2020 - WordPress.com · 2020. 5. 2. · Replication fork is the junction between the two _____ a)...

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UNIT 1

MULTIPLE CHOICE QUESTIONS:

1. Which of the following types of DNA polymerase has 3’→5’ exonuclease

activity?

a) DNA polymerase I

b) DNA polymerase II

c) DNA polymerase III

d) DNA polymerase IV

2. Which of the following is used in prokaryotic replication?

a) DNA polymerase I



d) DNA polymerase δ

3. Replication fork is the junction between the two ___________

a) Unreplicated DNA

b) Newly synthesized DNA

c) Newly separated DNA strands and newly synthesized DNA strands

d) Newly separated DNA strands and the unreplicated DNA

4. Who was the first person to analyze the process of replication and on which

organism?

a) Arthur Kornberg: E. coli

b) John Cairns: E. coli

c) Arthur Kornberg: Bacillus subtilis

d) John Cairns: Bacillus subtilis

5. Primer synthesis short stretches of DNA for replication.

a) True

DNA and RNA, Chemical Structure, Types and Properties, Experimental Proof of DNA as genetic material,

Genome-- Concept. Plant, Animal. Bacterial and Viral Genome, DNA Replication. Types, Experimental

proof of semi conservative replication. Replicon- Concept, proteins and enzymes involved in replication

in prokaryotes and eukaryotes, Modes of DNA replication. Unidirectional, Bidirectional, Types of DNA

replication, Y shaped, θ mode, rolling circle mechanism.

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b) False

6. Eukaryotes differ from prokaryote in mechanism of DNA replication due to

a) Use of DNA primer rather than RNA primer

b) Different enzyme for synthesis of lagging and leading strand

c) Discontinuous rather than semi-discontinuous replication

d) Unidirectional rather than semi-discontinuous replication

7. The reaction in DNA replication catalyzed by DNA ligase is

a) Addition of new nucleotides to the leading strand

b) Addition of new nucleotide to the lagging strand

c) Formation of a phosphodiester bond between the 3’-OH of one Okazaki

fragment and the 5’-phosphate of the next on the lagging strand

d) Base pairing of the template and the newly formed DNA strand

8. Which of the following enzymes is the principal replication enzyme in E. coli?

a) DNA polymerase I



d) None of these

9. Which of the following enzymes remove supercoiling in replicating DNA

ahead of the replication fork?

a) DNA polymerases

b) Helicases

c) Primases

d) Topoisomerases

10. Eukaryotes differ from prokaryote in mechanism of DNA replication due to

a) Use of DNA primer rather than RNA primer

b) Different enzyme for synthesis of lagging and leading strand

c) Discontinuous rather than semi-discontinuous replication

d) Unidirectional rather than semi-discontinuous replication

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SHORT ANSWER TYPE QUESTION:

1. Write a note on semi conservative mode of DNA replication?

2. Write a note on Meselson and Stahl experiment?

3. Write a note DNA polymerase?

4. Write a note Cairns model of replication?

5. Write a note Okazaki fragment?

6. Write a note on Animal Genome?

7. Write a note on Replication bubble?

8. Write a note on Rolling Circle mechanism of replication?

9. Write a note on theta model of replication?

10. Replication of DNA follows semi conservative mode. Write the experimental

LONG ANSWER TYPE QUESTION:

1. Explain the DNA replication in eukaryotes?

2. Explain the DNA replication in prokaryotes?

3. Write a long note on the chromosomal replication model?

4. Write a long note on enzymes used in the DNA replication?

5. Draw a neat diagram of general model of replication.

6. Write experimental proofs of DNA as a genetic material?

7. How a plant genome is different from an animal genome. Explain in detail?

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ANSWERS TO MCQS

1. ANSWER: A

Explanation: DNA polymerases I, II, III and IV all has 5’→3’ exonuclease activity.

DNA polymerases I is the only polymerase to have the 3’→5’ exonuclease

activity which is the proof reading activity of DNA polymerase.

2. ANSWER: C

Explanation: Prokaryotic replication is polymerized by the enzyme DNA

polymerase III. DNA polymerase I, DNA polymerase II and DNA polymerase δ

all take part in the eukaryotic replication.

3. ANSWER: D

Explanation: As both the strands of DNA occur simultaneously the two

template strands undergo separation. The junction between the newly

separated DNA strands and the unreplicated DNA is known as the replication

fork.

4. ANSWER: B

Explanation: The person who first analyzed the process of replication was John

Cairns in which E. coli were grown in the presence of radioactive Thymidine.

This allowed subsequent visualization of newly replicated DNA by

autoradiography.

5. ANSWER: B

Explanation: Primer synthesizes short stretches of RNA for replication. These

RNA serves as primers for the synthesis of both the leading and lagging strand

during replication.

6. ANSWER: C

Explanation: In eukaryotes one strand of DNA is synthesized continuously but

the other one is made of Okazaki fragments.

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7. ANSWER: C

Explanation: DNA ligase catalyzes the formation of a phosphodiester bond

between 3’-OH of one Okazaki fragment and 5’-phosphate of the next.

8. ANSWER: C

Explanation: Only DNA pol III is the principal replication enzyme in E. coli.

9. ANSWER: D

Explanation: Strand separation creates topological stress in the helical DNA

structure which is relieved by the action of topoisomerases.

10. ANSWER: C

Explanation: In eukaryotes one strand of DNA is synthesized continuously but

the other one is made of Okazaki fragments.

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UNIT 2


1. In the beads on a string model, the bead is made up of __________

a) 6 histone proteins

b) 8 histone proteins

c) 6 histone proteins and DNA

d) 8 histone proteins and DNA

2. The unpacked stretches of DNA is the extra chromosomal load found in

eukaryotic genome ___________

a) True

b) False

3. How many types of histone molecules are found in nature?

a) 3

b) 4

c) 5

d) 6

4. Nucleosome is made up of __________

a) DNA, histone core protein

b) DNA, histone core protein, linker H1

c) RNA, histone core protein

d) RNA, histone core protein, linker H1

5. Histones have a high content of negatively charged amino acids.

a) True

b) False

6. With respect to assembly of every core histone which of the following is

wrong?

a) A conserved region

b) Histone fold domain

Eukaryotic chromosomal organization, Euchromatin, Heterochromatin, chromatin structure,

nucleosomes, histone and non-histone proteins, Histone modifications. Introduction to epigenetics.

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c) Disc shaped structure

d) 2 α helices and an unstructured loop

7. Which of the following histone pairs forms tetramers in solution?

a) H1, H2A

b) H2A, H2B

c) H2B, H3

d) H3, H4

8. With respect to the “tails” of the histone molecules which of the following is

not true?

a) N – terminal extension

b) Lacks defined structure

c) Required for the association of nucleosome

d) Sites for extensive modifications

9. How many contacts are observed between the DNA and the histone core

protein?

a) 14

b) 21

c) 54

d) 17

10. Association of DNA and histone is mediated by_________

a) Covalent bonding

b) Hydrogen bonding

c) Hydrophobic bonding

d) Vander Waals interactions

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1. Write a note on chromatin structure?

2. Write a note on heterochromatin?

3. Write a note Euchromatin?

4. Write a note nucleosomes?

5. Write a note histone proteins?

6. Write a note non histone proteins?

7. Write a note on histone modification?

8. Write a note on epigenetics?

9. Write the role of methylation in gene expression?

10. Write the role of acetylation in the gene expression?


1. Explain the eukaryotic chromosome organization in detail?

2. Explain the chromatin structure in detail?

3. Write a long note chromosomal organization levels in eukaryotes?

4. Write a long note chromosomal remodeling?

5. Explain the difference between the histone and non-histone proteins.

6. What is epigenetics? How epigenetic factors influence the gene expression.

7. Write in detail about the epigenetics factors and discuss two diseases which

are due to changes in gene expression via epigenetics?

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ANSWERS TO MCQS

1. ANSWER: B

Explanation: The “beads on a string” model is for the nucleosome. It consists of the

8 histone protein core or the bead and the DNA wound around imitating a string.

2. ANSWER: B

Explanation: Linker DNA is the stretches of DNA that are not packed into a

nucleosome. Typically these are the regions engaged in gene expression, replication

and recombination and are generally associated with non – histone proteins.

3. ANSWER: C

Explanation: Eukaryotic cells commonly contain five abundant histone molecules.

They are named as H1, H2A, H2B, H3 and H4.

4. ANSWER: B

Explanation: The core histone proteins are H2A, H2B, H3 and H4, over which the DNA

is wrapped. Histone H1 is not a part of nucleosome core particle, instead it binds to

the linker DNA and thus is referred to as linker histone. Thus, the histone core, linker

histone and DNA are the components of the nucleosome.

5. ANSWER: B

Explanation: As histones maintain a constant association with negatively charged

DNA thus histone molecules are made up of high content of positively charged amino

acid. Greater than 20% of the residues in each histone molecules are either lysine or

arginine.

6. ANSWER: D

Explanation: The histone fold is composed of 3 α helices and two unstructured loops.

In each of these cases the histone fold mediates the formation of head to tail

heterodimers of specific pairs of histone.

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7. ANSWER: D

Explanation: H3 and H4 histone first forms heterodimers then they come together

to form a tetramer with two molecules of each. In contrast, H2A and H2B form

heterodimers only in the solution and histone H1 only acts as the linker histone.

8. ANSWER: C

Explanation: The “tail” of the histone is not required for the association for the DNA

with the histone octamer into a nucleosome. This is proved when the nucleosome is

treated with the protease, trypsin. Trypsin is known to cleave proteins after positively

charged amino acid thus, when the N – terminal tail is removed no structural

variation is observable in the nucleosome.

9. ANSWER: A

Explanation: 14 distinct sites of contact are observed, one for each time the minor

grove of the DNA faces the histone octamer. 147 base pairs of DNA is wound around

the histone octamer and each minor grove occurs after 10 base pairs thus, 14

contacts are observable.

10. ANSWER: B

Explanation: Association of DNA and histone is mediated by a large number of

hydrogen bonds, that is, ≈140 bonds. The majority forms between the protein and

the oxygen of the phosphodiester backbone near the minor grove. Only 7 hydrogen

bonds are made between the protein side chains and the bases in the minor groves

of the DNA.

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UNIT 3


1. Who is known as the Father of Genetics?

a) Erich Tschemark

b) Carl Correns

c) Gregor Johann Mendel

d) Hugo de Vries

2. Mendel discovered factors which remain its identity in a hybrid, these factors

are _______

a) Genes

b) Alleles

c) DNA

d) Chromosomes

3. Which of the following specimen was chosen by Mendel for his experiment?

a) Drosophila

b) Fly

c) Rat

d) Pisum sativum

4. Which of the following is NOT Mendel’s law of inheritance?

a) Law of dominance

b) Law of segregation

c) Law of hetrozygous

d) Law of independent assortment

5. Out of the following, which law is also known as the law of purity of gametes?

a) Law of co-dominance

b) Law of independent assortment

c) Law of segregation

d) Law of dominance

Origin of life: Classical experiments and current concepts. Evolution of biological

macromolecules, Evolution of early forms. Mendelian genetics: Mendel’s law, Chromosomal

basis of heredity, Chromosomal analysis. Allelic variation, dominance. Linkage and crossing over.

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6. Name the cross by which law of independent assortment inferred.

a) Dihybrid cross

b) Monohybrid cross

c) Test cross

d) Back cross

7. The chromosomal theory of inheritance was proposed by ____________

a) Mendel

b) Watson and Crick

c) Darwin

d) Sutton and Boveri

8. The chromosomal theory of inheritance violates which of the following laws?

a) Law of dominance

b) Law of segregation

c) Law of independent assortment

d) None

9. In incomplete dominance__________________

a) Phenotype of both allele is expressed

b) Phenotype of only one allele is expressed

c) Phenotype of neither of the alleles are expressed

d) Phenotype of both allele is partially expressed

10. Codominance and incomplete dominance is the same thing.

a) True

b) False

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1. Write a note on Law of dominance?

2. Write a note on Law of segregation?

3. Write a note independent assortment?

4. Write a note linkage?

5. Write a note allelic variation?

6. Write a note classic experiments of evolution?

7. Write a note karyotyping?

8. Write a note on alleles?

9. Write a note on dominance?

10. Write a note on current concepts of evolution?


1. Explain the early classic theories of the evolution?

2. Explain the evolution of biomolecules?

3. Write a long note early forms of the life?

4. Write a long note Mendel’s law?

5. Explain the chromosomal basis of inheritance.

6. What is chromosomal analysis? Explain in detail?

7. Write in detail about linkage and co-dominance?

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ANSWERS TO MCQS

1. ANSWER: C

Explanation: Gregor Johann Mendel was an Austrian monk, who is known as the

Father of Genetics. He published the principle of inheritance in 1856 which are

popularly known as Mendel’s law. The rest of the three biologist rediscovered

Mendel’s work in 1900.

2. ANSWER: A

Explanation: Mendel discovered that individual traits retain their physical identity

during hybrid formation when inherited as discrete factors. These factors are

known as genes, which is also a unit of heredity.

3. ANSWER: D

Explanation: Pisum sativum is commonly known as a garden pea. Mendel chose

this species due to its various advantages.

4. ANSWER: C

Explanation: Law of heterozygous is not the law of inheritance proposed by

Mendel. Mendel had given three laws of inheritance which included law of

dominance, law of segregation of gametes, and the law of independent

assortment.

5. ANSWER: C

Explanation: Law of segregation is also known as law of purity of gametes as

gametes are always remained pure by separating the genes or factors at the time

of gamete formation.

6. ANSWER: A

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Explanation: Dihybrid cross is the cross which involves the analysis of two

independent traits. This law shows that during gametogenesis, assortment of one

pair of genes is independent to the other pair.

7. ANSWER: D

Explanation: The chromosomal theory of inheritance was unknown in Mendel’s

and Darwin’s time. It was proposed by Sutton and Boveri while Watson and Crick

gave the structure of the DNA.

8. ANSWER: D

Explanation: The chromosomal theory of inheritance violated none of Mendel’s

laws as the only difference was the genes being present in the chromosome,

other than that the laws are as they were.

9. ANSWER: D

Explanation: In case of incomplete dominance the expression of the phenotype

of neither of the allele is complete; although one is more expressed than another.

10. ANSWER: B

Explanation: In case of codominance both the alleles of heterozygote are

expressed whereas in case of incomplete dominance one of the allele is

expressed incompletely in case of heterozygous condition.

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UNIT 4


1. During DNA cloning which of the following is not a crucial requirement?

a) DNA inserts

b) Vector

c) Protein expression

d) Molecular cutter

2. Transformation does not involve ____________

a) Cutting

b) Recombination

c) Propagation

d) Expression

3. Which is the most common organism considered for genetic manipulations?

a) E. coli

b) Saccharomyces cerevisiae

c) Cyanobacteria

d) Bacillus Subtilis

4. Which of the following is an essential feature for being a perfect vector?

a) Origin of replication

b) Selectable marker

c) Restriction site

d) Virulent gene

5. DNA ligase can ligate restriction site ends produced by EcoRI to the ends of

DNA insert cut by the same enzyme _________

a) True

b) False

6. The vector and the DNA insert are cut by different enzymes for convenience

__________

Introduction to Recombinant DNA technology, Scope & importance. Gene cloning. PCR. Introduction to

Restriction endonuclease, Vectors for DNA transfer and their types: Plasmids, Phagemids, Cosmids, BAC,

Gene amplification.

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a) True

b) False

7. What is the major difference between cloning vectors and primary vectors?

a) Selectable marker

b) DNA inserts

c) Presence of promoter

d) Presence of two Ori

8. Which of the following is the primary use of an expression vector?

a) DNA library

b) DNA purification

c) Protein production

d) DNA cloning

9. Under the influence of which ion does E. coli takes up plasmid from the

environment?

a) Nickel

b) Copper

c) Lead

d) Sulphur

10. The process by which every type of transformant can be identified is

__________

a) Replica plating

b) Hybridization

c) Blotting

d) Insertional inactivation

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1. Write a note on recombinant endonuclease?

2. Write a note on nomenclature of recombinant endonuclease?

3. Write a note plasmid vector?

4. Write a note phagemid vector?

5. Write a note cosmid vector?

6. Write a note alkaline phosphatase?

7. Write a note on features of a good host?

8. Write a note sticky end and blunt end cut by RE?

9. What is the role of selection process in transformation?

10. Write a note on blue white selection method?


1. Explain the scopes of rDNA technology?

2. What is recombinant DNA technology? Explain the molecular tool of genetic

engineering?

3. Write a note on enzymes used in recombinant DNA technology?

4. What is PCR? Explain the applications of PCR?

5. What is vector? Explain the characteristics of a good vector taking PBR322 as

an example?

6. What are cloning vectors? Explain in detail?

7. Explain the gene cloning process in detail?

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ANSWERS TO MCQS

1. ANSWER: C

Explanation: DNA cloning typically involves a vector that carried the DNA insert into

a host cell. Molecular cutters are important to incorporate the DNA insert into the

vector thus giving rise to the chimera molecule. Hence cloning is complete if the

organism replicates and the DNA insert replicates along with it.

2. ANSWER: D

Explanation: Transformation specifically involves the cutting of vector and gene of

interest with specific cutters. These are then ligated and thus formed molecule is the

recombinant molecule. This molecule is then propagated into the host cell thereby

ending the process of transformation of the host.

3. ANSWER: A

Explanation: The DNA fragment to be cloned needs to be inserted within the vector

to be replicated within the host. By far the most common host used to propagate

DNA and thus genetic manipulations is E. coli.

4. ANSWER: D

Explanation: A vector typically has three characteristics:

i. It must contain an origin of replication.

ii. It must contain a selectable marker.

iii. It must have one or more restriction sites for restriction endonucleases.

5. ANSWER: A

Explanation: EcoRI generates protruding 5’ ends (sticky ends) that are

complementary to each other. Thus the ends are capable of reannealing with each

other. Thus when both vector the same enzyme and DNA insert are cut using same

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cutter the strands anneal themselves but leaves two nicks in both the strands. Thus

treatment with the enzyme ligase seals the nicks using ATP.

6. ANSWER: B

Explanation: A target DNA is cleaved with a restriction enzyme to generate potential

DNA inserts with sticky ends. Vector DNA that has been cut with the same enzyme

produces compatible over hangings thus making it convenient for the purpose of

annealing and ligation.

7. ANSWER: C

Explanation: The major difference is the presence of suitable promoter before the

DNA insert. In case of an expression vector the main motto is the production of

protein thus a promoter in an essential criteria but in case of the cloning vector it is

mainly used for amplification and/or production of library.

8. ANSWER: C

Explanation: An expression vector is the type of vector that is designed for the

expression of genes in cells. The can produce a large amount of proteins particularly

useful if the gene product is toxic or a subunit vaccine.

9. ANSWER: B

Explanation: The presence of copper (Cu2+) makes the cell wall of E. coli porous. This

facilitates the uptake of external plasmid DNA by applying little agitation.

10. ANSWER: D

Explanation: Insertional inactivation is the process by which a marker gene is

inactivated by inserting the DNA insert within that gene. This leads to the visual

identification if the gene inactivated gives a colored product when grown in suitable

medium. Also, the marker inactivated may be an antibiotic resistant gene where the

cells are grown in suitable antibiotics following the process of replica plating.

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UNIT 5


1. Plasmid replication is dependent on the host cell.

a) True

b) False

2. Who were the scientists who discovered the plasmid pBR322?

a) Rodriguez and Bolivar

b) Joller smith

c) Herbert Boyer

d) Stanley Cohen and Joller smith

3. Which one of the following is the first engineered plasmid vector?

a) pBR322

b) pBR320

c) pUC18

d) pSC101

4. Which base is generated due to the deamination of adenine?

a) Guanine

b) Cytosine

c) Uracil

d) Hypoxanthine

5. In the following compound which is one of the intercalating agents?

a) Ethidium

b) 5-bromouracil

c) Purine

d) Clastrogen

6. According to pairing concept of wobble hypothesis base “I” in the anticodon

does not pair with?

Plasmids: Types Properties and cloning vectors. Recombinant DNA techniques and cloning with

Restriction endonuclease, and recombinant DNA. Mutation, Types of mutations; Point mutation (Base

pair change-frame shift, deletion). Transcription, translation and gene expression in eukaryotes (yeast),

Alternate splicing.

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a) A

b) U

c) G

d) C

7. Which of the following is not a termination codon?

a) UGA

b) AGA

c) AGG

d) UAC

8. The rho protein has ____________ subunit.

a) 4

b) 6

c) 8

d) 10

9. The common sequence for all tRNAs at their 3’ end is __________

a) CCC

b) CCT

c) GGA

d) CCA

10. Which of the following is not a type of RNA processing?

a) Polyadenylation at the 3’ end

b) Capping of 5’ end

c) Removal of exons

d) Splicing

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1. Write a short note on properties of cloning vector?

2. Write a note on restriction endonuclease?

3. Write a note on frameshift mutation?

4. Write a note alternate splicing?

5. Write a note rho dependent termination?

6. What is wobble hypothesis?

7. Explain the role of ribosome in the translation?

8. Write a note on the RNA splicing and its importance?

9. Write a note on RNA processing?

10. Explain point mutation?


1. Write a long note on transcription?

2. Write a long note on translation?

3. Write a note on basic features of genetic code?

4. Explain the post translational modification?

5. Write in detail mutation and types of mutation?

6. Explain the properties of a good cloning vector in detail?

7. Write an essay on Recombinant DNA technology and its application in gene

therapy?

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ANSWERS TO MCQS

1. ANSWER: B

Explanation: The plasmid is an autonomous replicating genetic material. It has its

own origin of replication and complete replicating machinery thus can replicate

freely and is thus independent of the replication of the host genome.

2. ANSWER: A

Explanation: Plasmids are most commonly used as vector DNA. pBR322 is a plasmid

vector discovered by Rodriguez and Bolivar in 1977.

3. ANSWER: D

Explanation: Although pBR322 is the most commonly used vector in scientific

research. pSC101 is the first engineered plasmid vector. The pUC family vectors are

the derivative of the pBR family of vectors.

4. ANSWER: D

Explanation: Deamination converts adenine to hypoxanthine. Hypoxanthine forms

hydrogen bond to cytosine rather than to thymine.

5. ANSWER: A

Explanation: Intercalating agents are flat molecules that bind to the equally flat

purine or pyrimidine base of DNA. These agent causes deletion or addition of a base

pair or even a few base pair.

6. ANSWER: C

Explanation: The wobble hypothesis does not permit any single tRNA molecule to

recognize four different codons. Three codons, A, U and C can be recognized only

when inosine occupies the first (5’) position of the anticodon.

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7. ANSWER: D

Explanation: UGA, AGA and AGG are termination codons of which UGA is the

universal termination codon and AGA and AGG are mitochondrial termination

codons. But UAC is the universal codon for tyrosine.

8. ANSWER: B

Explanation: The rho protein is a hexameric protein containing 6 subunits. This

protein is known to mediate transcription and is known as the Rho dependent

transcription.

9. ANSWER: D

Explanation: All tRNAs have the common sequence CCA at their 3’ end. This sequence

is the site of amino acid attachment, so it is required for tRNA function during protein

synthesis.

10. ANSWER: C

Explanation: The processing events include the following:

i) Capping of the 5’ end of RNA.

ii) Splicing for removing the introns.

iii) Polyadenylation of the 3’ end of the RNA.

Thank you

Note: This question bank is made for educational purpose only.

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