Concordia University

BIOL 261

Before Final Exam

Question1)The polymerase chain reaction (PCR) involves repeated cycles of heating and cooling to allow

DNA strands and primers to dissociate and anneal. The practical application of PCR required the identification and commercialization of

1. Heat stable polymerases
2. Dideoxynucleotides
3. Helicases for strand unwinding
4. Primers with a high GC content
5. Restriction nucleases

Question 2

Two different restriction enzymes that recognize the same DNA sequence can always be used to generate DNA fragments that can be efficiently connected together

1. False because the same recognition sequence can give different sticky ends
2. True because the sticky ends have to be compatible
3. True because once the DNA is cut, ligase can connect the fragments
4. False because they will interfere with each other’s function
5. False because all enzymes that recognize the same sequence are by definition the same restriction enzyme

Question 3

DNA replication is called semiconservative because                                                   of the original duplex appears in the duplex formed during replication.

1. all
2. a significant fraction
3. hardly any
4. none
5. half

Question 4

The lagging strand of a DNA replication fork is made in short fragments called Okazaki fragments. These are connected together by the action of

1. DNA fusase
2. DNA ligase
3. RNA ligase
4. Restriction endonucleases
5. The proof-reading function of DNA polymerase

Question 5

In the DNA double helix, the bases are held together by                   bonds, and the side chains by               

bonds

1. hydrogen, covalent
2. covalent, ionic
3. covalent, hydrogen
4. hydrogen, ionic
5. ionic, covalent

Question 6

Sanger sequencing requires the occasional termination of a growing nucleotide chain to establish the order of nucleotide incorporation and thus the sequence of the template that is being

sequenced. The practical application of Sanger sequencing requires

1. Primers with a high GC content
2. Dideoxynucleotides
3. Restriction nucleases
4. Heat stable polymerases
5. Helicases for strand unwinding

Question 7

Type I restriction enzymes have specific recognition sites, but then cut at a site elsewhere in the genome. These enzymes won’t have associated modification systems.

1. False because bacteria never have both types of restriction systems
2. True because the cells don’t need protection from this type of cleavage
3. False because the modification system can block the recognition site
4. True because the type II modification systems will protect the DNA
5. True because the modification system has to block the cut site, and that is not defined

Question 8

Dispersive replication of DNA is characterized by each daughter molecule

1. containing some new and some old DNA on each strand
2. containing either just new or just original DNA
3. containing one strand of the old molecule, and one strand of the new
4. having heavy and light atoms of nitrogen
5. generated by different origins of replication Question 9

Eukaryotic chromosomes have multiple origins of replication because

1. they are GC rich
2. they are linear
3. they are big
4. they need to complete replication during M phase
5. they replicate conservatively

Question 10

In the DNA double helix, the specificity of the base pairing is established through                         bonds, but part of the strength of the molecule comes from                                          stacking interactions among the bases

1. hydrogen, hydrophobic
2. hydrogen, hydrophilic
3. covalent, ionic
4. ionic, covalent
5. covalent, hydrogen

Question 11

Hfr cells

1. do not form sex pili
2. can pass the main chromosome to a recipient cell
3. typically pass the entire F factor to recipient
4. lack the genes carried on the F factor

Question 12

Mutations in an rII gene that failed to recombine with several mutations, each of which recombined with the others, were interpreted to be:

1. point mutations.
2. deletion mutations.
3. nonsense mutations.
4. missense mutations.

Question 13

A microbial growth medium designed to encourage the growth of one type of organism and inhibit the growth of others is called a                                                        medium.

1. complete
2. minimal
3. rich
4. selective

Question 14

The presence of bacteriophage can be visualized on a lawn of E. coli cells by the formation of

lytic foci called:

1. plaques.
2. prophages.
3. cistrons.
4. lysates.

Question 15

Any process that results in the integration of new combinations of genes together in a single cell is:

1. meiosis
2. genetic recombination
3. fusion
4. genetic fission

Question 16

In a mating between Hfr and F^– cells, the F^– recipient:

1. becomes F'.
2. becomes F⁺.
3. remains F^–.
4. becomes an Hfr.

Question 17

In a mating between F+ and F^– cells, the F^– recipient:

1. remains F^–.
2. becomes F'.
3. becomes an Hfr.
4. becomes F⁺.

Question 18

An E. coli strain containing an integrated F plasmid is called a:

1. lysogen.
2. Hfr strain.
3. partial diploid.
4. virulent strain.

Question 19

An E. Coli strain containing the F plasmid independent of the bacterial genome is called:

1. virulent strain
2. F+ strain
3. partial diploid
4. Hfr Strain

Question 20

A wild-type bacterial strain capable of growth in a defined                                     medium containing only a carbon source and inorganic compounds must be a prototroph.

1. Minimal
2. Essential
3. Complete
4. Rich

Question 21

A researcher would like to map the location of galE and trpA genes in a new species of bacterium that appears to be closely related to E. coli. He decides to use cotransduction, and generates appropriate donor and recipient strains. He is disappointed when cotransduction is not seen in his experiment. What is the most reasonable explanation for this situation?

1. These two genes are too close together to be mapped by cotransduction.
2. His new bacterial species cannot survive a galE or trpA mutation.

3. His new bacterial species does not have galE or trpA genes.
4. These two genes are too far apart to be mapped by cotransduction.

Question 22

A process in which recipient cells acquire genes from free DNA molecules in the surrounding medium is called:

1. generalized transduction.
2. specialized transduction.
3. transformation.
4. conjugation.

Question 23

A process in which recipient cells acquire genes from DNA through direct cell-to-cell contact is called:

1. specialized transduction.
2. generalized transduction.
3. conjugation.
4. transformation.

Question 24

Which of the following statements is true?

1. The 3' end of mRNA corresponds to the carboxyl terminus of the protein.
2. Polypeptides are synthesized by addition of amino acids to the amino terminus.
3. RNA polymerase has a proofreading activity.
4. Prokaryotic RNA usually undergoes nuclear processing.

Question 25

The site where RNA polymerase binds to the DNA template is called a(n ):

1. leader sequence.
2. domain.
3. enhancer.
4. promoter.

Question 26

The genetic code is degenerate because:

1. frameshift mutations are tolerated.
2. the code is not universal among organisms.
3. some amino acids have more than one codon.
4. mRNA is rapidly degraded.

Question 27

In prokaryotes, the initiator codon              encodes the amino acid             .

1. AUG, N-formylmethionine
2. UGA, N-formylmethionine
3. AUG, methionine
4. UAA, methionine

Question 28

tRNAs are

1. single and double stranded molecules in the shape of a cloverleaf
2. Y shaped with single stranded loops
3. L-shaped with single and double stranded regions
4. single stranded molecules in the shape of a cloverleaf

Question 29

Which of the following features is common to both DNA replication and transcription?

1. A sugar-phosphate bond is formed between the 3' hydroxyl and the 5' phosphate.
2. Deoxyribonucleotides are incorporated into the growing sequence.
3. Nucleotides are added to the 5' end of the newly synthesized strand
4. Both RNA and DNA polymerases require oligonucleotide priming.

Question 30

Introns within primary eukaryotic transcripts:

1. vary considerably in size and number among different genes.
2. often function as exons in other genes.
3. are joined to form mature mRNA.
4. are highly conserved in nucleotide sequence.

Question 31

Which of the following is true regarding the machinery of translation?

1. tRNAs released from the ribosome are degraded.
2. Termination in eukaryotes requires three release factors.
3. Polycistronic mRNA usually has a single ribosome binding site.
4. A single mRNA can be translated simultaneously by several ribosomes.

Question 32

Which of the following is true regarding the machinery of translation?

1. tRNAs released from the ribosome are degraded.
2. A single mRNA can not be translated simultaneously by several ribosomes.
3. Polycistronic mRNA usually has multiple ribosome binding site.
4. Termination in eukaryotes requires three release factors.

Question 33

A mature eukaryotic RNA has

1. introns, poly A tail, 3’ untranslated region
2. 5’ cap, ORF, poly A tail
3. introns, exons and 5’ untranslated region
4. 5’ untranslated region, 3’ untranslated region, operon

Question 34

A eukaryotic pre-mRNA has

1. 5’ cap, ORF, poly A tail
2. introns, exons and 5’ untranslated region
3. introns, poly A tail, 3’ untranslated region
4. 5’ untranslated region, 3’ untranslated region, operon

Question 35

The addition of the amino acid to the tRNA is called                    and requires             .

1. charging, GTP
2. linking, ATP
3. charging, energy

4. linking, specificity

Question 36

Which of the following enzymes cleaves lactose to yield glucose and galactose?

1. lactose permease
2. lactoperoxidase
3. alpha-glucosidase
4. beta-galactosidase Question 37

The active repressor is formed by the combination of the co-repressor and a(n ):

1. attenuator
2. operator
3. promoter
4. aporepressor

Question 38

In the absence of tryptophan, the trp repressor (TrpR) is:

1. inactive and cannot bind the promoter
2. active and cannot bind the operator
3. active and can bind the operator
4. inactive and cannot bind the operator Question 39

the lac operon is highly expressed when

1. glucose is low and lactose is present
2. glucose is low and lactose is absent
3. glucose is high and lactose is present
4. glucose is high and lactose is absent

Question 40

The Gal4 protein is an activator of the Leloir pathway enzymes

1. it is inactivated by association with the Gal80 protein
2. it needs the catabolite activator protein to function

3. it is inactivated when a galactose derivative binds Gal80
4. it binds to its UAS elements when bound to galactose

Question 41

The product of the lacI gene:

1. induces lac operon transcription.
2. is cis dominant.
3. binds to RNA polymerase.
4. binds to the operator.

Question 42

The expression of the lac operon in E. coli is regulated by the:

1. attenuation.
2. methylation of the operator.
3. product of the lac z gene.
4. the cAMP-CRP complex.

Question 43

The attenuator system works in E. coli because

1. bacterial genes are in operons
2. tryptophan is a very abundant amino acid in E. coli proteins
3. bacteria need tryptophan from the environment because they cannot synthesize it directly
4. transcription and translation are linked

Question 44

If beta-galactosidase and permease are made whether or not lactose is present, a mutation in which sequence(s) is/are the likely cause

1. lacZ
2. lacI
3. operator
4. b or c are possible

Question 45

The regulation of galactose metabolism in yeast is similar to the regulation of lactose metabolism in E. coli

1. both use the alternate sugar in preference to glucose
2. both make enzymes to hydrolyze a disaccharide
3. both use a repressor to control the expression of metabolic enzymes in the absence of the sugar (lactose or galactose)
4. both inhibit the use of the alternate sugar (lactose or galactose) in the presence of glucose

Question 46

What kind of termini is produced by the restriction endonuclease PvuI, if the restriction site is 5'-CGAT | C-3'? (The vertical bar [ | ] represents the site of cleavage in each strand.)

1. Selectable ends
2. Reverse ends
3. Blunt ends
4. Sticky ends Question 47

Which of the following enzymes synthesizes DNA from a single-stranded RNA template?

1. Ligase
2. Reverse transcriptase
3. RNA polymerase
4. DNA polymerase

Question 48

A cDNA contains:

1. operator sequences.
2. exons.
3. introns, exons, and promoter sequences.
4. promoter sequences.

Question 49

E. coli cells can be induced to take up foreign DNA by a combination of                     and         .

1. acid treatment, cold shock

2. salt wash, heat shock
3. rich medium, 37C incubation
4. UV light, high temperature

Question 50

pBR322 was a useful vector because

1. inserts could be detected by blue/white screening
2. it was small and had several unique sites for 6 base cutting restriction enzymes
3. it had a single strand replication origin
4. it had a large multiple cloning site

Question 51

Enzymes that cleave DNA at sequence-specific sites are called:

1. DNA polymerases.
2. restriction endonucleases.
3. ligases
4. exonucleases.

Question 52

To make a cDNA copy of a gene you need

1. polyA+ mRNA, a polyT primer and DNA polymerase
2. polyT+ mRNA, a polyA primer and reverse transcriptase
3. polyA+ mRNA, a polyT primer and reverse transcriptase
4. genomic DNA, primers and reverse transcriptase

Question 53

The cloning site that contains unique cleavage sites for many different restriction enzymes is called a

1. polymerase complex.
2. polyA tail.
3. polylinker.
4. linkage group.

Question 54

A Southern blot