriptase
c
With reference to transcription, what is the "promoter"? a. It is a protein that stimulates the synthesis of RNA. b. It is a protein that stimulates cell division. c. It is a region of DNA that has the binding site for RNA polymerase. d. It is the enzyme that starts transcription. e. It is a protein that activates RNA polymerase.
c
A biochemist isolates and purifies various molecules needed for DNA replication. When she adds these molecules to DNA, complete replication occurs in the test tube. However, each of the resulting DNA molecules consist of a full length normal DNA strand paired with a strand made up of numerous segments of DNA, most only a few hundred nucleotides long. What has she probably left out of the mixture? a. primase b. Okazaki fragments c. DNA polymerase d. DNA ligase e. nucleotides
d
All of the following are DIRECTLY involved in translation EXCEPT a. mRNA b. aminoacyl-tRNA synthetase enzymes c. ribosomes d. DNA e. tRNA
d
Consider the mRNA codon 5' CCU 3'. Which amino acid corresponds to this codon? a. proline b. tryptophan c. methionine d. glycine e. arginine
d
Griffith's experiments showed that a benign strain of Streptococcus pneumonia could be converted into a disease-causing strain. How did he do this? a. by mutating the bacteria b. by injecting proteins into the bacteriac. by injecting enzymes into the bacteria d. by injecting both live benign bacteria and heat-killed disease-causing bacteria into mice e. by treating the bacteria with DNAase
d
How does one strand in the DNA double helix bind to the opposite strand? a. the 5' carbon on the ribose is linked to the 3' end of phosphate b. the 3' end of ribose is linked to the 5' end of the next ribose c. A and T are covalently linked and C and G are covalently linked d. the nitrogenous bases bind to each other by hydrogen bonds e. the negative charge on the phosphates binds to the positive charge on the bases
d
In any DNA sample, the amount of adenine equals the amount of thymine and the amount of guanine equals the amount of cytosine. Select the investigator(s) associated with this important discovery that contributed to our present knowledge of the structure of DNA. a. Griffith b. Hershey and Chase c. Avery, MacLeod, and McCarty d. Erwin Chargaff e. Meselson and Stahl
d
In eukaryotic cells, a "signal sequence" a. is located at the 5' end of a mRNA molecule and directs it to be secreted into the cisternal space of ER b. is a base pair sequence in DNA that is needed to bind RNA polymerase and initiate transcription c. is needed to terminate translation of the messenger RNA d. is located at the amino terminal end of a polypeptide that is dedstined to be secreted into the cisternal space of the ER e. is located at the origin of replication of a chromosome
d
In eukaryotic cells, transcription and translation a. are separated: Translation occurs in the nucleus, and transcription occurs in the cytoplasm. b. occur together in the cytosol. c. occur together in the nucleus. d. are separated: Translation occurs in the cytoplasm, and transcription occurs in the nucleus. e. are separated, except for proteins that bind to the DNA and ribosomes, which are translated in the nucleus.
d
In the genetic code a. there is one start codon and one stop codon b. there is a codon for start but none for stop c. there are three start codons and one stop codon d. there is one start codon and three stop codons e. there are redundant start codons
d
In the initiation stage of protein synthesis which of the following is not correct? a. The small subunit of the ribosome binds to mRNA. b. The anticodon UAC forms base pairs with the start codon. c. The amino acid methionine is positioned on the ribosome at the site of protein synthesis. d. The amino acid is covalently attached to the mRNA. e. In the last part of initiation, the large ribosomal subunit binds.
d
In which of the following metabolic pathways is oxygen used to make water? a. glycolysis b. fermentation c. Krebs cycle d. electron transport chain e. pyruvate ---> acetyl-Co-A
d
The Krebs cycle a. begins with pyruvate and ends with citrate. b. produces 2 ATP and 2 NADH molecules per glucose. c. combines citrate with oxygen to make CO2. d. removes electrons from an acetyl group to make NADH and FADH2. e. uses the NADH and ATP that was formed in glycolysis.
d
The number of hydrogen bonds between G and C in a GC base pair is a. 0 b. 1 c. 2 d. 3 e. 4
d
What is a nucleosome? a. the complex within the nucleus that makes ribosomes b. a protein complex that splices RNA c. a structure that forms the poles of the spindle apparatus d. a core of histone proteins, wrapped with DNA e. the protein that unwinds DNA during replication
d
What is beta-galactosidase? a. a protein that regulates the lac operon b. a sugar that can be eaten by E. coli c. a protein made by the lac I gene d. an enzyme that splits lactose into glucose and galactose e. an enzyme that synthesizes lactose
d
What molecules are used to make DNA? a. nucleotide monophosphates b. deoxynucleotide monophophates c. ATP, TTP, GTP, CTP d. dATP, dTTP, dCTP, dGTP e. dideoxynucelotides
d
Which of the following best describes the ribosome? a. It has a small subunit made of RNA and a large subunit made of protein. b. It is a large molecular complex that attaches amino acids to mRNA. c. It can bind to the DNA and synthesize a protein. d. It is a large complex, made of approximately 60% RNA and 40% protein. e. It is a large complex that can cut apart introns and exons.
d
Which of the following is not needed for PCR (the Polymerase Chain Reaction) a. a small amount of DNA to copy b. two primers, small fragments of DNA c. a heat stable DNA polymerase d. a heat stable RNA polymerase e. a mixure of deoxynucleotides (dNTP's)
d
A "Barr Body" is a. an active X chromosome in a female. b. an inactive X chromosome in a male. c. an extra chromosome. d. a Y chromosome. e. an inactive X chromosome in a female.
e
A key part of the experiments of Beadle and Tatum was to isolate strains of Neurospora that were unable to make specific amino acids. How did they identify these strains? a. by looking at the enzymes and seeing which ones were missing. b. by growing the cells and determining which amino acid was missing c. by mutating the DNA d. by determining which genes were deleted e. by seeing how the strains grew in different types of media that were missing different amino acids
e
A promoter: a. defines the boundaries of exons in eukaryotic mRNAs b. specifies which strand will be used as the template during transcription c. specifies where RNA Polymerase initiates transcription d. specifies where DNA Polymerase initiates DNA replication e. both b and c are correct
e
Gene expression can be regulated a. before transcription. b. after transcription and before translation. c. during translation. d. after translation. e. All of the above
e
In methylation-directed mismatch repair of DNA a. methyl groups are added to the damaged nucleotide to repair it. b. the mutated nucleotide is marked by the attachment of a methyl group. c. RNA polymerase replaces the mutated DNA with RNA. d. the mutation is converted to a thymine dimer. e. the older strand of DNA is marked by the attachment of methyl groups.
e
In the _______ of lactose, the lac _______ binds to the lac _______ site. a. presence; operator; repressor b. presence; repressor; promoter c. absence; operator; promoter d. absence; operator; repressor e. absence; repressor; operator
e
What are the major components of cilia? a. actin fibers and myosin b. actin fibers and dynein c. kinesin and dynein d. keratin and flagellin e. microtubules and dynein.
e
What happens during anaphase in the second meiotic division? a. crossing-over of chromosomes b. chromosome line up in the middle of the nucleus c. tetrads split into two chromosomes d. condensation of chromatids e. chromosomes move to the poles
e
What information can be obtained from a DNA microarray experiment? (Several of these are possibly correct, but what is the best answer?) a. the DNA content of a single cell b. the number of mutations in a genome c. the difference in the number of genes present in the nuclei of normal versus diseased cells d. the order of genes on a chromosome e. the relative amount of RNA expressed from specific genes in normal versus diseased cells
e
What is an operon? a. It is a name for the small region of DNA that binds RNA polymerase b. It is a protein complex that transcribes DNA into RNA. c. It is the binding site for the lac repressor. d. It is a protein that binds cAMP. e. It is a region of bacterial DNA that codes for two or more functionally related genes.
e
What is the distinction between an intron and an exon? a. All exons start with ATG. b. Introns always ends with TAA, TAG or TGA. c. Introns are made of nucleotides, exons are made of amino acids. d. Introns are never found in RNA. e. The sequence in the exons can specify the amino acid sequence of a protein.
e
When a ribosome first attaches to an mRNA molecule, one tRNA binds to the ribosome. The tRNA that recognizes the initiation codon binds to the a. amino acid site or "acceptor" (A site) of the ribosome only. b. peptide site (P site) of the ribosome only. c. large ribosomal subunit only. d. second tRNA before attaching to the ribosome. e. Both a and c are correct.
e
Which of these molecules contains a peptide bond? a. starch b. RNA c. phospholipid d. amino acid e. protein
e
Why are ddNTPs used for DNA sequencing? a. The ddNTPs lack a nitrogenous base. b. The ddNTPs are identical in structure to dNTPs. c. The ddNTPs lack the sugar component. d. The ddNTPs lack a 5' triphosphate. e. The ddNTPs lack a 3' hydroxyl group.
e
