All questions of Genetic Recombination and Gene Linkage for Grade 9 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.
Which of the following statements about the wobble hypothesis is correct?- a)The first base of the codon can pair with multiple bases of the anticodon
- b)The third base of the codon can pair with multiple bases of the anticodon
- c)The second base of the codon shows wobble pairing
- d)All three bases of the codon show wobble pairing
Correct answer is option 'B'. Can you explain this answer?
a)
The first base of the codon can pair with multiple bases of the anticodon
b)
The third base of the codon can pair with multiple bases of the anticodon
c)
The second base of the codon shows wobble pairing
d)
All three bases of the codon show wobble pairing
 | Lead Academy answered |
The correct answer is Option B - The third base of the codon can pair with multiple bases of the anticodon
According to the wobble hypothesis proposed by Francis Crick, flexible or non-standard pairing occurs at the third base of the codon (the 3' end of the codon) with the first base of the anticodon (the 5' end of the anticodon).
The first two positions of the codon pair by strict Watson-Crick base pairing, which enforces exact complementary geometry and prevents wobble at those positions.
This wobble at the third codon base explains the degeneracy of the genetic code, allowing fewer distinct tRNA species to recognise multiple codons that differ only in the third base.
For example, when inosine is present at the 5' position of an anticodon, it can pair with A, U or C, enabling a single tRNA to read several synonymous codons that vary at the third position.
Therefore, statements claiming wobble at the first or second codon bases, or claiming that all three bases wobble, are incorrect because only the third base of the codon exhibits this flexible pairing behaviour.
Which of the following statements about the genetic code is NOT correct?- a)The genetic code is comma-less
- b)The genetic code is overlapping
- c)The genetic code is nearly universal
- d)The genetic code is unambiguous
Correct answer is option 'B'. Can you explain this answer?
a)
The genetic code is comma-less
b)
The genetic code is overlapping
c)
The genetic code is nearly universal
d)
The genetic code is unambiguous
 | Ujwal Singh answered |
The Genetic Code Explained
The genetic code is a set of rules by which information encoded in genetic material is translated into proteins. Understanding its characteristics is crucial in molecular biology.
Key Characteristics of the Genetic Code
- Comma-less: The genetic code does not have gaps or punctuation between codons. This means that the codons are read continuously without any breaks.
- Overlapping: This statement is incorrect. The genetic code is not overlapping; instead, each nucleotide is part of only one codon. In an overlapping code, a single nucleotide could belong to multiple codons, which is not the case here.
- Nearly Universal: The genetic code is nearly universal across different organisms, with some minor variations. This universality allows for gene transfer between species.
- Unambiguous: Each codon specifies only one amino acid, meaning that there is no ambiguity in the translation process. This characteristic ensures that the same codon will always produce the same amino acid in virtually all organisms.
Conclusion
In summary, the correct answer is option 'B' because the genetic code is not overlapping; each nucleotide is assigned to a single codon, making the translation process straightforward and efficient. Understanding these properties helps in grasping how genetic information is expressed in living organisms.
The genetic code is a set of rules by which information encoded in genetic material is translated into proteins. Understanding its characteristics is crucial in molecular biology.
Key Characteristics of the Genetic Code
- Comma-less: The genetic code does not have gaps or punctuation between codons. This means that the codons are read continuously without any breaks.
- Overlapping: This statement is incorrect. The genetic code is not overlapping; instead, each nucleotide is part of only one codon. In an overlapping code, a single nucleotide could belong to multiple codons, which is not the case here.
- Nearly Universal: The genetic code is nearly universal across different organisms, with some minor variations. This universality allows for gene transfer between species.
- Unambiguous: Each codon specifies only one amino acid, meaning that there is no ambiguity in the translation process. This characteristic ensures that the same codon will always produce the same amino acid in virtually all organisms.
Conclusion
In summary, the correct answer is option 'B' because the genetic code is not overlapping; each nucleotide is assigned to a single codon, making the translation process straightforward and efficient. Understanding these properties helps in grasping how genetic information is expressed in living organisms.
Which of the following statements correctly explains the role of tRNA during translation?- a)tRNA carries genetic information from DNA to ribosome
- b)tRNA acts as a structural component of ribosome
- c)tRNA recognises codons on mRNA through its anticodon and brings specific amino acids
- d)tRNA synthesizes mRNA from DNA
Correct answer is option 'C'. Can you explain this answer?
Which of the following statements correctly explains the role of tRNA during translation?
a)
tRNA carries genetic information from DNA to ribosome
b)
tRNA acts as a structural component of ribosome
c)
tRNA recognises codons on mRNA through its anticodon and brings specific amino acids
d)
tRNA synthesizes mRNA from DNA
 | Avantika Mehta answered |
Role of tRNA in Translation
During the process of translation, tRNA (transfer RNA) plays a crucial role in protein synthesis. Here's a detailed explanation of its function:
Recognition of Codons
- tRNA molecules have a specific structure that includes an anticodon region.
- The anticodon is a sequence of three nucleotides that is complementary to the mRNA codons.
- This complementary pairing allows tRNA to accurately recognize and bind to the corresponding codon on the mRNA strand.
Bringing Specific Amino Acids
- Each tRNA molecule carries a specific amino acid attached to its 3' end.
- The amino acid corresponds to the codon that the tRNA recognizes.
- When a tRNA molecule matches with its complementary codon on the mRNA, it delivers the specific amino acid to the growing polypeptide chain.
Formation of Polypeptide Chain
- As the ribosome moves along the mRNA, tRNA molecules continue to bring in the appropriate amino acids in the sequence specified by the mRNA.
- This process continues until a stop codon is reached, completing the formation of the polypeptide chain.
Conclusion
- Thus, option 'C' accurately describes the function of tRNA during translation: it recognizes codons on mRNA through its anticodon and brings specific amino acids.
- Other options do not correctly represent the role of tRNA, highlighting the importance of understanding this key biological process.
During the process of translation, tRNA (transfer RNA) plays a crucial role in protein synthesis. Here's a detailed explanation of its function:
Recognition of Codons
- tRNA molecules have a specific structure that includes an anticodon region.
- The anticodon is a sequence of three nucleotides that is complementary to the mRNA codons.
- This complementary pairing allows tRNA to accurately recognize and bind to the corresponding codon on the mRNA strand.
Bringing Specific Amino Acids
- Each tRNA molecule carries a specific amino acid attached to its 3' end.
- The amino acid corresponds to the codon that the tRNA recognizes.
- When a tRNA molecule matches with its complementary codon on the mRNA, it delivers the specific amino acid to the growing polypeptide chain.
Formation of Polypeptide Chain
- As the ribosome moves along the mRNA, tRNA molecules continue to bring in the appropriate amino acids in the sequence specified by the mRNA.
- This process continues until a stop codon is reached, completing the formation of the polypeptide chain.
Conclusion
- Thus, option 'C' accurately describes the function of tRNA during translation: it recognizes codons on mRNA through its anticodon and brings specific amino acids.
- Other options do not correctly represent the role of tRNA, highlighting the importance of understanding this key biological process.
The clover-leaf structure of tRNA consists of how many arms or loops including the acceptor arm?- a)Three
- b)Four
- c)Five
- d)Six
Correct answer is option 'B'. Can you explain this answer?
The clover-leaf structure of tRNA consists of how many arms or loops including the acceptor arm?
a)
Three
b)
Four
c)
Five
d)
Six
 | Infinity Academy answered |
The correct answer is Option B - Four
tRNA is a single-stranded RNA of about ~76 nucleotides that folds into a characteristic cloverleaf secondary structure composed of four arms or loops.
- Acceptor arm: formed by base-pairing of the 5′ and 3′ ends and terminating in the conserved 3′-CCA sequence where the amino acid is covalently attached.
- D-arm: contains dihydrouridine residues and helps in recognition by aminoacyl-tRNA synthetases.
- Anticodon arm: contains the anticodon triplet that base-pairs with the mRNA codon during translation.
- TψC arm: contains the conserved TψC sequence (with pseudouridine, ψ) and participates in ribosome interaction.
There may also be a short variable loop (extra arm) in some tRNAs, but the canonical cloverleaf secondary structure is described by the four main arms listed above.
Therefore, the cloverleaf structure of tRNA consists of four arms including the acceptor arm.
Which of the following statements about tRNA are correct?
A. tRNA acts as an adapter molecule between mRNA and amino acids.
B. tRNA has a clover-leaf secondary structure.
C. The amino acid attachment site is at the 3' end having CCA sequence.
D. tRNA has a double-stranded linear structure.
E. All tRNA molecules have identical anticodon sequences.- a)A, B and C only
- b)B, C and D only
- c)A, D and E only
- d)C, D and E only
Correct answer is option 'A'. Can you explain this answer?
A. tRNA acts as an adapter molecule between mRNA and amino acids.
B. tRNA has a clover-leaf secondary structure.
C. The amino acid attachment site is at the 3' end having CCA sequence.
D. tRNA has a double-stranded linear structure.
E. All tRNA molecules have identical anticodon sequences.
a)
A, B and C only
b)
B, C and D only
c)
A, D and E only
d)
C, D and E only
 | Dr. Mohit Rajpoot answered |
Correct Option - A
The correct answer is Option A - A, B and C only
Statement A is correct: tRNA functions as an adapter molecule by carrying a specific amino acid and using its anticodon to pair with the mRNA codon at the ribosome, ensuring correct incorporation of amino acids into the growing polypeptide.
Statement B is correct: a single-stranded tRNA folds by internal base pairing into a characteristic clover-leaf secondary structure composed of the acceptor stem, D arm, anticodon arm, variable loop and TψC arm.
Statement C is correct: the amino acid attachment site is at the unpaired 3' end of tRNA, which contains the conserved terminal sequence CCA; the amino acid is esterified to the hydroxyl of the terminal adenosine.
Statement D is incorrect: tRNA is not a continuous double-stranded linear molecule; it is a single-stranded RNA that forms short double-helical stems by intramolecular base pairing, not a long double-stranded linear structure.
Statement E is incorrect: anticodon sequences vary between different tRNA species to recognise different codons; they are not identical for all tRNAs. The wobble at the third codon position allows some tRNAs to pair with more than one codon, but anticodons remain specific to each tRNA type.
Therefore, Statements A, B and C are correct and the remaining statements are incorrect, matching the listed option.
The process by which genetic information from DNA is copied into RNA is called:- a)Translation
- b)Replication
- c)Transcription
- d)Reverse transcription
Correct answer is option 'C'. Can you explain this answer?
a)
Translation
b)
Replication
c)
Transcription
d)
Reverse transcription
 | Top Rankers answered |
The correct answer is Option - Transcription
Transcription is the synthesis of an RNA molecule using a DNA strand as the template; this reaction is catalysed by the enzyme RNA polymerase.
In eukaryotes transcription occurs in the nucleus, while in prokaryotes it takes place in the cytoplasm; during the process, uracil pairs with adenine instead of thymine.
The stages of transcription are initiation, elongation and termination, producing a primary RNA transcript that may be processed to mature mRNA in eukaryotic cells.
For comparison: Replication makes DNA from DNA (enzyme: DNA polymerase); Translation decodes mRNA into a polypeptide at the ribosome with help from tRNA; Reverse transcription generates DNA from an RNA template using reverse transcriptase.
Thus, the process by which genetic information in DNA is copied into RNA is correctly identified as Transcription.
During transcription, the RNA polymerase moves along the DNA template strand in which direction?- a)3' to 5' direction along template strand
- b)5' to 3' direction along template strand
- c)Both directions simultaneously
- d)Direction is random
Correct answer is option 'A'. Can you explain this answer?
During transcription, the RNA polymerase moves along the DNA template strand in which direction?
a)
3' to 5' direction along template strand
b)
5' to 3' direction along template strand
c)
Both directions simultaneously
d)
Direction is random
 | EduRev NEET answered |
The correct answer is Option A - 3' to 5' direction along template strand
RNA polymerase moves along the DNA template strand in the 3' to 5' direction while synthesizing RNA.
As it moves, new ribonucleotides pair with the template and are added to the growing RNA chain at the 3'-OH end, so the RNA is synthesized in the 5' to 3' direction.
Incoming ribonucleoside triphosphates (rNTPs) form complementary base pairs with the template; the enzyme catalyses formation of the phosphodiester bond and releases pyrophosphate, enabling chain elongation in the 5' to 3' direction while the polymerase traverses the template from 3' to 5'.
Therefore, the movement of the polymerase along the template is in the 3' to 5' direction, which makes Option A correct.
Which of the following statements regarding the structure of tRNA is correct?
Statement I: The tRNA molecule has a clover-leaf structure in its two-dimensional form.
Statement II: The tRNA molecule has an inverted L-shaped structure in its three-dimensional form.- a)Both Statement I and Statement II are correct
- b)Statement I is correct but Statement II is incorrect
- c)Statement I is incorrect but Statement II is correct
- d)Both Statement I and Statement II are incorrect
Correct answer is option 'A'. Can you explain this answer?
Which of the following statements regarding the structure of tRNA is correct?
Statement I: The tRNA molecule has a clover-leaf structure in its two-dimensional form.
Statement II: The tRNA molecule has an inverted L-shaped structure in its three-dimensional form.
Statement I: The tRNA molecule has a clover-leaf structure in its two-dimensional form.
Statement II: The tRNA molecule has an inverted L-shaped structure in its three-dimensional form.
a)
Both Statement I and Statement II are correct
b)
Statement I is correct but Statement II is incorrect
c)
Statement I is incorrect but Statement II is correct
d)
Both Statement I and Statement II are incorrect
 | Ambition Institute answered |
The correct answer is Option A - Both Statement I and Statement II are correct
Statement I is correct: the two-dimensional secondary structure of a tRNA is conventionally drawn as a clover-leaf, consisting of the acceptor stem, the D-arm (with the D-loop), the anticodon arm (with the anticodon loop), the variable loop, and the TψC arm (with the TψC loop); the stems are formed by complementary base pairing.
Key molecular features in this representation include the conserved 3'-terminal CCA sequence on the acceptor stem, which is the site of amino-acid attachment, and several modified bases (for example, pseudouridine and dihydrouridine) that occur in specific loops.
Statement II is correct: the actual three-dimensional conformation of tRNA is an inverted L-shaped tertiary structure produced by folding and long-range interactions (notably between the D-loop and the TψC loop); this 3D fold places the anticodon at one end and the amino-acid attachment site (3'-CCA) at the opposite end, allowing proper interaction with both mRNA codon and aminoacyl-tRNA synthetases/ribosome during translation.
In summary, the clover-leaf is the correct description of tRNA secondary structure and the inverted L-shaped form is the correct description of its tertiary structure; therefore both statements are true.
How many total codons are present in the genetic code, including stop codons?- a)61
- b)62
- c)63
- d)64
Correct answer is option 'D'. Can you explain this answer?
a)
61
b)
62
c)
63
d)
64
| | Lead Academy answered |
The correct answer is Option D - 64
A codon is a sequence of three nucleotide bases on mRNA that specifies an amino acid or a translation stop signal; because there are 4 different nucleotide bases and each codon is a three-base triplet, the total number of possible codons is 43 = 64.
Of these 64 codons, 61 are sense codons that code for the standard amino acids, and 3 are stop codons that terminate translation; the stop codons are UAA, UAG and UGA.
Therefore, including the stop codons, the genetic code contains a total of 64 codons.
Match List-I with List-II:
Choose the correct answer from the options given below:- a)(A)-(II), (B)-(I), (C)-(IV), (D)-(III)
- b)(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
- c)(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
- d)(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
Correct answer is option 'A'. Can you explain this answer?
Match List-I with List-II:
Choose the correct answer from the options given below:
a)
(A)-(II), (B)-(I), (C)-(IV), (D)-(III)
b)
(A)-(I), (B)-(II), (C)-(III), (D)-(IV)
c)
(A)-(III), (B)-(IV), (C)-(II), (D)-(I)
d)
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
| | Dr. Mohit Rajpoot answered |
The correct answer is Option A - A: (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
Unambiguous code means that each codon specifies only one particular amino acid, which corresponds to statement (II).
Degenerate code (or redundant code) means that more than one codon can specify the same amino acid; this matches statement (I). The redundancy commonly arises from variability at the third base of the codon (wobble position).
Universal code denotes that the genetic code is conserved in most organisms, i.e., the same codon assignments are used broadly across species; this corresponds to statement (IV).
Non-overlapping code means that codons are read as discrete, sequential triplets without sharing nucleotides between adjacent codons, so codons do not overlap; this matches statement (III).
All four mappings in the chosen option are therefore correct, since each term aligns with the corresponding definition given above.
The anticodon region of tRNA molecule is located in which of the following loops?- a)DHU loop
- b)TψC loop
- c)Anticodon loop
- d)Acceptor arm
Correct answer is option 'C'. Can you explain this answer?
a)
DHU loop
b)
TψC loop
c)
Anticodon loop
d)
Acceptor arm
| | Dr. Mohit Rajpoot answered |
Correct Option - C
The correct answer is Option C - Anticodon loop
The tRNA molecule adopts a characteristic cloverleaf secondary structure composed of the acceptor arm (at the 3' end with the conserved CCA sequence), the DHU loop, the anticodon loop, and the TψC loop.
The acceptor arm carries the amino acid that becomes attached to the terminal adenosine of the CCA sequence by an aminoacylation reaction catalysed by aminoacyl-tRNA synthetases.
The anticodon is a triplet of nucleotides that is complementary to the mRNA codon; these three bases are positioned within the anticodon loop, enabling specific codon-anticodon pairing during translation on the ribosome.
Because the anticodon triplet is located in the anticodon loop, the option stating the Anticodon loop is correct.
The genetic code is described as degenerate because:- a)One codon codes for multiple amino acids
- b)Multiple codons can code for the same amino acid
- c)Some amino acids are not coded by any codon
- d)Each codon codes for a unique amino acid only
Correct answer is option 'B'. Can you explain this answer?
a)
One codon codes for multiple amino acids
b)
Multiple codons can code for the same amino acid
c)
Some amino acids are not coded by any codon
d)
Each codon codes for a unique amino acid only
| | Infinity Academy answered |
The correct answer is Option B - Multiple codons can code for the same amino acid
A codon is a sequence of three nucleotides (a triplet) on messenger RNA that specifies a single amino acid or a termination signal during translation.
There are 43 = 64 possible codons but only 20 standard amino acids; this numerical disparity makes it possible for more than one codon to specify the same amino acid.
Because different codons can correspond to the same amino acid, the genetic code is described as degenerate (also termed redundant).
Most redundancy occurs at the third base of the codon (the wobble position), where nonstandard base pairing allows one tRNA anticodon to recognise multiple codons for the same amino acid.
Certain codons have unique roles: AUG acts as the usual start codon and codes for methionine, while UAA, UAG, UGA are stop codons that do not code for amino acids; these facts do not contradict the degeneracy of the code.
Thus, the statement in Option B correctly captures why the genetic code is called degenerate.
The amino acid attachment site in tRNA molecule is located at:- a)Anticodon loop
- b)DHU loop
- c)3' end with CCA sequence
- d)TψC loop
Correct answer is option 'C'. Can you explain this answer?
a)
Anticodon loop
b)
DHU loop
c)
3' end with CCA sequence
d)
TψC loop
| | Dr. Mohit Rajpoot answered |
Correct Option - The correct option label i.e. C
The correct answer is Option C - 3' end with CCA sequence
Transfer RNA has a cloverleaf secondary structure with an acceptor stem formed by base-pairing between the 5' and 3' ends; the unpaired 3' end terminates in the conserved CCA sequence.
The amino acid is covalently attached to the 3' terminal adenosine of this CCA sequence via an ester linkage, catalysed by the enzyme aminoacyl-tRNA synthetase.
The anticodon loop contains the triplet that base-pairs with the mRNA codon and is not the site of amino acid attachment; the DHU loop and the TψC loop are other characteristic tRNA loops with distinct modified bases.
Hence, the amino acid attachment site is correctly identified as the 3' end with CCA sequence, making Option C the correct choice.
Which of the following is the initiator codon that also codes for methionine?- a)UAA
- b)AUG
- c)UUU
- d)GGG
Correct answer is option 'B'. Can you explain this answer?
a)
UAA
b)
AUG
c)
UUU
d)
GGG
| | Top Rankers answered |
Correct Option - B
The correct answer is Option B - AUG
AUG functions as the universal start codon that signals the beginning of translation and codes for the amino acid methionine.
In prokaryotes, the initiator tRNA brings N-formylmethionine (fMet) to the ribosome while recognizing the AUG codon; in eukaryotes, the initiator tRNA brings an unmodified methionine, but the initiating codon remains AUG.
The other listed codons are not initiator codons: UAA is a stop codon, UUU codes for phenylalanine, and GGG codes for glycine, so they do not serve as start codons that specify methionine.
Therefore, AUG is the codon that both initiates translation and specifies methionine.
Which one of the following CANNOT be a recognition sequence for a Type II restriction enzyme? - a)GAATTC
- b)AGCT
- c)GCGGCCGC
- d)ATGCCT
Correct answer is option 'D'. Can you explain this answer?
Which one of the following CANNOT be a recognition sequence for a Type II restriction enzyme?
a)
GAATTC
b)
AGCT
c)
GCGGCCGC
d)
ATGCCT
 | Priya Singh answered |
Explanation:
Recognition sequences are specific DNA sequences that are recognized and cleaved by Type II restriction enzymes. These enzymes typically recognize palindromic sequences, which read the same forward and backward on both strands of DNA. The recognition sequence is usually 4-8 base pairs in length.
Let's analyze each option to determine if it can be a recognition sequence for a Type II restriction enzyme:
a) GAATTC: This sequence is the recognition sequence for the restriction enzyme EcoRI. It is a palindromic sequence, reading the same forward and backward on both strands: 5'-GAATTC-3' on one strand and 3'-CTTAAG-5' on the complementary strand.
b) AGCT: This sequence is not palindromic and therefore cannot be a recognition sequence for a Type II restriction enzyme. It reads 5'-AGCT-3' on one strand and 3'-TCGA-5' on the complementary strand.
c) GCGGCCGC: This sequence is the recognition sequence for the restriction enzyme NotI. It is a palindromic sequence: 5'-GCGGCCGC-3' on one strand and 3'-CGCCGGCG-5' on the complementary strand.
d) ATGCCT: This sequence is not palindromic and therefore cannot be a recognition sequence for a Type II restriction enzyme. It reads 5'-ATGCCT-3' on one strand and 3'-TACGGA-5' on the complementary strand.
Therefore, option D (ATGCCT) cannot be a recognition sequence for a Type II restriction enzyme because it is not palindromic. The correct answer is D.
Recognition sequences are specific DNA sequences that are recognized and cleaved by Type II restriction enzymes. These enzymes typically recognize palindromic sequences, which read the same forward and backward on both strands of DNA. The recognition sequence is usually 4-8 base pairs in length.
Let's analyze each option to determine if it can be a recognition sequence for a Type II restriction enzyme:
a) GAATTC: This sequence is the recognition sequence for the restriction enzyme EcoRI. It is a palindromic sequence, reading the same forward and backward on both strands: 5'-GAATTC-3' on one strand and 3'-CTTAAG-5' on the complementary strand.
b) AGCT: This sequence is not palindromic and therefore cannot be a recognition sequence for a Type II restriction enzyme. It reads 5'-AGCT-3' on one strand and 3'-TCGA-5' on the complementary strand.
c) GCGGCCGC: This sequence is the recognition sequence for the restriction enzyme NotI. It is a palindromic sequence: 5'-GCGGCCGC-3' on one strand and 3'-CGCCGGCG-5' on the complementary strand.
d) ATGCCT: This sequence is not palindromic and therefore cannot be a recognition sequence for a Type II restriction enzyme. It reads 5'-ATGCCT-3' on one strand and 3'-TACGGA-5' on the complementary strand.
Therefore, option D (ATGCCT) cannot be a recognition sequence for a Type II restriction enzyme because it is not palindromic. The correct answer is D.
During transcription, which of the following correctly describes the role of the coding strand?- a)It is used by RNA polymerase as a template for RNA synthesis
- b)It has the same sequence as RNA except thymine is replaced by uracil
- c)It is complementary to the RNA formed
- d)It is synthesized during transcription
Correct answer is option 'B'. Can you explain this answer?
During transcription, which of the following correctly describes the role of the coding strand?
a)
It is used by RNA polymerase as a template for RNA synthesis
b)
It has the same sequence as RNA except thymine is replaced by uracil
c)
It is complementary to the RNA formed
d)
It is synthesized during transcription
| | Ambition Institute answered |
The coding strand (non-template strand) has the same sequence as the RNA transcript except that thymine (T) is replaced by uracil (U). The template strand is actually used by RNA polymerase for RNA synthesis.
Match List-I with List-II:
List-I (Component) List-II (Function in transcription) (A) Promoter (I) Signals the end of transcription (B) Template strand (II) Recognition site for RNA polymerase (C) Terminator (III) Provides the nucleotide sequence for RNA synthesis (D) Coding strand (IV) Has same sequence as mRNA (except T for U)
Choose the correct answer from the options given below:- a)(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
- b)(A)-(I), (B)-(IV), (C)-(II), (D)-(III)
- c)(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
- d)(A)-(IV), (B)-(I), (C)-(III), (D)-(II)
Correct answer is option 'A'. Can you explain this answer?
| List-I (Component) | List-II (Function in transcription) |
|---|---|
| (A) Promoter | (I) Signals the end of transcription |
| (B) Template strand | (II) Recognition site for RNA polymerase |
| (C) Terminator | (III) Provides the nucleotide sequence for RNA synthesis |
| (D) Coding strand | (IV) Has same sequence as mRNA (except T for U) |
a)
(A)-(II), (B)-(III), (C)-(I), (D)-(IV)
b)
(A)-(I), (B)-(IV), (C)-(II), (D)-(III)
c)
(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
d)
(A)-(IV), (B)-(I), (C)-(III), (D)-(II)
| | Infinity Academy answered |
Correct Option - A
The correct answer is Option A - (A)-(II), (B)-(III), (C)-(I), (D)-(IV)
Promoter is a specific DNA sequence that serves as the recognition site for RNA polymerase and associated transcription factors; it directs the enzyme to the correct start site for transcription initiation.
The template strand is the DNA strand that is read by RNA polymerase and therefore provides the nucleotide sequence for RNA synthesis; the RNA produced is complementary to this strand.
The terminator is a DNA sequence that causes RNA polymerase to stop transcription and release the nascent RNA, thus it signals the end of transcription.
The coding strand (also called the non-template strand) has the same nucleotide sequence as the produced mRNA except that every thymine (T) in DNA corresponds to uracil (U) in RNA; it is not used as the direct template during synthesis.
Each component therefore matches as follows: Promoter → recognition site for RNA polymerase; Template strand → provides sequence for RNA synthesis; Terminator → signals end of transcription; Coding strand → same sequence as mRNA (T replaced by U), which confirms the given option.
Which of the following statements regarding the genetic code are correct?
A. The genetic code is nearly universal across all organisms.
B. The genetic code is overlapping in nature.
C. The codon AUG has a dual function as both initiator and codes for methionine.
D. The genetic code is degenerate with 61 codons coding for amino acids.
E. All stop codons also code for amino acids.- a)A, B and C only
- b)A, C and D only
- c)B, D and E only
- d)A, B and D only
Correct answer is option 'B'. Can you explain this answer?
A. The genetic code is nearly universal across all organisms.
B. The genetic code is overlapping in nature.
C. The codon AUG has a dual function as both initiator and codes for methionine.
D. The genetic code is degenerate with 61 codons coding for amino acids.
E. All stop codons also code for amino acids.
a)
A, B and C only
b)
A, C and D only
c)
B, D and E only
d)
A, B and D only
| | Dr. Mohit Rajpoot answered |
The correct answer is Option B - A, C and D only
Statement A is correct: the genetic code is described as nearly universal, meaning that the same codon assignments apply across most organisms with only a few well-characterised exceptions (for example, some mitochondrial codes and a few protists and bacteria).
Statement B is incorrect: the standard genetic code is non-overlapping, so each nucleotide is read as part of only one codon in a sequential, triplet reading frame; overlapping codons (where a nucleotide would belong to more than one codon) are not a feature of canonical translation.
Statement C is correct: the codon AUG functions as the primary start codon to initiate translation and also specifies the amino acid methionine; in prokaryotes the initiating methionine is commonly modified to formylmethionine (fMet).
Statement D is correct: the genetic code is degenerate because several codons can specify the same amino acid. Out of the 64 codons possible, 3 stop codons exist, leaving 61 codons that code for amino acids.
Statement E is incorrect: the stop codons (UAA, UAG, UGA) do not code for amino acids; they signal termination of polypeptide synthesis.
Thus, the true statements are A, C and D, which corresponds to the option stated above.
During transcription in eukaryotes, which enzyme is primarily responsible for synthesizing mRNA?- a)RNA polymerase I
- b)RNA polymerase II
- c)RNA polymerase III
- d)DNA polymerase
Correct answer is option 'B'. Can you explain this answer?
a)
RNA polymerase I
b)
RNA polymerase II
c)
RNA polymerase III
d)
DNA polymerase
| | Top Rankers answered |
The correct answer is Option B - RNA polymerase II
RNA polymerase II is the nuclear enzyme in eukaryotes that synthesizes the primary transcripts of protein-coding genes, i.e., the precursors of messenger RNA.
This enzyme transcribes DNA into RNA in the 5'→3' direction using ribonucleoside triphosphates as substrates and it initiates transcription without the need for a DNA primer (no primer requirement).
The initial product synthesized by RNA polymerase II is pre-mRNA (heterogeneous nuclear RNA), which is processed by 5' capping, splicing (removal of introns), and 3' polyadenylation to form mature mRNA.
For contrast, RNA polymerase I primarily transcribes most ribosomal RNA (rRNA) in the nucleolus, and RNA polymerase III transcribes tRNA and 5S rRNA.
DNA polymerase, by comparison, functions in DNA replication, requires a primer, and synthesizes DNA rather than RNA, so it does not synthesize mRNA.
Therefore, the enzyme responsible for synthesizing mRNA in eukaryotes is RNA polymerase II.
Which of the following is NOT a stop codon in the genetic code?- a)UAA
- b)UAG
- c)UGA
- d)AUG
Correct answer is option 'D'. Can you explain this answer?
a)
UAA
b)
UAG
c)
UGA
d)
AUG
| | Top Rankers answered |
The correct answer is Option D - AUG
The triplet codons UAA, UAG and UGA function as stop codons (termination codons) in the genetic code.
Stop codons do not code for any amino acid; they signal the termination of translation by allowing release factors to bind and promote release of the newly synthesized polypeptide from the ribosome.
By contrast, AUG is the start codon and specifies the amino acid methionine (and the initiating amino acid is N-formylmethionine in prokaryotes). Thus AUG initiates translation rather than terminating it.
Therefore, AUG is not a stop codon, which makes Option D the correct choice.
Match List-I with List-II:
List-I (Codon) List-II (Function/Amino acid) (A) UAA (I) Methionine (B) AUG (II) Stop codon (C) UUU (III) Phenylalanine (D) UAG (IV) Stop codon (amber)
Choose the correct answer from the options given below:- a)(A)-(II), (B)-(I), (C)-(III), (D)-(IV)
- b)(A)-(I), (B)-(II), (C)-(IV), (D)-(III)
- c)(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
- d)(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
Correct answer is option 'A'. Can you explain this answer?
| List-I (Codon) | List-II (Function/Amino acid) |
|---|---|
| (A) UAA | (I) Methionine |
| (B) AUG | (II) Stop codon |
| (C) UUU | (III) Phenylalanine |
| (D) UAG | (IV) Stop codon (amber) |
a)
(A)-(II), (B)-(I), (C)-(III), (D)-(IV)
b)
(A)-(I), (B)-(II), (C)-(IV), (D)-(III)
c)
(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
d)
(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
| | Dr. Mohit Rajpoot answered |
Correct Option - A
The correct answer is Option A - A: (A)-(II), (B)-(I), (C)-(III), (D)-(IV)
Codon denotes a triplet of ribonucleotides on mRNA that specifies either an amino acid or a translation stop signal.
AUG functions as the principal start codon in translation and encodes the amino acid Methionine, so (B) → (I) is correct.
UAA is one of the standard stop codons that terminates polypeptide synthesis; therefore (A) → (II) is correct.
UAG is also a stop codon, specifically called the amber codon, so (D) → (IV) is correct.
UUU specifies the amino acid Phenylalanine, hence (C) → (III) is correct.
Each codon-to-function mapping above independently verifies the matched pairs in the chosen option; therefore Option A is correct.
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