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Questions and Answers
What is the term used for the factor that advances the cell cycle?
What is the term used for the factor that advances the cell cycle?
Which process directly follows mitosis during cell division?
Which process directly follows mitosis during cell division?
What structure is responsible for organizing and sorting chromosomes during mitotic cell division?
What structure is responsible for organizing and sorting chromosomes during mitotic cell division?
During which phase of the cell cycle does DNA replication occur?
During which phase of the cell cycle does DNA replication occur?
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What happens to sister chromatids during cell division?
What happens to sister chromatids during cell division?
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What is the duration of the G1 phase for a cell that divides in 24 hours?
What is the duration of the G1 phase for a cell that divides in 24 hours?
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What type of proteins combine to form an activated complex that advances the cell cycle?
What type of proteins combine to form an activated complex that advances the cell cycle?
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Which checkpoint is responsible for ensuring that all DNA has been replicated before cell division?
Which checkpoint is responsible for ensuring that all DNA has been replicated before cell division?
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What is the role of checkpoint proteins in the cell cycle?
What is the role of checkpoint proteins in the cell cycle?
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During which phase do cyclins level rise and fall?
During which phase do cyclins level rise and fall?
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What happens during the M phase of the cell cycle?
What happens during the M phase of the cell cycle?
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What is the primary function of the metaphase checkpoint?
What is the primary function of the metaphase checkpoint?
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What was studied by Masui and Markert regarding frog oocytes?
What was studied by Masui and Markert regarding frog oocytes?
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What phase of mitosis involves the alignment of sister chromatids along the metaphase plate?
What phase of mitosis involves the alignment of sister chromatids along the metaphase plate?
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During which phase does the nuclear envelope completely fragment?
During which phase does the nuclear envelope completely fragment?
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What event occurs during anaphase?
What event occurs during anaphase?
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What is the role of microtubules during cytokinesis in animals?
What is the role of microtubules during cytokinesis in animals?
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In which type of cell does the cleavage furrow form during cytokinesis?
In which type of cell does the cleavage furrow form during cytokinesis?
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What happens to chromosomes at the end of telophase?
What happens to chromosomes at the end of telophase?
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What initiates the separation of cells in plant cytokinesis?
What initiates the separation of cells in plant cytokinesis?
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Which phase marks the beginning of visible chromatid condensation?
Which phase marks the beginning of visible chromatid condensation?
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What is the purpose of the eukaryotic cell cycle?
What is the purpose of the eukaryotic cell cycle?
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What occurs during the S phase of the cell cycle?
What occurs during the S phase of the cell cycle?
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What is the haploid number of chromosomes in human gametes?
What is the haploid number of chromosomes in human gametes?
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Which phase of the cell cycle is characterized by a cell exiting and entering a non-dividing state?
Which phase of the cell cycle is characterized by a cell exiting and entering a non-dividing state?
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What is the chromosome composition of a diploid human cell?
What is the chromosome composition of a diploid human cell?
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How do homologous chromosomes differ from each other?
How do homologous chromosomes differ from each other?
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What primarily happens during mitosis in the cell cycle?
What primarily happens during mitosis in the cell cycle?
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Which of the following best describes cytokinesis?
Which of the following best describes cytokinesis?
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How many chromosomes are present in a set of human chromosomes?
How many chromosomes are present in a set of human chromosomes?
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What is the main difference between mitosis and meiosis?
What is the main difference between mitosis and meiosis?
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Which principle of the chromosome theory of inheritance states that genes are located on chromosomes?
Which principle of the chromosome theory of inheritance states that genes are located on chromosomes?
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During meiosis, how do the members of different chromosome pairs behave?
During meiosis, how do the members of different chromosome pairs behave?
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What is the result of fertilization in terms of chromosome numbers?
What is the result of fertilization in terms of chromosome numbers?
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How many chromosomes would result from meiosis if starting with a diploid cell that has 8 chromosomes?
How many chromosomes would result from meiosis if starting with a diploid cell that has 8 chromosomes?
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Which of the following correctly describes the inheritance of chromosomes?
Which of the following correctly describes the inheritance of chromosomes?
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What role do gametes play in the process of sexual reproduction?
What role do gametes play in the process of sexual reproduction?
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What is the purpose of homologous chromosome pairing during meiosis?
What is the purpose of homologous chromosome pairing during meiosis?
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What is the definition of a locus in genetics?
What is the definition of a locus in genetics?
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What is created when two haploid gametes unite during sexual reproduction?
What is created when two haploid gametes unite during sexual reproduction?
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Which of the following is NOT a disadvantage of sexual reproduction?
Which of the following is NOT a disadvantage of sexual reproduction?
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In which type of species is the multicellular organism primarily diploid?
In which type of species is the multicellular organism primarily diploid?
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What occurs immediately after haploid cells unite to form a diploid zygote in haploid-dominant species?
What occurs immediately after haploid cells unite to form a diploid zygote in haploid-dominant species?
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Which life cycle involves both a diploid multicellular stage and a haploid multicellular stage?
Which life cycle involves both a diploid multicellular stage and a haploid multicellular stage?
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During which phase does meiosis occur in the life cycle of a sporophyte?
During which phase does meiosis occur in the life cycle of a sporophyte?
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What is one of the key advantages of sexual reproduction as compared to asexual reproduction?
What is one of the key advantages of sexual reproduction as compared to asexual reproduction?
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Which of the following organisms typically exhibits a haploid-dominant life cycle?
Which of the following organisms typically exhibits a haploid-dominant life cycle?
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Study Notes
Eukaryotic Cell Cycle, Mitosis, and Meiosis
- The human body contains between 10 and 50 trillion cells.
- DNA sequences in all cells are the same, except for rare mutations.
- Cell reproduction maintains genetic integrity through mitosis and meiosis.
Chapter 16 Outline
- The Eukaryotic Cell Cycle
- Mitotic Cell Division
- Meiosis
- The Chromosome Theory of Inheritance
- Sexual Reproduction
- Variation in Chromosome Structure and Number
Cell Division
- Cytogenetics is the field of genetics involving microscopic examination of chromosomes.
The Eukaryotic Cell Cycle
- A cell cycle is a series of events leading to cell division.
- Chromosomes condense when cells prepare to divide.
- Cytogenetics examines chromosomes microscopically.
Karyotype
- A karyotype is a photographic representation of chromosomes.
- A diploid human cell has 46 chromosomes (2 complete sets).
- Karyotypes display sets of chromosomes from a single cell.
Sets of Chromosomes
- Eukaryotic chromosomes occur in sets.
- A human has 23 different chromosomes per set (n=23).
- 22 autosomes (non-sex chromosomes).
- Sex chromosomes: X and Y
- Most human cells are diploid (2n = 46 chromosomes total).
- Gametes (sperm and eggs) are haploid (n = 23).
Homologs
- In diploid species, members of a chromosome pair are called homologs.
- Homologous pairs have nearly identical size and genetic composition but with slight sequence variations.
- Sex chromosomes (X and Y) differ significantly in size and composition.
The Cell Cycle
- G1: first gap phase; cell growth
- S: synthesis phase; DNA replication
- G2: second gap phase; preparation for mitosis
- M: mitosis and cytokinesis; cell division
- G0: non-dividing phase
The Cell Cycle Summary
- G1: cell growth, commitment to divide, accumulating changes promoting progression.
- S: chromosome replication; each chromosome replicates to form a pair of sister chromatids.
- G2: cell synthesizes proteins for chromosome sorting and cell division. Growth may occur.
- M: mitosis; one cell nucleus divides into two, distributing duplicated chromosomes; cytokinesis; divides cytoplasm into two daughter cells.
- Cell cycle length varies; can be minutes (embryos) to months (slow-growing cells) to 10-24 hours (fast-dividing cells in adults.)
Control of the Cell Cycle
- Cyclins and cyclin-dependent kinases (Cdks) control advancement through the cell cycle.
- Cyclin levels change throughout the cell cycle.
- Cyclin and Cdk combine to form an activated complex, phosphorylating & activating other proteins to advance the cell cycle.
Cell Cycle Checkpoints
- Checkpoint proteins act as sensors to determine if a cell is in proper condition to divide, ensuring proper progression.
- G1 checkpoint monitors DNA damage.
- G2 checkpoint checks for DNA damage and ensures replication is complete.
- Metaphase checkpoint ensures all chromosomes are correctly attached to the spindle apparatus.
Overview of Mitosis
- Mitosis produces two genetically identical daughter cells from a single mother cell.
- Mitosis involves the division of one nucleus into two.
- Mitosis is followed by cytokinesis (cell division).
Phases of Mitosis
- Prophase: Chromosomes condense, nuclear membrane fragments, nucleolus disappears.
- Prometaphase: Nuclear envelope completely fragments, spindle apparatus fully forms, sister chromatids attach to kinetochore microtubules from opposite poles.
- Metaphase: Chromosomes aligned in a single row along the metaphase plate.
- Anaphase: Sister chromatids separate, pulled toward opposite poles.
- Telophase: Chromosomes reach poles and decondense, nuclear membranes reform, two separate nuclei produced.
Cytokinesis
- Cytoplasm division.
- In animals: cleavage furrow constricts to separate the cells.
- In plants: Golgi vesicles form cell plate, forming a cell wall between the two daughter cells.
Meiosis
- Meiosis produces haploid cells from a diploid cell.
- Meiosis involves two rounds of cell division to reduce the chromosome number by half.
- Meiosis results in four genetically unique daughter cells (haploid).
- Meiosis is used for gamete production in sexually reproducing organisms.
Mitosis versus Meiosis
- Two key events start meiosis I:
- Homologous pairs associate to become a bivalent.
- Crossing over occurs (exchange of segments between chromosomes.)
- Crossing over increases genetic variation.
- The connections are called chiasmata.
Meiosis I
- Prophase I: Homologous chromosomes condense, pair up, crossover occurs.
- Prometaphase I: Nuclear envelope fragments, bivalents attach to the spindle.
- Metaphase I: Bivalents align along the metaphase plate.
- Anaphase I: Homologous chromosomes separate.
- Telophase I: Chromosomes reach poles, nuclear envelope reforms (and cytokinesis).
Meiosis II
- DNA is not replicated between meiosis I and meiosis II.
- Similar to mitosis, separating sister chromatids.
Outcome of Mitosis vs Meiosis
- Mitosis produces two diploid daughter cells from one diploid parent cell.
- Meiosis produces four haploid daughter cells from one diploid parent cell.
Chromosome Theory of Inheritance
- Mendel's laws are explained by pairing and segregation of homologous chromosomes during meiosis.
- The Chromosome theory states that specific traits can be explained by chromosome behaviour during meiosis.
Sexual Reproduction
- Two haploid gametes unite in a fertilization event.
- Fusing gametes creates a diploid zygote that undergoes mitosis to create a multicellular organism.
- Sexual reproduction differs from asexual reproduction; it creates genetically unique offspring, allowing stronger adaptation to environmental changes.
Life Cycles
- Life Cycles: Sequence of events that produces another generation of organisms.
- Diploid-dominant life cycles—have dominant diploid stage, gametes produced by meiosis.
- Haploid-dominant life cycles—have dominant haploid stage, gametes fuse to create a diploid zygote.
- Life cycles with alternation of generations—alternate between multicellular haploid and diploid stages.
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Description
Test your knowledge on the cell cycle and mitosis with this quiz. It covers key concepts including DNA replication, cell cycle checkpoints, and the roles of various proteins during cell division. Perfect for biology students studying cellular processes.
