Download Removal of introns CORRECT ANSWER

Self Assessment Question 1
• Which of the following statements is true?
A. RNA polymerase has a proofreading activity.
B. Prokaryotic RNA usually undergoes nuclear
processing.
C. Polypeptides are synthesized by addition of amino
acids to the amino terminus.
D. The 3' end of mRNA corresponds to the carboxyl
terminus of the protein.
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Self Assessment Question 1 Answer
• Which of the following statements is true?
A. RNA polymerase has a proofreading activity.
B. Prokaryotic RNA usually undergoes nuclear
processing.
C. Polypeptides are synthesized by addition of amino
acids to the amino terminus.
D. The 3' end of mRNA corresponds to the
carboxyl terminus of the protein. CORRECT
ANSWER
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DNA is read in 5’ to 3’ direction
Protein is made from the amino terminus to carboxyl terminus
Fig. 8.3
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Self Assessment Question 2
• Which of the following is true regarding RNA
processing?
A. It involves removal of introns.
B. It occurs before transcription.
C. It is a rare event that only occurs in response to
DNA damage.
D. It occurs in prokaryotes.
E. None of the above
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Self Assessment Question 2 Answer
• Which of the following is true regarding RNA
processing?
A. It involves removal of introns. CORRECT
ANSWER
B. It occurs before transcription.
C. It is a rare event that only occurs in response to
DNA damage.
D. It occurs in prokaryotes.
E. None of the above
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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 (100-250 As)
•RNA splicing - introns
excised and exonic sequences
ligated together
WH Freeman, Molecular Cell
Biology, 5th Edition, 2004.
Self Assessment Question 3
• Which of the following features is common to both
DNA replication and transcription?
A. Nucleotides are added to the 5' end of the
newly synthesized strand.
B. A sugar-phosphate bond is formed between the
3' hydroxyl and the 5' phosphate.
C. Deoxyribonucleotides are incorporated into the
growing sequence.
D. Both RNA and DNA polymerases require
oligonucleotide priming.
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Self Assessment Question 3 Answer
• Which of the following features is common to both
DNA replication and transcription?
A. Nucleotides are added to the 5' end of the
newly synthesized strand.
B. A sugar-phosphate bond is formed between
the 3' hydroxyl and the 5' phosphate.
CORRECT ANSWER
C. Deoxyribonucleotides are incorporated into the
growing sequence.
D. Both RNA and DNA polymerases require
oligonucleotide priming.
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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.
Self Assessment Question 4
• The site of RNA polymerase binding to the DNA
template is called:
A.
B.
C.
D.
E.
Enhancer
Domain
Leader sequences
Carboxyl end
Promoter
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Self Assessment Question 4 Answer
• The site of RNA polymerase binding to the DNA
template is called:
A.
B.
C.
D.
E.
Enhancer
Domain
Leader sequences
Carboxyl end
Promoter CORRECT ANSWER
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TRANSCRIPTION:
WH Freeman, Molecular Cell Biology, 5th Edition, 2004.
Self Assessment Question 5
• All of the following may result from promoter
mutations, except:
A.
B.
C.
D.
E.
Decreased affinity for RNA polymerase
Increased affinity for RNA polymerase
Mutant RNA polymerase
Unregulated transcription
A new phenotype
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Self Assessment Question 5 Answer
• All of the following may result from promoter
mutations, except:
A.
B.
C.
D.
E.
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.
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Self Assessment Question 6
• Introns within primary eukaryotic transcripts:
A. Are joined to form mature mRNA
B. Are highly conserved in nucleotide
sequence
C. Often function as exons in other genes
D. Vary considerably in size and number among
different genes
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Self Assessment Question 6 Answer
• Introns within primary eukaryotic transcripts:
A. Are joined to form mature mRNA
B. Are highly conserved in nucleotide
sequence
C. Often function as exons in other genes
D. Vary considerably in size and number
among different genes CORRECT ANSWER
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Self Assessment Question 7
• Which of the following statements is true of
polypeptide chains and nucleotide chains?
A. Both have a sugar-phosphate backbone.
B. Both are chains consisting of 20 types of
repeating units.
C. Both types of polymers are linear and
unbranched.
D. Both types of molecules contain unambiguous
and interconvertible triplet codes.
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Self Assessment Question 7 Answer
• Which of the following statements is true of
polypeptide chains and nucleotide chains?
A. Both have a sugar-phosphate backbone.
B. Both are chains consisting of 20 types of
repeating units.
C. Both types of polymers are linear and
unbranched. CORRECT ANSWER
D. Both types of molecules contain unambiguous
and interconvertible triplet codes.
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Self Assessment Question 8
• Which of the following is unique to
eukaryotes?
A. 5' polyadenylation of mRNA
B. Polycistronic mRNA
C. Coupled transcription-translation
D. Removal of introns
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Self Assessment Question 8 Answer
• Which of the following is unique to
eukaryotes?
A. 5' polyadenylation of mRNA
B. Polycistronic mRNA
C. Coupled transcription-translation
D. Removal of introns CORRECT
ANSWER
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Self Assessment Question 9
• Which of the following is unique to prokaryotes?
A.
B.
C.
D.
E.
Coupled transcription-translation
Removal of introns
3' polyadenylation
mRNA capping
Promoter sequences
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Self Assessment Question 9 Answer
• Which of the following is unique to prokaryotes?
A. Coupled transcription-translation CORRECT
ANSWER
B. Removal of introns
C. 3' polyadenylation
D. mRNA capping
E. Promoter sequences
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Self Assessment Question 10
• The genetic code is degenerate because:
A.
B.
C.
D.
E.
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.
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Self Assessment Question 10 Answer
• The genetic code is degenerate because:
A. mRNA is rapidly degraded.
B. The code is not universal among organisms.
C. Some amino acids have more than one
codon. CORRECT ANSWER
D. Frameshift mutations are tolerated.
E. Stop codons may have corresponding tRNA
molecules.
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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
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Self Assessment Question 11
• All of the following are directly involved in
translation except:
A.
B.
C.
D.
E.
mRNA
tRNA
DNA
Ribosomes
Elongation Factor (ELF) proteins
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Self Assessment Question 11 Answer
• All of the following are directly involved in
translation except:
A.
B.
C.
D.
E.
mRNA
tRNA
DNA CORRECT ANSWER
Ribosomes
Elongation Factor (ELF) proteins
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Self Assessment Question 12
• Which of the following is true regarding gene
expression?
A. Only one gene can be present within a given DNA
sequence.
B. Mistakes in transcription are corrected by RNA
polymerase.
C. The ribosome binding site lies at the 3' end of
mRNA.
D. A change in genotype always results in a changed
phenotype.
E. A second round of transcription can begin before
the preceding transcript is completed.
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Self Assessment Question 12 Answer
• Which of the following is true regarding gene
expression?
A. Only one gene can be present within a given DNA
sequence.
B. Mistakes in transcription are corrected by RNA
polymerase.
C. The ribosome binding site lies at the 3' end of
mRNA.
D. A change in genotype always results in a changed
phenotype.
E. A second round of transcription can begin
before the preceding transcript is completed.
CORRECT ANSWER
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WH Freeman, Molecular Cell Biology, 5th Edition, 2004.
Questions?
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