Podcast
Questions and Answers
Which event occurs during prophase?
Which event occurs during prophase?
- Chromosomes align at the metaphase plate
- Nuclear envelope disassembly
- Chromatin condenses into chromosomes (correct)
- Sister chromatids are pulled apart
What is a critical event in prometaphase?
What is a critical event in prometaphase?
- Chromosomes begin decondensation
- All spindle fibers attach to kinetochores (correct)
- Centromeres split
- Nuclear envelope reformation
During which phase do chromosomes align at the metaphase plate?
During which phase do chromosomes align at the metaphase plate?
- Anaphase
- Metaphase (correct)
- Telophase
- Prometaphase
What happens to sister chromatids during anaphase?
What happens to sister chromatids during anaphase?
Which statement describes telophase accurately?
Which statement describes telophase accurately?
What is the main role of the spindle checkpoint during metaphase?
What is the main role of the spindle checkpoint during metaphase?
What event is characterized by chromatin decondensation?
What event is characterized by chromatin decondensation?
Which structure is crucial for chromosome movement during prometaphase?
Which structure is crucial for chromosome movement during prometaphase?
What is not a characteristic of prophase?
What is not a characteristic of prophase?
What happens to the centromeres during anaphase?
What happens to the centromeres during anaphase?
What is the primary role of cohesin during metaphase?
What is the primary role of cohesin during metaphase?
What happens during the metaphase checkpoint if a single kinetochore is unattached?
What happens during the metaphase checkpoint if a single kinetochore is unattached?
What is the first major step in sister chromatid separation?
What is the first major step in sister chromatid separation?
Which statement accurately describes APC's role in cell cycle regulation?
Which statement accurately describes APC's role in cell cycle regulation?
What is the consequence of an error during prophase related to chromosome condensation?
What is the consequence of an error during prophase related to chromosome condensation?
How does MAD2 contribute to spindle attachment checkpoint regulation?
How does MAD2 contribute to spindle attachment checkpoint regulation?
What initiates the synthesis of G1 cyclin following APC activation?
What initiates the synthesis of G1 cyclin following APC activation?
Which of the following events would stall a cell at the spindle attachment checkpoint?
Which of the following events would stall a cell at the spindle attachment checkpoint?
What is the role of separase in the process of sister chromatid separation?
What is the role of separase in the process of sister chromatid separation?
What characterizes symmetric cytokinesis?
What characterizes symmetric cytokinesis?
Which of the following involves the creation of the cleavage furrow?
Which of the following involves the creation of the cleavage furrow?
During embryogenesis, what role do polarity proteins play?
During embryogenesis, what role do polarity proteins play?
What is one result of asymmetric cell division during embryogenesis?
What is one result of asymmetric cell division during embryogenesis?
Which protein complex is responsible for positioning the contractile ring?
Which protein complex is responsible for positioning the contractile ring?
What occurs during the final separation phase of cytokinesis?
What occurs during the final separation phase of cytokinesis?
In somatic mitosis, how is the distribution of organelles and cytoplasm managed?
In somatic mitosis, how is the distribution of organelles and cytoplasm managed?
Which step of cytokinesis follows the formation of the contractile ring?
Which step of cytokinesis follows the formation of the contractile ring?
Which statements about cytokinesis during embryogenesis are true?
Which statements about cytokinesis during embryogenesis are true?
What is the consequence of improper alignment of chromosomes during metaphase?
What is the consequence of improper alignment of chromosomes during metaphase?
Which stalling point is associated with errors during anaphase?
Which stalling point is associated with errors during anaphase?
What may result from the failure of cytokinesis?
What may result from the failure of cytokinesis?
How do microtubules contribute to anaphase?
How do microtubules contribute to anaphase?
What could be a consequence if spindles fail to pull chromatids apart?
What could be a consequence if spindles fail to pull chromatids apart?
What role do actin and myosin play in cytokinesis?
What role do actin and myosin play in cytokinesis?
What happens if a significant issue triggers a post-mitotic checkpoint?
What happens if a significant issue triggers a post-mitotic checkpoint?
What defines the final step in the cell cycle?
What defines the final step in the cell cycle?
What can occur as a consequence of aneuploidy during cell division?
What can occur as a consequence of aneuploidy during cell division?
Which error is most closely associated with incomplete chromosome segregation?
Which error is most closely associated with incomplete chromosome segregation?
Flashcards are hidden until you start studying
Study Notes
Mitosis Phases and Major Events
- Prophase: Chromatin condenses into visible chromosomes with sister chromatids; nucleus remains intact; spindle apparatus begins formation from centrosomes.
- Prometaphase: Nuclear envelope disassembles; spindle fibers attach to kinetochores at chromosome centromeres; chromosomes start moving toward the metaphase plate.
- Metaphase: Chromosomes align at the metaphase plate; spindle checkpoint ensures all chromosomes are correctly attached to spindle fibers before proceeding.
- Anaphase: Sister chromatids are pulled apart toward opposite poles once the centromeres split; cell elongates as microtubules push against each other.
- Telophase: Chromosomes reach poles and decondense; nuclear envelope reforms around each chromosome set; spindle apparatus disassembles.
- Cytokinesis: Division of the cytoplasm, creating two daughter cells; differs in animals (cleavage furrow) and plants (cell plate formation).
Metaphase Checkpoint and Chromosome Separation
- Alignment is driven by kinetochore attachment; an unattached kinetochore can stall mitosis via the anaphase promoting complex (APC).
- Cohesin complex holds sister chromatids together until anaphase; degradation of securin frees separase to cleave cohesin, enabling separation.
- Rate limiting steps include CDC20 synthesis and APC phosphorylation.
Consequences of APC Activation
- Activation of APC leads to the degradation of securin, freeing separase to cleave cohesin for chromatid separation.
- APC activation facilitates the degradation of m-phase cyclin and initiates G1 cyclin synthesis.
Spindle Attachment Checkpoint
- Ensures all chromosomes are properly attached before separation; a single unattached kinetochore can inhibit CDC20, stalling mitosis.
- MAD2 proteins sequester CDC20 at unattached kinetochores, blocking the progression into anaphase.
Errors in Mitosis
- Prophase Errors: Failure in chromosome condensation or spindle formation can lead to incomplete segregation; stalling at the G2/M checkpoint.
- Metaphase Errors: Improper alignment can cause aneuploidy; stalling occurs at the metaphase checkpoint if chromosomes are misaligned.
- Anaphase Errors: Failure to separate chromatids results in uneven distribution, leading to potential aneuploidy; errors may trigger apoptosis or unchecked cell growth.
- Telophase/Cytokinesis Errors: Incomplete reformation of the nuclear envelope or failed cytokinesis may cause multinucleated cells or chromosomal abnormalities; potential post-mitotic checkpoint may lead to apoptosis.
Cytokinesis Features and Steps
- Final stage of cell division, dividing cytoplasm into two daughter cells after mitosis.
- Actin and myosin filaments form a contractile ring that pinches the cell into two; divisions can be symmetric or asymmetric.
Steps for Proper Cytokinesis
- Formation of Contractile Ring: Positioning at the equator through signals like Rho-GEF and Ect-2; microtubules guide the central spindle complex.
- Contraction of Contractile Ring: Actin and myosin tighten the ring to form a cleavage furrow.
- Cleavage Furrow Formation: Actin and microtubules guide spatial distribution for even cell division.
- Final Separation: The midbody ring coordinates the separation of daughter cells.
- Distribution of Organelles: Ensures equal division of organelles and cytoplasm for viability.
Differences in Cytokinesis: Somatic Mitosis vs. Embryogenesis
- In somatic mitosis, division is nearly even; each daughter cell receives approximately equal cytoplasmic contents.
- In embryogenesis, asymmetrical divisions create concentration gradients; polarity proteins and Rho-GTPases contribute to unique material distribution affecting cell fate, crucial for morphogenesis and specialization.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
