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Molecular Biology and plant genetic engineering
Posted Date: 24 Oct 2007 Resource Type: Articles/Knowledge Sharing Category: AdSense Revenue Sharing
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Posted By: balkis Member Level: Bronze
Rating:  Points: 5
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Molecular Biology
1. Which of the following is true of DNA double helix?
a Total number of purine bases is equal to the total number of pyrimidine bases.
b The 5’ end of one DNA strand is aligned with 5’ end of the other strand.
c The sequence of bases on one strand is identical to the sequence of bases on the other strand.
d None of the above.
2. Of the four different DNA molecules below, which one would you expect to denature at a lower temperature?
a GCATTGCCAATGC
b ATTAGCCTATCGG
c GCCACCGAATCCG
d ATATTTTACTGCC
3. Which of the following is true
a DNA polymerase recognizes ‘ori’ in parental DNA and unwinds the double helix at these sites so that DNA replication can occur.
b Helicases recognize replication fork and unwinds the double helix at replication fork so that DNA replication can occur.
c Helicases recognize origin of replication in parental DNA and unwinds the double helix at these sites so that DNA replication can occur.
d None of the above.
4. Which of the following steps are involved in the process of template preparation during DNA replication?
a Unwinding of double helix
b Breakage of hydrogen bonds
c Coating of single stranded template to prevent them from reannealing
d All the above
5 The 3’ to 5’ exonuclease activity of E. coli DNA polymerase I and III allows
a Polymerases to synthesize a new stand in 3’ to 5’ direction
b Polymerase to remove misincorporated nucleotides thereby reducing the number of errors made during DNA replication
c Polymerase to join Okazaki fragments
d None of the above
6 If the following parental DNA strand is used as a template DNA strand the newly synthesized, antiparallel strand would be as follows
3’ GGCATATTCGCTGCAGT 5’
a 3’ CCGTATAAGCGACGTCA 5’
b 5’ CCGTATAAGCGACGTCA 3’
c 5’ TGACGTCGCTTATACGG 3’
d 3’ GGCATATTCGCTGCAGT 5’
7. In E. coli, a DNA polymerase lacking 5’ to 3’ exonuclease activity would not be able to
a Synthesize the leading strand
b Remove RNA primers
c Remove misincorporated nucleotides
d All the above
8 If the DNA structure is compared with a spiral staircase, which of the following would be analogous to the steps of the staircase?
a Linked deoxyribose and phosphate group
b Purine and pyrimidiine base pairs
c Adenine – guanine base pairs
d Guanine – thymine base pairs
9 Which of the following events occurs during DNA replication in E. coli?
a Removal of Okazaki fragments by DNA polymerase III
b Discontinuous synthesis of DNA on the leading strand
c Synthesis of short RNA primers
d Unwinding of the double helix by DNA polymerase I
10 Which of the following true statements was NOT suggested by the rules formulated by Chargaff?
a The number of adenines is approximately the same as number of thymines in any molecular of DNA
b The number of guanines is approximately the same as number of cytosines in any molecular of DNA
c The number of purines is approximately the same as number of pyrimidines in any molecular of DNA
d If the sequence of one DNA stand is known, the sequence of other DNA strand can be determined.
11 At the completion of DNA replication, each newly synthesized DNA strand is
a Identical in sequence to the strand opposite which it was synthesized
b Complementary in sequence to the strand opposite which it was synthesized.
c A hybrid stand consisting both DNA and RNA strand
d Oriented in the same direction as the strand which it was synthesized/
12 The sequence of one strand of DNA is 5’-AGTCGACGA-3’. What would be the 5’ to 3’ sequence of the complementary strand?
a 5’ – TCAGCTGCT – 3’
b 5’ – TCGTCGACT – 3’
c 5’ – AGTCGACGA - 3’
d None of the above
13 Who proved that DNA replicates semi-conservatively?
a Hershey and Chase
b Meselson and Stahl
c Franklin and Wilkins
d Watson and Crick
14 Watson, Crick and Wilkins were awarded Noble prize in
a Molecular biology
b Chemistry or physics
c Physiology or medicine
d Peace
15 In Eukaryotes, the DNA replication occurs during
a S phase
b G1 phase
c G2 phase
d All phases
16 DNA ligase
a Unwinds the helical DNA by breaking the hydrogen bonds between complementary bases
b Adds DNA nucleotides to the RNA primer
c Links the DNA fragments of the lagging strand together
d Synthesizes a short RNA primer at the beginning of each origin of replication
17 The 5' end of the DNA is the one with
a the terminal phosphate group on the 5' carbon of the deoxyribose
b a terminal hydroxyl (OH) group on the deoxyribose of the 3' carbon of the deoxyribose
c a terminal hydroxyl (OH) group on the deoxyribose of the 5' carbon of the deoxyribose
d None of the above
18 _________ is one correct reason why Okazaki fragments are created during lagging strand DNA synthesis
a DNA is only polymerized in the 3' to 5' direction.
b DNA polymerase requires RNA priming
c DNA is only polymerized in the 5' to 3' direction
d DNA polymerase requires a 5' -0H on the growing polymer
19 Transcription is the process of
a Synthesizing a DNA molecule from RNA template
b Using DNA strand as a template to synthesize a complementary RNA molecule.
c Using DNA strand as template to synthesize identical RNA molecule
d Synthesizing a protein using information carried in the nucleotide sequence of a messenger RNA
20 What is the sequence of events during transcription?
I. Initiation and elongation of mRNA strand
II. Binding of an RNA polymerase to DNA
III. Separation of new strand of DNA
IV. Release of completed mRNA from the DNA
a III, II, IV, I
b II, III, I, IV
c III, I, II, IV
d II, I, III, IV
21 The direction of synthesis of a new mRNA molecule is
a 5’ to 3’ from a 5’ to 3’ DNA template strand
b 5’ to 3’ from a 3’ to 5’ RNA template strand
c 5’ to 3’ from a 5’ to 3’ RNA template strand
d 5’ to 3’ from a 3’ to 5’ DNA template strand
22 Promoters are highly conserved nucleotide sequences in
a The DNA that determines the sites where RNA synthesis is initiated
b The DNA that determines the sites where DNA synthesis is initiated
c The RNA that determines the sites where DNA synthesis is initiated
d None of the above
23 The non-coding DNA that occurs within eukaryotic gene is referred to as
a Spacer DNA
b Promoter
c terminator
d Intron DNA
24 The RNA polymerases copy
a Entire gene sequence into RNA
b Exon DNA only
c Intron DNA only
d None of the above
25 From the initial transcripts, the intron sequence is removed by
a Small nuclear ribonucleoproteins (snRNPs)
b Ligase
c Endonucleases
d None of the above
26 The intron sequence is released while the primary transcript is
a located in nucleus
b located in cyotplasm
c Located in ribosomes
d None of the above
27 In RNA capping a modified guanine nucleotide is added to the
a 3’ end of the primary transcript
b 5’ end of the primary transcript
c 5’ end of the matured transcript
d 3’ end of the matured transcript
28 The 5’ cap structure on a mRNA is used to
a locate the start site for protein synthesis on that mRNA
b locate the termination of protein synthesis on that mRNA
c locate the presence of intron sequences
d none of the above
29 In polyadenaylation, a long tail of adenine residue is added
a to the 3’ ends of template DNA
b to the 5’ end of mRNA
c to the 3’ end of mRNA
d None of the above
30 A single-stranded molecule is synthesized form a DNA template according to the complementary base paring rules. The newly synthesized single-stranded molecule is then shortened and the shortened molecule is used as a template for the synthesis of protein. The shortened molecule is most likely
a Primary RNA
b Bacterial mRNA
c Eukaryotic mRNA
d rRNA
31 Which of the following statements about introns is incorrect? Introns are
a Found in most eukaryotic genes and not translated during protein synthesis
b Removed during RNA processing
c Normally not transcribed
d Responsible for the fact that the most eukaryotic mRNAs are much shorter than the genes from which they are derived.
32 Which of the following process occur in the nucleus of eukaryotic cell?
a DNA replication
b RNA processing
c Transcription
d All the above
33 The addition of 7-methyl guanosine cap and 3’ poly (A) tail to the mRNA is done
a Before the introns are spliced
b Before the export of mRNA to cytoplasm
c After the export of mRNA to cytoplasm
d After the mRNA is attached to ribosomes
34 DNA is double stranded. One strand is called the coding strand and the other the non-coding strand. The non-coding strand is used as the template to make mRNA. The relationship between the base sequence of the coding strand and the base sequence of the mRNA (ignoring the fact that mRNA will contain uracil instead of thymine) is
a Complementary
b Identical
c None of the above
d Partially identical
35 Which of the following is not needed by the RNA polymerase
a a Primer
b GTP, CTP, UTP, ATP
c a promoter sequence
d a DNA template
36 Which one of the following statement about DNA and RNA synthesis is incorrect?
a Both DNA and RNA polymerase carry out synthesis of their respective nucleic acid in 5’ to 3’ direction only
b DNA polymerase use dNTPs to make DNA where as RNA polymerase use NTPs.
c The new DNA synthesized by DNA polymerase usually remain hydrogen bonded to the template strand, whereas the new RNA synthesized by RNA polymerase peels off the template strand.
d DNA polymerases require a single stranded DNA template, whereas RNA polymerases require a single stranded RNA template.
37 The RNA strand synthesized during transcription elongates until
a The entire chromosome has been copied into RNA
b The RNA polymerase runs into the next gene
c An intron encountered on the DNA template strand
d A specific termination sequence is reached on the DNA template strand.
38 In Eukaryotes, the transcription is mediated by
a Single RNA polymerase
b Single DNA polymerase
c Multiple DNA polymerase
d Multiple RNA polymerase
39 Which region of an intron’s nucleotide sequence is important?
a Whole intron sequence
b Short sequence near each end of the intron
c A 25 base repeat in the middle of intron sequence
d None of the above
40 In prokaryotes, the matured mRNA is
a Identifcal to the initial mRNA
b Shorter than the initial mRNA
c Longer than the initial mRNA
d None of the above
41 What further modification needs to occur to make a pre-mRNA or initial mRNA ready for export into the cytoplasm?
a 5’ end of mRNA must have a cap structure (7-methyl guanosine cap) attached to it.
b 3’ end of the mRNA should have a poly (A) tail.
c RNA splicing
d All the above
42 The genetic code is said to be degenerate because
a More than one triplet of nucleotides can code for a single amino acid
b the same triplet of nucleotides can code for different amino acids
c There are more different amino acids than there are different codons.
d Once mRNA is translated, it is degraded.
43 A protein composed of 300 amino acids would be encoded by an mRNA of
a 300 nucleotides
b 100 nucleotides
c 600 nucleotides
d 900 nucleotides
44 The ________in a tRNA molecule base pair with a group of three nucleotides called the _________in the mRNA template molecule.
a Codon; anticodon
b Anticodon; codon
c Codon; triplet codon
d Triplet codon; anticodon
45 Which of the following statement about the ribosome complex is correct?
a Small subunit binds an mRNA and large subunit joint with the mRNA/small subunit complex to form a complete ribosome
b The large ribosomal subunit has a P site (peptidyl site) that holds the growing polypeptide chain and an A site (aminoacyl site) that binds the next amino acid to be added to the growing polypeptide chain.
c The addition of new amino acid in the A site to the growing polypeptide chain is catalyzed by one of the enzymes that form the large ribosomal subunit.
d All the above
46 In tRNA , __________ the site of attachment to the mRNA
a Middle loop located at the bottom
b 3’ end of the tRNA
c 5’ end of the tRNA
d None of the above
47 The ability of the tRNA molecules to form non-Watson-Crick base pair with the third base of the mRNA codon is referred to as
a Wobble
b degenerate
c Charged
d None of the above
48 Anticodon is a part of the tRNA molecule that is responsible for specific attachment to the
a mRNA
b Amino acid
c Ribosomal complex
d rRNA
49 Complementary base paring between the anticodon and codon ensures that the
a Correct amino acid is aligned on the mRNA template
b Small and large subunit of ribosome forms a complex
c Peptide bonds are formed
d All the above
50 Aminoacyl-tRNA synthetase enzyme catalyzes
a Attachment of anticodon to a corresponding codon in mRNA
b Attachment of amino acid to a specific tRNA
c Formation of peptide bond
d All the above
51 In most bacterial mRNAs, the initiator codon is preceded by a special sequence called
a Ribosome binding site
b 5’-Methylguanosine cap
c Poly A tail
d a and b
52 A mRNA that give rise to multiple different proteins is said to be a
a Monocistronic
b Polycistronic
c Shine-Dalgarno sequence
d None of the above
53 In Eukaryotes, to locate the initiator codon, the small ribosomal subunit has to first locate
a The 5’-methyl guanosine cap
b Ribosome binding site
c Shine-Dalgarno sequence
d All the above
Plant Genetic Engineering
1 Which of the following statement about plasmids is incorrect?
a Plasmids are replicons that are stably inherited in an extra-chromosomal state
b Plasmids possess an origin of replication so that they are able to multiply with in the cell independent of bacterial chromosome
c Plasmids carry one or more genes.
d If both strands of plasmid are intact then the molecules are described as open circular
2 In lambda DNA, the cohesive ends are referred as
a Gene A
b Cos sites
c prophage
d None of the above
3 Phage M13 DNA is
a Single stranded circular
b Single stranded linear
c Double stranded circular
d Double stranded linear
4 The enzyme that removes phosphate group present at 5’ terminus of DNA molecule is
a Polynucleotide kinase
b Terminal deoxy nucleotidyl transferase
c Alkaline phosphatase
d Klenow fragment
5 Cloning genes in pUC18 involves
a Insertional inactivation of tetracycline resistance gene
b Insertional inactivation of ampicillin resistance gene
c Insertional inactivation of LacZ’ gene
d Insertional inactivation of ?cI gene
6 Lambda phage DNA is introduced into host cells efficiently by a process called
a Transformation
b Transfection
c In vitro packaging
d All the above
7 At the end of ligation reaction with a vector and DNA fragment, the ligation product will consists of
a Self ligated vector
b Recombinant vector with right molecule
c Recombinant vector with wrong insert
d All the above
8 An example for a phagemid is
a pBluescript II series of vectors
b pUC series of vectors
c EMBL8
d Lambda gt10
9 The vector that can clone about 300 kbp DNA fragment in E. coli are
a BAC
b YAC
c PACMID
d cosmid
10 In the construction of cDNA library, the first strand cDNA is imitated using
a Oligo (dT) primer
b Random hexamer
c Oligo(dT) + random hexamer
d All the above
11 Subtractive library is
a A collection of cDNA clones representing mRNA that are expressed in only one of two or more cell types
b A collection of cDNA clones representing mRNA that are expressed in all cell types
c A collection of cDNA clones representing mRNA that are not expressed in all cell types
d None of the above
12 An example for Direct DNA transfer method for plants is
a Agrobaceterium rhizogenes-mediated delivery
b Particle bombardment mediated transformation
c Vectors based on plant viruses
d None of the above
13 The most widely used promoter to express foreign genes in a dicotyledonous plants is
a Tubulin
b CaMV35S
c Actin
d Maize ubiquitin promoter
14 RT-PCR means
a Reverse transcriptase polymerase chain reaction
b Rightward template polymerase chain reaction
c Rotating tube polymerase chain reaction
d None of the above
15 What is the difference between a PAC and a BAC?
a One is a plasmid-based vector and the other is derived from a yeast chromosome
b One is derived from bacteriophage P1 and the other is derived from bacteriophage B1
c One is derived from bacteriophage P1 and the other is derived from the E. coli F-plasmid
d One is based on M13 and the other is based on lambda DNA
16 In higher eukaryotes, which of the following are differences between genomic and cDNA clones?
a Only genomic DNA contains genes
b Only genomic DNA contains introns
c Only cDNA contains a coding region
d None of the above
17 Which of the following library screening strategies does NOT depend on expression?
a Screening using degenerate oligonucleotide primers
b Screening using an antibody
c Functional screening
d All the above
18 T-DNA is
a DNA of plasmid origin which is transferred to the Agrobacterium chromosome
b DNA from the chromosome of Agrobacterium species which is transferred to the plant genome
c DNA of plasmid origin which is transferred to the plant genome
d None of the above
19 One of the following promoter is not derived from Agrobacterium
a tubulin
b Nos
c Ocs
d mas
20 The first commercially released GM crop in India is
a Cotton expressing cryIAb gene
b Brinjal expressing cry1Ab gene
c Corn expressing cryIAb gene
d Cotton expressing cryIAc gene
Short answer
1. Briefly describe the particle bombardment mediated transformation? How particle bombardment mediated transformation is advantageous over other method of transformation?
2. What is the role of different vir genes in T-DNA transfer into plant cells? How Agrobacterium-mediated transformation is advantageous over other method of transfer?
3. Describe the different approaches and methods to obtain marker free transgenic plants?
4. What is the role of promoter and terminator elements in gene expression cassette? Give an example for constitutive promoter, seed specific promoter, fruit specific promoter, anther specific promoter and tuber specific promoter
5. Why the expression of prokaryotic gene expression is low in plants? How will you increase the expression of native bt gene in plant?
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