Podcast
Questions and Answers
What occurs during telophase?
What occurs during telophase?
- The sister chromatids are pulled apart to opposite poles
- The chromosomes align at the cell equator
- The nuclear envelopes reassemble around each set of chromosomes (correct)
- The spindle fibers begin to disassemble
Which type of microtubule is primarily responsible for the movement of chromosomes toward the poles during anaphase?
Which type of microtubule is primarily responsible for the movement of chromosomes toward the poles during anaphase?
- Interpolar microtubules
- Kinetochore microtubules (correct)
- Polar microtubules
- Astral microtubules
What initiates cytokinesis in animal cells?
What initiates cytokinesis in animal cells?
- Disassembly of the mitotic spindle
- Reassembly of the nuclear envelope
- Separation of chromatids
- Formation of a contractile ring (correct)
Which motor proteins are involved in the movements of microtubules during anaphase?
Which motor proteins are involved in the movements of microtubules during anaphase?
What is the primary function of the contractile ring during cytokinesis in animal cells?
What is the primary function of the contractile ring during cytokinesis in animal cells?
Which phase of mitosis is characterized by the separation of chromosomes?
Which phase of mitosis is characterized by the separation of chromosomes?
What happens during the S-phase of the cell cycle?
What happens during the S-phase of the cell cycle?
What is the role of cohesin proteins during the S-phase?
What is the role of cohesin proteins during the S-phase?
What is the spindle-assembly checkpoint responsible for during mitosis?
What is the spindle-assembly checkpoint responsible for during mitosis?
Which phase of mitosis involves the preparation for the physical separation of chromosomes?
Which phase of mitosis involves the preparation for the physical separation of chromosomes?
What role do microtubules play during mitosis?
What role do microtubules play during mitosis?
During which phase of the cell cycle are centrosomes duplicated?
During which phase of the cell cycle are centrosomes duplicated?
What distinguishes condensin proteins from cohesin proteins?
What distinguishes condensin proteins from cohesin proteins?
What occurs during cytokinesis?
What occurs during cytokinesis?
Which structure assembles during prophase to assist with chromosome movement?
Which structure assembles during prophase to assist with chromosome movement?
What happens to chromosomes at the end of interphase?
What happens to chromosomes at the end of interphase?
What is the primary function of the mitotic spindle during mitosis?
What is the primary function of the mitotic spindle during mitosis?
What is the significance of the spindle-assembly checkpoint during metaphase?
What is the significance of the spindle-assembly checkpoint during metaphase?
What role do kinetochores play during cell division?
What role do kinetochores play during cell division?
What stabilizes the attachment of microtubules to kinetochores during metaphase?
What stabilizes the attachment of microtubules to kinetochores during metaphase?
What happens at the Spindle-Assembly Checkpoint when all kinetochores are properly attached?
What happens at the Spindle-Assembly Checkpoint when all kinetochores are properly attached?
What prevents the exit from metaphase when there are unattached kinetochores?
What prevents the exit from metaphase when there are unattached kinetochores?
What is the main purpose of cohesins in cell division?
What is the main purpose of cohesins in cell division?
How does the APC/C affect M-cyclin and cohesins?
How does the APC/C affect M-cyclin and cohesins?
During which phase are chromosomes aligned on the metaphase plate?
During which phase are chromosomes aligned on the metaphase plate?
What is the primary indicator that the Spindle-Assembly Checkpoint is satisfied?
What is the primary indicator that the Spindle-Assembly Checkpoint is satisfied?
What is the primary purpose of the mitotic spindle during cell division?
What is the primary purpose of the mitotic spindle during cell division?
During which phase do microtubules begin attaching to kinetochores?
During which phase do microtubules begin attaching to kinetochores?
What component is NOT part of the mitotic spindle?
What component is NOT part of the mitotic spindle?
What initiates the breakdown of the nuclear envelope during prometaphase?
What initiates the breakdown of the nuclear envelope during prometaphase?
What is a spindle pole in the context of the mitotic spindle?
What is a spindle pole in the context of the mitotic spindle?
Which of the following correctly describes the spindle-assembly checkpoint?
Which of the following correctly describes the spindle-assembly checkpoint?
Which is NOT a characteristic of microtubules in the mitotic spindle?
Which is NOT a characteristic of microtubules in the mitotic spindle?
Flashcards
DNA Replication (S phase)
DNA Replication (S phase)
The process where the cell's genetic material (DNA) is copied, creating two identical copies called sister chromatids. These copies remain attached.
Cohesin Proteins
Cohesin Proteins
Proteins that act like molecular glue, holding the sister chromatids together after DNA replication.
G2 Phase
G2 Phase
The stage of the cell cycle where the cell prepares for cell division. This includes the duplication of organelles and the production of proteins needed for mitosis.
Mitotic Spindle
Mitotic Spindle
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Prophase
Prophase
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Prometaphase
Prometaphase
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Spindle-Assembly Checkpoint
Spindle-Assembly Checkpoint
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Anaphase
Anaphase
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Cytokinesis
Cytokinesis
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Mitosis
Mitosis
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Condensin
Condensin
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Kinetochore Microtubules
Kinetochore Microtubules
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Nuclear Lamins
Nuclear Lamins
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Kinetochore
Kinetochore
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Contractile ring
Contractile ring
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Cell plate formation
Cell plate formation
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What is a centromere?
What is a centromere?
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What is a kinetochore?
What is a kinetochore?
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What are cohesins?
What are cohesins?
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What is the metaphase plate?
What is the metaphase plate?
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What is bi-orientation?
What is bi-orientation?
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What is the spindle-assembly checkpoint?
What is the spindle-assembly checkpoint?
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What is the Anaphase Promoting Complex (APC/C)?
What is the Anaphase Promoting Complex (APC/C)?
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What is anaphase?
What is anaphase?
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Study Notes
Exam Instructions
- Computer screens must be in BRIGHT MODE and Canvas displayed in full screen.
- Only Canvas software should be running.
- Do not highlight any text on your Canvas site.
- Turn off phones, smartwatches, and calculators, and keep them in backpacks until 1:15.
- Use colored paper as scrap paper, but do not write on it before the exam starts.
- Leaving the seat during the preliminary exam is allowed only in emergencies.
- The exam duration is 45 minutes.
- Close your laptop or turn your tablet upside down upon finishing and submitting the exam.
- If you finish the exam before 1:00 pm, you can leave the exam room after showing your submission page at the exit and returning the scrap paper.
- Remain in the exam room in exam mode (no phones) until 1:15 if you finish after 1:00 pm
Mitosis Learning Objectives
- Understand the organization of microtubules in the mitotic spindle and which associate with centrosomes and kinetochores.
- Understand the events that occur in each phase of mitosis.
- Understand how chromosomes become attached to appropriate microtubules: "bi-orientation."
- Understand the mitosis checkpoint (spindle-assembly checkpoint) and how it's satisfied.
Today's Topics (M-Phase)
- Overview of events in M-phase and preparation for M-phase.
- Prophase and the mitotic spindle.
- Chromosome attachment in prometaphase and the spindle-assembly checkpoint in metaphase.
- Anaphase (separation of chromosomes).
- Telophase and cytokinesis (cell division).
The Cell Cycle
- The cell cycle is divided into four phases: interphase (G1, S, G2), and M-phase (mitosis and cytokinesis).
- G1 phase: Growth and preparation for S phase.
- S phase: DNA replication.
- G2 phase: Growth and preparation for mitosis.
- M phase: Mitosis (nuclear division) and cytokinesis (cytoplasmic division)
S-Phase Details
- The genome is replicated (duplicated) by DNA polymerase during S phase.
- Cohesin proteins bind to the genome forming rings that hold duplicated sister chromatids together.
- Sister chromatids are exact copies of the same chromosome, consisting of DNA and histone proteins.
Centrosome Replication
- The centrosome is replicated during S and G2 phases.
- Centrosomes are microtubule organization centers (MTOCs) composed of γ-tubulin complexes.
- Microtubules play a critical role in chromatid segregation.
Mitotic Spindle
- The mitotic spindle is responsible for segregating sister chromatids into separate nuclei.
- It's made of microtubules, motors, and the two centrosomes.
- It has a built-in quality control system - the spindle-assembly checkpoint.
Prometaphase
- The nuclear envelope breaks down and microtubules begin attaching to chromosomes during prometaphase.
- Phosphorylation of nuclear lamins and nuclear pore proteins breaks down the nuclear envelope into vesicles.
- Microtubules attach to kinetochores.
Kinetochore Microtubules
- The kinetochore links centromeres to kinetochore microtubules.
- The centromere(s) is/are a special region of DNA within each chromosome.
- The kinetochore is a protein complex that attaches microtubules to the centromere of each chromosome.
Metaphase
- During metaphase, chromosomes are arranged on the "metaphase plate."
- The metaphase plate is positioned midway between the spindle poles.
Anaphase Details
-
Anaphase is characterized by two simultaneous processes: anaphase A and anaphase B.
- Anaphase A: Shortening of kinetochore microtubules pulling chromosomes towards the spindle poles.
- Anaphase B: Pushing and pulling of poles apart through interpolar microtubules.
-
Microtubules depolymerize at the kinetochore pulling the chromosome to the pole, which causes separation.
-
A sliding force and a pulling force between interpolar microtubules drive the poles apart.
Telophase
- During telophase, nuclear envelopes reassemble around each set of chromosomes producing two nuclei.
- Cytokinesis is initiated, including the formation of a contractile ring in animal cells.
Cytokinesis
- During cytokinesis, the cell completes the division process by separating the cytoplasm, creating two daughter cells.
- This process differs between plant and animal cells. Animal cells have a contractile ring.
Spindle Assembly Checkpoint Overview
- The spindle assembly checkpoint ensures all chromosomes are correctly attached to spindle fibers before anaphase.
- If not, the checkpoint prevents anaphase promoting complex (APC) activation – and with it chromosome separation.
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Description
Test your knowledge on key concepts of mitosis, including the phases, microtubule functions, and cytokinesis in animal cells. This quiz covers essential details such as the role of cohesin proteins and the spindle-assembly checkpoint. Perfect for students studying cell biology!
