Selection, Screening, And Analysis Of Recombinant DNA Quiz

The explanation for the given correct answer is that if the genome sequence for the target organism is available, a computer can indeed be used to search for any particular sequence in the genome. With the genome sequence, computer algorithms can be applied to analyze and search for specific sequences of DNA or RNA within the genome. This process is commonly used in bioinformatics and genomics research to identify genes, regulatory elements, or specific genetic variations in organisms.

In any cloning experiment, it is crucial to identify the desired gene sequence among the various recombinants that may be formed. This is because the desired gene sequence is the specific sequence that researchers are interested in studying or manipulating. Without being able to accurately identify the desired gene sequence, the experiment would not be successful as researchers would not be able to isolate and work with the specific gene of interest. Therefore, the statement that success in any cloning experiment depends on being able to identify the desired gene sequence is true.

The X-gal detection system relies on the presence of a functional β-galactosidase gene in the host/vector system. X-gal is a substrate for β-galactosidase, and when it is cleaved by the enzyme, it produces a blue color. Therefore, if the β-galactosidase gene is present and functional, the X-gal detection system can be used to detect its activity. This statement is true.

The availability of a particular probe depends on the knowledge of the target gene sequence. This means that if the sequence of the target gene is known, a specific probe can be designed to detect and bind to that sequence. On the other hand, if the sequence is not known or not well characterized, it may be difficult or impossible to design a probe that specifically targets that gene. Therefore, the statement is true.

Blotting techniques, such as Southern blotting, can indeed be used in combination with restriction enzyme digestion and gel electrophoresis to identify specific regions of a gene in a cloned fragment of DNA. This is achieved by transferring the DNA fragments from the gel onto a membrane, which is then probed with a labeled DNA probe that is complementary to the target region of interest. The probe will bind to the target region, allowing for the identification and visualization of the specific gene region in the cloned DNA fragment. Therefore, the statement is true.

Sequencing can indeed range from a small-scale project involving a single gene to sequencing entire genomes. This means that sequencing can be done on a smaller scale, focusing on specific genes, or on a larger scale, covering the entire genetic material of an organism. Therefore, the statement is true.

Antibiotic resistance marker genes are used in genetic engineering to select for cells that have taken up a vector. These marker genes provide a simple and reliable way to identify and select cells that have successfully incorporated the vector. By introducing antibiotic resistance genes into the vector, cells that have not taken up the vector will be killed when exposed to the corresponding antibiotic, while cells that have taken up the vector will survive. This allows researchers to easily identify and select cells that contain the desired vector. Therefore, the statement that antibiotic resistance marker genes provide a simple and reliable way to select for the presence of vectors in cells is true.

The availability of genome sequences allows researchers to use computer-based searches to locate specific genes. This means that instead of relying solely on traditional methods, such as laboratory experiments, scientists can now utilize computational tools to identify and analyze genes of interest. This has greatly expedited the process of gene discovery and has revolutionized the field of genetics.

The statement is true because when a suitable probe is obtained, it can be labeled with a radioactive isotope such as 32P. This is commonly done in molecular biology research to track and visualize specific molecules or sequences. The radioactive isotope allows for detection and measurement of the labeled probe, providing valuable information about the target molecule or sequence.

Determining the sequence of a cloned fragment is indeed essential when studying gene structure. This is because the sequence of the cloned fragment provides information about the specific arrangement of nucleotides in the gene, which in turn helps in understanding its function and potential interactions with other genes or proteins. By knowing the sequence, researchers can also identify specific regions within the gene that are important for its activity or regulation. Therefore, it is true that determining the sequence of a cloned fragment is crucial for studying gene structure.

The plasmid pBR322 does indeed contain genes for ampicillin resistance (Apr) and tetracycline resistance (Tcr). This means that if the plasmid is present in a bacterial cell, it will confer resistance to both ampicillin and tetracycline antibiotics.

The explanation for the given correct answer is that restriction mapping is a technique used to determine the location of specific DNA sequences on a DNA molecule. It involves cutting the DNA molecule with restriction enzymes, which are proteins that recognize specific DNA sequences and cut the DNA at those sites. By using different restriction enzymes, the DNA can be cut into different fragments. The number and size of these fragments can then be analyzed to determine the location of the specific DNA sequences. Therefore, the basic principle of restriction mapping is indeed that the cloned DNA is usually cut with a variety of restriction enzymes to determine the number of fragments produced by each enzyme.

Genetic selection and screening methods rely on the expression or non-expression of certain traits. This means that these methods involve selecting or screening individuals based on whether they exhibit specific traits or not. This is done to identify and propagate desirable traits or to eliminate undesirable traits in a population. Therefore, the statement "Genetic selection and screening methods rely on the expression (or non-expression) of certain traits" is true.

The explanation for the given correct answer is that the first blotting technique was indeed developed by Ed Southern and is commonly referred to as Southern blotting. This technique is used to detect specific DNA sequences in a sample by separating the DNA fragments based on size and then transferring them onto a membrane for further analysis.

Northern blotting is a technique used to study gene expression by detecting specific mRNA molecules in a sample. It involves separating the mRNA molecules using gel electrophoresis and then transferring them onto a membrane. The membrane is then hybridized with a labeled probe that is complementary to the mRNA of interest. By analyzing the hybridization patterns, researchers can determine which regions of a cloned DNA fragment will hybridize to a particular mRNA. Therefore, the statement that Northern blotting is most useful in determining hybridization patterns in mRNA samples and can be used to determine which regions of a cloned DNA fragment will hybridize to a particular mRNA is true.

The presence of the plasmid pBR322 in cells can be detected by plating potential transformants on an agar medium that contains either ampicillin or tetracycline antibiotics. This is because pBR322 contains resistance genes for both of these antibiotics. Therefore, if the plasmid is present in the cells, they will be able to grow on the agar medium despite the presence of the antibiotics. If the plasmid is not present, the cells will not be able to grow on the agar medium.

The use of oligonucleotide probes is possible when there is existing amino acid sequence data for the protein encoded by the target gene. This is because oligonucleotide probes are designed to specifically bind to complementary DNA or RNA sequences. By having amino acid sequence data, researchers can use this information to design probes that will specifically bind to the target gene's DNA or RNA, allowing for the detection or analysis of the gene of interest.

This statement is true because antibiotics can be used to select for the presence of vector molecules. Antibiotics are often used in genetic selection methods to kill off cells that do not contain the desired vector molecules, allowing only the cells with the desired vectors to survive and grow. This method is commonly used in molecular biology and genetic engineering to select for cells that have successfully taken up the desired vectors.

Genomic DNA probes are indeed fragments of cloned sequences that are used for various purposes, such as identifying other clones that contain additional parts of a specific gene or as heterologous probes. This means that the statement is correct.

Both HART and HRT rely on hybridizing cloned DNA fragments to mRNA prepared from the cell or tissue type from which the clones have been derived. This means that both techniques involve using cloned DNA fragments and mRNA to study gene expression. Therefore, the statement is true.

Selection is a process in genetic engineering where certain conditions or pressures are applied to identify and isolate cells that have successfully taken up and expressed the desired recombinant DNA. One common method of selection is the use of antibiotics, where only cells that have incorporated the antibiotic resistance gene from the recombinant DNA will survive and grow. Therefore, the statement that selection involves the application of pressure, such as the presence of an antibiotic, during the growth of host cells containing recombinant DNA is true.

Generating a restriction map of a cloned DNA fragment is indeed one of the first tasks in analyzing the clone. A restriction map shows the locations of specific DNA sequences that can be recognized and cut by restriction enzymes. By determining the positions of these restriction sites, researchers can gain valuable information about the structure and organization of the cloned DNA fragment. This information is crucial for further genetic and molecular studies on the clone. Therefore, the statement "Generating a restriction map of a cloned DNA fragment is usually one of the first tasks in analyzing the clone" is true.

If the insert interrupts the coding sequence of a gene, it means that the cloned DNA fragment has been successfully inserted into the gene. This interruption can be detected through various methods such as DNA sequencing or PCR analysis. Therefore, the statement "The presence of cloned DNA fragments can be detected if the insert interrupts the coding sequence of a gene" is true.

Screening is a process used to analyze a population of cells in order to identify specific sequences. This can be done through various methods such as genetic testing or biochemical assays. The correct answer is TRUE because screening does involve analyzing cells to identify desired sequences.

A cDNA clone is a copy of a specific mRNA molecule, which represents a specific gene. By using this cDNA clone as a probe, it is possible to screen a genomic library, which contains fragments of DNA from an entire genome, to identify the gene sequence itself. This process allows for the isolation of the specific gene sequence from the genomic library. Therefore, the statement is true.

Blotting without separation of sequences can be a useful technique for determining the amount of a specific sequence in a sample. This is commonly used in gene expression studies to measure transcript levels.

Nucleic acid hybridization is a process in which two complementary DNA or RNA strands bind together through hydrogen bonding. This process is highly specific and accurate, as complementary sequences will only bind to each other with a high degree of fidelity. This property makes nucleic acid hybridization a powerful technique in various applications, such as DNA sequencing, genetic testing, and gene expression analysis. Therefore, the statement "The power of nucleic acid hybridization lies in the fact that complementary sequences will bind to each other with a very high degree of fidelity" is true.

The statement is true because there are indeed three main types of DNA probe: cDNA, genomic DNA, and oligonucleotides. These probes are used in various molecular biology techniques such as hybridization and PCR to detect and analyze specific DNA sequences. cDNA probes are complementary to mRNA sequences and are used to study gene expression. Genomic DNA probes are derived from the entire genome and can be used to detect specific genes or genetic variations. Oligonucleotide probes are short synthetic DNA molecules that are specific to a particular DNA sequence and are commonly used in diagnostic tests and DNA sequencing.

Hybrid-arrest translation (HART) and hybrid-release translation (HRT) are indeed used to identify the protein product. These techniques involve the use of hybridization to arrest or release the translation process, allowing for the detection and identification of the protein being translated. Therefore, the statement "TRUE" is the correct answer.

The degenerate nature of the genetic code refers to the fact that multiple codons can code for the same amino acid. This means that there is redundancy in the genetic code, making it impossible to predict the exact sequence with complete accuracy. Therefore, the statement is true.

Monoclonal antibodies do not recognize all antigenic determinants. They are produced from a single clone of B cells and therefore only recognize a specific epitope on an antigen. This specificity allows them to target and bind to specific molecules or cells in the body.

Antibiotic resistance can be used as an insertional inactivation system if DNA fragments are cloned into a restriction site within an antibiotic-resistance gene. This is because the insertion of the DNA fragments disrupts the function of the antibiotic-resistance gene, making the bacteria sensitive to the antibiotic. Therefore, the statement that antibiotic resistance cannot be used as an insertional inactivation system in this scenario is false.

The statement is false because plaque morphology can be used as a screening method for certain λ vectors, including λgt10, which contain the cI gene. Plaque morphology refers to the appearance of plaques formed by bacteriophages on a bacterial lawn. By observing the size, shape, and other characteristics of the plaques, researchers can determine if a specific phage vector is present. Therefore, plaque morphology can be used as a screening method for λ vectors like λgt10 that contain the cI gene.

The explanation for the given correct answer is that the production of a cDNA or genomic DNA library is not referred to as the 'blotting' approach. Blotting refers to a technique used to transfer DNA, RNA, or protein molecules onto a solid support for further analysis. In the case of creating a DNA library, the process involves cloning and amplifying DNA fragments, not blotting. Therefore, the statement is false.

Hybridization refers to the process of combining two separate nucleic acid molecules by forming bonds between their complementary bases. This process involves the formation of phosphodiester bonds. Therefore, the statement is true.

Ligation is a technique used in molecular biology to join DNA fragments together. In the context of screening clone libraries, ligation can be used to insert a DNA fragment into a vector, creating a recombinant DNA molecule. This recombinant DNA can then be introduced into host cells, allowing for the screening and identification of specific clones of interest. Therefore, ligation is indeed a useful tool for screening clone libraries.

The LacZ gene does not encode the cI repressor. The LacZ gene encodes the enzyme beta-galactosidase, which is involved in the metabolism of lactose. The cI repressor is encoded by the cI gene and is responsible for regulating the expression of genes involved in lysogeny. Therefore, the statement is false.

Antibodies are not produced in response to challenge with purified DNA. Instead, antibodies are produced in response to challenge with antigens, which can be proteins, carbohydrates, or other molecules that are recognized as foreign by the immune system. DNA itself is not typically recognized as an antigen by the immune system. Therefore, the correct answer is FALSE.

Polyclonal antisera actually contain antibodies that recognize multiple antigenic determinants of the antigen, not just a single one. This is because polyclonal antibodies are produced by different B cells, each of which recognizes a different epitope or antigenic determinant on the antigen. Therefore, the statement that polyclonal antisera contain antibodies that recognize single antigenic determinants is incorrect.

Nucleic acid hybridization is a powerful method to screen clone banks and can be used to detect specific DNA sequences. However, it is not a technique used to amplify a gene. Amplification of a gene is typically done using techniques like polymerase chain reaction (PCR). Therefore, the statement is false.

The statement is false because PCR screening is used to amplify DNA, not identify protein products. Nucleic acid probes, on the other hand, are used to detect specific DNA or RNA sequences and can be used to identify the protein product of a cloned gene. Therefore, the correct answer is false.

The origin of replication is a sequence of DNA that is necessary for the initiation of DNA replication. It is typically found in vectors used for cloning purposes. Therefore, the statement that the origin of replication can be used to identify a vector carrying a cloned insert is incorrect. The origin of replication is used to ensure that the vector is replicated in host cells, but it does not provide information about the presence or identity of a cloned insert.

Antibody screening does not specifically identify carbohydrates synthesized from expression libraries. Antibody screening is a technique used to identify specific antibodies that can bind to a particular antigen. It is not directly related to the identification of carbohydrates. Therefore, the given statement is false.

Direct complementation of a defined mutation may not be feasible if the gene system is unknown and an appropriate mutant is available.

Matching the cloned sequence with the plasmid that it encodes is not useful in clone identification. Clone identification is typically done through other methods such as DNA sequencing or restriction enzyme digestion. Matching the cloned sequence with the plasmid may be useful for other purposes, such as confirming the correct insertion of the sequence into the plasmid, but it is not directly related to clone identification.

Using a defined nucleic acid probe can indeed be used to identify specific clones of interest in a cDNA or genomic DNA library. Therefore, the correct answer is FALSE.

Homologous or heterologous probes may be used in screening protocols if the genes have sequences similar enough to enable stable hybridization under relatively high stringency conditions. Therefore, the correct answer is FALSE because the statement suggests that unstable hybridization occurs under high stringency conditions, which is incorrect.

The statement is false because the number of plaques that can be cleaved on each filter is not an important factor in screening genomic libraries by nucleic acid hybridization. The important factors in this process include the specificity and sensitivity of the probe used, the stringency of the hybridization conditions, and the ability to detect and visualize the hybridized DNA. The number of plaques that can be cleaved on each filter may affect the efficiency of the screening process, but it is not a crucial factor.

The statement is false because the antiparallel nature of DNA strands does not necessarily make a sequence-specific probe a powerful screening tool. While a sequence-specific probe can be useful in identifying and detecting specific DNA sequences, the antiparallel nature of DNA strands refers to their opposite orientations, not their ability to be targeted by probes. Other factors such as probe design, sensitivity, and specificity determine the effectiveness of a screening tool.

Amplicon cannot be screened by producing a copy of the colonies or plaques on a nitrocellulose or nylon filter. Amplicon refers to the amplified DNA fragments produced through PCR (Polymerase Chain Reaction), and screening them typically involves methods such as gel electrophoresis or DNA sequencing.