EXAM 4: QUIZ METHODS: GENES

Question 1

True or false: Restriction nucleases recognize specific sequences on single-stranded DNA.

Answer 1

f

Question 2

A nuclease hydrolyzes the 22 bonds in a nucleic acid.

Answer 2

phosphodiester

Question 3

True or false: The sizes of the fragments left after a restriction digest do not depend on the total size of the genome; they depend on the sequence of the genome and the frequency with which the restriction enzyme recognition site is found in the genome.

Answer 3

t

Question 4

You have an oligonucleotide probe that hybridizes to part of gene A from a eucaryotic cell. Indicate whether a cDNA library (a) or a genomic DNA library (b) will be more appropriate for use in the following applications. You discover that gene A is alternatively spliced and you want to see which predicted alternative splice products the cell actually produces.

Answer 4

cDNA

Question 5

Which of the following limits the use of PCR to detect and isolate genes?

Answer 5

The sequence at the beginning and end of the DNA to be amplified must be known.

Question 6

The technique of 56 hybridization can be used to detect a specific RNA expression in a particular region of the brain.

Answer 6

in situ

Question 7

True or false: During Southern blotting, double-stranded DNA is loaded onto the agarose gel. The DNA becomes denatured (and thus single stranded) as it gets transferred by the alkali solution from the gel to the nitrocellulose or nylon sheet.

Answer 7

t

Question 8

True or false: A labeled DNA probe binds to the DNA by hybridization.

Answer 8

t

Question 9

A piece of DNA used to detect a specific sequence in a nucleic acid by hybridization is known as a(n) __.

Answer 9

probe

Question 10

In situ hybridization can be used to determine the _________________.

Answer 10

distribution of a given type of mRNA in different tissues

Question 11

Millions of copies of a DNA sequence can be made entirely in vitro by the 26 technique.

Answer 11

Gel electrophoresis

Question 12

Northern blotting detects a specific sequence in 57.

Answer 12

RNA

Question 13

True or false: Some restriction nucleases cut in a staggered fashion, leaving short single-stranded regions of DNA at the ends of the cut molecule.

Answer 13

t

Question 14

True or false: A reproducible set of DNA fragments will be produced every time a restriction nuclease digests a known piece of DNA.

Answer 14

t

Question 15

You have an oligonucleotide probe that hybridizes to part of gene A from a eucaryotic cell.Indicate whether a cDNA library (a) or a genomic DNA library (b) will be more appropriate for use in the following applications. Gene A encodes a tRNA and you wish to isolate a piece of DNA containing the full-length sequence of the tRNA

Answer 15

Genomic DNA

Question 16

true or false: PCR is particularly powerful because after each cycle of replication, there is a linear increase in the amount of DNA available.

Answer 16

f

Question 17

During gel electrophoresis, DNA fragments _______________________.

Answer 17

travel through a matrix containing a microscopic network of pores

Question 18

A DNA library has been constructed by purifying chromosomal DNA from mice, cutting the DNA with the restriction enzyme NotI, and inserting the fragments into the NotI site of a plasmid vector. What information cannot be retrieved from this library?

Answer 18

sequences of the telomeres

Question 19

You have an oligonucleotide probe that hybridizes to part of gene A from a eucaryotic cell.Indicate whether a cDNA library (a) or a genomic DNA library (b) will be more appropriate for use in the following applications. You want to study the promoter of a gene A.

Answer 19

Genomic DNA

Question 20

true or false You want to design a DNA probe used for hybridization to isolate a clone from a cDNA library.: The shorter the DNA probe used to probe the library, the greater the number of colonies to which the probe will hybridize.

Answer 20

t

Question 21

True or false: A RE that has a 4-base-pair recognition sequence cuts on average once every 44 or 256 base pairs; one that has a 6-base-pair recognition sequence cuts once every 46 or 4096 base pairs; one that has an 8-base-pair recognition sequence cuts once every 48 or 65,536 base pairs; one that has a 12- base-pair recognition sequence cuts once every 412 or 16 million base pairs. To obtain fragments of about 70 kb in size, you would cut with a nuclease that recognizes an 8-base-pair site.

Answer 21

false

Question 22

Southern blotting detects a specific sequence in 58.

Answer 22

DNA

Question 23

Why are dideoxyribonucleoside triphosphates used during DNA sequencing?

Answer 23

incorporation of a didoxyribonucleoside triphosphate leads to the termination of replication for that strand.

Question 24

You have a piece of circular DNA that can be cut by the restriction nucleases XhoI and SmaI, only one time each. If you were to cut this circular piece of DNA with both XhoI and SmaI, how many fragments of DNA would you end up with?

Answer 24

2

Question 25

You have an oligonucleotide probe that hybridizes to part of gene A from a eucaryotic cell. Indicate whether a cDNA library (a) or a genomic DNA library (b) will be more appropriate for use in the following applications. You want to find both gene A and the genes located near gene A on the chromosome.

Answer 25

Genomic DNA

Question 26

Nucleases that cut DNA only at Specific short sequences are known as _23_.

Answer 26

restriction nucleases

Question 27

You are interested in a single-stranded DNA molecule that contains the following sequence: 5?- GATTGCAT -3? Which molecule can be used as a probe that will hybridize to your sequence of interest?

Answer 27

5?-ATGCAATC-3?

Question 28

You have been hired to create a cat that will not cause allergic reactions in cat-lovers. Your co-workers have cloned the gene encoding a protein found in cat saliva, expressed the protein in bacteria, and shown that it causes violent allergic reactions in people. But you soon realize that even if you succeed in making a knockout cat lacking this gene, anyone who buys one will easily be able to make more hypoallergenic cats just by breeding them. Which of the following will ensure that people will always have to buy their hypoallergenic cats from you?

Answer 28

surgically remove the sexual organs of all the knockouts before you sell them.Neutering all the knockout animals that you sell is the only option of the four listed that will prevent happy pet owners from becoming happy pet breeders. The situation described in choice

Question 29

Restriction enzymes that cut DNA straight across the double helix produce fragments of DNA with _28_.

Answer 29

blunt ends

Question 30

You have purified DNA from your recently deceased goldfish. Which of the following restriction nucleases would you use if you wanted to end up with DNA fragments with an average size of 70 kilobase pairs (kb) after complete digestion of the DNA? The recognition sequence for each enzyme is indicated.

Answer 30

NotI-GCGGCCGC

Question 31

A double-stranded DNA molecule can be separated into single strands by heating it to 90°C because _______________________.

Answer 31

heat disrupts hydrogen bonding between complementary nucleotides

Question 32

True or false: if a fragment the size of an entire genome were inserted into a bacterial vector, you would have to screen only one colony to find a clone that hybridized to your probe, but it would be very difficult to find out where on the insert your gene of interest lay.

Answer 32

t

Question 33

A fragment of DNA is inserted into a _29_ in order to be cloned in bacteria.

Answer 33

vector

Question 34

A short, single-stranded DNA is a(n) __.

Answer 34

oligonucleotide

Question 35

A _30_ library contains a collection of DNA clones derived from mRNAs.

Answer 35

cDNA

Question 36

Which of the following describes a feature found in bacterial expression vectors but not in cloning vectors?

Answer 36

promoter DNA sequences

Question 37

You have an oligonucleotide probe that hybridizes to part of gene A from a eucaryotic cell. Indicate whether a cDNA library (a) or a genomic DNA library (b) will be more appropriate for use in the following applications. You want to express gene A in bacteria to produce lots of protein A.

Answer 37

cDNA

Question 38

True or false: The DNA that is separated on a gel is not labeled.

Answer 38

t

Question 39

True or false: In this technique, single-stranded DNA is separated by electrophoresis.

Answer 39

f

Question 40

True or false: The smaller the gene you are seeking, the more likely it is that the gene will be found on a single clone.

Answer 40

t

Question 41

Two fragments of DNA can be joined together by _27_.

Answer 41

DNA ligase

Question 42

Match the features of a cloning vector in bacteria must contain with the right reason: a bacterial replication origin.

Answer 42

to allow the plasmid to be replicated

Question 43

A _31_ library contains a collection of DNA clones derived from chromosomal DNA.

Answer 43

genomic

Question 44

DNA can be introduced into bacteria by a mechanism called ____________.

Answer 44

transformation

Question 45

Why is a heat-stable DNA polymerase from a thermophilic bacterium (the Taq polymerase) used in the polymerase chain reaction PCR rather than a DNA polymerase from E. coli or humans? PCR involves heating the reaction at the beginning of each cycle to separate the newly synthesized ds DNA into single strands so that they can act as templates for the next round.

Answer 45

Using Taq avoids having to add it afresh for each round of DNA replication.

Question 46

True or false: The larger the genome of the organism from which a library is derived, the larger the fragments inserted into the vector will tend to be.

Answer 46

f

Question 47

__ can be used to separate DNA fragments of different sizes.

Answer 47

Gel electrophoresis

Question 48

True or false: This technique involves the transfer of DNA molecules from gel onto nitrocellulose paper or nylon paper.

Answer 48

t

Question 49

Match the features of a cloning vector in bacteria must contain with the right reason: an antibiotic-resistance gene.

Answer 49

selectable marker gene to allow selection for bacteria that have taken up the recombinant plasmids

Question 50

True or false: The larger the size of the fragments used to make the library, the fewer colonies you will have to examine to find a clone that hybridizes to your probe.

Answer 50

t

Question 51

True or false: The larger the size of the fragments used to make the library, the more difficult it will be to find your gene of interest once you have identified a clone that hybridizes to your probe.

Answer 51

t

Question 52

True or false: the larger the gene you are cloning, the more likely it is that there will be a restriction fragment in the gene, and hence the less likely it is that the entire gene will be found in a clone.

Answer 52

t

Question 53

Match the features of a cloning vector in bacteria must contain with the right reason: at least one unique restriction site.

Answer 53

to allow easy insertion of foreign DNA

Question 54

DNA composed of sequences from different sources is known as _24_.

Answer 54

recombinant DNA

Question 55

True or false: Some bacteria use restriction nucleases as protection from foreign DNA.

Answer 55

t