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Questions and Answers
A cell spends most of its time in which phase of the cell cycle?
A cell spends most of its time in which phase of the cell cycle?
- M phase
- Mitotic phase
- Interphase (correct)
- Cytokinesis
Which of the following represents the correct sequence of events during interphase?
Which of the following represents the correct sequence of events during interphase?
- G2, S, G1
- S, G1, G2
- G1, S, G2 (correct)
- G1, G2, S
DNA replication occurs during which phase of the cell cycle?
DNA replication occurs during which phase of the cell cycle?
- S phase (correct)
- G1 phase
- G2 phase
- Mitotic phase
Which of the following processes occurs during the mitotic phase?
Which of the following processes occurs during the mitotic phase?
What is the primary function of cytokinesis?
What is the primary function of cytokinesis?
In which phase of the cell cycle does the cell prepare for division by synthesizing proteins and organelles?
In which phase of the cell cycle does the cell prepare for division by synthesizing proteins and organelles?
Which of the following is NOT a function of cell division?
Which of the following is NOT a function of cell division?
During which phase does a cell increase in size and synthesize new proteins and organelles?
During which phase does a cell increase in size and synthesize new proteins and organelles?
What would be the immediate consequence if cytokinesis did not occur following mitosis?
What would be the immediate consequence if cytokinesis did not occur following mitosis?
A researcher introduces a drug that inhibits DNA synthesis. In which phase of the cell cycle would cells likely arrest?
A researcher introduces a drug that inhibits DNA synthesis. In which phase of the cell cycle would cells likely arrest?
What is the primary function of the centromere in a chromosome?
What is the primary function of the centromere in a chromosome?
During what phase of the cell cycle does chromosome duplication primarily occur?
During what phase of the cell cycle does chromosome duplication primarily occur?
What are sister chromatids?
What are sister chromatids?
Where does the assembly of spindle microtubules start?
Where does the assembly of spindle microtubules start?
If a cell has 46 chromosomes during G1 phase, how many sister chromatids will be present after the S phase?
If a cell has 46 chromosomes during G1 phase, how many sister chromatids will be present after the S phase?
What is the relationship between a chromosome and a DNA molecule?
What is the relationship between a chromosome and a DNA molecule?
Which of the following events directly relies on the separation of sister chromatids?
Which of the following events directly relies on the separation of sister chromatids?
How would disruption of the centrosome affect cell division?
How would disruption of the centrosome affect cell division?
If a drug prevented the duplication of the centromere, what would be the most likely consequence?
If a drug prevented the duplication of the centromere, what would be the most likely consequence?
Which of the following correctly describes the order of events during cell division?
Which of the following correctly describes the order of events during cell division?
In organisms exhibiting alternation of generations, such as plants and some algae, what process directly follows meiosis?
In organisms exhibiting alternation of generations, such as plants and some algae, what process directly follows meiosis?
What is the ploidy of the zygote in organisms that undergo sexual reproduction?
What is the ploidy of the zygote in organisms that undergo sexual reproduction?
What is the primary component driving the formation of the cleavage furrow during cytokinesis in animal cells?
What is the primary component driving the formation of the cleavage furrow during cytokinesis in animal cells?
Which of the following is a key difference between meiosis in animals and meiosis in fungi?
Which of the following is a key difference between meiosis in animals and meiosis in fungi?
In plant cells, what is the origin of the materials that build the new cell wall during cytokinesis?
In plant cells, what is the origin of the materials that build the new cell wall during cytokinesis?
A cell with 46 chromosomes undergoes meiosis. How many chromosomes will each daughter cell have at the end of meiosis II?
A cell with 46 chromosomes undergoes meiosis. How many chromosomes will each daughter cell have at the end of meiosis II?
What is the main purpose of meiosis in sexually reproducing organisms?
What is the main purpose of meiosis in sexually reproducing organisms?
Which of the following structures is characteristic of animal cell cytokinesis but not plant cell cytokinesis?
Which of the following structures is characteristic of animal cell cytokinesis but not plant cell cytokinesis?
What is the relationship between the metaphase plate and the location of the cleavage furrow in animal cell cytokinesis?
What is the relationship between the metaphase plate and the location of the cleavage furrow in animal cell cytokinesis?
Which process contributes to genetic variation in sexually reproducing organisms?
Which process contributes to genetic variation in sexually reproducing organisms?
How do sister chromatids and homologous chromosomes differ during meiosis?
How do sister chromatids and homologous chromosomes differ during meiosis?
Which of the following best describes the phragmoplast's role in plant cell cytokinesis?
Which of the following best describes the phragmoplast's role in plant cell cytokinesis?
What would be the most likely outcome if myosin were inhibited during animal cell cytokinesis?
What would be the most likely outcome if myosin were inhibited during animal cell cytokinesis?
In the context of sexual life cycles, what is the role of fertilization?
In the context of sexual life cycles, what is the role of fertilization?
A karyotype reveals that a human cell has 47 chromosomes. Which of the following most likely occurred?
A karyotype reveals that a human cell has 47 chromosomes. Which of the following most likely occurred?
How does cytokinesis differ fundamentally between animal and plant cells?
How does cytokinesis differ fundamentally between animal and plant cells?
A researcher introduces a drug into plant cells that prevents the Golgi apparatus from producing vesicles. What is the most likely consequence?
A researcher introduces a drug into plant cells that prevents the Golgi apparatus from producing vesicles. What is the most likely consequence?
If a plant species has a diploid number of 12 ($2n = 12$), what is the haploid number ($n$) in its gametes?
If a plant species has a diploid number of 12 ($2n = 12$), what is the haploid number ($n$) in its gametes?
If a cell lacked centrioles, what aspect of cell division would be most directly affected?
If a cell lacked centrioles, what aspect of cell division would be most directly affected?
During plant cell cytokinesis, what initiates the formation of the cell plate?
During plant cell cytokinesis, what initiates the formation of the cell plate?
Flashcards
Cell Cycle
Cell Cycle
The repeating series of growth, DNA replication, and division.
Interphase
Interphase
The stage involving cell growth and preparation for division.
G1 Phase
G1 Phase
The first growth phase of interphase.
S Phase
S Phase
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G2 Phase
G2 Phase
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Mitosis
Mitosis
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Cytokinesis
Cytokinesis
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Cell Division Functions
Cell Division Functions
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Mitotic (M) Phase
Mitotic (M) Phase
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Interphase Duration
Interphase Duration
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Chromosome
Chromosome
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DNA molecules
DNA molecules
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Sister Chromatids
Sister Chromatids
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Centromere
Centromere
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Chromosome Arm Duplication
Chromosome Arm Duplication
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Centromere
Centromere
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Separation of Sister Chromatids
Separation of Sister Chromatids
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Centrosome
Centrosome
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Spindle Microtubules
Spindle Microtubules
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Microtubule Assembly
Microtubule Assembly
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Diploid
Diploid
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Haploid
Haploid
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Fertilization
Fertilization
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Karyotype
Karyotype
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Gamete
Gamete
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Diploid Zygote
Diploid Zygote
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Spores
Spores
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Homologous Chromosomes
Homologous Chromosomes
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Centrioles
Centrioles
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Cleavage Furrow
Cleavage Furrow
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Contractile Ring
Contractile Ring
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Cell Plate
Cell Plate
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Phragmoplast
Phragmoplast
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Telophase
Telophase
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Actin microfilaments
Actin microfilaments
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Coalesce
Coalesce
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Study Notes
- Cell division functions in reproduction, growth, and repair/tissue renewal
Cell Cycle Overview
- Cell cycle stages are interphase and mitotic phase
- Mitotic (M) phase alternates with the much longer interphase
- Interphase accounts for about 90% of the cell cycle
Interphase Details
- Interphase consists of G1 phase, S phase, and G2 phase
- G1 phase involves cell growth
- S phase involves growth and DNA synthesis
- G2 phase involves growth and preparation for cell division
Mitotic Phase Details
- Mitotic phase includes mitosis and cytokinesis
- Mitosis is nuclear division
- Cytokinesis is division of the cytoplasm
Chromosomes
- Chromosomes are made of DNA molecules
- Chromosome duplication includes DNA synthesis
- Sister chromatids form after duplication
- Sister chromatids separate during cell division at the centromere
Mitosis Stages
- Mitosis includes prophase, prometaphase, metaphase, anaphase, telophase
- During prophase, chromatin condenses, nucleoli disappear, and the mitotic spindle forms
- The centrosomes move away from each other, propelled by microtubules
- In prometaphase, the nuclear envelope fragments
- Microtubules extend into nuclear area and attach to kinetochores
- Metaphase involves the chromosomes aligning at the metaphase plate
- In anaphase, sister chromatids separate and move to opposite ends of the cell
- Telophase involves the formation of two daughter nuclei
- Nuclear envelopes reform, chromosomes decondense
Spindle Microtubules
- Assembly of the spindle microtubules starts in the centrosome
- The centrosome is the microtubule-organizing center
- Animal cells have a pair of centrioles at the center of the centrosome
- The function of centrioles is somewhat undefined
Cytokinesis
- Cytokinesis, division of the cytoplasm typically follows mitosis
- In animal cells, the first sign of cytokinesis (cleavage) is the appearance of a cleavage furrow
- The cleavage furrow is a contractile ring of actin microfilaments associated with myosin
- The ring contracts and deepens to divide the cell
- In plant cells, during telophase, vesicles from the Golgi coalesce (phragmoplast) at the metaphase plate, forming a cell plate
- The cell plate grows until it fuses with plasma membrane
Meiosis and Sexual Life Cycles
- Meiosis is a type of cell division that reduces the number of sets of chromosomes from two to one
- Fertilization is union of gametes
- Results in offspring with the same number of chromosomes as their parents
Karyotype
- Karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell
- Pair of homologous replicated chromosomes with centromere and sister chromatids
- Metaphase chromosome with sister chromatids
Chromosome Sets
- 2n = 6 means maternal set of chromosomes (n = 3) and paternal set of chromosomes (n = 3)
- Two sister chromatids of one replicated chromosome connected at the centromere
- Pair of homologous chromosomes (one from each set)
Meiosis I and II
- Interphase I of meiosis features a homologous pair of chromosomes in a diploid parent cell (2n)
- Chromosomes replicate forming homologous pair of replicated chromosomes with sister chromatids
- Meiosis I involves the separation of homologous chromosomes resulting in haploid cells with replicated chromosomes
- Meiosis II involves the separation of sister chromatids, resulting in haploid cells with unreplicated chromosomes
Meiosis I Details
- During prophase I, homologous chromosomes pair and crossing over occurs
- In metaphase I, homologous pairs line up at the metaphase plate
- In anaphase I, homologous chromosomes separate
- In telophase I, two haploid cells form, each with duplicated chromosomes
Meiosis II Details
- During prophase II, a spindle apparatus forms
- In metaphase II, sister chromatids align at the metaphase plate
- In anaphase II, sister chromatids separate
MITOSIS vs MEIOSIS
- During mitosis Parent cell chromosome replication, chromosomes align at the metaphase plate, sister chromatids separate during anaphase
- Results in two identical daughter cells
- During meiosis Parent cell chromosome replication, tetrads align at the metaphase plate during Meiosis I
- Homologous chromosomes separate during anaphase I and sister chromatids separate during anaphase II
- Results in four genetically distinct daughter cells
Microsporogenesis
- Microsporogenesis is formation of spores called microspores
- Development of microspore into the microgametophyte or the pollen tube
- Includes meiotic and mitotic division in the development of pollen
Megagametogenesis
- Megasporogenesis refers to the development of a female gametophyte or embryo sac
Mitosis vs Meiosis - Summary
| Feature | Mitosis | Meiosis |
|---|---|---|
| DNA replication | Occurs during interphase before nuclear division begins | Occurs once, during the interphase before meiosis I begins |
| Number of divisions | One, including prophase, metaphase, anaphase, and telophase | Two, each including prophase, metaphase, anaphase, and telophase |
| Synapsis of homologous chromosomes | Does not occur | Synapsis is unique to meiosis, involves homologous chromosomes joining along their length forming tetrads; associated with crossing over between nonsister chromatids |
| Number of daughter cells and genetic composition | Two diploid (2n) are genetically identical to the parent cell | Four haploid (n), each with chromosome half as parent has; Genetic non identical to parent cells |
| Role | Enables multicellular adult to arise from zygote; produces cells for growth and tissue repair | Produces gametes; reduces chromosome number by half and introduces genetic variability among the gametes |
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