MCB3020 exam 3 UPDATED Questions
and CORRECT Answers
biotechnology - CORRECT ANSWER - the use of living organisms to create products that
are useful to humans
genetic engineering - CORRECT ANSWER - the deliberate modification of an organism's
genome sequence
Recombinant DNA technology - CORRECT ANSWER - set of procedures used to
combine genetic material from multiple sources and create DNA sequences that are otherwise
not found in biological organisms
Cloning - CORRECT ANSWER - generation of a larger number of identical DNA
molecules from a single DNA molecule
What are the five steps of gene cloning - CORRECT ANSWER - 1. isolate DNA to be
cloned
2. use restriction enzymes to "chop up" the DNA into fragments
3. insert the fragments into a cloning vector (i.e., bacterial plasmid), creating recombinant DNA
4. culture the host cell, growing many identical copies
Restriction enzymes - CORRECT ANSWER - - a type of endonuclease that cut DNA at
specific sites
- they recognize restriction/recognition sequences and cut DNA within those sites
,Restriction enzymes cut target DNA in which way - CORRECT ANSWER - staggered
cuts that produce sticky ends
what enzyme forms covalent bonds between the cloned gene and the plasmid, creating
recombinant DNA - CORRECT ANSWER - DNA ligase
What do reverse transcriptases produce? - CORRECT ANSWER - complementary DNA
(cDNA)
double stranded DNA is created from a single-stranded RNA
what are the 4 steps to construct cDNA? - CORRECT ANSWER - 1. apply a short poly-T
primer to a single-stranded RNA template
2. add reverse transcriptase and the 4 nucleotides to produce the DNA-RNA hybrid
3. add RNaseH enzyme to cut the RNA and regenerate the RNA primers
4. add DNA polymerase and DNA ligase to synthesize a new strand.
gel electrophoresis - CORRECT ANSWER - separates DNA/RNA and proteins based on
their size and electrical charge
it is important because it determines which fragments are larger than others and tells us the
approximate size for each fragment
DNA and RNA are (negatively/positively) charged due to their ____________ so they travel
through the gel towards the (negative/positive) electrode - CORRECT ANSWER -
negatively, phosphate backbones, positive
The (longer/shorter) and (heavier/lighter) DNA travels a shorter distance towards the positive
electrode - CORRECT ANSWER - longer and heavier
,What is the name of the dye that stains the DNA in gel electrophoresis - CORRECT
ANSWER - ethidium bromide
what is PCR? - CORRECT ANSWER - a technique for quickly and easily making many
copies of even a very small amount of DNA
What things does PCR require? - CORRECT ANSWER - -DNA of interest
-primers
- thermostable DNA polymerase
-d(A/C/G/T)TP to grow the DNA strand during replication
what is the most likely source of Taq polymerase and why are thermostable polymerases needed
for PCR? - CORRECT ANSWER - thermophilic bacterium found in hydrothermal vents,
because PCR increases the temperature of the mixture a lot
T/F: In PCR, hydrogen bonds of double-stranded DNA molecules are broken by subjecting the
DNA to high levels of radiation. - CORRECT ANSWER - False, under high levels of
HEAT
what is a thermocycler? - CORRECT ANSWER - an instrument that cyclically increases
and decreases the temperature of the solution
What are the steps of PCR with temperature included - CORRECT ANSWER - 1.
denaturation: heat to 90 C to separate DNA strands
2. annealing: cool to 50 C to allow the primers to hydrogen-bond to their complementary
sequence
3. elongation: heat to 70 C to allow the heat-stable DNA polymerase to add nucleotides to the
primers
T/F: Each cycle of PCR doubles the DNA content so you have 2^n copies of DNA after n rounds
- CORRECT ANSWER - True (6 cycles produces 2^6 = 64 copies)
, cloning vector - CORRECT ANSWER - provides a means for transferring a gene of
interest to a host organism during the cloning process
what are the 3 characteristics of "good" cloning vectors - CORRECT ANSWER - - origin
of replication
- a selectable marker
- unique restriction sites (MCSs or polylinkers)
what is the purpose of a selectable marker - CORRECT ANSWER - it allows scientists to
easily identify the bacteria with the plasmid that contains the gene of interest so that they can
isolate them
ex: a gene that conveys resistance to ampicillin
what are the 4 categories of cloning vectors? - CORRECT ANSWER - - plasmid (MOST
COMMON AND ONLY IN PROKARYOTES): self-replicating piece of extrachromosomal
DNA
- bacteriophage: a virus that infects bacteria
- cosmid: a hybrid between a plasmid and a phage
- artificial chromosome: synthetic chromosomes that contain fragments of DNA integrated into a
host chromosomes, BACs and YACs, YACs can carry larger fragments
genomic library - CORRECT ANSWER - a collection of an organism's entire genomic
DNA, which is stored in a population of identical vectors, each of which has a fragment of the
DNA
and CORRECT Answers
biotechnology - CORRECT ANSWER - the use of living organisms to create products that
are useful to humans
genetic engineering - CORRECT ANSWER - the deliberate modification of an organism's
genome sequence
Recombinant DNA technology - CORRECT ANSWER - set of procedures used to
combine genetic material from multiple sources and create DNA sequences that are otherwise
not found in biological organisms
Cloning - CORRECT ANSWER - generation of a larger number of identical DNA
molecules from a single DNA molecule
What are the five steps of gene cloning - CORRECT ANSWER - 1. isolate DNA to be
cloned
2. use restriction enzymes to "chop up" the DNA into fragments
3. insert the fragments into a cloning vector (i.e., bacterial plasmid), creating recombinant DNA
4. culture the host cell, growing many identical copies
Restriction enzymes - CORRECT ANSWER - - a type of endonuclease that cut DNA at
specific sites
- they recognize restriction/recognition sequences and cut DNA within those sites
,Restriction enzymes cut target DNA in which way - CORRECT ANSWER - staggered
cuts that produce sticky ends
what enzyme forms covalent bonds between the cloned gene and the plasmid, creating
recombinant DNA - CORRECT ANSWER - DNA ligase
What do reverse transcriptases produce? - CORRECT ANSWER - complementary DNA
(cDNA)
double stranded DNA is created from a single-stranded RNA
what are the 4 steps to construct cDNA? - CORRECT ANSWER - 1. apply a short poly-T
primer to a single-stranded RNA template
2. add reverse transcriptase and the 4 nucleotides to produce the DNA-RNA hybrid
3. add RNaseH enzyme to cut the RNA and regenerate the RNA primers
4. add DNA polymerase and DNA ligase to synthesize a new strand.
gel electrophoresis - CORRECT ANSWER - separates DNA/RNA and proteins based on
their size and electrical charge
it is important because it determines which fragments are larger than others and tells us the
approximate size for each fragment
DNA and RNA are (negatively/positively) charged due to their ____________ so they travel
through the gel towards the (negative/positive) electrode - CORRECT ANSWER -
negatively, phosphate backbones, positive
The (longer/shorter) and (heavier/lighter) DNA travels a shorter distance towards the positive
electrode - CORRECT ANSWER - longer and heavier
,What is the name of the dye that stains the DNA in gel electrophoresis - CORRECT
ANSWER - ethidium bromide
what is PCR? - CORRECT ANSWER - a technique for quickly and easily making many
copies of even a very small amount of DNA
What things does PCR require? - CORRECT ANSWER - -DNA of interest
-primers
- thermostable DNA polymerase
-d(A/C/G/T)TP to grow the DNA strand during replication
what is the most likely source of Taq polymerase and why are thermostable polymerases needed
for PCR? - CORRECT ANSWER - thermophilic bacterium found in hydrothermal vents,
because PCR increases the temperature of the mixture a lot
T/F: In PCR, hydrogen bonds of double-stranded DNA molecules are broken by subjecting the
DNA to high levels of radiation. - CORRECT ANSWER - False, under high levels of
HEAT
what is a thermocycler? - CORRECT ANSWER - an instrument that cyclically increases
and decreases the temperature of the solution
What are the steps of PCR with temperature included - CORRECT ANSWER - 1.
denaturation: heat to 90 C to separate DNA strands
2. annealing: cool to 50 C to allow the primers to hydrogen-bond to their complementary
sequence
3. elongation: heat to 70 C to allow the heat-stable DNA polymerase to add nucleotides to the
primers
T/F: Each cycle of PCR doubles the DNA content so you have 2^n copies of DNA after n rounds
- CORRECT ANSWER - True (6 cycles produces 2^6 = 64 copies)
, cloning vector - CORRECT ANSWER - provides a means for transferring a gene of
interest to a host organism during the cloning process
what are the 3 characteristics of "good" cloning vectors - CORRECT ANSWER - - origin
of replication
- a selectable marker
- unique restriction sites (MCSs or polylinkers)
what is the purpose of a selectable marker - CORRECT ANSWER - it allows scientists to
easily identify the bacteria with the plasmid that contains the gene of interest so that they can
isolate them
ex: a gene that conveys resistance to ampicillin
what are the 4 categories of cloning vectors? - CORRECT ANSWER - - plasmid (MOST
COMMON AND ONLY IN PROKARYOTES): self-replicating piece of extrachromosomal
DNA
- bacteriophage: a virus that infects bacteria
- cosmid: a hybrid between a plasmid and a phage
- artificial chromosome: synthetic chromosomes that contain fragments of DNA integrated into a
host chromosomes, BACs and YACs, YACs can carry larger fragments
genomic library - CORRECT ANSWER - a collection of an organism's entire genomic
DNA, which is stored in a population of identical vectors, each of which has a fragment of the
DNA
