1. Self Assessment Question 1
Which of the following statements is true?
RNA polymerase has a proofreading activity.     
Prokaryotic RNA usually undergoes nuclear processing.     
Polypeptides are synthesized by addition of amino acids to the amino terminus.     
The 3' end of mRNA corresponds to the carboxyl terminus of the protein.

2. Self Assessment Question 1 Answer
Which of the following statements is true?
RNA polymerase has a proofreading activity.     
Prokaryotic RNA usually undergoes nuclear processing.     
Polypeptides are synthesized by addition of amino acids to the amino terminus.     
The 3' end of mRNA corresponds to the carboxyl terminus of the protein. CORRECT ANSWER   

3. DNA is read in 5’ to 3’ direction
Protein is made from the amino terminus to carboxyl terminus
Fig. 8.3

4. Self Assessment Question 2
Which of the following is true regarding RNA processing?
It involves removal of introns.
It occurs before transcription.     
It is a rare event that only occurs in response to DNA damage.     
It occurs in prokaryotes.     
None of the above

5. Self Assessment Question 2 Answer
Which of the following is true regarding RNA processing?
It involves removal of introns. CORRECT ANSWER   
It occurs before transcription.     
It is a rare event that only occurs in response to DNA damage.     
It occurs in prokaryotes.     
None of the above

6. mRNA Processing in Eukaryotes:
Important points:
Exons - coding sequences
Introns- non-coding sequences
5’ end is processed by addition of a 5’methylated cap
3’ end is processed by cleavage by an endonuclease to yield a 3’ hydroxyl group where adenylic acid residues are added by poly (A) polymerase to give a poly(A) tail ( As)
RNA splicing - introns excised and exonic sequences ligated together
WH Freeman, Molecular Cell Biology, 5th Edition, 2004.

7. Self Assessment Question 3
Which of the following features is common to both DNA replication and transcription?
Nucleotides are added to the 5' end of the newly synthesized strand.     
A sugar-phosphate bond is formed between the 3' hydroxyl and the 5' phosphate.   
Deoxyribonucleotides are incorporated into the growing sequence.     
Both RNA and DNA polymerases require oligonucleotide priming.

8. Self Assessment Question 3 Answer
Which of the following features is common to both DNA replication and transcription?
Nucleotides are added to the 5' end of the newly synthesized strand.     
A sugar-phosphate bond is formed between the 3' hydroxyl and the 5' phosphate. CORRECT ANSWER   
Deoxyribonucleotides are incorporated into the growing sequence.     
Both RNA and DNA polymerases require oligonucleotide priming.

9. TRANSCRIPTION:
Polymerization of ribonucleotides by RNA polymerase during trancription
Important points:
One strand of DNA acts as the template - determining the order in which ribonucleoside triphosphate monomers (rNTPs) are polymerized to form a complementary RNA chain.
Polymerization reaction is catalyzed by RNA polymerase.
A phosphodiester bond is formed between the 3’ oxygen and the alpha phosphate of the incoming rNTP.
RNA molecules are always synthesized in a 5’ to 3’ direction.
WH Freeman, Molecular Cell Biology, 5th Edition, 2004.

10. Self Assessment Question 4
The site of RNA polymerase binding to the DNA template is called:
Enhancer     
Domain     
Leader sequences     
Carboxyl end     
Promoter  

11. Self Assessment Question 4 Answer
The site of RNA polymerase binding to the DNA template is called:
Enhancer     
Domain     
Leader sequences     
Carboxyl end     
Promoter CORRECT ANSWER  

12. TRANSCRIPTION: WH Freeman, Molecular Cell Biology, 5th Edition, 2004.
Transcription occurs in 3 stages – initiation, elongation and termination. RNA Polymerase binds to specific site which it recognizes – the promoter sequence. Nuclear RNAs may require transcription factors to bind to the promoter sequence. The polymerase melts the DNA duplex - approximately 14 base pairs of DNA around the transcription start site.
WH Freeman, Molecular Cell Biology, 5th Edition, 2004.

13. Self Assessment Question 5
All of the following may result from promoter mutations, except:
Decreased affinity for RNA polymerase     
Increased affinity for RNA polymerase     
Mutant RNA polymerase
Unregulated transcription     
A new phenotype

14. Self Assessment Question 5 Answer
All of the following may result from promoter mutations, except:
Decreased affinity for RNA polymerase     
Increased affinity for RNA polymerase     
Mutant RNA polymerase CORRECT ANSWER   
Unregulated transcription     
A new phenotype
*Mutant RNA polymerase is not the result of a mutation in a promoter sequence but is the result of a mutation in the actual coding sequence of RNA polymerase.

15. Self Assessment Question 6
Introns within primary eukaryotic transcripts:
Are joined to form mature mRNA     
Are highly conserved in nucleotide sequence     
Often function as exons in other genes     
Vary considerably in size and number among different genes

16. Self Assessment Question 6 Answer
Introns within primary eukaryotic transcripts:
Are joined to form mature mRNA     
Are highly conserved in nucleotide sequence     
Often function as exons in other genes     
Vary considerably in size and number among different genes CORRECT ANSWER

17. Self Assessment Question 7
Which of the following statements is true of polypeptide chains and nucleotide chains?  
Both have a sugar-phosphate backbone.     
Both are chains consisting of 20 types of repeating units.     
Both types of polymers are linear and unbranched.   
Both types of molecules contain unambiguous and interconvertible triplet codes.  

18. Self Assessment Question 7 Answer
Which of the following statements is true of polypeptide chains and nucleotide chains?  
Both have a sugar-phosphate backbone.     
Both are chains consisting of 20 types of repeating units.     
Both types of polymers are linear and unbranched. CORRECT ANSWER   
Both types of molecules contain unambiguous and interconvertible triplet codes.  

19. Self Assessment Question 8
Which of the following is unique to eukaryotes?
5' polyadenylation of mRNA     
Polycistronic mRNA     
Coupled transcription-translation     
Removal of introns

20. Self Assessment Question 8 Answer
Which of the following is unique to eukaryotes?
5' polyadenylation of mRNA     
Polycistronic mRNA     
Coupled transcription-translation     
Removal of introns CORRECT ANSWER

21. Self Assessment Question 9
Which of the following is unique to prokaryotes?
Coupled transcription-translation
Removal of introns     
3' polyadenylation     
mRNA capping     
Promoter sequences

22. Self Assessment Question 9 Answer
Which of the following is unique to prokaryotes?
Coupled transcription-translation CORRECT ANSWER   
Removal of introns     
3' polyadenylation     
mRNA capping     
Promoter sequences

23. Self Assessment Question 10
The genetic code is degenerate because:
mRNA is rapidly degraded.     
The code is not universal among organisms.     
Some amino acids have more than one codon.
Frameshift mutations are tolerated.     
Stop codons may have corresponding tRNA molecules.

24. Self Assessment Question 10 Answer
The genetic code is degenerate because:
mRNA is rapidly degraded.     
The code is not universal among organisms.     
Some amino acids have more than one codon. CORRECT ANSWER   
Frameshift mutations are tolerated.     
Stop codons may have corresponding tRNA molecules.

25. Genetic Code
Most of the codons were determined from in vitropolypeptide synthesis
Genetic code is universal = the same triplet codons specify the same amino acids in all species
Mutations occur when changes in codons alter amino acids in proteins

26. Self Assessment Question 11
All of the following are directly involved in translation except:
mRNA     
tRNA     
DNA   
Ribosomes     
Elongation Factor (ELF) proteins  

27. Self Assessment Question 11 Answer
All of the following are directly involved in translation except:
mRNA     
tRNA     
DNA CORRECT ANSWER   
Ribosomes     
Elongation Factor (ELF) proteins  

28. Self Assessment Question 12
Which of the following is true regarding gene expression?
Only one gene can be present within a given DNA sequence.     
Mistakes in transcription are corrected by RNA polymerase.     
The ribosome binding site lies at the 3' end of mRNA.     
A change in genotype always results in a changed phenotype.     
A second round of transcription can begin before the preceding transcript is completed.

29. Self Assessment Question 12 Answer
Which of the following is true regarding gene expression?
Only one gene can be present within a given DNA sequence.     
Mistakes in transcription are corrected by RNA polymerase.     
The ribosome binding site lies at the 3' end of mRNA.     
A change in genotype always results in a changed phenotype.     
A second round of transcription can begin before the preceding transcript is completed. CORRECT ANSWER

30. WH Freeman, Molecular Cell Biology, 5th Edition, 2004.

31. Questions?