PCB 3063- Exam 4 Questions and Answers Fully Solved Latest Update 2025-2026
recombinant DNA - Answers joining of DNA molecules; produced by artificially joining DNA from
different biological sources not found together in nature
cloning - Answers the process of making many copies of a specific DNA sequence
types of cloning - Answers PCR and cloning with a vector through recombination
restriction enzymes - Answers produced by bacteria as a defense mechanism against bacteriophages;
DNA-cutting enzymes
palindrome sequences - Answers targeted by restriction enzymes, symmetry exhibited by recognition
sequence and allow enzymes to cut both strands
sticky ends - Answers Single stranded ends of DNA left after cutting with enzymes
blunt ends - Answers fragment ends of a DNA molecule that are fully base paired, resulting from
cleavage by a restriction enzyme
DNA ligase - Answers seals the phosphodiester backbone to create intact DNA
vectors - Answers carrier DNA molecules; can replicate in host cells independent of host cell
chromosome; usually have many restriction enzymes
selectable gene marker - Answers distinguish host cells that have taken them up from those that have
not; usually an antibiotic resistance gene
plasmids - Answers extrachromosomal double-stranded DNA molecules and can be genetically modified
transformation - Answers process in which plasmids are introduced into bacteria
2 main techniques of transformation - Answers 1. use calcium ions and brief heat shock to force cells to
take up DNA
2. Electroporation
Electroporation - Answers a brief but high intensity pulse of electricity to move DNA into bacterial cells
selectable marker genes - Answers genes that provide resistance to antibiotics
blue-white selection - Answers Used to identify cells containing recombinant
and nonrecombinant DNA; plasmid contains lacZ gene, which encodes B-galactosidase
blue-white screening mechanism - Answers agar plates contain X-gal, when X-gal is cleaved by enzyme it
turns blue
, cell type that turns blue from blue-white mechanism - Answers bacterial cells with functional lacZ gene
carrying nonrecombinant plasmid
cell type that turns white from blue-white mechanism - Answers bacterial cells with recombinant
plasmid
DNA libraries - Answers represent collection of cloned DNA fragments (genomic and complementary)
genomic library - Answers complete collection of cloned DNA fragments from an organism
complementary DNA (cDNA) library - Answers Contains complementary DNA copies made from mRNAs
present in cell population; Represents genes active transcriptionally at the time cells were collected for
mRNA isolation
cDNA library is constructed by - Answers isolating mRNA from cells, synthesizing complementary DNA
using reverse transcriptase, cloning cDNA molecules into vector
polymerase chain reaction - Answers rapid method of DNA cloning that eliminates the need to host cells
for cloning
PCR steps - Answers 1. denaturation 2. primer annealing 3. extension (steps repeated over and over)
PCR primers - Answers short, single stranded, one complementary to each end
what do primers do - Answers anneal to denature DNA
how are complementary strands synthesized? - Answers heatstable DNA polymerase
limitations of PCR - Answers contamination from other sources (ANY DNA that the primers bind to will
be amplified), high error rate, some info is required
applications of PCR - Answers diagnostic tests, screens for mutations, widely used in genetics and
molecular biology
reverse transcription PCR - Answers generate cDNA from RNA, then converted to DNA
quantitative real-time PCR - Answers allows researchers to quantify amplification reactions as they occur
in real time
restriction maps - Answers show the lengths of DNA fragments between restriction sites in a strand of
DNA
southern blot - Answers used to characterize size and identify of DNA fragments; separate, transfer,
hybridization
northern blot analysis - Answers uses probes to detect mRNA, used to determine whether gene is
actively being expressed in given cell or tissue
recombinant DNA - Answers joining of DNA molecules; produced by artificially joining DNA from
different biological sources not found together in nature
cloning - Answers the process of making many copies of a specific DNA sequence
types of cloning - Answers PCR and cloning with a vector through recombination
restriction enzymes - Answers produced by bacteria as a defense mechanism against bacteriophages;
DNA-cutting enzymes
palindrome sequences - Answers targeted by restriction enzymes, symmetry exhibited by recognition
sequence and allow enzymes to cut both strands
sticky ends - Answers Single stranded ends of DNA left after cutting with enzymes
blunt ends - Answers fragment ends of a DNA molecule that are fully base paired, resulting from
cleavage by a restriction enzyme
DNA ligase - Answers seals the phosphodiester backbone to create intact DNA
vectors - Answers carrier DNA molecules; can replicate in host cells independent of host cell
chromosome; usually have many restriction enzymes
selectable gene marker - Answers distinguish host cells that have taken them up from those that have
not; usually an antibiotic resistance gene
plasmids - Answers extrachromosomal double-stranded DNA molecules and can be genetically modified
transformation - Answers process in which plasmids are introduced into bacteria
2 main techniques of transformation - Answers 1. use calcium ions and brief heat shock to force cells to
take up DNA
2. Electroporation
Electroporation - Answers a brief but high intensity pulse of electricity to move DNA into bacterial cells
selectable marker genes - Answers genes that provide resistance to antibiotics
blue-white selection - Answers Used to identify cells containing recombinant
and nonrecombinant DNA; plasmid contains lacZ gene, which encodes B-galactosidase
blue-white screening mechanism - Answers agar plates contain X-gal, when X-gal is cleaved by enzyme it
turns blue
, cell type that turns blue from blue-white mechanism - Answers bacterial cells with functional lacZ gene
carrying nonrecombinant plasmid
cell type that turns white from blue-white mechanism - Answers bacterial cells with recombinant
plasmid
DNA libraries - Answers represent collection of cloned DNA fragments (genomic and complementary)
genomic library - Answers complete collection of cloned DNA fragments from an organism
complementary DNA (cDNA) library - Answers Contains complementary DNA copies made from mRNAs
present in cell population; Represents genes active transcriptionally at the time cells were collected for
mRNA isolation
cDNA library is constructed by - Answers isolating mRNA from cells, synthesizing complementary DNA
using reverse transcriptase, cloning cDNA molecules into vector
polymerase chain reaction - Answers rapid method of DNA cloning that eliminates the need to host cells
for cloning
PCR steps - Answers 1. denaturation 2. primer annealing 3. extension (steps repeated over and over)
PCR primers - Answers short, single stranded, one complementary to each end
what do primers do - Answers anneal to denature DNA
how are complementary strands synthesized? - Answers heatstable DNA polymerase
limitations of PCR - Answers contamination from other sources (ANY DNA that the primers bind to will
be amplified), high error rate, some info is required
applications of PCR - Answers diagnostic tests, screens for mutations, widely used in genetics and
molecular biology
reverse transcription PCR - Answers generate cDNA from RNA, then converted to DNA
quantitative real-time PCR - Answers allows researchers to quantify amplification reactions as they occur
in real time
restriction maps - Answers show the lengths of DNA fragments between restriction sites in a strand of
DNA
southern blot - Answers used to characterize size and identify of DNA fragments; separate, transfer,
hybridization
northern blot analysis - Answers uses probes to detect mRNA, used to determine whether gene is
actively being expressed in given cell or tissue
