Cell Cycle and Mitosis Quiz
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Questions and Answers

What is the term used for the factor that advances the cell cycle?

  • Spindle organizing factor
  • Cell division factor
  • Maturation-promoting factor (correct)
  • Cyclin-dependent kinase

Which process directly follows mitosis during cell division?

  • Interphase
  • Cytokinesis (correct)
  • Apoptosis
  • DNA replication

What structure is responsible for organizing and sorting chromosomes during mitotic cell division?

  • Plasma membrane
  • Nuclear envelope
  • Centromere
  • Spindle apparatus (correct)

During which phase of the cell cycle does DNA replication occur?

<p>S phase (C)</p> Signup and view all the answers

What happens to sister chromatids during cell division?

<p>They separate and move to opposite poles (C)</p> Signup and view all the answers

What is the duration of the G1 phase for a cell that divides in 24 hours?

<p>11 hours (D)</p> Signup and view all the answers

What type of proteins combine to form an activated complex that advances the cell cycle?

<p>Cyclins and cyclin-dependent kinases (C)</p> Signup and view all the answers

Which checkpoint is responsible for ensuring that all DNA has been replicated before cell division?

<p>G2 checkpoint (C)</p> Signup and view all the answers

What is the role of checkpoint proteins in the cell cycle?

<p>They ensure cells divide only when conditions are favorable. (D)</p> Signup and view all the answers

During which phase do cyclins level rise and fall?

<p>Throughout the cell cycle (A)</p> Signup and view all the answers

What happens during the M phase of the cell cycle?

<p>Cell division takes place. (D)</p> Signup and view all the answers

What is the primary function of the metaphase checkpoint?

<p>To check the spindle apparatus and chromosome attachment (B)</p> Signup and view all the answers

What was studied by Masui and Markert regarding frog oocytes?

<p>Dormancy and maturation processes (A)</p> Signup and view all the answers

What phase of mitosis involves the alignment of sister chromatids along the metaphase plate?

<p>Metaphase (D)</p> Signup and view all the answers

During which phase does the nuclear envelope completely fragment?

<p>Prometaphase (A)</p> Signup and view all the answers

What event occurs during anaphase?

<p>Connections between sister chromatids are broken (D)</p> Signup and view all the answers

What is the role of microtubules during cytokinesis in animals?

<p>Assisting in the cleavage furrow formation (D)</p> Signup and view all the answers

In which type of cell does the cleavage furrow form during cytokinesis?

<p>Animal cells (A)</p> Signup and view all the answers

What happens to chromosomes at the end of telophase?

<p>They reach their respective poles and decondense (D)</p> Signup and view all the answers

What initiates the separation of cells in plant cytokinesis?

<p>Fusing of vesicles from the Golgi apparatus (B)</p> Signup and view all the answers

Which phase marks the beginning of visible chromatid condensation?

<p>Prophase (A)</p> Signup and view all the answers

What is the purpose of the eukaryotic cell cycle?

<p>To regulate a series of events leading to cell division (B)</p> Signup and view all the answers

What occurs during the S phase of the cell cycle?

<p>Each chromosome is replicated to form sister chromatids (D)</p> Signup and view all the answers

What is the haploid number of chromosomes in human gametes?

<p>23 chromosomes (A)</p> Signup and view all the answers

Which phase of the cell cycle is characterized by a cell exiting and entering a non-dividing state?

<p>G0 phase (C)</p> Signup and view all the answers

What is the chromosome composition of a diploid human cell?

<p>Two sets of chromosomes totaling 46 (D)</p> Signup and view all the answers

How do homologous chromosomes differ from each other?

<p>They contain some sequence differences for genetic variation (B)</p> Signup and view all the answers

What primarily happens during mitosis in the cell cycle?

<p>One cell nucleus divides into two (D)</p> Signup and view all the answers

Which of the following best describes cytokinesis?

<p>The division of the cytoplasm into two daughter cells (A)</p> Signup and view all the answers

How many chromosomes are present in a set of human chromosomes?

<p>23 chromosomes, including sex chromosomes (C)</p> Signup and view all the answers

What is the main difference between mitosis and meiosis?

<p>Mitosis produces two genetically identical diploid daughter cells while meiosis produces four genetically different haploid daughter cells. (D)</p> Signup and view all the answers

Which principle of the chromosome theory of inheritance states that genes are located on chromosomes?

<p>Chromosomes contain DNA, which is the genetic material. (C)</p> Signup and view all the answers

During meiosis, how do the members of different chromosome pairs behave?

<p>They segregate independently into daughter cells. (A)</p> Signup and view all the answers

What is the result of fertilization in terms of chromosome numbers?

<p>It produces a diploid cell. (C)</p> Signup and view all the answers

How many chromosomes would result from meiosis if starting with a diploid cell that has 8 chromosomes?

<p>4 haploid daughter cells with 2 chromosomes each. (D)</p> Signup and view all the answers

Which of the following correctly describes the inheritance of chromosomes?

<p>Diploid organisms receive both chromosome sets from each parent. (A)</p> Signup and view all the answers

What role do gametes play in the process of sexual reproduction?

<p>They provide the genetic material needed for zygote formation. (D)</p> Signup and view all the answers

What is the purpose of homologous chromosome pairing during meiosis?

<p>To facilitate independent assortment of alleles. (A)</p> Signup and view all the answers

What is the definition of a locus in genetics?

<p>A physical location of a gene on a chromosome (B)</p> Signup and view all the answers

What is created when two haploid gametes unite during sexual reproduction?

<p>A zygote (B)</p> Signup and view all the answers

Which of the following is NOT a disadvantage of sexual reproduction?

<p>Produces offspring with low genetic variation (D)</p> Signup and view all the answers

In which type of species is the multicellular organism primarily diploid?

<p>Diploid-dominant species (D)</p> Signup and view all the answers

What occurs immediately after haploid cells unite to form a diploid zygote in haploid-dominant species?

<p>The zygote undergoes meiosis to produce spores (D)</p> Signup and view all the answers

Which life cycle involves both a diploid multicellular stage and a haploid multicellular stage?

<p>Alternation of generations (C)</p> Signup and view all the answers

During which phase does meiosis occur in the life cycle of a sporophyte?

<p>To generate haploid spores (D)</p> Signup and view all the answers

What is one of the key advantages of sexual reproduction as compared to asexual reproduction?

<p>Greater genetic variation among offspring (A)</p> Signup and view all the answers

Which of the following organisms typically exhibits a haploid-dominant life cycle?

<p>Some protists and many fungi (D)</p> Signup and view all the answers

Flashcards

What is the cell cycle?

A highly regulated series of events that leads to cell division.

What is the purpose of the S phase in the cell cycle?

During the S phase, each chromosome is replicated, forming a pair of sister chromatids.

What occurs during the G1 phase of the cell cycle?

The cell grows, synthesizes proteins and organelles, and becomes committed to dividing.

Explain the role of the G2 phase in the cell cycle.

The cell synthesizes proteins essential for chromosome sorting and cell division, and some growth may occur.

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What is the relationship between mitosis and cytokinesis?

Mitosis divides the nucleus into two, while cytokinesis divides the cytoplasm to form two daughter cells.

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What is the difference between a diploid and a haploid cell?

Diploid cells have two sets of chromosomes (2n), while haploid cells have only one set of chromosomes (n).

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Explain the process of chromosome replication.

Each chromosome replicates to form two identical sister chromatids, attached at the centromere. This ensures each daughter cell receives a complete set of genetic information.

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What is the function of a karyotype?

A photographic representation of chromosomes, used to visualize chromosome number and structure in a cell.

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What are homologous chromosomes?

Pairs of chromosomes that are nearly identical in size and genetic composition, but differ slightly in DNA sequences.

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What is the G0 phase, and why might a cell enter it?

A non-dividing phase that cells can enter when they are not actively dividing.

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Maturation-Promoting Factor (MPF)

A factor that promotes the transition of a cell through the cell cycle, specifically during mitosis and meiosis.

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Mitotic Cyclin

A protein that regulates the activity of cyclin-dependent kinases (CDKs), essential for driving the cell through the cell cycle.

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Cyclin-Dependent Kinase (CDK)

An enzyme that is activated by cyclins to phosphorylate target proteins and regulate cell cycle progression.

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Sister Chromatids

Two identical copies of a single chromosome, connected at the centromere, that are produced during DNA replication.

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Centrosome

A structure in the cytoplasm that serves as a microtubule-organizing center (MTOC) and plays a crucial role in cell division.

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Cell Cycle Length

The duration of a complete cell cycle varies depending on cell type and growth rate. It can take several minutes in rapidly dividing embryos, several months in slow-growing adult cells, or around 10 to 24 hours for fast-dividing mammalian cells like skin cells.

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Cell Cycle Phases

The cell cycle consists of four distinct phases: G1 (gap 1), S (synthesis), G2 (gap 2), and M (mitosis). These phases represent distinct stages of growth, DNA replication, and cell division.

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Cell Cycle Regulation

The progression of the cell cycle is tightly controlled by a complex molecular machinery to ensure that cells divide only when appropriate and avoid errors.

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Cyclins

Cyclins are proteins whose levels fluctuate during the cell cycle. They act as regulatory molecules, controlling the progression of the cell cycle by binding to and activating cyclin-dependent kinases (CDKs).

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Cyclin/CDK Complex

The binding of a cyclin to a CDK forms an active complex. This complex phosphorylates target proteins, allowing the cell to progress through the cell cycle.

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Cell Cycle Checkpoints

Cell cycle checkpoints are control points that monitor the state of the cell and ensure that important processes are completed correctly before the cell can proceed to the next stage.

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G1 Checkpoint (Restriction Point)

The G1 checkpoint determines if the cell has the necessary nutrients, growth factors, and DNA integrity to proceed with DNA replication. It acts as a key point of control, preventing cells with damaged DNA from dividing.

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Mitosis Stages

Mitosis unfolds in a series of ordered phases: prophase, prometaphase, metaphase, anaphase, and telophase, each with distinct events.

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Prophase

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

During this phase, the nuclear envelope completely fragments, allowing the spindle fibers to attach to chromosomes.

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Metaphase

Sister chromatids align along the metaphase plate, a central plane dividing the cell into two halves, ensuring equal distribution.

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Anaphase

Sister chromatids separate as kinetochore microtubules shorten, pulling chromosomes to opposite poles and moving the poles further apart.

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Telophase

Chromosomes reach the poles, de-condense, and the nuclear envelope reforms around each set of chromosomes, resulting in two separate nuclei.

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Cytokinesis

The division of the cytoplasm, following mitosis, resulting in two daughter cells each with a complete nucleus and cytoplasm.

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Cytokinesis Differences

Cytokinesis in animals involves a cleavage furrow formed by a contractile ring, while in plants, a cell plate is formed from Golgi vesicles, eventually creating a new cell wall.

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What is Meiosis?

A type of cell division that reduces the number of chromosomes in half, producing four haploid daughter cells from one diploid cell.

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What is the difference between mitosis and meiosis?

Mitosis produces two diploid daughter cells that are genetically identical, while meiosis reduces the number of chromosomes in half, producing four haploid daughter cells.

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How do Mendel's laws relate to meiosis?

Mendel's laws of inheritance can be explained by the pairing and segregation of homologous chromosomes during meiosis.

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What is the Chromosome Theory of Inheritance?

This theory proposed by Theodor Boveri and Walter Sutton explains how chromosome behavior during meiosis accounts for the patterns of inheritance we observe.

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What is the first principle of the Chromosome Theory?

Chromosomes contain DNA, which is the genetic material. Genes are found in the chromosomes.

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What is the second principle of the Chromosome Theory?

Chromosomes are replicated and passed from parent to offspring, and from cell to cell during multicellular development.

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What is the third principle of the Chromosome Theory?

The nucleus of a diploid cell contains two sets of chromosomes, which are found as homologous pairs. One member of each pair is inherited from the mother and the other from the father. Each set carries a full complement of genes.

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What is the fourth principle of the Chromosome Theory?

At meiosis, one member of each chromosome pair segregates into one daughter nucleus, and its homologue segregates into the other daughter nucleus. During the formation of haploid cells, the members of different chromosome pairs segregate independently.

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Locus

The specific physical location of a gene on a chromosome.

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Alleles

Different versions of the same gene found at the same locus on homologous chromosomes.

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Homologous Chromosomes

Pairs of chromosomes that are nearly identical in size and genetic composition, carrying the same genes but potentially different alleles.

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What is the chromosomal basis of allele segregation?

During meiosis, homologous chromosomes separate, ensuring that each gamete receives only one allele for each gene.

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What is the chromosomal basis of independent assortment?

During meiosis, homologous chromosomes align independently of each other, leading to different combinations of alleles in gametes.

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What is the difference between sexual and asexual reproduction?

Sexual reproduction involves the fusion of two gametes, resulting in greater genetic variation in offspring. Asexual reproduction involves a single parent, producing genetically identical offspring.

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Haploid Cell

A cell that contains only one set of chromosomes (n), often produced through meiosis.

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Diploid Cell

A cell that contains two sets of chromosomes (2n), usually resulting from the fusion of two haploid gametes.

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What are the different types of life cycles?

Life cycles vary in the relative dominance of haploid and diploid stages. Diploid-dominant species have a multicellular diploid organism, while haploid-dominant species have a multicellular haploid organism. Plants and algae exhibit alternation of generations, with both diploid and haploid multicellular stages.

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What is the relationship between sporophyte and gametophyte?

In plants and some algae, the sporophyte is the diploid multicellular stage that produces haploid spores through meiosis. The gametophyte is the haploid multicellular stage that produces haploid gametes.

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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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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.

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