DNA Sequencing, Mutation and Repair

Q1: Frame shift mutation may occur as a result of

A formation of a thymine-dimer

B deamination of cytosine to uracil

C conversion of guanine to xanthine

D none of the above

ANS:D - none of the above

Nucleotide change from guanine to xanthine can result in frameshift mutation as during translation it will not be considered.

Q2: Genetic variations are

A temporary

B influenced by the environment

C stable

D not heritable

ANS:C - stable

Genetic variation is influenced by surrounding where one lives.

Q3: Which of the following(s) is/are steps in excision repair mechanisms?

A Excision

B Incision

C Ligation

D All of these

ANS:D - All of these

No answer description is available.

Q4: When mutations involve vital functions so that the mutants are nonviable, it is a

A nonsense mutation

B lethal mutation

C transversion

D none of these

ANS:C - transversion

Vital activity helps organism survive in corresponding condition.

Many enzymes should be synthesized in obligatory (compulsory) manner as they play an imp role in metabolism of either eukaryote or prokaryote. If there is a mutation in the gene of the enzymes, transporter gene, ion channels etc may lead to the death of the object and any mutation leading to the death of the object is termed as LETAL MUTAION.

Q5: Differentiation of four different bases in automated sequencing systems is that each base has

A different radioactive tag

B cytosine at start

C unique antibody bound to it

D distinctive fluorescent tag

ANS:D - distinctive fluorescent tag

No answer description is available.

Q6: Which of these mechanisms for thymine dimers repair lead to mutations?

A Excision repair

B Photoreactivation

C SOS repair

D Never leads to mutation

ANS:C - SOS repair

No answer description is available.

Q7: Which of the following mutations arise without exposure to external agents?

A Spontaneous mutations

B Analogous mutations

C Induced mutations

D None of these

ANS:A - Spontaneous mutations

No answer description is available.

Q8: The promoter on an expression vector used to overproduce proteins in bacteria is

A a bacterial promoter

B expressed both in bacteria and mammalian cells

C not a regulated promoter

D the natural promoter of the gene being cloned

ANS:A - a bacterial promoter

No answer description is available.

Q9: The whole-genome shotgun sequencing approach depends primarily on

A rapidly sequencing thousands of small randomly cloned fragments

B methodical sequencing a few large cloned fragments of DNA

C sequencing the bacterial chromosome while it is still intact

D all of the above

ANS:A - rapidly sequencing thousands of small randomly cloned fragments

What happens in whole genome shotgun sequencing?

And where is this method used?

Q10: Which of the following mutation affects only a single nucleotide?

A Aerial mutation

B Site mutation

C Point mutation

D Regional mutation

ANS:C - Point mutation

No answer description is available

Q11: What was the first eukaryotic chromosome to be sequenced?

A Yeast chromosome III

B Yeast chromosome XI

C Arabidopsis chromosome IV

D None of these

ANS:A - Yeast chromosome III

Explain the answer, please.

Q12: A mutagen is defined as

A an enzyme that repairs mutations

B a chemical or physical agent that induces mutations

C an inhibitor of gene modification

D a molecule which stabilizes DNA thus prevents mutations from occurring

ANS:B - a chemical or physical agent that induces mutations

No answer description is available

Q13: The mutation which will not affect the length of a protein is,

A nonsense mutation

B missense mutation

C frameshift mutation

D all of these

ANS:B - missense mutation

A missense mutation is also called point mutation.

Q14: A nonsense mutation introduced into the DNA sequence of a gene may

A cause premature termination of the mRNA

B shorten the length of the protein encoded by the gene

C have no effect on the transcript or protein made

D cause a shift in reading frame

ANS:B - shorten the length of the protein encoded by the gene

It may be premature termination of mRNA that resultant protein is short.

Q15: Thymine dimers are directly repaired with the help of visible light by process known as

A phosphorylation

B excision repair

C photosynthesis

D photoreactivation

ANS:D - photoreactivation

No answer description is available.

Q16: Which of the following bacterial genome was sequenced first?

A E. coli

B S. pneumoniae

C H. influenzae

D S. thermophilus

ANS:C - H. influenzae

No answer description is available.

Q17: A nonsense mutation may result into

A an abnormal elongation of a polypeptide

B a large deletion within the reading frame of a gene

C a premature termination of the synthesis of a polypeptide

D modification of mRNA

ANS:C - a premature termination of the synthesis of a polypeptide

As described in answer of 2nd que, nonsense mutation results in to formation of the nonsense codon in the transcript. So when a transcript (m-RNA) goes to get translated, it terminates at the nonsense codon that is resulted during nonsense mutation.

Q18: Changes in which of the following characterizes mutations?

A Phenotype

B Genotype

C Both (a) and (b)

D None of these

ANS:C - Both (a) and (b)

Some time phenotype may change beside genotype does not, this is studied in 'epigenetics'. Henceforth, mutation can be defined with the C option suitably.

Q19: The DNA sequences of rRNA genes can be used to

A assess relatedness of eukaryotes but not prokaryotes

B obtain a tentative identification of a new microorganism

C predict the pulsed field gel pattern of a microorganism

D predict whether a bacteria will be gram-positive or gram-negative

ANS:B - obtain a tentative identification of a new microorganism

No answer description is available.

Q20: Due to which of the following DNA repair mechanisms, one is able to distinguish newly synthesized DNA strands from older one?

A New strands do not contain cytosine bases

B New strands are lower in molecular size

C Old strands are methylated while new strands are not

D New strands are methylated while old strands are not

ANS:C - Old strands are methylated while new strands are not

I think option D should be correct.



img not found
img

For help Students Orientation
Mcqs Questions

One stop destination for examination, preparation, recruitment, and more. Specially designed online test to solve all your preparation worries. Go wherever you want to and practice whenever you want, using the online test platform.