Mitosis
55 flashcards covering Mitosis for the MCAT Biology & Biochemistry section.
Mitosis is the process by which a single cell divides to produce two identical daughter cells, each with the same number of chromosomes as the original. This happens in somatic cells and is essential for growth, tissue repair, and asexual reproduction in organisms. During mitosis, the cell's nucleus divides in a series of organized stages, ensuring that genetic material is accurately duplicated and distributed, while the rest of the cell also splits to form two functional units.
On the MCAT, mitosis appears in Biology and Biochemistry questions that test your understanding of the cell cycle, including its phases like prophase, metaphase, anaphase, and telophase. You'll encounter multiple-choice items involving diagrams, comparisons with meiosis, or scenarios of errors leading to issues like cancer. Common traps include confusing the stages or overlooking regulatory checkpoints, so focus on key events, such as chromosome alignment and spindle formation, to avoid mistakes in application-based problems.
Practice sketching the stages from memory for better recall.
Terms (55)
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Mitosis
Mitosis is the process of cell division that results in two daughter cells with the same number and kind of chromosomes as the parent nucleus, essential for growth, repair, and asexual reproduction in eukaryotic cells.
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Interphase
Interphase is the phase of the cell cycle preceding mitosis, during which the cell grows, carries out normal functions, and duplicates its DNA in preparation for division.
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Prophase
Prophase is the first stage of mitosis where chromosomes condense, the nuclear envelope breaks down, and the mitotic spindle begins to form.
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Prometaphase
Prometaphase is the stage following prophase in mitosis, characterized by the breakdown of the nuclear envelope and attachment of chromosomes to the mitotic spindle via kinetochores.
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Metaphase
Metaphase is the stage of mitosis where chromosomes align at the equatorial plate of the cell, ensuring each daughter cell will receive an identical set of chromosomes.
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Anaphase
Anaphase is the stage of mitosis when sister chromatids separate and are pulled to opposite poles of the cell by the spindle fibers.
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Telophase
Telophase is the final stage of mitosis where chromosomes decondense, the nuclear envelope reforms around each set of chromosomes, and the cell prepares for cytokinesis.
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Cytokinesis
Cytokinesis is the process that divides the cytoplasm of a parental cell into two daughter cells, typically following mitosis, and varies between animal and plant cells.
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Spindle apparatus
The spindle apparatus is a structure made of microtubules that organizes and separates chromosomes during mitosis and meiosis, originating from the centrosomes.
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Centrosome
The centrosome is an organelle that serves as the main microtubule organizing center in animal cells, helping to form the spindle apparatus during cell division.
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Kinetochore
The kinetochore is a protein structure on chromatids where spindle microtubules attach during mitosis, ensuring proper chromosome segregation.
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Chromatin condensation
Chromatin condensation is the process during prophase of mitosis where DNA and proteins compact into visible chromosomes, facilitating their movement and separation.
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Nuclear envelope breakdown
Nuclear envelope breakdown occurs in prophase of mitosis, allowing spindle fibers to access chromosomes for alignment and separation.
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Chromosome alignment
Chromosome alignment happens in metaphase of mitosis, with chromosomes lining up at the cell's equator to ensure equal distribution to daughter cells.
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Sister chromatid separation
Sister chromatid separation takes place in anaphase of mitosis, where the cohesin proteins holding them together are cleaved, allowing movement to opposite poles.
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Cell plate formation
Cell plate formation is the process in plant cells during cytokinesis where a new cell wall forms between daughter cells, originating from the center of the cell.
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Cleavage furrow
The cleavage furrow is an indentation in animal cells during cytokinesis, formed by the contraction of an actin ring, which divides the cell into two.
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G1 phase
The G1 phase is the first gap phase in interphase of the cell cycle, where the cell grows and synthesizes proteins needed for DNA replication.
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S phase
The S phase is the synthesis phase in interphase where DNA replication occurs, resulting in each chromosome consisting of two identical sister chromatids.
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G2 phase
The G2 phase is the second gap phase in interphase, during which the cell grows, checks for DNA damage, and prepares for mitosis.
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G1 checkpoint
The G1 checkpoint is a control point in the cell cycle that ensures conditions are favorable for DNA synthesis, halting the cycle if damage is detected.
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G2 checkpoint
The G2 checkpoint verifies that DNA replication is complete and accurate before mitosis begins, preventing division of damaged cells.
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M checkpoint
The M checkpoint, or spindle assembly checkpoint, ensures all chromosomes are properly attached to the spindle before anaphase, avoiding unequal chromosome distribution.
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Cyclin-dependent kinases
Cyclin-dependent kinases are enzymes that regulate the cell cycle by phosphorylating target proteins, becoming active when bound to specific cyclins.
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Cyclins
Cyclins are proteins that regulate the cell cycle by activating cyclin-dependent kinases at specific stages, with levels fluctuating throughout the cycle.
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Maturation promoting factor
Maturation promoting factor is a complex of cyclin B and CDK1 that triggers the transition from G2 to M phase in the cell cycle.
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p53 protein
p53 is a tumor suppressor protein that halts the cell cycle at the G1 checkpoint if DNA damage is detected, allowing for repair or triggering apoptosis.
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Oncogenes
Oncogenes are mutated genes that promote uncontrolled cell division, often by affecting mitosis regulation, leading to potential cancer development.
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Mitosis vs. Meiosis
Mitosis produces two identical diploid daughter cells for growth and repair, while meiosis produces four genetically diverse haploid cells for sexual reproduction.
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Diploid cells
Diploid cells contain two sets of chromosomes, one from each parent, and undergo mitosis to maintain this state in somatic cells.
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Haploid cells
Haploid cells have a single set of chromosomes and are produced by meiosis, not mitosis, for gamete formation.
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Asexual reproduction
Asexual reproduction involves mitosis to produce genetically identical offspring from a single parent, common in some plants and unicellular organisms.
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Binary fission
Binary fission is a form of asexual reproduction in prokaryotes, similar to mitosis but without a nucleus, where the cell divides into two identical cells.
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Role of mitosis in growth
Mitosis enables growth by increasing the number of cells in multicellular organisms, allowing tissues and organs to develop and expand.
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Mitotic index
The mitotic index is the ratio of cells undergoing mitosis to the total number of cells, used to measure cell proliferation rates in tissues.
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Aneuploidy
Aneuploidy is an abnormal chromosome number resulting from errors in mitosis, such as nondisjunction, which can lead to genetic disorders.
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Nondisjunction
Nondisjunction is a failure of chromosomes to separate properly during mitosis or meiosis, resulting in daughter cells with unequal chromosome numbers.
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Cancer and mitosis
Cancer arises from uncontrolled mitosis due to mutations in cell cycle regulators, leading to rapid, unregulated cell division and tumor formation.
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Colchicine
Colchicine is a drug that inhibits mitosis by binding to tubulin and preventing spindle fiber formation, used in research and treating gout.
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Microtubules in mitosis
Microtubules are dynamic protein filaments that form the spindle apparatus in mitosis, facilitating chromosome movement and cell division.
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Astral microtubules
Astral microtubules extend from centrosomes to the cell periphery during mitosis, helping to position the spindle and organize cytokinesis.
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Kinetochore microtubules
Kinetochore microtubules attach to chromosomes at the kinetochore during mitosis, pulling sister chromatids apart in anaphase.
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Polar microtubules
Polar microtubules extend from opposite poles of the cell during mitosis and interact to push the poles apart, elongating the cell.
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Anaphase A
Anaphase A is the phase of anaphase where chromosomes are pulled toward the poles by shortening kinetochore microtubules.
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Anaphase B
Anaphase B is the phase of anaphase where the poles move apart due to sliding polar microtubules, separating the chromosomes.
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Telomeres
Telomeres are protective caps on chromosome ends that shorten with each cell division, potentially limiting the number of mitotic divisions a cell can undergo.
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DNA replication
DNA replication occurs in the S phase before mitosis, ensuring each daughter cell receives an exact copy of the genetic material.
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Phosphorylation in mitosis
Phosphorylation by kinases like CDKs regulates key events in mitosis, such as chromosome condensation and spindle formation, by activating or inactivating proteins.
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Mitosis in plant cells
Mitosis in plant cells includes the formation of a cell plate during cytokinesis, unlike in animal cells, and occurs without centrioles.
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Mitosis in animal cells
Mitosis in animal cells involves centrioles and results in a cleavage furrow for cytokinesis, supporting growth and tissue repair.
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Chromosome number maintenance
Mitosis maintains the chromosome number in daughter cells, ensuring genetic stability across cell generations in multicellular organisms.
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Apoptosis and mitosis
Apoptosis, or programmed cell death, balances mitosis to maintain tissue homeostasis, preventing overgrowth from excessive cell division.
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Stem cells and mitosis
Stem cells use mitosis to self-renew and produce differentiated cells, crucial for development and tissue regeneration.
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Mitotic spindle orientation
Mitotic spindle orientation determines the plane of cell division, influencing tissue architecture and cell fate in developing organisms.
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Error in spindle assembly
Errors in spindle assembly can lead to mitotic catastrophe, where cells fail to divide properly and may undergo apoptosis to prevent genomic instability.