This set of Genetic Engineering Multiple Choice Questions & Answers (MCQs) focuses on “YAC and Expression Systems”.
1. When YAC is used to clone DNA. What is the size of the DNA that can be cloned?
a) Large (upto megabases)
b) Small (upto few hundred bases)
c) No size restriction
d) Medium (upto kilobases)
View Answer
Explanation: YACs are sophisticated cloning vectors that are used for propagating large stretches of DNA which are upto a few megabases.
2. TEL is the ______ sequence derived from the ends of ribosomal RNA-encoding molecules from the macromolecules of the protozoan Tetrahyena.
a) centromeric
b) telomeric
c) can be either centromeric or telomeric
d) can be present anywhere on the chromosome
View Answer
Explanation: TEL is the telomeric sequence derived from the ends of ribosomal RNA-encoding molecules from the macromolecules of the protozoan Tetrahyena. It is a part of YAC.
3. Choose the incorrect statement for YAC vectors.
a) The YAC molecule is approximately 10 kb in size
b) It contains both yeast origin of replication and prokaryotic origin of replication
c) It doesn’t contain ampicillin resistant gene
d) It contains TEL sequence
View Answer
Explanation: YAC vectors are approximately 10kb in size. It contains both yeast origin of replication and prokaryotic origin of replication. It also contains TEL sequence and an ampicillin resistant gene.
4. If YAC DNA is digested with BamHI and ECoRI, how many fragments are generated?
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: If YAC DNA is digested with BamHI and ECoRI, three fragments are generated. Two fragments are having TEL sequence and one is lacking this sequence.
5. Transformed cells in the case of YAC can be selected by the presence of both URA3 and TRP1 genes.
a) True
b) False
View Answer
Explanation: Transformed cells in the case of YAC can be selected by the presence of both URA3 and TRP1 genes. The presence of both these indicates that both the arms of YAC are acquired.
6. GAL1 is a controllable promoter and is obtained from genes for galactose metabolism. It is known for encoding ______
a) UDP-galactose-4-empirase
b) Galactokinase
c) Both UDP-galactose-4-empirase and galactokinase
d) Glucokinase
View Answer
Explanation: GAL1 is a controllable promoter and is obtained from genes for galactose metabolism. It encodes for galactokinase and GAL10 encodes for UDP-galactose-4-empirase.
7. Transcription of GAL1 and GAL10 is suppressed in the presence of _______
a) glucose
b) galactose
c) maltose
d) fructose
View Answer
Explanation: Transcription of GAL1 and GAL10 is suppressed in the presence of glucose and elevated in the presence of galactose.
8. How many deletion variations of GAL1 promoter are there?
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: In GAL1 promoter, there are 2 deletion variations present. These deletion variations are known as GALL and GALS.
9. Promoters such as GAL1 can be used to direct synthesis of either unmodified or fusion proteins.
a) True
b) False
View Answer
Explanation: Promoters such as GAL1 can be used to direct synthesis of either unmodified or fusion proteins. The fusion proteins can incorporate products of GAL1 or other sequences such as lacZ.
10. Which of the following are advantageous to be used for expression of eukaryotic cells?
a) Prokaryotic systems
b) Yeast cells
c) Fungi cells
d) Algae cells
View Answer
Explanation: It is advantageous to use yeast cells for expression of eukaryotic cells in place of prokaryotic cells. It is so because in yeast cells post-translational modifications can be done but these modifications are not possible in prokaryotic cells.
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