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All questions of Molecular Genetics for Grade 12 Exam
Which of the following steps in transcription is catalysed by RNA polymerase?
- a)Initiation
- b)Elongation
- c)Termination
- d)All of the above
Correct answer is option 'B'. Can you explain this answer?
Which of the following steps in transcription is catalysed by RNA polymerase?
a)
Initiation
b)
Elongation
c)
Termination
d)
All of the above
|
Anjali Iyer answered |
RNA polymerase moves along the template strand, synthesising an mRNA molecule. In prokaryotes RNA polymerase is a holoenzyme consisting of a number of subunits, including a sigma factor (transcription factor) that recognises the promoter. In eukaryotes there are three RNA polymerases: I, II and III. The process includes a proofreading mechanism.
The strand of DNA that forms mRNA is called?
- a)Lagging strand
- b)Coding strand
- c)Antisense strand
- d)Template strand
Correct answer is option 'D'. Can you explain this answer?
The strand of DNA that forms mRNA is called?
a)
Lagging strand
b)
Coding strand
c)
Antisense strand
d)
Template strand
|
Vijay Bansal answered |
The strand of DNA that forms mRNA is called the template strand or the antisense strand. During transcription, the DNA molecule unwinds, and one of the strands (the template strand) is used as a template to synthesize a complementary RNA molecule, which is called messenger RNA (mRNA). The other strand of DNA, which is not used as a template during transcription, is called the coding strand or the sense strand because it has the same sequence as the mRNA molecule (except for the presence of thymine instead of uracil).
Transformation was discovered by: [2014]- a)Meselson and Stahl
- b)Hershey and Chase
- c)Griffith
- d)Watson and Crick
Correct answer is option 'C'. Can you explain this answer?
Transformation was discovered by: [2014]
a)
Meselson and Stahl
b)
Hershey and Chase
c)
Griffith
d)
Watson and Crick
|
Yash Saha answered |
(c) Frederick Griffith (in 1928), a British Medical officer described the phenomenon of bacterial transformation. He carried out experiment with Streptococcus pneumoniae (bacterium causing pneumonia) which is used to infect mice. By using S Strain (heat killed) and R strain (live) it was concluded that R strain has been transformed by some material of S strain which makes R strain virulent and enable to synthesize smooth polysachharide.
Which one of the following is wrongly matched? [2014]- a)Transcription – Writing information from DNA to tRNA.
- b)Translation – Using information in mRNA to make protein
- c)Repressor protein – Binds to operator to stop enzyme synthesis.
- d)Operon – Structural genes, operator and promoter
Correct answer is option 'A'. Can you explain this answer?
Which one of the following is wrongly matched? [2014]
a)
Transcription – Writing information from DNA to tRNA.
b)
Translation – Using information in mRNA to make protein
c)
Repressor protein – Binds to operator to stop enzyme synthesis.
d)
Operon – Structural genes, operator and promoter
|
Aman Sharma answered |
(a) Process of copying genetic information from DNA to RNA is called transcription. At a time only one DNA strand is being transcribed into RNA. The strand of DNA with polarity 3' → 5' act as template strand and the DNA strand with polarity 5' → 3' act as coding strand.
Removal of the introns and joining of the exons in a defined order in a transcription unit is called- a)Capping
- b)Transformation
- c)Tailing
- d)Splicing
Correct answer is 'D'. Can you explain this answer?
Removal of the introns and joining of the exons in a defined order in a transcription unit is called
a)
Capping
b)
Transformation
c)
Tailing
d)
Splicing
|
Avantika Gupta answered |
Splicing is the process of removing introns and joining exons in a defined order in a transcription unit. This process takes place in the nucleus of eukaryotic cells and is mediated by a complex called the spliceosome.
Explanation:
• Transcription is the process of synthesizing RNA from a DNA template. During transcription, the entire DNA sequence is transcribed into RNA, including both the introns and exons.
• Introns are non-coding sequences within a gene, while exons are the coding sequences that specify the amino acid sequence of a protein. Introns need to be removed from the RNA sequence before translation can occur.
• Splicing is the process of removing introns and joining exons in a defined order, resulting in a mature messenger RNA (mRNA) molecule that can be translated into a protein.
• The splicing process is mediated by the spliceosome, a complex that consists of small nuclear RNAs (snRNAs) and proteins. The snRNAs base-pair with the intron sequences, while the proteins catalyze the chemical reactions that remove the introns and join the exons.
• Splicing is essential for the proper expression of genes, as it allows for the creation of multiple protein variants from a single gene by alternative splicing. Mutations that affect splicing can lead to a variety of diseases, including cancer and genetic disorders.
In conclusion, splicing is the process of removing introns and joining exons in a defined order in a transcription unit, and it is essential for the proper expression of genes.
Explanation:
• Transcription is the process of synthesizing RNA from a DNA template. During transcription, the entire DNA sequence is transcribed into RNA, including both the introns and exons.
• Introns are non-coding sequences within a gene, while exons are the coding sequences that specify the amino acid sequence of a protein. Introns need to be removed from the RNA sequence before translation can occur.
• Splicing is the process of removing introns and joining exons in a defined order, resulting in a mature messenger RNA (mRNA) molecule that can be translated into a protein.
• The splicing process is mediated by the spliceosome, a complex that consists of small nuclear RNAs (snRNAs) and proteins. The snRNAs base-pair with the intron sequences, while the proteins catalyze the chemical reactions that remove the introns and join the exons.
• Splicing is essential for the proper expression of genes, as it allows for the creation of multiple protein variants from a single gene by alternative splicing. Mutations that affect splicing can lead to a variety of diseases, including cancer and genetic disorders.
In conclusion, splicing is the process of removing introns and joining exons in a defined order in a transcription unit, and it is essential for the proper expression of genes.
DNA contains nucleobases, sugar and phosphate. Removal of which among these from a DNA sample will not significantly affect the length of DNA?- a)Nucleobases
- b)Sugar
- c)Phosphate
- d)None of the above
Correct answer is option 'A'. Can you explain this answer?
DNA contains nucleobases, sugar and phosphate. Removal of which among these from a DNA sample will not significantly affect the length of DNA?
a)
Nucleobases
b)
Sugar
c)
Phosphate
d)
None of the above
|
Kamlesh Bhivsane answered |
NUCLEOBASE(it is base pairing between nitrogen bases i.e A ,T,G,C) therefore it does not affect the length of DNA where as sugar phosphate bond is the back bone of DNA therefore they both affect the length of DNA
Protein synthesis occurs over- a)Cytoplasm
- b)Ribosomes
- c)Amino acids
- d)Mitochondria
Correct answer is option 'B'. Can you explain this answer?
Protein synthesis occurs over
a)
Cytoplasm
b)
Ribosomes
c)
Amino acids
d)
Mitochondria
|
Sathvika Tadri answered |
Ribosomes are site of protein synthesis and are known as protein factory
The amino acid attaches to the tRNA at its- a)5′ end
- b)Anticodon site
- c)3′ end
- d)DHU loop
Correct answer is option 'C'. Can you explain this answer?
The amino acid attaches to the tRNA at its
a)
5′ end
b)
Anticodon site
c)
3′ end
d)
DHU loop
|
Rohit Shah answered |
TRNA with an attached amino acid is said to be "charged". The enzyme that attaches the amino acid to the 3'-OH is called an aminoacyl tRNA synthetase (aaRS). There is a specific tRNA for each amino acid, 20 in all. Similarly, there is a specific aaRS for each tRNA.
During transcription, the DNA site at which RNA polymerase binds is called- a)Enhancer
- b)Receptor
- c)Promoter
- d)Regulator
Correct answer is option 'C'. Can you explain this answer?
During transcription, the DNA site at which RNA polymerase binds is called
a)
Enhancer
b)
Receptor
c)
Promoter
d)
Regulator
|
|
Prashanth Chatterjee answered |
The site at which RNA polymerase binds during transcription is called the promoter. It is a specific region of DNA that is recognized by RNA polymerase, which then initiates the process of transcription. The promoter is located upstream of the transcriptional start site and contains specific DNA sequences that are recognized by RNA polymerase and other transcription factors.
The promoter plays a crucial role in regulating gene expression, as different promoters can activate or repress transcription depending on the cellular context. The strength of the promoter can also affect the rate of transcription, with stronger promoters resulting in higher levels of mRNA production.
There are different types of promoters, including constitutive promoters, which are active in all cells, and inducible promoters, which are activated in response to specific signals or conditions. The sequence and structure of the promoter can vary depending on the gene being transcribed and the organism in which it is expressed.
In summary, the promoter is a critical element in the process of transcription, serving as the site at which RNA polymerase binds and initiating the production of mRNA from DNA. It plays a crucial role in regulating gene expression and can vary in strength and specificity depending on the cellular context and the gene being transcribed.
The promoter plays a crucial role in regulating gene expression, as different promoters can activate or repress transcription depending on the cellular context. The strength of the promoter can also affect the rate of transcription, with stronger promoters resulting in higher levels of mRNA production.
There are different types of promoters, including constitutive promoters, which are active in all cells, and inducible promoters, which are activated in response to specific signals or conditions. The sequence and structure of the promoter can vary depending on the gene being transcribed and the organism in which it is expressed.
In summary, the promoter is a critical element in the process of transcription, serving as the site at which RNA polymerase binds and initiating the production of mRNA from DNA. It plays a crucial role in regulating gene expression and can vary in strength and specificity depending on the cellular context and the gene being transcribed.
In E. coli, the lac operon gets switched on when- a)Lactose is present and it binds to the repressor
- b)RNA polymerase binds to the operator
- c)Lactose is present and it binds to RNA polymerase
- d)Repressor binds to operator
Correct answer is 'A'. Can you explain this answer?
In E. coli, the lac operon gets switched on when
a)
Lactose is present and it binds to the repressor
b)
RNA polymerase binds to the operator
c)
Lactose is present and it binds to RNA polymerase
d)
Repressor binds to operator
|
Geetika Shah answered |
In case of lactose presence
(i) Lactose acts as an inducer which binds to the repressor and forms an inactive repressor.
(ii) The repressor fails to bind to the operator region.
(iii) The RNA polymerase binds to the operator and transcript lac mRNA.
(iv) lac mRNA is polycistronic, i.e., produces all three enzymes, β -galactosidase, permeaseand transacetylase.
(v) The lac operon is switched on.
In case of lactose absence
(i) When lactose is absent, i gene regulates and produces repressor mRNA which translate repression.
(ii) The repressor protein binds to the operator region of the operon and as a resultprevents RNA polymerase to bind to the operon.
(iii) The operon is switched off.
There is no DNA in- a)Hair root
- b)An enucleated ovum
- c)A mature spermatozoan
- d)Mature RBCs
Correct answer is option 'D'. Can you explain this answer?
There is no DNA in
a)
Hair root
b)
An enucleated ovum
c)
A mature spermatozoan
d)
Mature RBCs
|
Hansa Sharma answered |
In mature RBCs nucleus is absent and there is no DNA. Mature DNA do not divide to form new cells.
In DNA replication, the leading strand replicates in the
- a)5′ → 3′ direction discontinuously
- b)5’→ 3′ direction continuously
- c)3′ → 5′ direction discontinuously
- d)3’→ 5′ direction continuously
Correct answer is option 'B'. Can you explain this answer?
In DNA replication, the leading strand replicates in the
a)
5′ → 3′ direction discontinuously
b)
5’→ 3′ direction continuously
c)
3′ → 5′ direction discontinuously
d)
3’→ 5′ direction continuously
|
|
Anjana Sharma answered |
The replication occurs in three steps in both prokaryotes and eukaryotes. These are include-
• Initiation
• Elongation
• Termination
The elongation steps involve the synthesis of leading and lagging strands.
The helicase and Dna B unzips the double-stranded DNA for replication, making a forked structure. The primase then performs the task of generating short strands of RNA that bind to the single-stranded DNA to initiate DNA synthesis with the help of DNA polymerase. This enzyme can work only in the 5′5′ to 3′3′ direction, the replication of the leading strand is done continuously whereas lagging-strand replication is discontinuous, with short Okazaki fragments being formed and later linked together.
So, the leading strand is the one that replicates in the 5′→3' direction continuously.
• Initiation
• Elongation
• Termination
The elongation steps involve the synthesis of leading and lagging strands.
The helicase and Dna B unzips the double-stranded DNA for replication, making a forked structure. The primase then performs the task of generating short strands of RNA that bind to the single-stranded DNA to initiate DNA synthesis with the help of DNA polymerase. This enzyme can work only in the 5′5′ to 3′3′ direction, the replication of the leading strand is done continuously whereas lagging-strand replication is discontinuous, with short Okazaki fragments being formed and later linked together.
So, the leading strand is the one that replicates in the 5′→3' direction continuously.
Repressor proteins are coded for by ______ genes.- a)Promoter
- b)Structural
- c)Regulator
- d)Operator
Correct answer is option 'C'. Can you explain this answer?
Repressor proteins are coded for by ______ genes.
a)
Promoter
b)
Structural
c)
Regulator
d)
Operator
|
|
Gaurav Kumar answered |
Regulator genes codes for repressor proteins during translation of DNA into protein via mRNA.
Out of 64 codons, the number of codons with GGG is- a)4
- b)1
- c)2
- d)6
Correct answer is option 'B'. Can you explain this answer?
Out of 64 codons, the number of codons with GGG is
a)
4
b)
1
c)
2
d)
6
|
|
Sankar Banerjee answered |
GGG code is present only 1 tym nd the amino acid produced by GGG is glycine.
Commonly used vectors for human genome sequencing are: [2014]- a)T-DNA
- b)BAC and YAC
- c)Expression Vectors
- d)T/A Cloning Vectors
Correct answer is option 'B'. Can you explain this answer?
Commonly used vectors for human genome sequencing are: [2014]
a)
T-DNA
b)
BAC and YAC
c)
Expression Vectors
d)
T/A Cloning Vectors
|
Anirudh Datta answered |
(b) Human genome sequencing is a process that determines the complete DNA sequence of an organism's genome at a single time. This requires sequencing all of an organism's chromosomal DNA as well as DNA contained in the mitochondria and, for plants, in the chloroplast. Commonly used vectors for human genome sequencing are BAC (Bacterial artificial chromosomes) and YAC (Yeast artificial chromosomes).
A complex of ribosomes attached to a single strand of RNA is known as [2016]- a)Polysome
- b)Polymer
- c)Polypeptide
- d)Okazaki fragment
Correct answer is option 'A'. Can you explain this answer?
A complex of ribosomes attached to a single strand of RNA is known as [2016]
a)
Polysome
b)
Polymer
c)
Polypeptide
d)
Okazaki fragment
|
Dipika Das answered |
(a) A polysome or polyribosome is a complex of an mRNA molecule and two or more ribosomes, which is formed during the active translation process. They were initially named as ergosomes in 1963. However, further research by Jonathan Warner and Alex Rich characterized polysome.
An abnormal human baby with 'XXX' sex chromosomes was born due to- a)formation of abnormal sperms in the father
- b)formation of abnormal ova in the mother
- c)fusion of two ova and one sperm
- d)fusion of two sperms and one ovum
Correct answer is option 'B'. Can you explain this answer?
An abnormal human baby with 'XXX' sex chromosomes was born due to
a)
formation of abnormal sperms in the father
b)
formation of abnormal ova in the mother
c)
fusion of two ova and one sperm
d)
fusion of two sperms and one ovum
|
Mrinalini Bajaj answered |
Alleles are different molecular forms of a gene, representing altemate forms of a given character.
Height of a pea plant-T for tallness and t for dwarfness.
T and t are altemate forms for given character of height.
Heterozygotes and homozygotes refers to inheritance of two different and similar travels for a character respectively.
The portion of DNA which contains information for an entire polypeptide is called- a)Operon
- b)Recon
- c)Muton
- d)Cistron
Correct answer is option 'D'. Can you explain this answer?
The portion of DNA which contains information for an entire polypeptide is called
a)
Operon
b)
Recon
c)
Muton
d)
Cistron
|
Nikita Singh answered |
Cistron is a nucleotide sequence responsible for the synthesis of a polypeptide sequence of a functional protein.
The word cistron is used to emphasize that genes exhibit a specific behavior in a cis-trans test, distinct positions (or loci) within a genome are cistronic.
A pleiotropic gene: [2015 RS]- a)is a gene evolved during Pliocene.
- b)controls a trait only in combination with another gene
- c)controls multiple traits in an individual.
- d)is expressed only in primitive plants
Correct answer is option 'C'. Can you explain this answer?
A pleiotropic gene: [2015 RS]
a)
is a gene evolved during Pliocene.
b)
controls a trait only in combination with another gene
c)
controls multiple traits in an individual.
d)
is expressed only in primitive plants
|
Arindam Khanna answered |
(c) A pleiotropic gene regulates multiple traits (characte- ristics) in an individual.
The coding segment of DNA isa)Mutonb)Repliconc)Intrond)CodonCorrect answer is option 'D'. Can you explain this answer?
|
|
Anjali Iyer answered |
Exon: The coding sequences or expressed sequences are defined as exon. Exons are said to be those sequences that appear in mature or processed RNA.
Identify the purine base of nucleic acids in the following- a)Cytosine
- b)Thymine
- c)Uracil
- d)Adenine
Correct answer is option 'D'. Can you explain this answer?
Identify the purine base of nucleic acids in the following
a)
Cytosine
b)
Thymine
c)
Uracil
d)
Adenine
|
Soumya Ahuja answered |
Purines have two rings in their structure, but pyrimidine bases have only one ring.Adenine has two rings in its structure.
Jacob and Monod studied lactose metabolism in E.coli and proposed operon concept. Operon concept is applicable for[2002]- a)all prokaryotes
- b)all prokaryotes and some eukaryotes
- c)all prokaryotes and all eukaryotes
- d)all prokaryotes and some protozoans
Correct answer is option 'B'. Can you explain this answer?
Jacob and Monod studied lactose metabolism in E.coli and proposed operon concept. Operon concept is applicable for
[2002]
a)
all prokaryotes
b)
all prokaryotes and some eukaryotes
c)
all prokaryotes and all eukaryotes
d)
all prokaryotes and some protozoans
|
Nilanjan Chakraborty answered |
Gene regulation of eukaryotes is complex as compared to that of prokaryotes.
Which of the following are not the components of RNA?- a)Thymine
- b)Adenine
- c)Guanine
- d)Cytosine
Correct answer is option 'A'. Can you explain this answer?
Which of the following are not the components of RNA?
a)
Thymine
b)
Adenine
c)
Guanine
d)
Cytosine
|
Ishani Nambiar answered |
Thymine is present in DNA but not in RNA.
Why are UGA, UAG and UAA called termination codons?- a)They terminate anticodons
- b)They are presenting at the beginning of mRNA
- c)They indicate initiation of translation
- d)They do not specify any amino acid
Correct answer is option 'D'. Can you explain this answer?
Why are UGA, UAG and UAA called termination codons?
a)
They terminate anticodons
b)
They are presenting at the beginning of mRNA
c)
They indicate initiation of translation
d)
They do not specify any amino acid
|
|
Supriya Senapati answered |
Since The stop codons are UAA, UAG, and UGA. They encode no amino acid. The ribosome pauses and falls off the mRNA.
Which particular process was used by Meselson and Stahl in order to study the semi-conservative replication of DNA?
- a)Density gradient centrifugation
- b)Chromatography
- c)Centrifugation
- d)Buoyant density centrifugation
Correct answer is option 'A'. Can you explain this answer?
Which particular process was used by Meselson and Stahl in order to study the semi-conservative replication of DNA?
a)
Density gradient centrifugation
b)
Chromatography
c)
Centrifugation
d)
Buoyant density centrifugation
|
|
Sahil Basu answered |
Density Gradient Centrifugation
Meselson and Franklin used density gradient centrifugation to study the semi-conservative replication of DNA. This technique is based on the principle that molecules of different densities will settle at different positions in a gradient when subjected to centrifugal force.
Steps Involved in the Process
1. Growing bacteria in a medium containing a heavy isotope of nitrogen
The experiment involved growing E. coli bacteria in a medium containing a heavy isotope of nitrogen, 15N, for many generations. This resulted in all the bacterial DNA being labeled with 15N.
2. Transferring bacteria to a medium containing a lighter isotope of nitrogen
Next, the bacteria were transferred to a medium containing a lighter isotope of nitrogen, 14N, and allowed to grow for one generation.
3. Isolation of DNA
The bacterial cells were then harvested and their DNA was extracted.
4. Density gradient centrifugation
The DNA samples were subjected to density gradient centrifugation, which involved placing the DNA in a tube containing a gradient of cesium chloride. The tube was then spun at high speeds in a centrifuge, causing the DNA molecules to migrate to the position in the gradient that corresponded to their buoyant density.
5. Observations
The resulting DNA bands were observed under ultraviolet light. If DNA replication was conservative, the DNA band would have been a single band of intermediate density, whereas if it was semi-conservative, two bands would have been observed, one of intermediate density and one of lighter density.
6. Conclusion
Meselson and Franklin observed that the DNA bands were indeed two distinct bands, one of intermediate density and one of lighter density. This provided evidence for the semi-conservative replication of DNA.
Conclusion
Density gradient centrifugation was a crucial technique used by Meselson and Franklin to study the semi-conservative replication of DNA. This technique allowed them to separate the newly synthesized DNA from the parental DNA and provided evidence for the semi-conservative mode of DNA replication.
Meselson and Franklin used density gradient centrifugation to study the semi-conservative replication of DNA. This technique is based on the principle that molecules of different densities will settle at different positions in a gradient when subjected to centrifugal force.
Steps Involved in the Process
1. Growing bacteria in a medium containing a heavy isotope of nitrogen
The experiment involved growing E. coli bacteria in a medium containing a heavy isotope of nitrogen, 15N, for many generations. This resulted in all the bacterial DNA being labeled with 15N.
2. Transferring bacteria to a medium containing a lighter isotope of nitrogen
Next, the bacteria were transferred to a medium containing a lighter isotope of nitrogen, 14N, and allowed to grow for one generation.
3. Isolation of DNA
The bacterial cells were then harvested and their DNA was extracted.
4. Density gradient centrifugation
The DNA samples were subjected to density gradient centrifugation, which involved placing the DNA in a tube containing a gradient of cesium chloride. The tube was then spun at high speeds in a centrifuge, causing the DNA molecules to migrate to the position in the gradient that corresponded to their buoyant density.
5. Observations
The resulting DNA bands were observed under ultraviolet light. If DNA replication was conservative, the DNA band would have been a single band of intermediate density, whereas if it was semi-conservative, two bands would have been observed, one of intermediate density and one of lighter density.
6. Conclusion
Meselson and Franklin observed that the DNA bands were indeed two distinct bands, one of intermediate density and one of lighter density. This provided evidence for the semi-conservative replication of DNA.
Conclusion
Density gradient centrifugation was a crucial technique used by Meselson and Franklin to study the semi-conservative replication of DNA. This technique allowed them to separate the newly synthesized DNA from the parental DNA and provided evidence for the semi-conservative mode of DNA replication.
According to Chargaff’s rule, which one is correct?- a)[A] + [T] = [G] + [C]
- b)[A] + [C] = [G] + [T]
- c)[A] + [G] = [T] + [C]
- d)All of these
Correct answer is option 'C'. Can you explain this answer?
According to Chargaff’s rule, which one is correct?
a)
[A] + [T] = [G] + [C]
b)
[A] + [C] = [G] + [T]
c)
[A] + [G] = [T] + [C]
d)
All of these
|
|
Geetika Shah answered |
According to Chargaff’s rule in all cellular DNA, regardless of the species, number of adenosine residues is equal to the number of thymidine residues which means that A = T and the number of guanosine residues is equal to the number of cytidine residues; G = C . Hence, that the sum of the purine residues equals the sum of the pyrimidine residues; i.e., A + G = T + C.
Which of the following is not required for any of the techniques of DNA fingerprinting available at present ? [2016]- a)Polymerase chain reaction
- b)Zinc finger analysis
- c)Restriction enzymes
- d)DNA-DNA hybridization
Correct answer is option 'B'. Can you explain this answer?
Which of the following is not required for any of the techniques of DNA fingerprinting available at present ? [2016]
a)
Polymerase chain reaction
b)
Zinc finger analysis
c)
Restriction enzymes
d)
DNA-DNA hybridization
|
Pooja Choudhary answered |
(b) Zinc-finger analysis is used for protein analysis. The zinc finger proteins are a super family of proteins involved in numerous activities of plant growth and development.
Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as ‘start’ or ‘stop’codon ?[2003]- a)UAC – Tyrosine
- b)UCG – Start
- c)UUU – Stop
- d)UGU – Leucine
Correct answer is option 'A'. Can you explain this answer?
Which one of the following triplet codes, is correctly matched with its specificity for an amino acid in protein synthesis or as ‘start’ or ‘stop’codon ?
[2003]
a)
UAC – Tyrosine
b)
UCG – Start
c)
UUU – Stop
d)
UGU – Leucine
|
Palak Khanna answered |
AUG is initiating codon. UCG codes for serine, UUU codes for phenylalan, UGU codes for cysteine.
Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a triplet?- a)Nirenberg and Matthaei
- b)Hershey and Chase
- c)Beadle and Tatum
- d)Morgan and Sturtevant
Correct answer is option 'A'. Can you explain this answer?
Whose experiments cracked the DNA and discovered unequivocally that a genetic code is a triplet?
a)
Nirenberg and Matthaei
b)
Hershey and Chase
c)
Beadle and Tatum
d)
Morgan and Sturtevant
|
|
Rajat Kapoor answered |
The existence of a triplet code was simply an assumption till 1961 when Nirenberg and Methaei proved its existence by experiment. They were able to synthesise artificial mRNA, which contained only one nitrogenous base, ie, uracil. This synthetic poly-U sequence was then placed in a cell-free system containing protein synthesizing enzymes (extracted from bacterium E. coil) and 20 amino acids together with necessary ATP. During the process, a small polypeptide molecule was produced, which was formed by the linking of phenylalanine. This issuggested that UUU is code for phenylalanine. Nirenberg got Nobel Prize for his contributions.
Which of the following important biochemical reactions in living systems is catalyzed by a ribozyme?
a)Formation of peptide bondb)Repair of DNAc)Electron transfer chaind)Organization of MTOC during cell divisonCorrect answer is option 'A'. Can you explain this answer?
|
|
Gaurav Kumar answered |
In prokaryotes (bacteria) the 23srRNA of the larger subunit of ribosome is the enzyme ribozyme that catalyzes peptide bond formation.
Hence, the correct option is A.
NCERT Reference: Page no. 115 of topic “6.7 TRANSLATION” of chapter 6.
NCERT Reference: Page no. 115 of topic “6.7 TRANSLATION” of chapter 6.
In E.coli during lactose metabolism repressor binds to[2002]- a)regulator gene
- b)operator gene
- c)structural gene
- d)promoter gene
Correct answer is option 'B'. Can you explain this answer?
In E.coli during lactose metabolism repressor binds to
[2002]
a)
regulator gene
b)
operator gene
c)
structural gene
d)
promoter gene
|
Vaibhav Basu answered |
Regulator gene for ms a biochemical for suppressing the activity of operator gene. Promoter gene is the gene which provides point of attachment to RNA polymerase required for transcription of structural genes. Structural genes are genes which transcribe m RNA for polypeptide synthesis.
Some amino acids are coded by more than one codon; hence, the code is- a)Unambiguous
- b)Universal
- c)Degenerate
- d)Initiator
Correct answer is option 'C'. Can you explain this answer?
Some amino acids are coded by more than one codon; hence, the code is
a)
Unambiguous
b)
Universal
c)
Degenerate
d)
Initiator
|
|
Anjali Iyer answered |
The genetic code is degenerate: Some amino acids are encoded by more than one codon, inasmuch as there are 64 possible base triplets and only 20 amino acids. In fact, 61 of the 64 possible triplets specify particular amino acids and 3 triplets (called stop codons) designate the termination of translation. Thus, for most amino acids, there is more than one code word.
The chromosomes in which centromere is situated close to one end are: [2015 RS]- a)Acrocentric
- b)Telocentric
- c)Sub-metacentric
- d)Metacentric
Correct answer is option 'A'. Can you explain this answer?
The chromosomes in which centromere is situated close to one end are: [2015 RS]
a)
Acrocentric
b)
Telocentric
c)
Sub-metacentric
d)
Metacentric
|
|
Aman Sharma answered |
(a) In acrocentric chromosomes, one arm is very short but another is long.
In sea urchin DNA, which is double stranded, 17% of the bases were shown to be cytosine. The percentages of the other three bases expected to be present in this DNA are :- [2015 RS]- a)G 17%, A 16.5%, T 32.5%
- b)G 17%, A 33%, T 33%
- c)G 8.5%, A 50%, T 24.5%
- d)G 34%, A 24.5%, T 24.5%
Correct answer is option 'B'. Can you explain this answer?
In sea urchin DNA, which is double stranded, 17% of the bases were shown to be cytosine. The percentages of the other three bases expected to be present in this DNA are :- [2015 RS]
a)
G 17%, A 16.5%, T 32.5%
b)
G 17%, A 33%, T 33%
c)
G 8.5%, A 50%, T 24.5%
d)
G 34%, A 24.5%, T 24.5%
|
Diya Datta answered |
(b) Chargaff's rule states that A = T and G º C. The molar amount of adenine = molar amount of thymine. The molar amount of guanine = molar amount of cytosine. Hence, G is 17%, so, C = 17% A = 33%, so, T = 33%
Codon is made up of- a)Single nucleotide
- b)Four nucleotides
- c)three nucleotides
- d)two nucleotides
Correct answer is option 'C'. Can you explain this answer?
Codon is made up of
a)
Single nucleotide
b)
Four nucleotides
c)
three nucleotides
d)
two nucleotides
|
|
Gopikas S answered |
Codons are found in mRNA.A sequence of three nucleotides in messenger RNA makes a codon for an amino acid. A codon is a sequence of three adjacent nucleotides constituting the genetic code that determines the insertion of a specific amino acid in a polypeptide chain during protein synthesis or the signal to stop protein synthesis. A codon is defined by the initial nucleotide from which translation starts.
DNA is made of two chains that twist about one another in the shape of a _______.- a)Broken ladder
- b)Straight ladder
- c)Straight spiral
- d)Double helix
Correct answer is option 'D'. Can you explain this answer?
DNA is made of two chains that twist about one another in the shape of a _______.
a)
Broken ladder
b)
Straight ladder
c)
Straight spiral
d)
Double helix
|
|
Ananya Duney answered |
They are twist in a right handed double helical way therefore it's called double helix DNA which was given by Watson and crick
"hope it'll help"
"hope it'll help"
Which of the following is true about phosphodiester linkage?- a)5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
- b)3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
- c)5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
- d)3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
Correct answer is option 'A'. Can you explain this answer?
Which of the following is true about phosphodiester linkage?
a)
5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
b)
3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
c)
5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
d)
3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
|
|
Vaibhav Basu answered |
5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide.
In a DNA percentage of thymine is 20% then what will be the percentage of guanine?[2002]- a)20%
- b)40%
- c)30%
- d)60%
Correct answer is option 'C'. Can you explain this answer?
In a DNA percentage of thymine is 20% then what will be the percentage of guanine?
[2002]
a)
20%
b)
40%
c)
30%
d)
60%
|
Tejas Chavan answered |
According to Chargaff's rule, the ratio of purine bases to pyrimidine bases is equal.
A = T, C = G.
If T is 20% then A is 20% and C and G are 30%, 30%.
A = T, C = G.
If T is 20% then A is 20% and C and G are 30%, 30%.
Match column with column II and select the correct option from the given codes.
- a)A-(i), B-(i), C-(iii)
- b)A-(i), B-(iii), C-(ii)
- c)A-(iii), B-(i), C-(ii)
- d)A-(ii), B-(iii), C-(i)
Correct answer is option 'B'. Can you explain this answer?
Match column with column II and select the correct option from the given codes.
a)
A-(i), B-(i), C-(iii)
b)
A-(i), B-(iii), C-(ii)
c)
A-(iii), B-(i), C-(ii)
d)
A-(ii), B-(iii), C-(i)
|
Aabha Ambastha answered |
Correct answer is B as in DNA replication lagging strand (3'-5') forms discontinuous strand known as okazaki fragments
similarly DNA depending RNA polymerase is involved in transcription initiates by promotor at 5' end of the structural gene and lastly aminoacetylation process occurs in translation which is also called charging of amino acids to form polypeptide of protein
similarly DNA depending RNA polymerase is involved in transcription initiates by promotor at 5' end of the structural gene and lastly aminoacetylation process occurs in translation which is also called charging of amino acids to form polypeptide of protein
Which chromosome of human genome contains least number of genes?- a)Chromosome 12
- b)Chromosome X
- c)Chromosome Y
- d)Chromosome 1
Correct answer is option 'C'. Can you explain this answer?
Which chromosome of human genome contains least number of genes?
a)
Chromosome 12
b)
Chromosome X
c)
Chromosome Y
d)
Chromosome 1
|
|
Muraad answered |
Chromosome 1 contains a maximum of 2968 genes and chromosome y contains the minimum 231 genes.
DNA has genetic properties was revealed for the first time by- a)Chargaff
- b)Griffith
- c)Avery
- d)Wilkins
Correct answer is option 'C'. Can you explain this answer?
DNA has genetic properties was revealed for the first time by
a)
Chargaff
b)
Griffith
c)
Avery
d)
Wilkins
|
|
Pooja Choudhury answered |
The discovery that DNA has genetic properties was first revealed by Oswald Avery and his team of scientists in 1944. Avery was a molecular biologist who worked at the Rockefeller Institute for Medical Research in New York City.
Experiment
Avery and his team conducted a series of experiments to determine whether DNA was the genetic material responsible for the transformation of bacteria. They used two strains of Streptococcus pneumoniae, one that was virulent (able to cause disease) and one that was non-virulent. The virulent strain had a capsule made of a complex sugar that protected it from the immune system, while the non-virulent strain lacked this capsule and was easily destroyed by the immune system.
Results
Avery and his team extracted various biochemical components from the virulent strain of bacteria, including proteins, lipids, RNA, and DNA. They then mixed each of these components with the non-virulent strain to see if they could induce transformation. Only the DNA extract was able to transform the non-virulent strain into a virulent one, proving that DNA was the genetic material responsible for the transformation.
Conclusion
Avery's discovery was groundbreaking because it showed that DNA, which was previously thought to be a simple molecule with no biological significance, was in fact the carrier of genetic information. This discovery paved the way for the development of the field of molecular biology and our current understanding of genetics.
Experiment
Avery and his team conducted a series of experiments to determine whether DNA was the genetic material responsible for the transformation of bacteria. They used two strains of Streptococcus pneumoniae, one that was virulent (able to cause disease) and one that was non-virulent. The virulent strain had a capsule made of a complex sugar that protected it from the immune system, while the non-virulent strain lacked this capsule and was easily destroyed by the immune system.
Results
Avery and his team extracted various biochemical components from the virulent strain of bacteria, including proteins, lipids, RNA, and DNA. They then mixed each of these components with the non-virulent strain to see if they could induce transformation. Only the DNA extract was able to transform the non-virulent strain into a virulent one, proving that DNA was the genetic material responsible for the transformation.
Conclusion
Avery's discovery was groundbreaking because it showed that DNA, which was previously thought to be a simple molecule with no biological significance, was in fact the carrier of genetic information. This discovery paved the way for the development of the field of molecular biology and our current understanding of genetics.
The following code codes for which of the amino acid respectively?
AUG and GUG- a)Phenylalanine, tyrosine
- b)Methionine, valine
- c)Methionine, alanine
- d)Lysine, valine
Correct answer is option 'B'. Can you explain this answer?
The following code codes for which of the amino acid respectively?
AUG and GUG
AUG and GUG
a)
Phenylalanine, tyrosine
b)
Methionine, valine
c)
Methionine, alanine
d)
Lysine, valine
|
|
Riya Banerjee answered |
Three base triplets form a codon that codes for an amino acid. Thus AUG codes for methionine and GUG codes for Valine. AUG and GUG are both initiating codons for translation.
What is called Griffith effect?- a)DNA transcription
- b)RNA translation
- c)Bacterial transduction
- d)Bacterial transformation
Correct answer is option 'D'. Can you explain this answer?
What is called Griffith effect?
a)
DNA transcription
b)
RNA translation
c)
Bacterial transduction
d)
Bacterial transformation
|
|
Mathi Mathi answered |
Bacteria can take up forigen DNA in a process called transformation. It occurs after restriction digest and ligation and transfers newly made plasmid to bacteria.
Bacteria with a plasmid are antibiotic resistant, and each will form a colony.
Bacteria with a plasmid are antibiotic resistant, and each will form a colony.
The code AUG stands for- a)Aniline
- b)Methionine
- c)Glycine
- d)N-formyl methionine
Correct answer is option 'B'. Can you explain this answer?
The code AUG stands for
a)
Aniline
b)
Methionine
c)
Glycine
d)
N-formyl methionine
|
|
Vijay Bansal answered |
The genetic code consists of 64 triplets of nucleotides. These triplets are called codons.With three exceptions, each codon encodes for one of the 20 amino acids used in the synthesis of proteins. That produces some redundancy in the code: most of the amino acids being encoded by more than one codon.
One codon, AUG serves two related functions:
1. it signals the start of translation
2. it codes for the incorporation of the amino acid methionine (Met) into the growing polypeptide chain
Multiple alleles are present : [2015 RS]- a)At different loci on the same chromosome
- b)At the same locus of the chromosome
- c)On non-sister chromatids
- d)On different chromosomes
Correct answer is option 'B'. Can you explain this answer?
Multiple alleles are present : [2015 RS]
a)
At different loci on the same chromosome
b)
At the same locus of the chromosome
c)
On non-sister chromatids
d)
On different chromosomes
|
Krish Patel answered |
(b) All alleles of a gene are situated on the same loci of chromosome in organisms.
Which one of the following also acts as a catalyst in a bacterial cell ?[2011]- a)5 sr RNA
- b)sn RNA
- c)hn RNA
- d)23 sr RNA
Correct answer is option 'D'. Can you explain this answer?
Which one of the following also acts as a catalyst in a bacterial cell ?
[2011]
a)
5 sr RNA
b)
sn RNA
c)
hn RNA
d)
23 sr RNA
|
Abhishek Choudhary answered |
23sr RNA acts as a catalyst in a bacterial cell.
Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the category mentioned against it?[2008]- a)Thymine, Uracil - Pyrimidines
- b)Uracil, Cytosine - Pyrimidines
- c)Guanine, Adenine - Purines
- d)Adenine, Thymine - Purines
Correct answer is option 'D'. Can you explain this answer?
Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the category mentioned against it?
[2008]
a)
Thymine, Uracil - Pyrimidines
b)
Uracil, Cytosine - Pyrimidines
c)
Guanine, Adenine - Purines
d)
Adenine, Thymine - Purines
|
Lekshmi Banerjee answered |
Purine is an organic nitrogenous base sparingly soluble in water, that gives rise to a group of biologically important derivatives, notably adenine and guanine, which occur in nucleotides and nucleic acids (DNA and RNA).
Removal of introns and joining the exons in a defined order in a transcription unit is called:[2009]- a)tailing
- b)transformation
- c)capping
- d)splicing
Correct answer is option 'D'. Can you explain this answer?
Removal of introns and joining the exons in a defined order in a transcription unit is called:
[2009]
a)
tailing
b)
transformation
c)
capping
d)
splicing
|
Ayush Choudhury answered |
Splicing is the removal of introns and joining the exons in a defined order in a transcription unit. In molecular biology, splicing is a modification of RNA after transcription, in which introns are removed and exons are joined.
The hybridization of probes having radioactive isotopes with various sequence of nitrogen bases with ssVNTR is called?- a)Eastern blotting
- b)Southern blotting
- c)Western blotting
- d)Northern blotting
Correct answer is option 'B'. Can you explain this answer?
The hybridization of probes having radioactive isotopes with various sequence of nitrogen bases with ssVNTR is called?
a)
Eastern blotting
b)
Southern blotting
c)
Western blotting
d)
Northern blotting
|
|
Ankita Raj answered |
The hybridization of probes having radioactive isotopes with various sequence of nitrogen bases with ssVNTR is called southern blotting. Southern blotting is a laboratory technique used to detect a specific DNA sequence in a blood or tissue sample. A restriction enzyme is used to cut a sample of DNA into fragments that are separated using gel electrophoresis. The DNA fragments are transferred out of the gel to the surface of a membrane. The membrane is exposed to a DNA probe labeled with a radioactive or chemical tag. If the probe binds to the membrane, then the probe sequence is present in the sample. Hence, the correct answer is option 'B'.
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