Which of the following sequences correctly represents flow of genetic info?
ADNA → Protein → RNA
BRNA → DNA → Protein
CDNA → RNA → Protein
DProtein → RNA → DNA
Answer:
C. DNA → RNA → Protein
Read Explanation:
The Central Dogma of Molecular Biology
- The standard flow of genetic information is represented as: DNA → RNA → Protein.
- This sequence is known as the Central Dogma, a term coined by Francis Crick in 1957.
Key Stages of the Process:
- Replication: The process where DNA makes an exact copy of itself, ensuring genetic material is passed on during cell division. This occurs in the nucleus of eukaryotic cells.
- Transcription: The process of copying a segment of DNA into RNA (specifically mRNA). This is catalyzed by the enzyme RNA polymerase.
- Translation: The final step where the information encoded in mRNA is used to synthesize a polypeptide chain (protein) at the ribosome.
Key Deviations and Exceptions:
- Reverse Transcription: Some viruses, such as HIV (a retrovirus), possess the enzyme reverse transcriptase, which allows them to synthesize DNA from an RNA template, reversing the standard flow (RNA → DNA).
- RNA Replication: Certain RNA viruses can replicate their RNA directly without DNA intermediates.
- Prions: Infectious proteins that can induce abnormal folding in normal cellular proteins, operating independently of the DNA-RNA-Protein pathway.