Deck 4: Fundamentals of Molecular Biology

Question 1

Gregor Mendel discovered the principles of genetics in his early experiments on

A) peas.
B) fruit flies.
C) mice.
D) humans.

Answer 1

A

Question 2

During formation of eggs and sperm, one member of each chromosome pair is transmitted to each progeny cell in a type of cell division called

A) mitosis.
B) gametogenesis.
C) cytokinesis.
D) meiosis.

Answer 2

D

Question 3

Animal cells and most cells of higher plants are

A) haploid.
B) diploid.
C) euploid.
D) tetraploid.

Answer 3

B

Question 4

Eggs and sperm are

A) haploid.
B) diploid.
C) euploid.
D) tetraploid.

Question 5

Our fundamental knowledge about mutation, genetic linkage, and the relationships between genes and chromosomes was acquired largely from experiments on the

A) bacterium Pneumococcus.
B) fruit fly Drosophila.
C) plant maize.
D) pea plant.

Question 6

DNA was identified as the genetic material in experiments done by

A) Mendel.
B) Chargaff.
C) Avery, MacLeod, and McCarty.
D) Watson and Crick.

Question 7

Deduction of the structure of DNA was based on X-ray diffraction patterns obtained by

A) Avery, MacLeod, and McCarty.
B) Pauling.
C) Meselson and Stahl.
D) Wilkins and Franklin.

Question 8

DNA is a double helix with _______ base pairs per complete turn of the helix.

A) 3.4
B) 10
C) 20
D) 34

Question 9

In the base pairing within a DNA double helix,

A) purines pair with purines.
B) A pairs with U and G pairs with C.
C) A pairs with G and C pairs with T.
D) A pairs with T and G pairs with C.

Question 10

When thymidine and adenosine interact within a DNA molecule, they form

A) two hydrogen bonds.
B) three hydrogen bonds.
C) nucleotide triphosphates.
D) two phosphodiester bonds.

Question 11

What is the complementary sequence to the following bases 5?-TCAAGG-3?

A) 5?-AGTTCC-3?
B) 5?-TCAAGG-3?
C) 5?-CCTTGA-3?
D) 5?-AGUUCC-3?

Question 12

DNA replicates

A) conservatively.
B) semiconservatively.
C) liberally.
D) by hybridization.

Question 13

In Meselson and Stahl's experiment, cells were grown in media containing ¹⁵N in place of ¹⁴N, and then the cells' DNA was separated by equilibrium centrifugation. This experiment demonstrated that DNA

A) replication requires DNA polymerase.
B) replication is conservative.
C) replication is semiconservative.
D) forms double helices by means of hydrogen bonding between base pairs.

Question 14

RNA molecules that serve as templates for protein synthesis are called _______ RNAs.

A) messenger
B) transfer
C) ribosomal
D) small nuclear

Question 15

You have identified an unknown protein of approximately 1,500 amino acids. The minimum length of its mRNA is approximately

A) 1,500 nucleotides.
B) 4,500 nucleotides.
C) 500 nucleotides.
D) 750 nucleotides.

Question 16

A codon is a

A) region of DNA coding for one protein.
B) sequence of three nucleotides on a tRNA that binds to an mRNA.
C) sequence of three nucleotides on an mRNA that binds to specific tRNAs.
D) sequence of three nucleotides on the coding strand of DNA.

Question 17

Because the genetic code has more than one codon for most amino acids, the code is said to be

A) redundant.
B) wobbly.
C) a template.
D) degenerate.

Question 18

How many different RNA triplets specify amino acids?

A) 36
B) 60
C) 61
D) 64

Question 19

Which of the following deletions will not change the reading frame of a gene?

A) One nucleotide
B) Two nucleotides
C) Three nucleotides
D) Four nucleotides

Question 20

Reverse transcriptase is an enzyme that catalyzes _______ synthesis.

A) DNA-directed RNA
B) RNA-directed DNA
C) DNA-directed DNA
D) RNA-directed RNA

Question 21

The restriction enzyme NotI recognizes a specific DNA sequence of eight base pairs and cleaves at that site. Statistically, in any genome there should be one NotI recognition site for every _______ base pairs.

A) 3⁸
B) 8³
C) 4⁸
D) 8⁴

Question 22

Restriction endonucleases are enzymes that

A) cleave DNA only at specific sequences.
B) act only on the ends of DNA strands.
C) act only in a single species of bacteria.
D) cleave only nuclear DNA.

Question 23

The first enzymatic step in making a cDNA uses

A) Taq polymerase.
B) DNA polymerase.
C) RNA polymerase.
D) reverse transcriptase.

Question 24

To clone genes, a plasmid vector should contain all of the following except

A) foreign DNA.
B) an origin of replication.
C) a restriction nuclease cut site.
D) an antibiotic resistance gene.

Question 25

Which technique would be used to clone intact pieces of human DNA that are 400 kb pairs long?

A) An E. coli plasmid
B) Bacteriophage $\lambda$
C) Yeast artificial chromosomes
D) Polymerase chain reaction

Question 26

The most common method of DNA sequencing is based on premature termination of DNA synthesis by inclusion of

A) dideoxynucleotides.
B) endonuclease.
C) ampicillin.
D) puromycin.

Question 27

Which vector would be used to express a human protein in E. coli?

A) An expression plasmid containing cDNA made from mRNA for the human protein
B) An expression plasmid containing an EcoRI-cut piece of the gene for the human protein
C) The human gene for the protein inserted into E. coli by a bacteriophage $\lambda$ expression vector
D) A yeast artificial chromosome containing the human gene for the protein

Question 28

Vectors for expressing a eukaryotic protein in a bacterium must contain

A) a eukaryotic promoter.
B) antibody recognition sequences.
C) an origin of replication.
D) EcoRI restriction enzyme recognition sites.

Question 29

Expression of a human protein in a bacterial cell is best done with human

A) cDNA in a bacterial expression vector.
B) genomic DNA in a bacterial expression vector.
C) cDNA in a virus-derived eukaryotic expression vector.
D) genomic DNA in a virus-derived eukaryotic expression vector.

Question 30

Taq polymerase is used in the polymerase chain reaction because it

A) is stable in organic solvents.
B) is stable at high temperatures.
C) recognizes specific primer sequences.
D) can make DNA sequences from RNA sequences.

Question 31

Which pair of primers will amplify the template DNA sequence shown below in a PCR?
5ʹ-AGGCTGCGAT...//...CCGTTAGATT-3ʹ
3ʹ-TCCGACGCTA...//...GGCAATCTAA-5ʹ

A) 5ʹ-AGGCTGCGAT-3ʹ and 5ʹ-CCGTTAGATT-3ʹ
B) 5ʹ-AGGCTGCGAT-3ʹ and 5ʹ-AATCTAACGG-3ʹ
C) 5ʹ-TCCGACGCTA-3ʹ and 5ʹ-GGCAATCTAA-3ʹ
D) 5ʹ-TCCGACGCTA-3ʹ and 5ʹ-CCGTTAGATT-3ʹ

Question 32

Heat-denatured DNA will renature when cooled to about

A) 95 $\degree$ C.
B) 65 $\degree$ C.
C) 37 $\degree$ C.
D) 20 $\degree$ C.

Question 33

Nucleic acid hybridization is the

A) mating of two genetically different organisms.
B) formation of hybrid nuclei when two cells are fused.
C) formation of a double-stranded molecule from the interaction of two complementary-sequence single-stranded molecules.
D) recombining of DNA molecules from two different organisms.

Question 34

The technique by which fragments of DNA are separated by gel electrophoresis, denatured, blotted on nitrocellulose paper, labeled with a complementary radioactive probe, and detected by autoradiography is called _______ blotting.

A) Southern
B) Northern
C) Western
D) Eastern

Question 35

Which method would be used to determine if drug treatment of a cell culture led to increased expression of mRNA?

A) Southern blotting
B) Northern blotting
C) Western blotting
D) Eastern blotting

Question 36

The technique by which a particular nucleic acid sequence is localized with labeled probes within a cell, tissue, or isolated chromosome is called _______ hybridization.

A) in vivo
B) in vitro
C) in situ
D) in toto

Question 37

To identify the protein against which a given sample has an antibody, the best technique to use would be _______ blotting.

A) Southern
B) Northern
C) Western
D) Eastern

Question 38

SDS-polyacrylamide gel electrophoresis (SDS-PAGE) separates proteins by

A) negative charge.
B) positive charge.
C) charge: size ratio.
D) size.

Question 39

Retroviral vectors can be advantageous over liposomes for stable introduction of DNA into animal cells because

A) retrovirus infected cells are more readily selectable.
B) one step in the viral life cycle is integration of its DNA into the host genome.
C) they allow insertion of larger DNA molecules.
D) All of the above

Question 40

The experimental introduction of DNA into eukaryotic cells is called

A) infection.
B) transfection.
C) transient expression.
D) transcription.

Question 41

DNA can be introduced into cells by

A) microinjection into the nucleus of a cell.
B) fusion of DNA-containing liposomes with cells.
C) infection with engineered retroviruses.
D) All of the above

Question 42

Most eukaryotic cells transfected with DNA using liposomes will only express the introduced genes for several days because

A) foreign DNA will be targeted by CRISPR/Cas.
B) foreign RNA will be targeted by antisense RNAs.
C) the introduced DNA will not be replicated with the cells' chromosomes.
D) miRNAs will block translation of the foreign mRNA.

Question 43

Transgenic mice are usually produced by

A) infecting mice with viruses carrying the gene.
B) injecting DNA containing the gene into the pronucleus of a fertilized egg.
C) injecting nuclei from embryonic stem cells into enucleated eggs.
D) injecting RNA coding for a human protein into the nucleus of a fertilized egg.

Question 44

Mutations may be introduced into selected genes of living cells by

A) homologous recombination with an altered cloned gene.
B) hybridization with antisense nucleic acid sequences.
C) the polymerase chain reaction.
D) ultraviolet laser irradiation.

Question 45

The CRISPR/Cas system has revolutionized the efficiency with which scientists can mutate a gene in vivo to investigate the functional role of the protein it encodes. Which component is not essential in the CRISPR/Cas system?

A) Guide RNA complementary to gene of interest
B) Access to target mRNA
C) Cas9 nuclease
D) Access to target gene

Question 46

When introduced into living cells, antisense RNA molecules bind

A) to complementary DNA sequences and block RNA synthesis.
B) to the sense strand of DNA and block RNA synthesis.
C) to complementary mRNA sequences and block protein synthesis.
D) proteins called RISC and cleave the complementary mRNA.

Question 47

In RNA interference, expression of a gene is most effectively inhibited by injection of

A) antisense RNA complementary to its mRNA.
B) sense RNA complementary to its mRNA.
C) double-stranded DNA.
D) double-stranded RNA.

Question 48

RNA is copied from DNA through a process called _______.

Question 49

Proteins are synthesized from RNA templates through a process called _______.

Question 50

In addition to mRNA, the two types of RNA necessary for protein synthesis are _______ and _______.

Question 51

The central dogma of molecular biology is _______ $\rightarrow$ _______ $\rightarrow$ _______.

Question 52

The three codons that do not specify amino acids serve as _______.

Question 53

A poly-U RNA template codes only for the amino acid _______.

Question 54

RNA viruses that replicate via a DNA intermediate are called _______.

Question 55

The enzyme discovered by Temin, Mizutani, and Baltimore, which synthesizes DNA from an RNA template, is called _______

Question 56

A schematic representation of a length of DNA showing the locations of cleavage sites for multiple different restriction endonucleases is called a _______.

Question 57

The DNA made from an mRNA is called _______.

Question 58

Methods of sequencing DNA that have made it possible to sequence whole genomes faster and less expensively than the Sanger dideoxy method are collectively referred to as .

Question 59

Eukaryotic genes expressed in bacteria produce products that differ from the eukaryotic protein in that they do not have _______ modification.

Question 60

A single species of antibodies produced from a cultured clone of B lymphocytes is called a(n) _______.

Question 61

When foreign DNA is injected into the nucleus of a fertilized mouse egg and integrated into the mouse genome, the egg can develop into a(n) _______ mouse.

Question 62

A cell that can give rise to an entire animal is called a(n) _______ cell.

Question 63

Site-specific mutations can be introduced into cultured animal cells by a technique that relies on _______ recombination.

Question 64

CRISPR were discovered in bacteria, where they are used as a defense against foreign genetic elements, such as _______.

Question 65

The use of double-stranded RNA to inhibit expression of a gene with a complementary sequence is called _______.

Question 66

Genes that do not normally separate from one another during meiosis are on the same chromosome.

Question 67

Meiosis results in a change of nuclear DNA from haploid to diploid.

Question 68

Avery, MacLeod, and McCarty showed that one type of bacteria could be transformed into another type by uptake of purified RNA.

Question 69

Erwin Chargaff found that in DNA, the amount of A is equal to that of T and the amount of G is equal to that of

Question 70

DNA contains the base uracil, whereas RNA contains the base thymine.

Question 71

Vectors usually contain an antibiotic-resistance gene so that cells that incorporate the vector can be selected by their resistance to the antibiotic.

Question 72

cDNA made from genomic DNA is used to create cDNA libraries.

Question 73

One method of DNA sequencing involves incorporation of dideoxynucleotides during synthesis of new DNA.

Question 74

A cDNA is especially useful for bacterial expression of a eukaryotic protein.

Question 75

The polymerase chain reaction is used to amplify specific fragments of DNA in vitro.

Question 76

Embryonic stem cells introduced into early mouse embryos can give rise to cells in all of the tissues of the mouse, including germ cells.

Question 77

The CRISPR/Cas system can knock out the expression of a gene in vivo and/or introduce a new mutation into a gene.

Question 78

Considering Mendel's findings on the genetics of peas, identify the genotypes of two yellow parent plants that produced a green offspring.

Question 79

Consider Mendel's experiments on the genetics of peas. What is the probability that two green parent pea plants would also have green offspring?

Question 80

Consider this statement: An increase in the levels of a protein within a cell indicates that expression of the gene encoding it was also increased. Why is the statement not necessarily true?