1. What are the structural differences between DNA and RNA?
Answer:
DNA (Deoxyribonucleic Acid) is a double-stranded helical molecule, while RNA (Ribonucleic Acid) is usually single-stranded. DNA contains the sugar deoxyribose, whereas RNA contains ribose, which has an additional hydroxyl (-OH) group. The nitrogenous bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T), while RNA replaces thymine with uracil (U). These structural differences contribute to their distinct functions.
2. Why is DNA more stable than RNA?
Answer:
DNA’s stability comes from its double-stranded structure and the absence of the reactive hydroxyl group on its sugar molecule. This makes DNA less prone to hydrolysis. RNA’s single-stranded nature and the presence of ribose with a hydroxyl group make it more chemically reactive and less stable, which is suitable for its temporary role in protein synthesis.
3. What are the primary functions of DNA?
Answer:
DNA stores genetic information essential for the development, functioning, growth, and reproduction of living organisms. It provides the instructions for synthesizing proteins and is passed down from generation to generation, ensuring the continuity of genetic information.
4. What are the main functions of RNA?
Answer:
RNA plays a key role in protein synthesis. Messenger RNA (mRNA) carries genetic information from DNA to ribosomes, transfer RNA (tRNA) brings amino acids to ribosomes, and ribosomal RNA (rRNA) forms the core of ribosomes, facilitating protein synthesis. Other RNA types, like microRNA (miRNA) and small interfering RNA (siRNA), regulate gene expression.
5. How does the sugar molecule differ in DNA and RNA?
Answer:
DNA contains deoxyribose, a sugar molecule lacking one oxygen atom at the 2′ position, while RNA contains ribose, which has a hydroxyl (-OH) group at the same position. This small difference significantly affects the chemical properties and stability of these molecules.
6. What role do nitrogenous bases play in DNA and RNA?
Answer:
Nitrogenous bases pair specifically to form the genetic code. In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). In RNA, adenine pairs with uracil (U) instead of thymine. These pairings enable DNA to store information and RNA to carry out transcription and translation.
7. What is the significance of the double helix structure of DNA?
Answer:
The double helix structure provides stability to DNA, protects genetic information, and allows the molecule to be compactly stored in the nucleus. It also facilitates accurate replication and repair processes, ensuring the integrity of genetic information.
8. How do DNA and RNA differ in terms of base pairing?
Answer:
DNA features complementary base pairing between adenine (A) and thymine (T) and guanine (G) and cytosine (C). RNA does not have thymine; instead, adenine pairs with uracil (U). This difference is critical for RNA’s function in transcription and translation.
9. Why is RNA more suitable for short-term tasks?
Answer:
RNA’s single-stranded structure and chemical reactivity make it ideal for temporary roles like carrying genetic messages (mRNA), aiding in protein synthesis (tRNA), or forming ribosomes (rRNA). Its transitory nature aligns with its short-lived functions.
10. What are the types of RNA, and what are their roles?
Answer:
- mRNA: Carries genetic information from DNA to ribosomes.
- tRNA: Transfers amino acids to ribosomes for protein synthesis.
- rRNA: Forms the structural and functional components of ribosomes.
- miRNA/siRNA: Regulates gene expression by silencing or degrading mRNA.
11. How does the absence of uracil in DNA affect its function?
Answer:
Uracil is more prone to mutation than thymine, so its absence in DNA increases the molecule’s stability. Thymine ensures the integrity of genetic information over long periods, essential for its role in inheritance.
12. Why is RNA necessary if DNA stores genetic information?
Answer:
RNA acts as an intermediary between DNA and proteins. DNA is stable and remains in the nucleus, while RNA carries the genetic instructions to ribosomes in the cytoplasm, where proteins are synthesized.
13. What is transcription, and how does it involve DNA and RNA?
Answer:
Transcription is the process of synthesizing RNA from a DNA template. RNA polymerase reads the DNA sequence and forms a complementary RNA strand, which then serves as a blueprint for protein synthesis.
14. How do DNA and RNA contribute to protein synthesis?
Answer:
DNA provides the instructions, while RNA translates these instructions into proteins. mRNA carries the code, tRNA delivers amino acids, and rRNA facilitates the assembly of proteins.
15. What is the role of RNA in gene regulation?
Answer:
Non-coding RNAs like miRNA and siRNA regulate gene expression by binding to mRNA, preventing translation, or promoting degradation. This allows cells to control protein production dynamically.
16. What is the importance of complementary base pairing?
Answer:
Complementary base pairing ensures accurate DNA replication and RNA transcription. It allows the genetic code to be faithfully copied and transferred, maintaining genetic consistency.
17. Why is DNA replication more precise than RNA synthesis?
Answer:
DNA replication involves proofreading and repair mechanisms that correct errors. RNA synthesis lacks these robust mechanisms, resulting in higher error rates, acceptable for its short-lived functions.
18. How do DNA and RNA differ in cellular location?
Answer:
DNA is primarily located in the nucleus, while RNA is found both in the nucleus and cytoplasm. RNA’s mobility enables it to carry genetic instructions from DNA to ribosomes.
19. What is reverse transcription, and how is RNA involved?
Answer:
Reverse transcription is the process of synthesizing DNA from an RNA template. This occurs in retroviruses like HIV and is facilitated by reverse transcriptase enzymes.
20. How does RNA’s structure enable its catalytic functions?
Answer:
RNA can form complex 3D structures, enabling it to act as a ribozyme (catalytic RNA). This allows RNA to catalyze chemical reactions, such as peptide bond formation in ribosomes.
21. How do mutations in DNA differ from those in RNA?
Answer:
DNA mutations are permanent and heritable, affecting the genetic code across generations. RNA mutations are temporary and typically impact only the current protein synthesis process.
22. What is the significance of the RNA World Hypothesis?
Answer:
The RNA World Hypothesis suggests that RNA was the first genetic material, capable of storing information and catalyzing reactions, predating DNA and proteins.
23. How do DNA and RNA differ in their role during evolution?
Answer:
DNA evolved to provide stable genetic storage, while RNA’s versatility allowed it to perform diverse functions, like catalysis and regulation, crucial for early life forms.
24. Why is RNA prone to degradation?
Answer:
RNA’s ribose sugar with an additional hydroxyl group makes it susceptible to hydrolysis. This property aligns with its transient functions in cellular processes.
25. How do DNA and RNA interact during replication?
Answer:
During replication, RNA primers are laid down by primase to provide a starting point for DNA polymerase. These primers are later replaced with DNA.
26. How does RNA mediate the flow of genetic information?
Answer:
RNA bridges DNA and proteins by transcribing genetic information (mRNA) and translating it into functional proteins at ribosomes.
27. What are the implications of RNA editing?
Answer:
RNA editing alters the nucleotide sequence of RNA after transcription. This process allows cells to diversify proteins without changing the DNA sequence.
28. What distinguishes ribosomal RNA (rRNA) from other RNA types?
Answer:
rRNA forms the core structural and functional components of ribosomes, directly participating in protein synthesis by catalyzing peptide bond formation.
29. How do DNA and RNA contribute to biotechnology?
Answer:
DNA is used in cloning, sequencing, and gene editing (e.g., CRISPR), while RNA is used in gene silencing (siRNA) and as templates for cDNA synthesis in reverse transcription.
30. How do DNA and RNA ensure genetic fidelity?
Answer:
DNA ensures fidelity through proofreading and repair, while RNA minimizes errors by allowing only transient functions and selective gene expression regulation.
