Mitosis and Chromosome Dynamics (2C) - MCAT Biological and Biochemical Foundations of Living Systems
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What is the defining event of metaphase?
What is the defining event of metaphase?
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Chromosomes align at the metaphase plate. Alignment at the equator ensures balanced tension and equal chromosome distribution to daughter cells.
Chromosomes align at the metaphase plate. Alignment at the equator ensures balanced tension and equal chromosome distribution to daughter cells.
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What is the defining event of prometaphase?
What is the defining event of prometaphase?
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Nuclear envelope breaks down and kinetochores attach to spindle. Envelope breakdown allows spindle access to chromosomes, enabling microtubule-kinetochore interactions for alignment.
Nuclear envelope breaks down and kinetochores attach to spindle. Envelope breakdown allows spindle access to chromosomes, enabling microtubule-kinetochore interactions for alignment.
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Which protein complex triggers anaphase by enabling sister chromatid separation?
Which protein complex triggers anaphase by enabling sister chromatid separation?
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APC/C (anaphase-promoting complex/cyclosome). APC/C degrades securin, activating separase to initiate chromatid separation and anaphase progression.
APC/C (anaphase-promoting complex/cyclosome). APC/C degrades securin, activating separase to initiate chromatid separation and anaphase progression.
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What enzyme cleaves cohesin to allow chromatid separation at anaphase?
What enzyme cleaves cohesin to allow chromatid separation at anaphase?
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Separase. Separase proteolytically cleaves cohesin subunits, releasing chromatids for poleward migration in anaphase.
Separase. Separase proteolytically cleaves cohesin subunits, releasing chromatids for poleward migration in anaphase.
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What is the kinetochore?
What is the kinetochore?
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Protein complex on centromere that binds spindle microtubules. Kinetochores facilitate chromosome movement by linking centromeres to microtubules during spindle assembly.
Protein complex on centromere that binds spindle microtubules. Kinetochores facilitate chromosome movement by linking centromeres to microtubules during spindle assembly.
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Identify the term for failure of sister chromatids to separate properly during mitosis.
Identify the term for failure of sister chromatids to separate properly during mitosis.
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Nondisjunction. Nondisjunction leads to aneuploidy by causing unequal chromosome distribution to daughter cells.
Nondisjunction. Nondisjunction leads to aneuploidy by causing unequal chromosome distribution to daughter cells.
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Which option best describes chromosome number per daughter cell after mitosis: $2n n 4n$?
Which option best describes chromosome number per daughter cell after mitosis: $2n n 4n$?
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$2n$. Mitosis preserves the diploid chromosome number by equally dividing replicated chromosomes between daughters.
$2n$. Mitosis preserves the diploid chromosome number by equally dividing replicated chromosomes between daughters.
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Identify the DNA content change in a diploid cell from G$1$ to G$2$ using C notation.
Identify the DNA content change in a diploid cell from G$1$ to G$2$ using C notation.
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G$1$: $2C$ G$2$: $4C$. DNA replication in S phase doubles the genome from unreplicated diploid to replicated diploid content.
G$1$: $2C$ G$2$: $4C$. DNA replication in S phase doubles the genome from unreplicated diploid to replicated diploid content.
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What is the cell plate in plant cytokinesis?
What is the cell plate in plant cytokinesis?
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Vesicle-derived partition that becomes the new cell wall. The plate forms from Golgi vesicles, depositing materials to build a new wall between plant daughter cells.
Vesicle-derived partition that becomes the new cell wall. The plate forms from Golgi vesicles, depositing materials to build a new wall between plant daughter cells.
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What structure forms the cleavage furrow during animal cell cytokinesis?
What structure forms the cleavage furrow during animal cell cytokinesis?
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Actin-myosin contractile ring. The ring constricts the plasma membrane, pinching the cell into two via actin-myosin contraction.
Actin-myosin contractile ring. The ring constricts the plasma membrane, pinching the cell into two via actin-myosin contraction.
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What is cytokinesis?
What is cytokinesis?
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Physical division of the cytoplasm into two daughter cells. Cytokinesis completes cell division by partitioning organelles and cytoplasm after nuclear separation.
Physical division of the cytoplasm into two daughter cells. Cytokinesis completes cell division by partitioning organelles and cytoplasm after nuclear separation.
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What is the mitotic spindle primarily composed of?
What is the mitotic spindle primarily composed of?
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Microtubules and associated motor proteins. The spindle apparatus organizes and separates chromosomes through dynamic microtubule polymerization and motor protein activity.
Microtubules and associated motor proteins. The spindle apparatus organizes and separates chromosomes through dynamic microtubule polymerization and motor protein activity.
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Which microtubules attach to kinetochores and move chromosomes?
Which microtubules attach to kinetochores and move chromosomes?
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Kinetochore microtubules. Kinetochore microtubules capture and align chromosomes, generating force for poleward movement in anaphase.
Kinetochore microtubules. Kinetochore microtubules capture and align chromosomes, generating force for poleward movement in anaphase.
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Which microtubules overlap at the midline and push spindle poles apart?
Which microtubules overlap at the midline and push spindle poles apart?
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Polar (interpolar) microtubules. Polar microtubules elongate the spindle by sliding past each other, facilitating cell elongation during anaphase.
Polar (interpolar) microtubules. Polar microtubules elongate the spindle by sliding past each other, facilitating cell elongation during anaphase.
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Which microtubules anchor spindle poles to the cell cortex?
Which microtubules anchor spindle poles to the cell cortex?
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Astral microtubules. Astral microtubules stabilize spindle orientation by interacting with cortical actin, ensuring symmetric division.
Astral microtubules. Astral microtubules stabilize spindle orientation by interacting with cortical actin, ensuring symmetric division.
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What is the defining event of prophase in mitosis?
What is the defining event of prophase in mitosis?
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Chromatin condenses into visible chromosomes. Condensation compacts DNA for efficient segregation, marking the start of mitotic chromosome visibility.
Chromatin condenses into visible chromosomes. Condensation compacts DNA for efficient segregation, marking the start of mitotic chromosome visibility.
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What is the defining event of telophase?
What is the defining event of telophase?
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Nuclear envelopes reform and chromosomes decondense. Reformation restores nuclear integrity, while decondensation prepares chromosomes for interphase functions.
Nuclear envelopes reform and chromosomes decondense. Reformation restores nuclear integrity, while decondensation prepares chromosomes for interphase functions.
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What is the spindle assembly checkpoint monitoring?
What is the spindle assembly checkpoint monitoring?
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Proper kinetochore attachment and tension before anaphase. The checkpoint prevents anaphase onset until all chromosomes are bipolarly attached, avoiding segregation errors.
Proper kinetochore attachment and tension before anaphase. The checkpoint prevents anaphase onset until all chromosomes are bipolarly attached, avoiding segregation errors.
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What is the defining event of anaphase?
What is the defining event of anaphase?
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Sister chromatids separate and move to opposite poles. Separation allows replicated chromosomes to be pulled apart, ensuring each pole receives a complete set.
Sister chromatids separate and move to opposite poles. Separation allows replicated chromosomes to be pulled apart, ensuring each pole receives a complete set.
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What is cohesin?
What is cohesin?
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Protein complex that holds sister chromatids together. Cohesin maintains chromatid pairing post-replication, ensuring accurate alignment until anaphase trigger.
Protein complex that holds sister chromatids together. Cohesin maintains chromatid pairing post-replication, ensuring accurate alignment until anaphase trigger.
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What is the primary purpose of mitosis in multicellular eukaryotes?
What is the primary purpose of mitosis in multicellular eukaryotes?
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Produce two genetically identical somatic daughter cells. Mitosis maintains genetic stability by duplicating and evenly distributing chromosomes to support growth and repair in somatic tissues.
Produce two genetically identical somatic daughter cells. Mitosis maintains genetic stability by duplicating and evenly distributing chromosomes to support growth and repair in somatic tissues.
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What is the correct order of mitotic phases (excluding interphase)?
What is the correct order of mitotic phases (excluding interphase)?
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Prophase prometaphase metaphase anaphase telophase. Mitotic phases progress from chromosome condensation to separation and nuclear reformation to ensure accurate genome distribution.
Prophase prometaphase metaphase anaphase telophase. Mitotic phases progress from chromosome condensation to separation and nuclear reformation to ensure accurate genome distribution.
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What is the key event of S phase that changes chromosome structure before mitosis?
What is the key event of S phase that changes chromosome structure before mitosis?
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DNA replication producing sister chromatids. S phase duplicates the genome, forming paired chromatids essential for equal segregation during mitosis.
DNA replication producing sister chromatids. S phase duplicates the genome, forming paired chromatids essential for equal segregation during mitosis.
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What is a sister chromatid?
What is a sister chromatid?
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One of two identical DNA copies joined at a centromere. Sister chromatids result from DNA replication, ensuring each daughter cell receives an identical genetic copy.
One of two identical DNA copies joined at a centromere. Sister chromatids result from DNA replication, ensuring each daughter cell receives an identical genetic copy.
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What is the centromere in a replicated chromosome?
What is the centromere in a replicated chromosome?
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Region where sister chromatids are held together. The centromere provides the attachment site for spindle fibers and maintains chromatid cohesion until anaphase.
Region where sister chromatids are held together. The centromere provides the attachment site for spindle fibers and maintains chromatid cohesion until anaphase.
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