Deck 7: Genomes and Chromosomes

Question 1

The nucleoids of bacteria and most archaea, as well as the nuclear DNA of eukaryotes, are kept __________ supercoiled.

A) positively
B) neutrally
C) negatively
D) reverse
E) extra

Answer 1

C

Question 2

The semiconservative mechanism of replication provides for each daughter duplex to be checked for __________, based on its parent strand.

A) pseudogenes
B) introns
C) plasmids
D) redundancy
E) accuracy

Answer 2

E

Question 3

A nucleoid gently released from E. coli appears as 30-100 tightly wound loops, each defined by anchoring proteins called:

A) histones
B) histone-like proteins
C) supercoils
D) gyrase
E) topoisomerase

Answer 3

B

Question 4

Which of the following is NOT true of DNA replication in E. coli?

A) It is conservative.
B) It is bidirectional.
C) The second strand is synthesized discontinuously.
D) DnaA triggers initiation.
E) Synthesis occurs in the 5'-to-3' direction.

Question 5

Hyperthermophilic archaea possess an unusual gyrase called __________, which introduces positive supercoils into the chromosome.

A) DNA ligase
B) DNA helicase
C) topoisomerase
D) reverse DNA gyrase
E) reverse transcriptase

Question 6

In a test tube, at chromosome packing density DNA is almost a:

A) solid
B) gel
C) gas
D) liquid
E) plasma

Question 7

Intestinal microbes contain __________ times more genes than the human genome?

A) 10
B) 20
C) 50
D) 100
E) 1,000

Question 8

The thermal stability of the helix is predominantly due to the __________ of the hydrophobic base pairs.

A) stacking
B) binding
C) repulsion
D) attraction
E) transformation

Question 9

__________ allowed genes to be mapped relative to each other based on the time of transfer.

A) Transformation
B) Transduction
C) Conjugation
D) Sanger sequencing
E) Polymerase chain reaction

Question 10

Supercoiling in bacteria is typically introduced by an enzyme called:

A) gyrase
B) helicase
C) ligase
D) polymerase
E) endonuclease

Question 11

Bacteria and archaea growing at extreme pH or temperature protect their DNA from denaturation through the use of:

A) DNA-binding proteins
B) Okazaki fragments
C) pseudogenes
D) introns
E) ligase

Question 12

It takes approximately how many minutes to move the entire E. coli chromosome from one cell to another?

A) 10
B) 20
C) 50
D) 100
E) 200

Question 13

Which of the following is NOT true about the two strands of DNA in a double helix?

A) base-pairing interactions
B) antiparallel
C) complementary
D) catenated
E) base-stacking interactions

Question 14

Bacteria are able to conduct __________ transmission-the transfer of genetic information from one cell to another.

A) vertical
B) horizontal
C) linear
D) transformation
E) pseudogene

Question 15

The smallest cellular genomes identified thus far are those of __________.

A) E. coli
B) Staphylococcus
C) Streptococcus
D) Mycoplasma
E) yeast

Question 16

Gene transfer from parent to child is called:

A) conjugation
B) horizontal transmission
C) vertical transmission
D) transformation
E) transduction

Question 17

The intestinal bacterium __________ was the initial focus of efforts to understand genes and genetics.

A) Escherichia coli
B) Salmonella typhi
C) Staphylococcus aureus
D) Mycoplasma genitalium
E) Enterobacter aerogenes

Question 18

__________ in the DNA helix provide DNA-binding proteins access to base sequences buried in the center of the molecule, so that proteins can interact with the bases without the strands being separated.

A) Breaks
B) Grooves
C) Nicks
D) Attractions
E) Repulsions

Question 19

When the chromosome replicates, how is the newly made strand related to its template strand?

A) The two strands have identical sequences and are parallel to each other.
B) The two strands have complementary sequences and are parallel to each other.
C) The two strands have identical sequences and are antiparallel to each other.
D) The two strands have complementary sequences and are antiparallel to each other.
E) The two strands have identical sequences and are antiparallel to each other, except that U replaces T.

Question 20

__________ are bicyclic bases and __________ are monocyclic.

A) Pyrimidines; purines
B) Adenines; guanines
C) Thymines; cytosines
D) Thymines; uracils
E) Purines; pyrimidines

Question 21

The DNA proofreading activity is intrinsic to:

A) DNA polI
B) DNA polII
C) DNA polIII
D) DNA polIV
E) DNA polV

Question 22

__________ is a process that involves cell-to-cell contact to move the plasmid from a donor cell to a recipient cell.

A) Transformation
B) Transduction
C) Pseudogene
D) Conjugation
E) Transposons

Question 23

The process of plasmid addiction is based on genes that code for:

A) short-lived toxin and short-lived antidote
B) long-lived toxin and long-lived antidote
C) long-lived toxin and short-lived antidote
D) short-lived toxin and long-lived antidote
E) high plasmid copy number

Question 24

Initiation of DNA replication is controlled by DNA __________ and by the binding of a specific initiator protein to the origin sequence.

A) methylation
B) ligase
C) helicase
D) restriction
E) gyrase

Question 25

What type of bond does DNA polymerase form?

A) aminoacyl bonds
B) peptide bonds
C) phosphodiester bonds
D) hydrogen bonds
E) disulfide bonds

Question 26

Which of the following is NOT true of plasmids?

A) They are found in archaea.
B) They are found in bacteria.
C) They are found in eukaryotes.
D) They are usually circular.
E) They are positively supercoiled.

Question 27

Okazaki fragments are approximately how many bases in length?

A) 10
B) 50
C) 100
D) 1,000
E) 2,000

Question 28

Enzymes that synthesize DNA or RNA can synthesize in a __________ direction.

A) forward
B) 3'-to-5'
C) 5'-to-3'
D) reverse
E) 5'-to-3' or 3'-to-5'

Question 29

Two kinds of extragenomic DNA molecules are __________ and the genomes of __________.

A) bacteriophages; pseudogenes
B) intron; bacteriophages
C) plasmids; bacteriophages
D) plasmids; introns
E) intron; exons

Question 30

Many phage genomes replicate __________, and they may copy only one strand.

A) bidirectionally
B) semiconservatively
C) conservatively
D) unidirectionally
E) linearly

Question 31

Which of the following is NOT involved in the replication termination process?

A) ter sites
B) Holliday junctions
C) XerC
D) XerD
E) DNA ligase

Question 32

A __________ occurs when multiple genomes are joined end to end.

A) concatemer
B) mutation
C) operon
D) intron
E) pseudogene

Question 33

The DNA of phage T4 replicates by the __________ method.

A) semiconservative
B) conservative
C) bidirectional
D) operon
E) rolling-circle

Question 34

Escherichia coli contains how many different DNA polymerase proteins?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 35

Which statement is NOT true about bacteriophage T4 and its replication?

A) It has a linear genome.
B) It circularizes within the host cell.
C) It uses rolling-circle replication.
D) It forms long, linear concatemers.
E) It precisely packages one full-length genome.

Question 36

Eukaryotic chromosomes are __________, contained within a nucleus, and their replication involves the process of __________ .

A) linear; meiosis
B) linear; mitosis
C) circular; mitosis
D) circular; meiosis
E) circular; rolling circle

Question 37

Which molecule is responsible for removing torsional stress during DNA replication?

A) DNA primase
B) single-stranded binding protein
C) RNase H
D) DNA gyrase
E) DNA ligase

Question 38

The lagging strand is synthesized __________ , while the leading strand can be synthesized __________.

A) continuously; discontinuously
B) discontinuously; continuously
C) 5'-to-3'; 3'-to-5'
D) 3'-to-5'; 5'-to-3'
E) quickly; slowly

Question 39

Which of the following is NOT true about histones?

A) They are rich in arginine and lysine.
B) They are positively charged.
C) They are acidic proteins.
D) They bind to negatively charged DNA.
E) They form units with DNA called nucleosomes.

Question 40

The primer in DNA replication is:

A) an RNA starter sequence with a free 3' OH group
B) an RNA starter sequence with a free 5' OH group
C) a DNA starter sequence with a free 3' OH group
D) a DNA starter sequence with a free 5' OH group
E) a telomere with a free 5' phosphate

Question 41

Which of the following is NOT a palindrome?

A) toot
B) rotor
C) racecar
D) radar
E) toto

Question 42

Describe how the name of a gene and its gene product are denoted.

Question 43

What is the correct order of the steps in a cycle of PCR?

A) annealing, denaturation, extension
B) denaturation, extension, annealing
C) extension, annealing, denaturation
D) denaturation, annealing, extension
E) annealing, extension, denaturation

Question 44

Which of the following terms refers to gene duplications that have decayed into nonfunctional entities?

A) introns
B) contigs
C) orthologs
D) pseudogenes
E) Okazaki fragments

Question 45

__________ allow for an RNA primer to be synthesized so that the end of the eukaryotic chromosome can be replicated.

A) Primases
B) RNA polymerases
C) Telomeres
D) DNA polymerases
E) Helicases

Question 46

Which step in DNA isolation from a bacterial cell is out of order?

A) Dissolve the cell membranes.
B) Lyse the cell.
C) Precipitate the proteins in a high-salt solution.
D) DNA is eluted from the DNA-binding column.
E) Perform alcohol precipitation of DNA.

Question 47

DNA contains structural genes and control sequences. Describe each.

Question 48

__________ naturally function to cut the DNA of invading plasmids and phages at specific points.

A) Histones
B) Gyrases
C) Ligases
D) Polymerases
E) Restriction enzymes

Question 49

Explain how understanding bacterial replication is important for human health.

Question 50

A genome is referred to by its length. If a genome is said to be 5 kbp, what does that mean? If it were 5 kb, what would that tell you?

Question 51

__________ and __________ are noncoding sequences that make up a large portion of eukaryotic chromosomes.

A) Exons; introns
B) Bacteriophages; plasmids
C) Plasmids; introns
D) Introns; pseudogenes
E) Pseudogenes; bacteriophages

Question 52

When E. coli was lysed and its chromosome released, researchers found that it was 1,500 times as long as the cell. List three questions that emerge from this finding.

Question 53

Describe the similarities and differences between DNA and RNA.

Question 54

Agarose gel electrophoresis separates DNA based on:

A) size
B) charge
C) sequence
D) all of the above
E) none of the above

Question 55

Describe how fluorescent microscopy was used to show that cellular DNA occupies most of the cytoplasmic space whereas the replisomes remain at approximately midcell. What does this say about movement of the DNA with respect to the replisome during the replication process?

Question 56

What determines when DNA replication begins?

Question 57

Archaea resemble eukaryotes in all of the following EXCEPT:

A) nuclear membrane
B) DNA-packing proteins
C) RNA polymerase
D) ribosomal components
E) DNA polymerase

Question 58

The ability of cohesive ends of DNA from different organisms to __________ forms the basis of recombinant DNA technology.

A) be methylated
B) be cut
C) be sequenced
D) repel
E) base pair

Question 59

When an E. coli chromosome is laid out, it is 1,500 times longer than the cell. How is E. coli able to make its chromosome fit into the cell?

Question 60

It takes 40 minutes for E. coli chromosome replication but only 20 minutes for cell division? How is this possible?

Question 61

Describe three functions of DNA polymerase III.

Question 62

Humans have an immune system that can distinguish self from nonself. How is the bacterial restriction-modification system similar?

Question 63

How have restriction enzymes revolutionized the field of microbiology?

Question 64

T4 DNA phage capsids are packaged from concatemers and contain 103% of the phage genome. Explain how this happens and what this means about the ends of the genome.

Question 65

How has the study of metagenomics allowed discovery of so many new species? How is it possible to know about these organisms without being able to grow them in a laboratory?

Question 66

Describe the role of the two RNA polymerases that are involved early on in the DNA replication process.

Question 67

How are archaeal genomes similar to both bacterial and eukaryotic genomes?

Question 68

Plasmids can be our enemy in the medical arena, but our friend in the research arena. Explain why this is so.

Question 69

How can plasmids ensure that they are passed on from one generation to the next?

Question 70

Why is replication of the lagging DNA strand a problem and how is this problem overcome?