Question 1

Which of the following statements about the human genome is INCORRECT?
A) There are approximately 3.1 billion bp in the human genome.
B) Human share a majority of genes with other species.
C) Less than 2 percent of the genome codes for proteins.
D) The human genome contains approximately 100,000 genes.
E) The functions of most human genes are still unknown.

Accepted Answer

The human genome actually contains an estimated 20,000-25,000 genes, not 100,000.

Question 2

Which of the following techniques is most efficient for transforming bacterial cells?
A) Gene gun
B) ES cell transfer
C) Electroporation
D) Pronuclear microinjection
E) Sperm-mediated transfer

Accepted Answer

Electroporation is the most efficient technique for transforming bacterial cells as it uses an electrical field to create temporary pores in the bacterial cell membrane, allowing DNA to enter. This method is quick, simple, and can transform a large number of cells at once, making it a preferred choice for many researchers. The other techniques listed, such as gene gun, ES cell transfer, pronuclear microinjection, and sperm-mediated transfer, are typically used for transforming eukaryotic cells rather than bacterial cells.

Question 3

You just cloned a new gene from mice. Which of the following techniques would be the best choice to use if you wanted to determine the number of copies of this gene in the mouse genome? A) Northern blot analysis B) RT-PCR C) Western blot analysis D) Southern blot analysis E) In situ hybridization

Accepted Answer

Southern blot analysis is the best choice for determining the number of copies of a gene in the genome as it involves the detection of specific DNA sequences using hybridization probes. This technique allows for the identification of the number and size of fragments that correspond to the gene of interest, providing information about the copy number and possible variations in the sequence among different individuals or strains. Northern blot analysis, RT-PCR, and Western blot analysis are useful for studying gene expression at the RNA or protein level, but cannot directly determine the copy number of a gene. In situ hybridization allows for the visualization of gene expression in specific tissues or cells, but does not provide information about the total number of gene copies in the genome.

Question 4

Which of the following vectors would be the best choice for gene transfer in plant cells?
A) Cosmid
B) Bacterial artificial chromosome
C) Bacteriophage vector
D) Ti vector
E) Plasmid

Accepted Answer

Ti (tumor-inducing) vector is often used in plant genetic engineering as it is a natural gene transfer system that has evolved in a way that allows it to integrate into the plant genome. The Ti vector can transfer large fragments of DNA into plant cells and is capable of delivering genes to multiple plant cells simultaneously. Additionally, the Ti vector is capable of integrating into the plant genome, meaning that the transferred genes can be permanently integrated into the plant's DNA.

Question 5

Which of the following techniques involves hybridizing a cDNA sample to a chip containing thousands of single-stranded DNA sequences, allowing one to study the expression of thousands of genes simultaneously?
A) PCR
B) Southern blot
C) FISH
D) Agarose gel electrophoresis
E) DNA microarray

Accepted Answer

The technique described here is DNA microarray. PCR, Southern blot, FISH, and agarose gel electrophoresis do not involve hybridizing a cDNA sample to a chip containing thousands of single-stranded DNA sequences.

Question 6

When making a complementary DNA (cDNA) library, which enzyme is used to copy mRNA into DNA?
A) DNA ligase
B) DNA polymerase
C) Primase
D) RNA polymerase
E) Reverse transcriptase

Accepted Answer

Reverse transcriptase is the enzyme used to copy mRNA into DNA during cDNA library construction. It is capable of reverse transcribing RNA into cDNA, which can be amplified and cloned to generate a complementary DNA library. DNA ligase is used to join DNA fragments together, DNA polymerase is used to synthesize new DNA strands during PCR, primase is used in DNA replication to synthesize RNA primers, and RNA polymerase copies DNA to RNA during transcription.

Question 7

During library screening, PCR, Southern blotting, and other techniques, binding two pieces of DNA to each other by hydrogen bonding is called ________.
A) autoradiography
B) hybridization
C) DNA ligation
D) reverse transcription
E) polyadenylation

Accepted Answer

The process of binding two pieces of DNA to each other by hydrogen bonding is called hybridization. Therefore, option B is the correct answer. Autoradiography is a technique used to visualize radioactive labels and is not related to the binding of DNA. DNA ligation is the joining of two DNA fragments and is not specifically related to the process of binding two pieces of DNA. Reverse transcription is the process of converting RNA into DNA and is not related to the binding of DNA. Polyadenylation is the addition of poly(A) tail to the 3' end of an RNA molecule and is not related to the binding of DNA.

Question 8

Which of the following is an INCORRECT statement about restriction enzymes?
A) Most restriction enzymes are isolated from bacteria.
B) Restriction enzymes usually recognize palindromic sequences.
C) Restriction enzymes create phosphodiester bonds between pieces of DNA in a cloning experiment.
D) Restriction enzymes can cut to create overlapping single-stranded ends of DNA.
E) Restriction enzymes can cut to create blunt-ended pieces of DNA.

Accepted Answer

Restriction enzymes cleave DNA by hydrolyzing phosphodiester bonds. However, in a cloning experiment, ligases are used to create phosphodiester bonds between pieces of DNA.

Question 9

In a recombinant DNA experiment, which enzyme is used to join together DNA fragments by forming phosphodiester bonds between nucleotides? Recall that this same enzyme joins together Okazaki fragments on the lagging strand during DNA replication.
A) DNA primase
B) DNA polymerase
C) DNA helicase
D) DNA ligase
E) Reverse transcriptase

Accepted Answer

DNA ligase is used to join together DNA fragments by forming phosphodiester bonds between nucleotides in a recombinant DNA experiment, as well as in the joining of Okazaki fragments during DNA replication.

Question 10

Approximately how many genes are present in the human genome?
A) 3 billion genes
B) 20 billion genes
C) 100,000 genes
D) 20,000 genes
E) 50,000 genes

Accepted Answer

The human genome contains approximately 20,000 genes.

Question 11

Approximately how large is the human genome?
A) 20,000 bp
B) 1 billion bp
C) 3 billion bp
D) 13 million bp
E) 30 billion bp

Accepted Answer

The human genome is approximately 3 billion base pairs (bp) long. This includes all of the DNA that makes up the human chromosomes. Option A is too small, option B is close but still an underestimate, option D is too small, and option E is an overestimate.

Question 12

A ________ consists of cloned DNA fragments for all expressed genes in a particular tissue
A) genomic DNA library
B) cDNA library
C) PCR library
D) Guggenheim library
E) shotgun library

Accepted Answer

A cDNA library consists of cloned DNA fragments for all expressed genes in a particular tissue. The other options are not applicable – a genomic DNA library would include non-expressed genes, a PCR library would only contain amplified fragments of a few specific genes, and Guggenheim library and shotgun library do not exist in molecular biology.

Question 13

Which of the following techniques is the best choice for amplifying DNA?
A) Southern blot analysis
B) PCR
C) DNA sequencing
D) Affinity chromatography
E) Microarray analysis

Accepted Answer

PCR (Polymerase Chain Reaction) is the best technique for amplifying DNA as it is a highly sensitive and specific technique that can amplify a small amount of DNA into billions of copies within a short amount of time. It can be used in a variety of applications, including genetic testing, diagnostics, and research. Southern blot analysis, DNA sequencing, and microarray analysis do not amplify DNA, while affinity chromatography is a purification technique and not used for amplification.

Question 14

________ is a DNA-binding dye that fluoresces when DNA in an agarose gel is illuminated with ultraviolet light.
A) Casein
B) Ethidium bromide
C) Malt
D) Lactic acid
E) Ethanol

Accepted Answer

Ethidium bromide is a common dye used in gel electrophoresis to visualize DNA, as it intercalates between the base pairs of DNA and fluoresces under UV light. It is not one of the other options listed (casein, malt, lactic acid, ethanol) which are not related to DNA visualization in gel electrophoresis.

Question 15

Transformation in a cloning experiment is ________.
A) ligating pieces of foreign DNA together
B) inserting DNA into bacteria cells
C) cutting DNA with restriction enzymes
D) using PCR to clone a gene
E) a technique for determining gene copy number in a genome

Accepted Answer

Transformation refers specifically to the process of introducing foreign DNA into bacterial cells, typically through the use of heat shock or electroporation. Ligating pieces of foreign DNA together, cutting DNA with restriction enzymes, and using PCR to clone a gene are all important steps in the cloning process but do not specifically involve transformation. Determining gene copy number in a genome is a separate technique altogether.

Question 16

Which of the following techniques is most commonly used to separate and analyze DNA by size?
A) PCR
B) Agarose gel electrophoresis
C) DNA microarray analysis
D) Hybridization
E) DNA libraries

Accepted Answer

Agarose gel electrophoresis is the most commonly used technique to separate and analyze DNA by size. This technique involves running a sample of DNA through a gel matrix, which separates the fragments based on size. The smaller the fragment, the farther it travels through the gel. This technique is useful for many applications, including DNA fingerprinting and DNA sequencing. PCR amplifies specific regions of DNA, DNA microarray analysis involves the hybridization of DNA to a microarray, hybridization involves the binding of two complementary nucleic acid strands, and DNA libraries involve the storage of DNA samples in a collection.

Question 17

Imagine you wanted to use a human genomic DNA library to clone the human gene for insulin. You will be using the rat insulin gene sequence as your DNA probe. In what order would you perform the following steps to accomplish this goal? 1. Use autoradiography to identify colonies containing DNA that hybridized to the probe
2) Grow transformed cells on media with antibiotics and X-gal for blue-white screening
3) Ligate genomic DNA and vector DNA
4) Cut genomic DNA and vector DNA with restriction enzymes
5) Hybridize library DNA with labeled probe for the rat insulin gene
6) Transform bacteria with recombinant plasmid
A) 2, 3, 6, 5, 4, 1
B) 1, 2, 5, 6, 4, 3
C) 4, 3, 6, 2, 5, 1
D) 4, 3, 5, 2, 6, 1
E) 2, 6, 5, 3, 1, 4

Accepted Answer

The correct order for cloning the human insulin gene using a rat insulin gene sequence as a probe involves: cutting both genomic DNA and vector DNA with restriction enzymes (4), ligating the genomic DNA into the vector (3), transforming bacteria with the recombinant DNA (6), growing the transformed cells on media for selection (2), hybridizing the library DNA with the labeled probe (5), and finally using autoradiography to identify the colonies that have hybridized with the probe (1).

Question 18

Based on what you know about which organisms naturally produce restriction enzymes and how restriction enzymes are named, which of the following enzymes is isolated from the bacterium Bacillus amyloliquefaciens? A) EcoRI B) BamHI C) SmaI D) PstI E) HindIII

Accepted Answer

Restriction enzymes are named after the bacterial species they are isolated from. In this case, "Bam" in BamHI stands for Bacillus amyloliquefaciens. Therefore, BamHI is the restriction enzyme that is isolated from the bacterium Bacillus amyloliquefaciens.

Question 19

Dideoxyribonucleotides (ddNTPs) used for DNA sequencing lack oxygen atoms at ________.
A) the 1' carbon of the pentose sugar
B) the 1' and 2' carbons of the pentose sugar
C) the 2' and 3' carbons of the pentose sugar
D) the 3' and 5' carbons of the pentose sugar
E) the 5' carbon of the pentose sugar

Accepted Answer

Dideoxyribonucleotides (ddNTPs) lack oxygen atoms at the 2' and 3' carbons of the pentose sugar. This lack of oxygen atoms prevents further extension of the DNA chain after the ddNTP has been incorporated, allowing for the sequencing of the DNA template.

Question 20

A ________ is a single-stranded DNA molecule attached to a radioactive or fluorescent compound that is complementary to a specific sequence of DNA. Such pieces of DNA are used to identify and study cloned genes in hybridization experiments.
A) polypeptide
B) promoter
C) vector
D) probe
E) plasmid

Accepted Answer

The description fits that of a DNA probe - a short, single-stranded DNA molecule labeled with radioactive or fluorescent molecules used to identify specific sequences of DNA. Polypeptides are chains of amino acids, promoters are DNA sequences that initiate transcription, vectors can refer to any DNA molecule used to transport genetic material, and plasmids are a specific type of circular DNA molecule used frequently in genetic engineering.

Quiz 3: Recombinant Dna Technology and Genomics

Which of the following statements about the human genome is INCORRECT?

Which of the following techniques is most efficient for transforming bacterial cells?

You just cloned a new gene from mice. Which of the following techniques would be the best choice to use if you wanted to determine the number of copies of this gene in the mouse genome?

Which of the following vectors would be the best choice for gene transfer in plant cells?

Which of the following techniques involves hybridizing a cDNA sample to a chip containing thousands of single-stranded DNA sequences, allowing one to study the expression of thousands of genes simultaneously?

When making a complementary DNA (cDNA) library, which enzyme is used to copy mRNA into DNA?

During library screening, PCR, Southern blotting, and other techniques, binding two pieces of DNA to each other by hydrogen bonding is called ________.

Which of the following is an INCORRECT statement about restriction enzymes?

In a recombinant DNA experiment, which enzyme is used to join together DNA fragments by forming phosphodiester bonds between nucleotides? Recall that this same enzyme joins together Okazaki fragments on the lagging strand during DNA replication.

Approximately how many genes are present in the human genome?

Approximately how large is the human genome?

A ________ consists of cloned DNA fragments for all expressed genes in a particular tissue

Which of the following techniques is the best choice for amplifying DNA?

________ is a DNA-binding dye that fluoresces when DNA in an agarose gel is illuminated with ultraviolet light.

Transformation in a cloning experiment is ________.

Which of the following techniques is most commonly used to separate and analyze DNA by size?

Based on what you know about which organisms naturally produce restriction enzymes and how restriction enzymes are named, which of the following enzymes is isolated from the bacterium Bacillus amyloliquefaciens?

Dideoxyribonucleotides (ddNTPs) used for DNA sequencing lack oxygen atoms at ________.

A ________ is a single-stranded DNA molecule attached to a radioactive or fluorescent compound that is complementary to a specific sequence of DNA. Such pieces of DNA are used to identify and study cloned genes in hybridization experiments.