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MCB 2050 Midterm exam questions updated version, Exams of Advanced Education

Cheyney University of PennsylvaniaAdvanced Education

MCB 2050 Midterm exam questions updated version

Typology: Exams

2025/2026

Available from 07/02/2026

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MCB 2050 Midterm exam questions updated
version
1. Which is not involved in transcriptional initiation?
1.
chromatin decondensation
2. acetylation of histones
3. DSIF
4.
mediator complex.
5.
TATA box: 3. DSIF
2.
Which is considered a negative regulator of transcription?
1. NELF
2.
P-
TEFb
3. TFIIH
4.
5' Cap
5. All of the above:
1. NELF
3.
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 tran-
scribed
5.
All
of
the
above
require
phosphorylation
of
the
CTD:
2. preventing
chromatin conden-sation
4. Place the following steps of transcriptional activation in the
correct order:
I.
binding of the mediator complex to the DNA
II. acetylation of histones
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff

Partial preview of the text

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1 /

MCB 2050 Midterm exam questions updated

version

  1. Which is not involved in transcriptional initiation?
  2. chromatin decondensation
  3. acetylation of histones
  4. DSIF
  5. mediator complex.
  6. TATA box: 3. DSIF
  7. Which is considered a negative regulator of transcription?
  8. NELF
  9. P-TEFb
  10. TFIIH
  11. 5' Cap
  12. All of the above: 1. NELF
  13. Phosphorylation of the CTD of RNA polymerase is necessary for all of the following EXCEPT:
  14. allowing detachment of RNA polymerase from the initiation factors
  15. preventing chromatin condensation
  16. allowing transcriptional elongation to proceed
  17. providing a docking site for enzymes that modify the RNA being tran-scribed
  18. All of the above require phosphorylation of the CTD: 2. preventing chromatin conden-sation
  19. Place the following steps of transcriptional activation in the correct order: I. binding of the mediator complex to the DNA II. acetylation of histones

2 / III. formation of the transcription bubble IV. recruitment of pioneer transcription factors V.phosphorylation of the CTD of RNA polymerase: IV, II, I, III, V

  1. A dysfunctional P-TEFb protein that has lost its kinase ability is expressed in a eukaryotic cell. Which could be expected to occur?
  2. NELF remains bound to the DNA
  3. DSIF is unable to keep RNA polymerase clamped onto the DNA
  4. Transcriptional elongation no longer proceeds
  5. NELF remains bound to DSIF
  6. All of the above could occur: 5. all of the above could occur
  7. Define Euchromatin: 'eu' = true --> lightly stained chromosome regions --> where most eukaryotic genes are located --> genetically active
  8. Define heterochromatin: 'hetero' = ditterent --> 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
  9. What is Pax6?: 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.
  10. What is an enhancer?: 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.
  11. What is a transcription factor?: a protein that controls the rate of transcription of genetic informa-tion from DNA to messenger RNA, by binding to a specific DNA sequence.
  12. What are the PAX6 enhancers: --> 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
  13. What is unique about PAX6: it has three alternative promoters that can

4 / template DNA entering the jaws of the polymerase to bend before it exits the polymerase

  1. What is the role of Carboxy-Terminal Domain?: Carboxy-terminal domain (CTD) or RPB1 is a special structure involved in multiple regulatory interactions
  2. How many repeats does CTD contain and what is the repeat?: CTD contains 26 repeats of Tyr-Ser-Pro-Thr-Ser-Pro-Ser
  3. How many repeats are there in CTD of mammals: there are 52 repeats
  4. What are the regions of CTD that most heavily transcribed, and what are they referred to as?: regions 74 EF and 75B, they are called PUFFS
  5. What are the RNA pol II GTFs that are labeled as TFII: TFIIA, TFIIB, TFIID, TFIIE, and TFIID
  6. What are the three elements that direct the positioning of the polymerase?- : TATA box, Initiator, BRE (TFIIB recognition element) or DPE (downstream promoter element)
  7. What are the positions of the Core Promoter Elements?: BRE -37 -> -32 TATA -31 -> - INR -2 -> + DPE +28 -> +
  8. What is a CPG island?: the promoters for about 70 percent of protein-coding genes in vertebrate, are characteristic of genes transcribed at a low rate. CpG rich DNA contains less nucleosomes and are easier to transcribe. Initiates in both directions, but proceeds only over the ORF
  9. What are the properties of a Promoter: 1. functions within a short distance; ~ several hundred bps from transcription initiation site
  10. immediately upstream from the initiation site (for RNA pol 2)
  11. position dependent: usually non-functional if moved
  12. orientation dependent: drive transcription in one direction only
  13. What are the properties of an Enhancer?: 1. can function over a long distance; maybe over tens of kbps from transcription initiation site
  14. can be upstream, downstream from the start of within introns

5 /

  1. position independent: usually still functional when moved
  2. orientation independent: function in either normal or the inverted orientation
  3. heavy chains and light chains are different in that::
  4. When B cell receptors encounter antigen, the cell will divide rapidly in a process called::
  5. What process creates immunoglobulin diversity?:
  6. What molecule does Western Blot study?:
  7. What molecule does Northern Blot study?:
  8. What molecule does Southern blot study?:
  9. T he point at which half of the DNA strands are denatured is called the of a given sequence:
  10. Which of the following best describes a 'probe' as used in molecular hy-bridization techniques?
  11. a ds DNA or RNA molecule under analysis
  12. the specific location of DNA or RNA within living or fixed cells
  13. a short single stranded labelled DNA or RNA molecule used to detect its complementary sequence within a mixture of DNA or RNA
  14. A labelled protein which binds to DNA or RNA of interest in order to visualize it
  15. a labeling molecule (ex. flurophore) which is used to visualize the DNA or RNA to which it is bound: 3?
  16. A molecule that is recognized by antibody to produce an immune response is called a/an:: Antigen?
  17. Which of the following contributes to Ab-Ag binding affinity? Select all that apply.
  18. hydrogen bonding between amino acids of the antigen binding site and the epitope

7 / both the heavy and light chains

  1. The full antibody molecule is a tetramer comprised of 4 identical polypep-tide chains
  2. The heavy and light chains are held together by hydrogen bonds: 2
  3. What conditions will cause double stranded DNA to denature?: high temp
  4. You wish to visualize the location of a particular protein in fixed cells, what is one method you could use to do this?
  5. Western Blot
  6. Immunofluorescence
  7. Southern Blot
  8. Fluorescence in situ
  9. hybridization
  10. Immunoprecipitation: 2
  11. An antibody generated against the mouse IgG constant domain and pro-duced in rabbits is referred to as:

8 /

  1. Rabbit anti-mouse
  2. More than one of these responses is correct
  3. Labeled secondary antibody
  4. Mouse anti-rabbit
  5. Primary antibody:
  6. Which of the following contributes to Ab-Ag binding affinity? Select all that apply.
  7. Physical complementation between the structure of the antigen binding site and the epitope
  8. Ionic bonds formed between the amino acids within the antigen binding site and the epitope
  9. Disulphide bonds formed between the amino acids within the antigen binding site and the epitope
  10. Similarity between the amino acid sequences of the antigen binding site and the epitope
  11. The combination of several weak non-covalent interactions: Not 3
  12. When double stranded DNA splits into two single stranded molecules this is called...: Denaturation
  13. The term molecular hybridization refers to:: annealing of single stranded DNA or RNA molecules to those with complimentary sequences
  14. What would be expected to decreases the melting temperature of double stranded DNA?: low G-C content and High A-T content
  15. Which cells of the immune system are responsible for producing secreted antibody?: not stem cells
  16. You wish to study the protein-protein interactions of a specific protein. Which of the following techniques is best suited for this task?: Co-Immunoprecip-itation

10 /

  1. The branch point A does not participate in base pairing with the to allow for the first reaction in RNA splicing via the group of the branch point A. A. U1 snRNA; polymerization; 3' OH

11 / B. 3' splice site; debranching; 5' PO C. 3' splice site; transesterification; 3' OH D. U2 snRNA; transesterification; 2' OH E. U2 snRNA; debranching; 2' OH: D

  1. Place the following events of RNA splicing in the correct sequence: I. Formation of a 2' 5' phosphodiester bond between the branch point and 5' end of the intron II. The first transesterification reaction, catalyzed by U2 and U III. Recruitment of U3, U4, and U5 to the preRNA IV. Binding of SF1 to the branch point A V.Joining of the two exons via a 3' 5' phosphodiester bond A. V, III, II, I, V B. I, IV, II, I, V C. V, III, I, II, V D. I, IV, II, V, I E. I, IV, III, I, V: A
  2. What is splicing: joining of two exons and removal of an intron
  3. What are the master regulators called that control the events of the cell cycle?: Cyclin Dependent Kinases (CDK)
  4. What is the regulatory subunit of CDKs called?: cyclins
  5. What do cyclins do?: activates the transition to the next stage and then gets degraded
  6. What is the cell cycle?: ordered series of events that lead to cell divisions and the production of two daughter cells
  7. What events are considered interphase?: G1+2+G
  8. What are checkpoints?: acts as brakes on cell cycle progression when events are not completed or when DNA is damaged
  9. What is the G1 phase?: gap phase between birth of new cell (M) and chromosome replication (S)-cell grows in preparation for the next mitosis
  10. What is the S phase?: synthesis phase - DNA is replicated to make an identical copy

13 /

  1. What is the M phase?: Mitosis phase - cell segregates one copy of each chromosome into each new daughter cell
  2. Where is the commitment point, and what does it do?: The decisions whether to divide or not is taken in late G1 phase. This decision is tightly regulated. Cells that will never divide arrest before this start point
  3. What happens in prophase?: Chromosomes condense Nuclear membrane disintegrates Centrioles move to opposite poles Spindle apparatus formed by microtubules
  4. What happens in metaphase?: Chromosomes line up in the middle of the cell
  5. What happens in anaphase?: Sister chromatids split and move to either pole (Disjunction)
  6. What happens in telophase?: Nuclear membrane reforms Chromosomes decondense
  7. What happens in cytokinesis?: cell divides into two daughter cells
  8. What is the spindle assembly checkpoint?: are all chromosomes attached to mitotic spindles?
  9. What is the chromosome segregation checkpoint?: have all chromosomes reached opposite poles?
  10. What is the G1 phase cyclin, what does it regulate and how: cyclin D, regulates CDK 4/ --> coordinate cell growth with entry into a new cell cycle in response to growth factors --> inactivates CDK inhibitors allowing activation of G1/S cyclins
  11. What is the G1/S phase cyclin, what does it regulate and how: cyclin E, regulates CDK --> inactive inhibitor (Rb) that suppresses S-phase CDK activity in G --> allows synthesis of genes controlling S phase progression including cyclin A
  12. What is the S phase cyclin, what does it regulate and how?: cyclin A, regulates CDK 2 --> stimulate DNA replication by phosphorylating components of prereplication complexes

14 /

  1. What is the M phase cyclin, what does it regulate and how?: cyclin B, regulates CDK 1 --> stimulates assembly of mitotic spindles, chromatin condensation, nuclear envelope breakdown