DNA and Protein Synthesis Quiz

Grade 9 · Science · Quiz

Test your knowledge of DNA structure, transcription, and translation with this challenging Grade 9 quiz.

Questions

1. Which of the following correctly describes the structure of a DNA nucleotide?

   1. Ribose sugar + phosphate + nitrogenous base
   2. Deoxyribose sugar + phosphate + nitrogenous base
   3. Deoxyribose sugar + amino acid + nitrogenous base
   4. Phosphate + amino acid + nitrogenous base
   Show answer

   Answer: Deoxyribose sugar + phosphate + nitrogenous base

   A DNA nucleotide contains deoxyribose sugar (not ribose, which is in RNA), a phosphate group, and one of four nitrogenous bases.

2. During transcription, which base in mRNA pairs with adenine (A) on the DNA template strand?

   1. Thymine (T)
   2. Adenine (A)
   3. Guanine (G)
   4. Uracil (U)
   Show answer

   Answer: Uracil (U)

   In RNA, uracil (U) replaces thymine (T). So when the DNA template has adenine, the mRNA strand incorporates uracil as the complementary base.

3. What is the function of tRNA during translation?

   1. To copy the DNA sequence into mRNA
   2. To carry amino acids to the ribosome and match them to mRNA codons
   3. To unwind the DNA double helix
   4. To transport mRNA from the nucleus to the cytoplasm
   Show answer

   Answer: To carry amino acids to the ribosome and match them to mRNA codons

   tRNA molecules each carry a specific amino acid and have an anticodon that pairs with the complementary mRNA codon at the ribosome during translation.

4. A mutation changes the DNA sequence from ATG to ACG. What is the most likely direct result?

   1. The mRNA codon changes, potentially altering the amino acid added
   2. The ribosome stops translation immediately
   3. The DNA double helix unwinds permanently
   4. Transcription is prevented entirely
   Show answer

   Answer: The mRNA codon changes, potentially altering the amino acid added

   A change in the DNA sequence changes the corresponding mRNA codon, which may cause a different amino acid to be incorporated into the protein, potentially altering its function.

5. Which of the following is the correct sequence of events in protein synthesis?

   1. Translation → Transcription → Protein folding
   2. Transcription → Translation → Protein folding
   3. Replication → Transcription → Translation
   4. Translation → Replication → Protein folding
   Show answer

   Answer: Transcription → Translation → Protein folding

   Transcription produces mRNA from the DNA template. Translation then reads the mRNA at ribosomes to build a polypeptide, which folds into a functional protein.

6. How many amino acids are coded by 30 mRNA bases?

   1. 5
   2. 10
   3. 15
   4. 30
   Show answer

   Answer: 10

   Each codon is 3 bases long. 30 bases ÷ 3 = 10 codons, each coding for one amino acid, giving 10 amino acids.

7. The start codon for translation in most organisms is AUG, which codes for the amino acid methionine.

   Show answer

   Answer: True

   AUG is the universal start codon. It signals the ribosome to begin translation and codes for the amino acid methionine in eukaryotes and formyl-methionine in prokaryotes.

8. The process of copying DNA into mRNA is called ___.

   Show answer

   Answer: transcription

   Transcription is the process in which RNA polymerase reads a DNA template strand and synthesizes a complementary mRNA strand in the nucleus.

Get a personalized course on DNA and Protein Synthesis built around your child.