Name: _______________________________________________________________Date: __________________________Block:___
Transcription + CODONS Questions
1. The product of transcription is
A. DNA.
B. protein.
C. mRNA.
D. a ribosome.
Use the following chart to answer question 2 and 3.
2. A strand of DNA has the following bases:
CACGGCC
If the adenine base was deleted, which amino acids would be
coded for?
A. valine, proline
B. glycine, alanine
C. proline, arginine
D. glycine, arginine
3. a) Determine the DNA base sequence that codes for the amino acid tryptophan. (1 mark)
• ACC (1 mark)
b) Determine the anticodon for tryptophan. (1 mark)
• ACC (1 mark)
4. A polypeptide found in the cytoplasm of a cell contains 12 amino acids. How many nucleotides would be required in the
mRNA for this polypeptide to be translated?
A. 4
B. 12
C. 24
D. 36
Use the following diagram to answer question 5.
5. Which process is shown on the right?
A. translation
B. elongation
C. replication
D. transcription
6. What is the purpose of transcription during protein synthesis? (1 mark)
 To assemble mRNA from a section of DNA (gene) that contains the code for one protein.
 To make mRNA.
 To carry complementary mRNA (codon) from DNA. any one for 1 mark
Use the following diagram to answer question 7.
7. A radioactive molecule is added to a cell culture where the process shown in the diagram is
taking place. Upon analysis, it is found that substance Y is radioactive but substance X is not.
Give a possible identity for the radioactive molecule which was added and explain why it is
only in substance Y. (2 marks: 1 mark for molecule; 1 mark for explanation)
molecule: radioactive uracil (1 mark)
explanation: The radioactive uracil was incorporated into the mRNA during complementary
base pairing during transcription. (1 mark)
OR molecule: radioactive ribose (1 mark)
explanation: RNA contains ribose while DNA contains deoxyribose. (1 mark)
Mrs. N Gill
Biology 12
Name: _______________________________________________________________Date: __________________________Block:___
8. a) In an experiment conducted to study protein synthesis, radioactive thymine and radioactive uracil were added to a
culture of human cells. A few hours later, the culture was analyzed and radioactive mRNA was found.
i) Explain how an mRNA molecule is produced. (2 marks)
 The DNA molecule “unzips”
 Complementary base pairing occurs between mRNA and DNA bases.
 Sugars and phosphates of adjacent mRNA nucleotides are joined together.any two for 1 mark each
ii) Explain why the mRNA produced is radioactive. (1 mark)
 During transcription, radioactive uracil is used to produce mRNA. (1 mark)
b) In a different experiment, radioactive uracil was added to a culture of human cells undergoing DNA replication. What will
be the characteristic of the resulting DNA in terms of radioactivity? Explain. (2 marks)
 No radioactive elements will be incorporated in the DNA molecule (1 mark) as adenine will bond only with thymine
and not uracil during replication (1 mark).
9. Describe how each of the following contributes to the production of a protein. (4 marks)
DNA:
• involved in transcription
• serves as a template for mRNA production
• contains or carries the genetic information for the protein to be produced
• contains the code which determines the sequence of a protein
• DNA code determines the mRNA codons any one for 1 mark
codon:
• determines the specific amino acid
• carries the information from the nucleus to the cytoplasm
• binds with the anticodon on tRNA
Use the following diagram to answer question 10.
10. Describe three ways in which molecule X differs from molecule Y. (3 marks)
• Molecule X contains deoxyribose whereas molecule Y contains ribose.
• Molecule X contains thymine whereas molecule Y contains uracil.
• Molecule X is double stranded and molecule Y is single stranded.
• Molecule X is found in the nucleus whereas molecule Y is found in the
cytoplasm and in the nucleus.
any three for 1 mark each
Use the following diagram to answer questions 10, 11 and 12.
10. What process produces molecule X?
A. translation
B. replication
C. denaturation
D. transcription
11. What type of bond joins the structure in box Y with the structure in box
Z?
A. ionic
B. peptide
C. covalent
D. hydrogen
12. What two components are part of the structure shown in box Y?
A. ribose and guanine
B. ribose and cytosine
C. deoxyribose and uracil
D. deoxyribose and adenine
Mrs. N Gill
Biology 12