MCB 2050 MIDTERM QUESTIONS AND ANSWERS
Which is not involved in transcriptional initiation?
1. chromatin decondensation
2. acetylation of histones
3. DSIF
4. mediator complex.
5. TATA box - Answers - 3. DSIF
Which is considered a negative regulator of transcription?
1. NELF
2. P-TEFb
3. TFIIH
4. 5' Cap
5. All of the above - Answers - 1. NELF
Phosphorylation of the CTD of RNA polymerase is necessary for all of the following
EXCEPT:
1. allowing detachment of RNA polymerase from the initiation factors
2. preventing chromatin condensation
3. allowing transcriptional elongation to proceed
4. providing a docking site for enzymes that modify the RNA being transcribed
5. All of the above require phosphorylation of the CTD - Answers - 2. preventing
chromatin condensation
Place the following steps of transcriptional activation in the correct order:
I. binding of the mediator complex to the DNA
II. acetylation of histones
III. formation of the transcription bubble
IV. recruitment of pioneer transcription factors
V. phosphorylation of the CTD of RNA polymerase - Answers - IV, II, I, III, V
A dysfunctional P-TEFb protein that has lost its kinase ability is expressed in a
eukaryotic cell. Which could be expected to occur?
1. NELF remains bound to the DNA
2. DSIF is unable to keep RNA polymerase clamped onto the DNA
3. Transcriptional elongation no longer proceeds
4. NELF remains bound to DSIF
5. All of the above could occur - Answers - 5. all of the above could occur
Define Euchromatin - Answers - 'eu' = true
--> lightly stained chromosome regions
--> where most eukaryotic genes are located
--> genetically active
, Define heterochromatin - Answers - 'hetero' = different
--> regions of chromosomes that are more intensely stained
--> DNA is more densely packed
--> rich in repetitive DNA mostly located in centromeres and telomeres
--> generally not accessible to transcriptional machinery
--> genetically inactive
What is Pax6? - Answers - an example of complex regulation of a eukaryotic gene
Pax6 protein is required for development of the eye, certain regions of the brain and the
spinal cord, and pancreas cells.
What is an enhancer? - Answers - a short (50-1500 bp) region of DNA that can be
bound by proteins (activators) to increase the likelihood that transcription of a particular
gene will occur.
What is a transcription factor? - Answers - a protein that controls the rate of transcription
of genetic information from DNA to messenger RNA, by binding to a specific DNA
sequence.
What are the PAX6 enhancers - Answers - --> PAX6 expression in day 10.5 embryo in
the retina and the pancreas is regulated by the "green enhancer element" upstream of
exon 0
--> PAX6 expression inthe day 14.5 embryo in the retina is regulated by the "orange
enhancer element" around exons 5,6, and 7
What is unique about PAX6 - Answers - it has three alternative promoters that can
produce three similar proteins
What does RNA polymerase I transcribe and what is its function? - Answers - it is a
ribosome component and it synthesizes only Pre-rRNA
What does RNA polymerase II transcribe and what is its function? - Answers - mRNA ->
encodes proteins
snRNA -> RNA splicing
siRNA-> translation control
miRNA-> translation control
What does RNA polymerase III transcribe and what is its function? - Answers - tRNA ->
protein synthesis
55 rRNA -> ribosome, protein synthesis
snRNA U6-> RNA splicing
75 RNA -> signal recognition particle for insertion of polypeptides into the endoplasmic
reticulum
Which is not involved in transcriptional initiation?
1. chromatin decondensation
2. acetylation of histones
3. DSIF
4. mediator complex.
5. TATA box - Answers - 3. DSIF
Which is considered a negative regulator of transcription?
1. NELF
2. P-TEFb
3. TFIIH
4. 5' Cap
5. All of the above - Answers - 1. NELF
Phosphorylation of the CTD of RNA polymerase is necessary for all of the following
EXCEPT:
1. allowing detachment of RNA polymerase from the initiation factors
2. preventing chromatin condensation
3. allowing transcriptional elongation to proceed
4. providing a docking site for enzymes that modify the RNA being transcribed
5. All of the above require phosphorylation of the CTD - Answers - 2. preventing
chromatin condensation
Place the following steps of transcriptional activation in the correct order:
I. binding of the mediator complex to the DNA
II. acetylation of histones
III. formation of the transcription bubble
IV. recruitment of pioneer transcription factors
V. phosphorylation of the CTD of RNA polymerase - Answers - IV, II, I, III, V
A dysfunctional P-TEFb protein that has lost its kinase ability is expressed in a
eukaryotic cell. Which could be expected to occur?
1. NELF remains bound to the DNA
2. DSIF is unable to keep RNA polymerase clamped onto the DNA
3. Transcriptional elongation no longer proceeds
4. NELF remains bound to DSIF
5. All of the above could occur - Answers - 5. all of the above could occur
Define Euchromatin - Answers - 'eu' = true
--> lightly stained chromosome regions
--> where most eukaryotic genes are located
--> genetically active
, Define heterochromatin - Answers - 'hetero' = different
--> regions of chromosomes that are more intensely stained
--> DNA is more densely packed
--> rich in repetitive DNA mostly located in centromeres and telomeres
--> generally not accessible to transcriptional machinery
--> genetically inactive
What is Pax6? - Answers - an example of complex regulation of a eukaryotic gene
Pax6 protein is required for development of the eye, certain regions of the brain and the
spinal cord, and pancreas cells.
What is an enhancer? - Answers - a short (50-1500 bp) region of DNA that can be
bound by proteins (activators) to increase the likelihood that transcription of a particular
gene will occur.
What is a transcription factor? - Answers - a protein that controls the rate of transcription
of genetic information from DNA to messenger RNA, by binding to a specific DNA
sequence.
What are the PAX6 enhancers - Answers - --> PAX6 expression in day 10.5 embryo in
the retina and the pancreas is regulated by the "green enhancer element" upstream of
exon 0
--> PAX6 expression inthe day 14.5 embryo in the retina is regulated by the "orange
enhancer element" around exons 5,6, and 7
What is unique about PAX6 - Answers - it has three alternative promoters that can
produce three similar proteins
What does RNA polymerase I transcribe and what is its function? - Answers - it is a
ribosome component and it synthesizes only Pre-rRNA
What does RNA polymerase II transcribe and what is its function? - Answers - mRNA ->
encodes proteins
snRNA -> RNA splicing
siRNA-> translation control
miRNA-> translation control
What does RNA polymerase III transcribe and what is its function? - Answers - tRNA ->
protein synthesis
55 rRNA -> ribosome, protein synthesis
snRNA U6-> RNA splicing
75 RNA -> signal recognition particle for insertion of polypeptides into the endoplasmic
reticulum
