Restriction Endonuclease

Question 1

Restriction endonucleases cut DNA molecules–
Internally and externally
Externally
Internally
At the 5’ end

Answer 1

Internally ✓

Question 2

Type I and Type II restriction enzymes (Res) differ in that -
Type I enzymes but 1000 base pairs away from the sequence they recognise
whereas type II cut within the recognition sequence
Type I produce blunt ends and Type II produce staggered ends
Type I enzymes cut only modified DNA but type II can cut any DNA
Prokaryotes have Type I and eukaryotes have Type II

Answer 2

Type I enzymes cut 1000 base pairs away from the sequence they recognise
whereas type II cut within the recognition sequence ✓

Question 3

The fourth restriction endonucleases isolated from the bacterium Nonamarea recticatens is
called
NreIV
Nre4
Nor4
NorIV

Answer 3

NreIV ✓

Question 4

According to standard naming for restriction enzymes, an enzyme from Grampositivobacter
skinius strain X would be called—
GskX I
Grp SK
Gsk Type I
GskK X

Answer 4

GskX I ✓

Question 5

Type II restriction enzymes are useful biotechnology tools for all of the following reasons
EXCEPT-
They can cut one of the two strands of the double helix
They recognise specific DNA sequences
They can cut both strands of DNA to produce sticky ends
They can cut both strands of DNA to produce blunt ends

Answer 5

They can cut one of the two strands of the double helix ✓

Question 6

All restriction endonucleases recognise palindromic sequences – there are none that
recognise non-palindromic sequences
True
False

Answer 6

False ✓

Question 7

Type II restriction enzymes are considered of little value in molecular biology. Only Type I
restriction enzymes can be used as specific cutting tools
True
False

Answer 7

False ✓

Question 8

Single-stranded tails produces across double stranded DNA by a restriction endonucleases
an also be referred to as overhangs
True
False

Answer 8

True ✓

Question 9

The restriction sequence of a recognition endonuclease cannot be found on the bacterium’s
own gene
True
False

Answer 9

False ✓

Question 10

In double stranded DNA, which of the following base ratios always equals 1?
(C/T)
(A+G)/(C+T)
(A+T)/(G+C)
(G/A)

Answer 10

(A+G)/(C+T) ✓

Question 11

The fourth restriction endonucleases isolated from the bacterium Nonamarea recticatens is
called
NorIV
NreIV
Nor4
Nre4

Answer 11

NreIV ✓

Question 12

The optimal temperature for all restriction digestions…
Is 30C
Is 37C
Will vary depending upon the restriction enzyzme used
Will depend upon restriction buffer used
Is 22C

Answer 12

Will vary depending upon the restriction enzyme used ✓

Question 13

Based on their recognition sequences and their cut sited, BAMHI and BgIII are examples of…
Isoschizomers
Isocaudamers
Neoschizomers

Answer 13

Isocaudamers ✓

Question 14

What do the letters Y & R represent in this recognition sequence for the restriction
endonucleases Smll?
Proline and Pyrimidine
Tyrosine and Arginine
Pyrimidine and Purine
Tyrosine and Adenine

Answer 14

Pyrimidine and Purine ✓

Question 15

The enzyme Avall recognises the sequence GGTCC. However, it is sensitive to methylation at
its 5’ end. It will therefore not cut if methylation occurs in which one of the following
sequences
… GGGTCCA…
…AGGTCCC…
…CGGTCCT…
…TGGTCCC…

Answer 15

…CGGTCCT… ✓

Question 16

. The restriction endonucleases Mlsll recognises the sequence 5’ GCTTAAGC 3’ if human DNA
was digested with this enzyme, statistically, how often would the recognition sequence be
likely to be found?
Once per 4096 bases
Once per 74764 bases
Once per 82640 bases
Once per 238642 bases

Answer 16

Once per 74764 bases ✓

Question 17

The best practical way to incubate restriction digestion tubes is in a hot air incubator
True
False

Answer 17

false

Question 18

Under non optimal conditions, restriction enzymes can cleave sequences that are similar to
but not the recognised target site. This phenomenon is commonly referred to as what?
Multiple site cutting
External cutting
Internal cutting
Star activity

Answer 18

star activity