All flashcards
Flashcard 1: What is the defining event of metaphase?
Answer: Chromosomes align at the metaphase plate. Alignment at the equator ensures balanced tension and equal chromosome distribution to daughter cells.
Flashcard 2: What is the defining event of prometaphase?
Answer: Nuclear envelope breaks down and kinetochores attach to spindle. Envelope breakdown allows spindle access to chromosomes, enabling microtubule-kinetochore interactions for alignment.
Flashcard 3: Which protein complex triggers anaphase by enabling sister chromatid separation?
Answer: APC/C (anaphase-promoting complex/cyclosome). APC/C degrades securin, activating separase to initiate chromatid separation and anaphase progression.
Flashcard 4: What enzyme cleaves cohesin to allow chromatid separation at anaphase?
Answer: Separase. Separase proteolytically cleaves cohesin subunits, releasing chromatids for poleward migration in anaphase.
Flashcard 5: What is the kinetochore?
Answer: Protein complex on centromere that binds spindle microtubules. Kinetochores facilitate chromosome movement by linking centromeres to microtubules during spindle assembly.
Flashcard 6: Identify the term for failure of sister chromatids to separate properly during mitosis.
Answer: Nondisjunction. Nondisjunction leads to aneuploidy by causing unequal chromosome distribution to daughter cells.
Flashcard 7: Which option best describes chromosome number per daughter cell after mitosis: 2n n 4n?
Answer: 2n. Mitosis preserves the diploid chromosome number by equally dividing replicated chromosomes between daughters.
Flashcard 8: Identify the DNA content change in a diploid cell from G1 to G2 using C notation.
Answer: G1: 2C G2: 4C. DNA replication in S phase doubles the genome from unreplicated diploid to replicated diploid content.
Flashcard 9: What is the cell plate in plant cytokinesis?
Answer: 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.
Flashcard 10: What structure forms the cleavage furrow during animal cell cytokinesis?
Answer: Actin-myosin contractile ring. The ring constricts the plasma membrane, pinching the cell into two via actin-myosin contraction.
Flashcard 11: What is cytokinesis?
Answer: Physical division of the cytoplasm into two daughter cells. Cytokinesis completes cell division by partitioning organelles and cytoplasm after nuclear separation.
Flashcard 12: What is the mitotic spindle primarily composed of?
Answer: Microtubules and associated motor proteins. The spindle apparatus organizes and separates chromosomes through dynamic microtubule polymerization and motor protein activity.
Flashcard 13: Which microtubules attach to kinetochores and move chromosomes?
Answer: Kinetochore microtubules. Kinetochore microtubules capture and align chromosomes, generating force for poleward movement in anaphase.
Flashcard 14: Which microtubules overlap at the midline and push spindle poles apart?
Answer: Polar (interpolar) microtubules. Polar microtubules elongate the spindle by sliding past each other, facilitating cell elongation during anaphase.
Flashcard 15: Which microtubules anchor spindle poles to the cell cortex?
Answer: Astral microtubules. Astral microtubules stabilize spindle orientation by interacting with cortical actin, ensuring symmetric division.
Flashcard 16: What is the defining event of prophase in mitosis?
Answer: Chromatin condenses into visible chromosomes. Condensation compacts DNA for efficient segregation, marking the start of mitotic chromosome visibility.
Flashcard 17: What is the defining event of telophase?
Answer: Nuclear envelopes reform and chromosomes decondense. Reformation restores nuclear integrity, while decondensation prepares chromosomes for interphase functions.
Flashcard 18: What is the spindle assembly checkpoint monitoring?
Answer: Proper kinetochore attachment and tension before anaphase. The checkpoint prevents anaphase onset until all chromosomes are bipolarly attached, avoiding segregation errors.
Flashcard 19: What is the defining event of anaphase?
Answer: Sister chromatids separate and move to opposite poles. Separation allows replicated chromosomes to be pulled apart, ensuring each pole receives a complete set.
Flashcard 20: What is cohesin?
Answer: Protein complex that holds sister chromatids together. Cohesin maintains chromatid pairing post-replication, ensuring accurate alignment until anaphase trigger.
Flashcard 21: What is the primary purpose of mitosis in multicellular eukaryotes?
Answer: 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.
Flashcard 22: What is the correct order of mitotic phases (excluding interphase)?
Answer: Prophase prometaphase metaphase anaphase telophase. Mitotic phases progress from chromosome condensation to separation and nuclear reformation to ensure accurate genome distribution.
Flashcard 23: What is the key event of S phase that changes chromosome structure before mitosis?
Answer: DNA replication producing sister chromatids. S phase duplicates the genome, forming paired chromatids essential for equal segregation during mitosis.
Flashcard 24: What is a sister chromatid?
Answer: 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.
Flashcard 25: What is the centromere in a replicated chromosome?
Answer: Region where sister chromatids are held together. The centromere provides the attachment site for spindle fibers and maintains chromatid cohesion until anaphase.