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What is the definition of a cell cycle?
What is the definition of a cell cycle?
The entire sequence of events happening from the end of one nuclear division to the beginning of the next.
What are the two main phases of the cell cycle?
What are the two main phases of the cell cycle?
Interphase and cell division proper.
What are the sub-phases of interphase?
What are the sub-phases of interphase?
G1 phase is considered the resting phase of the cell cycle.
G1 phase is considered the resting phase of the cell cycle.
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What occurs during the S phase?
What occurs during the S phase?
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G2 phase follows the S phase and encompasses the resting stage after DNA replication.
G2 phase follows the S phase and encompasses the resting stage after DNA replication.
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What is the name given to the division of the nucleus?
What is the name given to the division of the nucleus?
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What is the name given to the division of the cytoplasm?
What is the name given to the division of the cytoplasm?
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What type of cell division is responsible for the development of a zygote into an adult organism?
What type of cell division is responsible for the development of a zygote into an adult organism?
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Mitosis leads to the formation of new organs like roots, leaves, stems, and branches in plants.
Mitosis leads to the formation of new organs like roots, leaves, stems, and branches in plants.
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Mitosis plays a role in repairing damaged parts in both plants and animals.
Mitosis plays a role in repairing damaged parts in both plants and animals.
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Mitosis helps overcome aging by replacing old, decayed, and dead cells.
Mitosis helps overcome aging by replacing old, decayed, and dead cells.
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How does mitosis contribute to the production of identical progeny in vegetatively propagated crops?
How does mitosis contribute to the production of identical progeny in vegetatively propagated crops?
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Mitosis is crucial for maintaining the purity of types in crops because it does not allow segregation and recombination.
Mitosis is crucial for maintaining the purity of types in crops because it does not allow segregation and recombination.
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Mitosis helps in the continuous replacement of old tissue with new ones in animals.
Mitosis helps in the continuous replacement of old tissue with new ones in animals.
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Who coined the term 'mitosis'?
Who coined the term 'mitosis'?
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Mitosis is also known as somatic cell division.
Mitosis is also known as somatic cell division.
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Which of the following characteristics do NOT apply to daughter cells produced by mitosis?
Which of the following characteristics do NOT apply to daughter cells produced by mitosis?
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Cells in interphase are characterized by a deeply stained nucleus showing a definite number of nucleoli.
Cells in interphase are characterized by a deeply stained nucleus showing a definite number of nucleoli.
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During interphase, chromosomes are individually distinguishable and appear as distinct coiled threads.
During interphase, chromosomes are individually distinguishable and appear as distinct coiled threads.
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The cell is metabolically inactive during interphase.
The cell is metabolically inactive during interphase.
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Which of the following is NOT a stage of mitosis?
Which of the following is NOT a stage of mitosis?
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What happens to the nucleus during prophase?
What happens to the nucleus during prophase?
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What does the disintegration of the nuclear membrane signify?
What does the disintegration of the nuclear membrane signify?
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During metaphase, where are the chromosomes arranged?
During metaphase, where are the chromosomes arranged?
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The chromosomes at metaphase are the shortest and thickest.
The chromosomes at metaphase are the shortest and thickest.
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What is the name given to the orientation of centromeres at the equator?
What is the name given to the orientation of centromeres at the equator?
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What happens to the centromere of each chromosome during anaphase?
What happens to the centromere of each chromosome during anaphase?
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The chromosome number is reduced to half during anaphase.
The chromosome number is reduced to half during anaphase.
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What marks the beginning of telophase?
What marks the beginning of telophase?
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Cytokinesis typically occurs between late anaphase and the end of telophase.
Cytokinesis typically occurs between late anaphase and the end of telophase.
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In plant cells, cytokinesis occurs through the formation of a cell plate.
In plant cells, cytokinesis occurs through the formation of a cell plate.
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What is the process by which cytokinesis occurs in animal cells?
What is the process by which cytokinesis occurs in animal cells?
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The term meiosis was coined by J.B. Farmer in 1905.
The term meiosis was coined by J.B. Farmer in 1905.
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Meiosis is found in organisms that exhibit asexual reproduction.
Meiosis is found in organisms that exhibit asexual reproduction.
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What is the Greek word from which the term 'meiosis' is derived?
What is the Greek word from which the term 'meiosis' is derived?
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What are cells that undergo meiosis called?
What are cells that undergo meiosis called?
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Which of the following processes does NOT occur during meiosis?
Which of the following processes does NOT occur during meiosis?
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The first meiotic division is also known as reduction division.
The first meiotic division is also known as reduction division.
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What is another name for the first meiotic division?
What is another name for the first meiotic division?
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The second meiotic division is also known as homotypic division.
The second meiotic division is also known as homotypic division.
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Meiosis ultimately results in the production of four haploid daughter cells.
Meiosis ultimately results in the production of four haploid daughter cells.
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In a tetrad produced by meiosis, all four daughter cells are genetically identical.
In a tetrad produced by meiosis, all four daughter cells are genetically identical.
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Meiosis typically begins following an interphase that is significantly different from the interphase preceding mitosis.
Meiosis typically begins following an interphase that is significantly different from the interphase preceding mitosis.
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DNA duplication occurs during the S phase of the meiotic interphase.
DNA duplication occurs during the S phase of the meiotic interphase.
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Prophase I of meiosis is a short and simple stage.
Prophase I of meiosis is a short and simple stage.
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What are the sub-stages of prophase I?
What are the sub-stages of prophase I?
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During leptonema, chromosomes appear as long, loosely interwoven threads, resembling a tangled yarn.
During leptonema, chromosomes appear as long, loosely interwoven threads, resembling a tangled yarn.
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Bead-like structures called chromomeres can be found on chromosomes during zygonema.
Bead-like structures called chromomeres can be found on chromosomes during zygonema.
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Synteresis is the process by which homologous chromosomes pair during zygotene.
Synteresis is the process by which homologous chromosomes pair during zygotene.
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During pachytene, exchange of segments between non-sister chromatids of homologous chromosomes occurs, a process known as crossing over.
During pachytene, exchange of segments between non-sister chromatids of homologous chromosomes occurs, a process known as crossing over.
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During diplotene, homologous chromosomes begin to separate, but they remain attached at certain points along their length, called chiasmata.
During diplotene, homologous chromosomes begin to separate, but they remain attached at certain points along their length, called chiasmata.
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Terminalization of chiasmata occurs during diplotene.
Terminalization of chiasmata occurs during diplotene.
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During diakinesis, the nuclear membrane and nucleolus disappear.
During diakinesis, the nuclear membrane and nucleolus disappear.
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Metaphase I is characterized by the alignment of tetrads at the equator of the cell.
Metaphase I is characterized by the alignment of tetrads at the equator of the cell.
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During anaphase I, homologous chromosomes migrate to opposite poles of the cell.
During anaphase I, homologous chromosomes migrate to opposite poles of the cell.
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Each chromosome at the end of anaphase I has two chromatids.
Each chromosome at the end of anaphase I has two chromatids.
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Telophase I is marked by the division of the cytoplasm into two daughter cells.
Telophase I is marked by the division of the cytoplasm into two daughter cells.
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Prophase II of meiosis is similar to prophase of mitosis.
Prophase II of meiosis is similar to prophase of mitosis.
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During anaphase II, sister chromatids separate and move to opposite poles.
During anaphase II, sister chromatids separate and move to opposite poles.
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Cytokinesis after meiosis II always results in the formation of four daughter cells.
Cytokinesis after meiosis II always results in the formation of four daughter cells.
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Meiosis ensures that the chromosome number remains constant within a species.
Meiosis ensures that the chromosome number remains constant within a species.
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Meiosis is responsible for producing gametes with a diploid chromosome number.
Meiosis is responsible for producing gametes with a diploid chromosome number.
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The fusion of male and female gametes results in the formation of a diploid zygote.
The fusion of male and female gametes results in the formation of a diploid zygote.
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Meiosis facilitates both segregation and independent assortment of chromosomes and genes.
Meiosis facilitates both segregation and independent assortment of chromosomes and genes.
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Crossing over is a process that occurs during meiosis.
Crossing over is a process that occurs during meiosis.
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Meiosis is essential for the continuity of sexually reproducing species.
Meiosis is essential for the continuity of sexually reproducing species.
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Meiosis contributes to genetic variability within a population.
Meiosis contributes to genetic variability within a population.
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Meiosis is a key factor in evolution, allowing for the adaptation of species to changing environments.
Meiosis is a key factor in evolution, allowing for the adaptation of species to changing environments.
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Mitosis results in the production of daughter cells that are genetically identical to the parent cell.
Mitosis results in the production of daughter cells that are genetically identical to the parent cell.
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Meiosis results in the production of daughter cells that are genetically distinct from the parent cell.
Meiosis results in the production of daughter cells that are genetically distinct from the parent cell.
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Mitosis is a key process in the development of an adult organism from a single fertilized egg (zygote).
Mitosis is a key process in the development of an adult organism from a single fertilized egg (zygote).
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Meiosis is essential for the repair of damaged tissues.
Meiosis is essential for the repair of damaged tissues.
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Mitosis contributes to the production of new organs in plants.
Mitosis contributes to the production of new organs in plants.
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Meiosis is responsible for the continuous replacement of old cells with new ones in animals.
Meiosis is responsible for the continuous replacement of old cells with new ones in animals.
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Meiosis is involved in the production of genetically identical daughter cells.
Meiosis is involved in the production of genetically identical daughter cells.
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Mitosis is involved in the production of genetically distinct daughter cells.
Mitosis is involved in the production of genetically distinct daughter cells.
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Meiosis is a key process in the formation of gametes.
Meiosis is a key process in the formation of gametes.
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Mitosis is a key process in maintaining the genetic purity of vegetatively propagated crops.
Mitosis is a key process in maintaining the genetic purity of vegetatively propagated crops.
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Study Notes
Cell Cycle
- A cell cycle is the entire sequence of events from one nuclear division to the next
- It has two phases: interphase and cell division
- The time for completion varies by species
Interphase
- Often called the DNA synthesis phase
- Includes G1, S, and G2 subphases
- G1: Resting phase before DNA replication
- S: DNA replication occurs
- G2: Resting phase after DNA replication
G1 Phase
- Pre-DNA replication phase, between telophase and S phase
- Longest phase, typically 12 hours in Vicia faba
- Most variable phase in length
- Protein and RNA synthesis takes place
S Phase
- Follows G1
- Shorter than G1 (6 hours in Vicia faba)
- Chromosome and DNA replication occur
G2 Phase
- Post-DNA replication phase, last sub-stage of interphase
- 12 hours in Vicia faba
- Protein and RNA synthesis
Cell Division
- All cells arise from pre-existing cells
- Continuity of life depends on cell division
- Nucleus division is called karyokinesis
Mitosis
- Coined by Flemming in 1882
- Somatic cell division (root tips, etc.)
- Daughter cells are similar to parent cells in shape, size, and chromosome number
- Called homotypic or equational division
- Consists of interphase and four phases: prophase, metaphase, anaphase, telophase
Interphase
- Period between divisions
- Nucleus is deeply-stained with visible nucleoli
- Chromosomes are not individually distinct, appear as thin, coiled threads
Prophase
- Nucleus stains darkly
- Increasing nuclear size
- Chromosomes condense and shorten via coiling
- Nuclear membrane disintegrates
Metaphase
- Chromosomes spread across the cytoplasm
- Chromosomes shorten and thicken further
- Centromeres of each chromosome are aligned at the equator
- Auto-orientation
- Chromatids are held together at centromeres
Anaphase
- Centromere separates first, moving to opposite poles
- Shape of chromosomes depends on centromere position
- Chromosomes move to poles
Telophase
- Chromosomes lose their distinct identity, becoming chromatin
- Nucleus re-organizes
- Nuclear membrane reforms around chromosomes
Cytokinesis
- Cytoplasm division usually occurs between late anaphase and telophase
- In plants: a cell plate forms from the cell's center
- In animals: a cleavage furrow forms
Significance of Mitosis
- Zygote development
- Normal organism growth and development
- Organ formation (plants)
- Repair of damaged/dead tissues
- Asexual reproduction
Meiosis
- Coined by J.B. Farmer in 1905
- Involved in sexual reproduction
- Meiocytes – cells that undergo meiosis
- Crucial for maintaining chromosome number, creating variation
- Two divisions: Meiosis I and Meiosis II.
Meiosis-I
- Prophase I (long, complex)
- Leptotene (chromosomes visible as threads)
- Zygotene (homologous chromosomes pair/synapsis)
- Pachytene (thickened thread-like chromosomes; crossing-over)
- Diplotene (homologous chromosomes start separating but remain joined at chiasmata)
- Diakinesis (chromosomes shorten and thicken; nuclear membrane and nucleolus disappear)
- Metaphase I (bivalents align on the metaphase plate)
- Anaphase I (homologous chromosomes separate and move to opposite poles)
- Telophase I (chromosomes reach poles, nucleus re-organizes)
Meiosis-II
- Similiar to mitosis, but with haploid cells
- Prophase II (chromosomes condense; nuclear envelopes usually disappear)
- Metaphase II (chromosomes align on metaphase plate)
- Anaphase II (sister chromatids separate)
- Telophase II (chromosomes reach poles, nuclei reorganize; cytokinesis follows)
Differences Between Mitosis and Meiosis
| Feature | Mitosis | Meiosis |
|---|---|---|
| Nuclear divisions | 1 | 2 |
| Daughter cell number | 2 | 4 |
| Chromosome number | Same as parent cell (2n) | Half the parent cell number (n) |
| Daughter cell type | Identical | Different |
| Cell type | Somatic | Reproductive |
| DNA replication | During interphase before division | During interphase before meiosis I only |
| Homologous pairing | No | Yes |
| Crossing over | No | Yes |
| Variation | No | High |
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Description
Test your understanding of the cell cycle, including its phases such as interphase and cell division. Explore the specifics of G1, S, and G2 phases, as well as the process of mitosis. This quiz covers essential concepts that are fundamental to cell biology.
