Gene Expression — Flashcards & Quiz

Q1: State the central dogma of molecular biology.

The central dogma describes the flow of genetic information: DNA → (transcription) → mRNA → (translation) → protein. DNA is transcribed into messenger RNA, which is then translated into a polypeptide chain at the ribosome.

Q2: Distinguish between the template strand and coding strand of DNA.

The template strand (antisense) is read by RNA polymerase during transcription (3' to 5') and is complementary to the mRNA produced. The coding strand (sense) has the same base sequence as the mRNA (with T instead of U) and is not directly read during transcription.

Q3: What is the role of mRNA, tRNA and rRNA in protein synthesis?

mRNA (messenger RNA) carries the genetic code from DNA to the ribosome as a sequence of codons. tRNA (transfer RNA) has an anticodon that matches a specific codon and carries the corresponding amino acid to the ribosome. rRNA (ribosomal RNA) forms part of the ribosome structure and catalyses peptide bond formation between amino acids.

Q1: The central dogma of molecular biology states that information flows from protein to RNA to DNA.

Answer: FALSE

The central dogma states information flows from DNA → RNA → protein (transcription then translation). The reverse direction (protein → DNA) does not occur in normal biological processes.

Q2: tRNA molecules carry amino acids to the ribosome during translation.

Answer: TRUE

Each tRNA has an anticodon that recognises a specific mRNA codon and carries the corresponding amino acid. The ribosome facilitates the matching and peptide bond formation.