©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
MCB 2050 Midterm Exam Questions and
Answers 100% Solved
1) What are restriction endonucleases?
2) What do they do (or cut) specificically?
3) What happens to the ends of DNA cut by restriction enzymes? - ✔✔1)
enzymes that cut at specific sequences (restriction sites) within DNA
molecules
2) they break phosphodiester bonds that link nucleotides together
3) have single-stranded overhangs; ends are cohesive (complementary,
sticky)- they can reanneal
1) Who discovered restriction enzymes?
2) What do restriction enzymes do for bacteria and how?
3) How is the bacterial genome protected from restriction enzyme
degradation? What is this catalyzed by? - ✔✔1) Smith and Nathans
2) protect genetic material of bacteria from invasion by foreign DNA
(viruses) by restricting their intrusion
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
3) by methylation of nucleotides within the sequence recognized by the
restriction enzymes; specific methylases after DNA replication
1) How are restriction endonucleases named? Give an example.
2) What do restriction enzymes generally recognize? What do they create
as a result?
3) What is a palindrome? Give an example. - ✔✔1) According to the
bacterial strain in which it was originally identified; EcoR1: E.coli strain
RY13 restriction enzyme number 1.
2) palindromic sequences; either staggered (aka cohesive, sticky) or blunt
ends
3) a sequence that reads the same in either direction; the DNA is identical
but inverted in a complementary strand
What kind of ends do the following produce:
Sma1
Kpn1
BamH1 - ✔✔blunt
3'overhang
5'overhang
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
How does DNA ligase create a recombinant DNA molecule? - ✔✔DNA
ligase joins(ligates) the complementary single stranded ends produced by
restriction enzyme cleavage
What is the generic name of enzymes that recognize palindromic
sequences in dsDNA and cleave the DNA at that location? -
✔✔restriction endonucleases
The kind of ends following restriction endonuclease digestion that results in
single stranded DNA overhangs are called: - ✔✔cohesive (or sticky)
ends
1) What are cloning vectors used for?
2) Give five elements of cloning vectors
3) What are the three essential components of plasmid vectors? - ✔✔1)
isolation and amplification of DNA sequences
2) -mostly originated from bacteria (some from yeast)
-double-stranded circular DNA
-extra-chromosomal
-replicate independent of cell DNA (plasmids can be multi-copy: ie >1
plasmid/cell)
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
-small, up to about 10kb (for easy manipulation; maximum insert size
usually approx 15kilobase pairs)
3) -an origin of DNA replication (for amplification in bacterial cells)
-a selectable marker: antibiotic resistance gene
-at least one unique RE cleavage site outside of the origin and resistance
gene (many have multiple cloning sites, MCS)
What are the characteristics of the pBluescript cloning vector? - ✔✔-
bacterial origin of replication (to allow plasmid replication)
-multiple cloning site (MCS) to allow insertion of foreign DNA
-antibiotic resistance gene for selection of bacteria transformed with the
plasmid
-selectable marker (lacZ) to differentiate cells with plasmids containing
inserted foreign DNA from those without (blue/white screening)
-lac promoter to express mRNA (small (3kb) to allow for large insertions)
-all RE sites in the MCS are unique sites in the plasmid
1) What does the bluescript plasmid express?
2) Where is the MCS located?
3) What does insertion of foreign DNA into the MCS do? What is this
called? - ✔✔1) the E.coli lacZ gene (encodes beta-galactosidase)
MCB 2050 Midterm Exam Questions and
Answers 100% Solved
1) What are restriction endonucleases?
2) What do they do (or cut) specificically?
3) What happens to the ends of DNA cut by restriction enzymes? - ✔✔1)
enzymes that cut at specific sequences (restriction sites) within DNA
molecules
2) they break phosphodiester bonds that link nucleotides together
3) have single-stranded overhangs; ends are cohesive (complementary,
sticky)- they can reanneal
1) Who discovered restriction enzymes?
2) What do restriction enzymes do for bacteria and how?
3) How is the bacterial genome protected from restriction enzyme
degradation? What is this catalyzed by? - ✔✔1) Smith and Nathans
2) protect genetic material of bacteria from invasion by foreign DNA
(viruses) by restricting their intrusion
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
3) by methylation of nucleotides within the sequence recognized by the
restriction enzymes; specific methylases after DNA replication
1) How are restriction endonucleases named? Give an example.
2) What do restriction enzymes generally recognize? What do they create
as a result?
3) What is a palindrome? Give an example. - ✔✔1) According to the
bacterial strain in which it was originally identified; EcoR1: E.coli strain
RY13 restriction enzyme number 1.
2) palindromic sequences; either staggered (aka cohesive, sticky) or blunt
ends
3) a sequence that reads the same in either direction; the DNA is identical
but inverted in a complementary strand
What kind of ends do the following produce:
Sma1
Kpn1
BamH1 - ✔✔blunt
3'overhang
5'overhang
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
How does DNA ligase create a recombinant DNA molecule? - ✔✔DNA
ligase joins(ligates) the complementary single stranded ends produced by
restriction enzyme cleavage
What is the generic name of enzymes that recognize palindromic
sequences in dsDNA and cleave the DNA at that location? -
✔✔restriction endonucleases
The kind of ends following restriction endonuclease digestion that results in
single stranded DNA overhangs are called: - ✔✔cohesive (or sticky)
ends
1) What are cloning vectors used for?
2) Give five elements of cloning vectors
3) What are the three essential components of plasmid vectors? - ✔✔1)
isolation and amplification of DNA sequences
2) -mostly originated from bacteria (some from yeast)
-double-stranded circular DNA
-extra-chromosomal
-replicate independent of cell DNA (plasmids can be multi-copy: ie >1
plasmid/cell)
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
-small, up to about 10kb (for easy manipulation; maximum insert size
usually approx 15kilobase pairs)
3) -an origin of DNA replication (for amplification in bacterial cells)
-a selectable marker: antibiotic resistance gene
-at least one unique RE cleavage site outside of the origin and resistance
gene (many have multiple cloning sites, MCS)
What are the characteristics of the pBluescript cloning vector? - ✔✔-
bacterial origin of replication (to allow plasmid replication)
-multiple cloning site (MCS) to allow insertion of foreign DNA
-antibiotic resistance gene for selection of bacteria transformed with the
plasmid
-selectable marker (lacZ) to differentiate cells with plasmids containing
inserted foreign DNA from those without (blue/white screening)
-lac promoter to express mRNA (small (3kb) to allow for large insertions)
-all RE sites in the MCS are unique sites in the plasmid
1) What does the bluescript plasmid express?
2) Where is the MCS located?
3) What does insertion of foreign DNA into the MCS do? What is this
called? - ✔✔1) the E.coli lacZ gene (encodes beta-galactosidase)
