All questions of Molecular Basis of Inheritance for NEET Exam

D

Overview of Protein Synthesis Steps
Protein synthesis is a vital biological process that involves several key steps. The correct sequence of events is crucial for accurate translation of mRNA into proteins.
Steps in the Correct Sequence
1. Charging or Aminoacylation of tRNA (iii)
- Before translation, tRNA molecules are charged with their respective amino acids by specific enzymes called aminoacyl-tRNA synthetases.
2. Attachment of mRNA and Smaller Sub-unit of Ribosome (ii)
- The small ribosomal subunit binds to the mRNA, scanning for the start codon (AUG), which signals the beginning of translation.
3. Attachment of Larger Sub-unit of Ribosome to the mRNA-tRNAMet Complex (iv)
- Once the start codon is recognized, the large ribosomal subunit attaches to form a complete ribosome, ready for translation.
4. Codon-Anticodon Reaction Between mRNA and Aminoacyl tRNA Complex (i)
- The charged tRNA with its corresponding amino acid binds to the mRNA codon through complementary base pairing between the codon and the tRNA's anticodon.
5. Linking of Adjacent Amino Acids (v)
- The ribosome facilitates the formation of peptide bonds between the amino acids brought by the tRNAs, elongating the polypeptide chain.
6. Formation of Polypeptide Chain (vi)
- As the ribosome moves along the mRNA, the polypeptide chain grows until a stop codon is reached, leading to the termination of translation.
Conclusion
The correct sequence (iii) → (ii) → (iv) → (i) → (v) → (vi) reflects the organized process of protein synthesis, ensuring that proteins are accurately synthesized based on the genetic code presented by mRNA. Thus, option 'D' is the correct answer.

Answer:

The process of transformation is a genetic process in which foreign genetic material is introduced into a cell, resulting in a genetic change. In this process, the foreign DNA is taken up by the recipient cell and incorporated into its own genome. However, not all enzymes have an effect on the process of transformation.

Enzymes that do not affect the process of transformation:
The correct answer is option C, which includes the enzymes B. RNase, C. Peptidase, and D. Lipase. Let's understand why these enzymes do not have an effect on the process of transformation:

1. RNase:
RNase is an enzyme that degrades RNA molecules. However, in the process of transformation, the focus is on DNA molecules and their uptake by the recipient cell. Since RNase specifically targets RNA and not DNA, it does not have any effect on the transformation process.

2. Peptidase:
Peptidase is an enzyme that catalyzes the breakdown of peptides into amino acids. It is involved in protein metabolism and does not directly interact with DNA or RNA. Therefore, it does not affect the process of transformation.

3. Lipase:
Lipase is an enzyme that catalyzes the breakdown of lipids (fats). It does not have any direct involvement in DNA or RNA metabolism. Therefore, lipase has no effect on the process of transformation.

Enzymes that do affect the process of transformation:
The enzyme A. DNase, on the other hand, does have an effect on the process of transformation. DNase is an enzyme that degrades DNA molecules. If DNase is present in the environment during the transformation process, it can degrade the foreign DNA that has been taken up by the recipient cell, preventing its incorporation into the genome. Therefore, DNase can hinder the success of transformation.

To summarize, enzymes like DNase can have a negative impact on the process of transformation by degrading foreign DNA. However, enzymes like RNase, peptidase, and lipase do not affect the transformation process as they do not directly interact with DNA molecules. Therefore, the correct answer is option C.

First of all this question's language is somewhat wrong.. there should be mentioned if they're talking about eukaryotes or prokaryotes.. For prokaryotes it's initiation transcriptional level and for eukaryotes answer would be all of these

Explanation:

Capping of hnRNA:
- The process of adding a modified nucleotide (menthyl guanosine triphosphate) to the 5' end of hnRNA is known as capping.
- This modification protects the mRNA from degradation and helps in the recognition of the mRNA by ribosomes during translation.

Function of capping:
- The capping of hnRNA is essential for the proper processing and translation of mRNA.
- It also plays a role in regulating gene expression and facilitating the export of mRNA from the nucleus to the cytoplasm.

Importance of capping:
- Capping helps in the stability of mRNA by protecting it from exonuclease degradation.
- It also assists in the initiation of translation by providing a recognition signal for ribosomes.
Therefore, in the given question, the addition of menthyl guanosine triphosphate to the 5' end of hnRNA is a part of the capping process, which is crucial for the proper functioning of mRNA in gene expression.

A complements T and C compliments G

Henceforth the complimentary DNA strand to ATGCATGCA will be "TACGTACFT" :)

In a mRNA molecule, untranslated regions (UTRs) are present at both the 5' end (before the start codon) and the 3' end (after the stop codon). The correct answer is option 'C'.

Explanation:
mRNA (messenger RNA) is a single-stranded RNA molecule that carries the genetic information from DNA to the ribosomes, where it serves as a template for protein synthesis. It contains several regions, including the coding region and the untranslated regions (UTRs).

1. Untranslated Regions (UTRs):
- Untranslated regions (UTRs) are the regions at the ends of the mRNA molecule that are not translated into protein. They are located both at the 5' end (before the start codon) and the 3' end (after the stop codon) of the mRNA molecule.
- UTRs play important regulatory roles in gene expression by influencing the stability, localization, and translation efficiency of the mRNA molecule.
- The 5' UTR, also known as the leader sequence, is present at the beginning of the mRNA molecule. It contains regulatory elements such as the Kozak sequence, which is involved in the initiation of translation.
- The 3' UTR, also known as the trailer sequence, is present at the end of the mRNA molecule. It contains regulatory elements such as binding sites for microRNAs and RNA-binding proteins, which can control mRNA stability and translation.

2. Coding Region:
- The coding region of mRNA contains the nucleotide sequence that encodes the amino acid sequence of a protein. It is located between the start codon (usually AUG) and the stop codon (UAA, UAG, or UGA).
- During translation, the ribosomes read the codons in the mRNA molecule and assemble the corresponding amino acids to form a protein.

In conclusion, untranslated regions (UTRs) are present at both the 5' and 3' ends of an mRNA molecule. They play important regulatory roles in gene expression by influencing mRNA stability, localization, and translation efficiency.

Polycistronic mRNA in Bacteria and Prokaryotes
Polycistronic mRNA refers to a type of messenger RNA that carries the information for multiple genes in a single transcript. This phenomenon is commonly observed in bacteria and prokaryotes.

Bacteria
- In bacteria, the genetic material is organized in a single circular chromosome, and the transcription and translation processes are coupled.
- Bacterial mRNA is often polycistronic, meaning that a single mRNA molecule can encode multiple proteins that are part of the same functional pathway or protein complex.
- This arrangement allows for the coordinated expression of multiple genes that are involved in related cellular functions.

Prokaryotes
- Prokaryotes, including bacteria, lack a true nucleus and have a simpler organization of genetic material compared to eukaryotic cells.
- In prokaryotes, such as archaea, polycistronic mRNA is also common, serving as an efficient way to regulate gene expression and coordinate the synthesis of multiple proteins.
- The presence of polycistronic mRNA in prokaryotes allows for the rapid adaptation to changing environmental conditions and the simultaneous expression of genes that are functionally related.

Conclusion
Polycistronic mRNA is a characteristic feature of bacteria and prokaryotes, where it plays a crucial role in the regulation of gene expression and coordination of protein synthesis. This unique feature highlights the differences in gene expression mechanisms between prokaryotic and eukaryotic cells.

Explanation:

The genetic code is a set of rules by which the DNA or mRNA sequence is translated into the amino acid sequence in a protein. Each amino acid is represented by a sequence of three nucleotides called codons. However, there are more codons than there are amino acids, which means that some amino acids are coded by more than one codon. This property of the genetic code is referred to as degeneracy.

Reasons for degeneracy:
The degeneracy of the genetic code has several reasons:

1. Redundancy: There are 20 different amino acids but only four different nucleotides (A, T/U, G, C). Since each codon is composed of three nucleotides, there are a total of 64 possible codons (4^3). Therefore, multiple codons can code for the same amino acid, leading to redundancy or degeneracy.

2. Protective mechanism: Degeneracy provides a protective mechanism against mutations. Mutations in the DNA sequence can lead to changes in a codon, but if the codon still codes for the same amino acid, the resulting protein may not be functionally affected.

3. Evolutionary advantage: Degeneracy allows for more flexibility in the genetic code. It provides a buffer against errors in DNA replication or transcription, as well as allowing for adaptation to changing environmental conditions.

Examples:
Some examples of degeneracy in the genetic code include:

1. The amino acid leucine is coded by six different codons: UUA, UUG, CUU, CUC, CUA, and CUG.

2. The amino acid serine is coded by six different codons: UCU, UCC, UCA, UCG, AGU, and AGC.

3. The amino acid arginine is coded by six different codons: CGU, CGC, CGA, CGG, AGA, and AGG.

Significance:
The degeneracy of the genetic code allows for redundancy and flexibility, which is important for several biological processes:

1. Translation efficiency: Multiple codons coding for the same amino acid allow for faster and more efficient protein synthesis.

2. Evolutionary adaptation: The degeneracy of the genetic code allows for the accumulation of genetic variations over time, leading to the evolution of new traits and species.

3. Genetic engineering: The ability to use different codons to code for the same amino acid is utilized in genetic engineering techniques to optimize protein expression in various organisms.

In conclusion, the genetic code is degenerate because some amino acids are coded by more than one codon. This degeneracy provides redundancy, protection against mutations, and flexibility in the genetic code, allowing for efficient protein synthesis and evolutionary adaptation.

Answer:

Promoter:
The site on a DNA molecule where RNA polymerase binds during transcription is called a promoter. Promoters are specific sequences of DNA that are located near the beginning of a gene.

Function of Promoter:
- Promoters play a crucial role in initiating the process of transcription by providing a binding site for RNA polymerase.
- They help in determining the starting point for transcription and also regulate the expression of genes by controlling the rate of transcription.

Types of Promoters:
- There are different types of promoters such as constitutive promoters, which are always active, and inducible promoters, which are activated in response to specific signals or environmental conditions.

Structure of Promoter:
- Promoters consist of several components, including the TATA box, which is a short sequence of DNA that helps in positioning RNA polymerase at the correct site to start transcription.
- Other elements like enhancers and silencers may also be present in the promoter region, which can influence transcriptional activity.

Importance of Promoter:
- Promoters are essential for the proper regulation of gene expression in cells. They ensure that genes are transcribed at the right time and in the right amount, which is crucial for the normal functioning of living organisms.
In conclusion, the promoter is a critical component of the transcription process as it serves as the binding site for RNA polymerase and helps in initiating the synthesis of RNA from DNA.

Role of tRNA in Protein Synthesis
During protein synthesis, the translation process requires the transportation of amino acids to the ribosome, where they are assembled into proteins. The molecule responsible for this critical function is transfer RNA (tRNA).
What is tRNA?
- tRNA is a type of RNA that serves as an adaptor molecule in protein synthesis.
- It has a unique structure with an anticodon region that pairs with the corresponding codon on the messenger RNA (mRNA).
- Each tRNA molecule is specific to one amino acid, which it carries to the ribosome.
Function of tRNA
- Amino Acid Transport: tRNA transports amino acids from the amino acid pool in the cytoplasm to the ribosome.
- Codon Recognition: The anticodon on tRNA matches with the codon on mRNA, ensuring the correct amino acid is incorporated into the growing polypeptide chain.
- Peptide Bond Formation: Once the correct tRNA is in place at the ribosome, the amino acid it carries is added to the nascent protein via peptide bonds.
Importance in Translation
- tRNA is essential for translating the genetic code carried by mRNA into a specific sequence of amino acids.
- Without tRNA, the ribosome would not be able to correctly interpret the mRNA sequence, resulting in nonfunctional or incorrectly formed proteins.
In summary, tRNA plays a vital role in translating the genetic information from mRNA into functional proteins by transporting the necessary amino acids during protein synthesis. Thus, the correct answer to the question is option 'C' - tRNA.

Enzymes involved in DNA synthesis

There are several enzymes involved in DNA synthesis, apart from DNA polymerase. These enzymes play crucial roles in different steps of DNA replication. The enzymes involved in DNA synthesis include:

1. Topoisomerase:
Topoisomerase is an enzyme that helps in relieving the tension generated during DNA replication. It does so by creating temporary breaks in the DNA strands, allowing them to unwind and preventing the DNA from becoming overwound or tangled. This process is essential for the smooth movement of the replication fork and ensures accurate DNA replication.

2. Helicase:
Helicase is an enzyme responsible for unwinding the DNA double helix during replication. It uses energy from ATP hydrolysis to break the hydrogen bonds between the complementary base pairs, separating the two DNA strands. This unwinding process creates the replication fork, where DNA polymerase can then bind and synthesize new DNA strands.

3. RNA primase:
RNA primase is an enzyme that synthesizes short RNA primers that are necessary for DNA replication. These primers provide a starting point for DNA polymerase to initiate DNA synthesis. RNA primase synthesizes a short RNA segment complementary to the DNA template, which is later replaced by DNA synthesized by DNA polymerase.

Why all of these enzymes are involved in DNA synthesis?

DNA replication is a complex process that requires the coordinated action of multiple enzymes. Each enzyme performs a specific function to ensure accurate and efficient DNA synthesis. Here's why all of these enzymes are involved:

- Topoisomerase: Without topoisomerase, the tension generated during DNA unwinding would hinder the progression of the replication fork. By creating temporary breaks in the DNA strands, topoisomerase allows for smooth unwinding and prevents DNA damage.

- Helicase: Helicase plays a crucial role in unwinding the DNA double helix, separating the two strands so that DNA polymerase can synthesize new strands. It is responsible for the initiation of DNA replication and is essential for the progression of the replication fork.

- RNA primase: RNA primase synthesizes short RNA primers that are necessary for DNA replication. These primers provide a starting point for DNA polymerase to begin synthesizing the new DNA strands. Without RNA primase, DNA polymerase would not have a primer to initiate DNA synthesis.

By working together, these enzymes ensure the accurate and efficient replication of DNA, which is essential for the maintenance of genetic information and cell division.

It's the central dogma given by Crick which depicts the unidirectional flow of information

DNA to hRNA is transcription
hRNA to mRNA is splicing in eukaryotes
mRNA to proteins is translation !!!

So correct option is "C" :)

The correct answer is option 'C': Transcription starts with the promoter region and ends in the terminator region. Let's break down the process of transcription and explain why this is the correct answer.

Transcription is the first step in gene expression, where the information encoded in DNA is transcribed into RNA. This process involves several key regions and factors that play important roles. Let's discuss each option and why they are correct or incorrect.

a) Starts with TATA box:
- The TATA box is a DNA sequence found upstream of the transcription start site in many eukaryotic genes. It serves as a binding site for transcription factors and helps in the initiation of transcription.
- While the TATA box is an important element in the promoter region, it is not the starting point of transcription. Therefore, option 'a' is incorrect.

b) Starts with palindromic regions and ends with rho factor:
- Palindromic regions are DNA sequences that read the same on both strands when oriented in the same direction. They can be involved in various regulatory processes, but they are not the starting points of transcription.
- The rho factor is a protein involved in the termination of transcription in prokaryotes. It binds to the RNA molecule and causes the release of the RNA from the DNA template.
- While these regions and factors are involved in transcription, they do not mark the starting point. Therefore, option 'b' is incorrect.

c) Starts with promoter region and ends in terminator region:
- The promoter region is the DNA sequence where RNA polymerase binds and initiates transcription. It contains specific sequences and elements, such as the TATA box, that help in the recognition and binding of transcription factors.
- The terminator region is a DNA sequence that signals the end of transcription. It contains signals for the termination of RNA synthesis and the release of the RNA molecule.
- Therefore, option 'c' is correct as transcription starts with the promoter region and ends in the terminator region.

d) Starts with CAAT region:
- The CAAT box is another DNA sequence found in the promoter region of many eukaryotic genes. It is involved in the binding of transcription factors and the regulation of gene expression.
- While the CAAT region is important in the promoter, it is not the starting point of transcription. Therefore, option 'd' is incorrect.

In summary, transcription starts with the promoter region and ends in the terminator region. These regions contain specific sequences and elements that play crucial roles in the initiation and termination of transcription.

Criteria for a molecule to act as a genetic material

A molecule that acts as genetic material must fulfill certain criteria to ensure the proper transmission of genetic information from one generation to the next. The criteria are:

1. It should be able to replicate:
The molecule must be able to replicate itself accurately and efficiently so that the genetic information can be passed on to the next generation without any errors.

2. It should be structurally and chemically stable:
The molecule must be chemically and structurally stable so that it can withstand the various chemical and physical processes that occur during replication and cell division.

3. It should be able to undergo slow mutations:
The molecule must be able to undergo slow mutations, which are necessary for the generation of genetic diversity and evolution.

4. It should be able to express itself in the form of Mendelian characters:
The molecule must be able to express itself in the form of Mendelian characters, which are the observable traits that are inherited from one generation to the next.

Correct answer:

The correct answer is option D, which includes all the above criteria. A molecule that acts as genetic material must be able to replicate accurately, be structurally and chemically stable, undergo slow mutations, and express itself in the form of Mendelian characters.