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Problem 1a
What is a gene?
Problem 1b
Why are genes for rRNA and tRNA considered to be genes even though they do not produce polypeptides?
Problem 2
In one to two sentences each, describe the three processes that commonly modify eukaryotic pre-mRNA.
Problem 3
Answer these questions concerning promoters. What role do promoters play in transcription?
Problem 3b
Answer these questions concerning promoters.
What is the common structure of a bacterial promoter with respect to consensus sequences?
Problem 3c
Answer these questions concerning promoters.
What consensus sequences are detected in the mammalian β-globin gene promoter?
Problem 3d
Answer these questions concerning promoters.
Eukaryotic promoters are more variable than bacterial promoters. Explain why.
Problem 3e
Answer these questions concerning promoters.
What is the meaning of the term alternative promoter? How does the use of alternative promoters affect transcription?
Problem 4a
The diagram below shows a DNA duplex. The template strand is identified, as is the location of the nucleotide.
Assume this region contains a gene transcribed in a bacterium. Identify the location of promoter consensus sequences and of the transcription termination sequence.
Problem 4b
The diagram below shows a DNA duplex. The template strand is identified, as is the location of the nucleotide. consensus sequences.
Assume this region contains a gene transcribed to form mRNA in a eukaryote. Identify the location of the most common promoter.
Problem 4c
The diagram below shows a DNA duplex. The template strand is identified, as is the location of the nucleotide.
If this region is a eukaryotic gene transcribed by RNA polymerase III, where are the promoter consensus sequences located?
Problem 5a
The following is a portion of an mRNA sequence:
3'-AUCGUCAUGCAGA-5'
During transcription, was the adenine at the left-hand side of the sequence the first or the last nucleotide used to build the portion of mRNA shown? Explain how you know.
Problem 5b
The following is a portion of an mRNA sequence:
3'-AUCGUCAUGCAGA-5'
Write out the sequence and polarity of the DNA duplex that encodes this mRNA segment. Label the template and coding DNA strands.
Problem 5c
The following is a portion of an mRNA sequence:
3'-AUCGUCAUGCAGA-5'
Identify the direction in which the promoter region for this gene will be located.
Problem 6
Compare and contrast the properties of DNA polymerase and RNA polymerase, listing at least three similarities and at least three differences between the molecules.
Problem 7a
The DNA sequences shown below are from the promoter regions of six bacterial genes. In each case, the last nucleotide in the sequence (highlighted in blue) is the nucleotide that initiates transcription. Examine these sequences and identify the Pribnow box sequence at approximately -10 for each promoter.
Problem 7b
The DNA sequences shown below are from the promoter regions of six bacterial genes. In each case, the last nucleotide in the sequence (highlighted in blue) is the nucleotide that initiates transcription. Determine the consensus sequence for the Pribnow box from these sequences.
Problem 8
Bacterial and eukaryotic gene transcripts can differ—in the transcripts themselves, in whether the transcripts are modified before translation, and in how the transcripts are modified. For each of these three areas of contrast, describe what the differences are and why the differences exist.
Problem 9
Describe the two types of transcription termination found in bacterial genes. How does transcription termination differ for eukaryotic genes?
