Mitosis and Cell Division Quiz
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Questions and Answers

What occurs to chromosomes during prophase?

  • They consist of two sister chromatids joined by centromeres. (correct)
  • They replicate to form four chromatids.
  • They start to align at the metaphase plate.
  • They decondense to facilitate transcription.

What role do centromeres play in prophase?

  • They are responsible for the replication of DNA.
  • They help decondense chromatin for transcription.
  • They facilitate the movement of chromosomes towards the poles.
  • They consist of repetitive DNA sequences that join sister chromatids. (correct)

What initiates the formation of the mitotic spindle during prophase?

  • Polymerisation of microtubules starting from the centrosome. (correct)
  • Polymerisation of microtubules starting from the cell membrane.
  • Duplication of kinetochores.
  • Degradation of microtubules.

Which protein structures are found at the centromeres of chromosomes during prophase?

<p>Kinetochore proteins. (A)</p> Signup and view all the answers

What occurs to centrosomes during the cell cycle leading up to prophase?

<p>They replicate during the S phase to form two new centrosomes. (A)</p> Signup and view all the answers

What structure disappears during prophase of mitosis in a plant cell?

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

Which stage of mitosis involves the alignment of chromosomes at the equatorial plane?

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

What is the primary mechanism of reproduction for prokaryotes?

<p>Binary fission (B)</p> Signup and view all the answers

During which phase of mitosis do the sister chromatids separate and move to opposite poles?

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

What structure is formed during cytokinesis in plant cells?

<p>Cell plate (B)</p> Signup and view all the answers

What constitutes a human somatic cell?

<p>A diploid cell with 46 chromosomes (C)</p> Signup and view all the answers

How long does bacterial replication typically take?

<p>1-3 hours (C)</p> Signup and view all the answers

During which phase of the cell cycle are chromosomes replicated?

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

What are homologous chromosomes?

<p>Chromosomes that carry the same genes at the same positions (C)</p> Signup and view all the answers

What happens to the nuclear envelope during prometaphase?

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

In binary fission, where does chromosome replication begin?

<p>Origin of replication (D)</p> Signup and view all the answers

What phase of the cell cycle is primarily characterized by DNA replication?

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

What type of cells are gametes?

<p>Haploid cells (C)</p> Signup and view all the answers

Which type of cells are described as terminally differentiated and permanently arrested in the G0 phase?

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

During mitosis, what structure is observed condensing that allows it to be seen under a light microscope?

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

How many total chromosomes does a human gamete contain?

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

What is the duration of the G1 phase in the interphase?

<p>5-6 hours (A)</p> Signup and view all the answers

What is a primary characteristic of interphase in the cell cycle?

<p>Chromosomes are not condensed (D)</p> Signup and view all the answers

In which phase do the chromosomes undergo replication to ensure genetic material is duplicated?

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

Which of the following is NOT a characteristic of the G2 phase?

<p>Involves DNA replication (D)</p> Signup and view all the answers

Which cells generally divide upon appropriate stimulation by growth factors?

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

What general function does interphase serve in the cell cycle?

<p>Cells prepare for cell division (D)</p> Signup and view all the answers

Which of the following statements is true regarding post-mitotic cells?

<p>They are permanently arrested in the G0 phase (A)</p> Signup and view all the answers

What is the primary function of cell division in unicellular organisms?

<p>Reproduction of the organism (C)</p> Signup and view all the answers

Which of the following is NOT a role of cell division in multicellular organisms?

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

Which factor plays a significant role in regulating the cell cycle through checkpoints?

<p>Cyclin-cdks (B)</p> Signup and view all the answers

What distinguishes benign tumors from malignant tumors?

<p>Malignant tumors invade surrounding tissues. (B)</p> Signup and view all the answers

Which of the following components are considered tumor suppressor genes involved in cell cycle regulation?

<p>Rb and p53 (B)</p> Signup and view all the answers

Which characteristic is NOT associated with cancer cells due to cell cycle dysregulation?

<p>Enhanced DNA repair mechanisms (D)</p> Signup and view all the answers

During which phase of the cell cycle does the cell prepare for mitosis?

<p>G2 phase (A)</p> Signup and view all the answers

What are cdk inhibitors (CKIs) primarily involved in during the cell cycle?

<p>Regulating cell cycle checkpoints (C)</p> Signup and view all the answers

What phase of the cell cycle involves the actual division of the nucleus?

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

Which phase is characterized by the preparation for DNA replication?

<p>G1 phase (A)</p> Signup and view all the answers

In unicellular eukaryotes, which type of cell division is considered to be intermediate between binary fission and mitosis?

<p>Multiple fission (B)</p> Signup and view all the answers

Which of the following phases does NOT involve active cell division?

<p>G1 phase (B)</p> Signup and view all the answers

During which stage do cells become non-dividing?

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

What process is characterized by the division of cytoplasm following mitosis?

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

How many phases comprise the cell cycle in eukaryotic cells?

<p>5 phases (C)</p> Signup and view all the answers

Which event occurs during the S phase of the cell cycle?

<p>DNA replication (B)</p> Signup and view all the answers

Flashcards

Cell division

The process by which a cell replicates itself, resulting in two genetically identical daughter cells.

Role of cell division in life

The formation of new cells is essential for the survival and growth of all organisms, from single-celled bacteria to complex multicellular animals.

Binary fission

The simplest form of cell division, used by single-celled organisms like bacteria, where one cell splits into two identical daughter cells.

Cell division in multicellular organisms

Cell division plays a crucial role in the development and growth of multicellular organisms, starting from a single fertilized egg, leading to the formation of complex tissues, organs, and ultimately, the whole body.

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Cell division for repair

Cell division is essential for repairing damaged tissues. When cells die or are injured, cell division replaces them, restoring the tissue's integrity.

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Cell cycle

The life cycle of a cell, encompassing all stages from its formation to its division into two daughter cells.

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Mitosis

The division of the genetic material (DNA) in the nucleus of a cell, leading to the formation of two identical sets of chromosomes.

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Stages of the cell cycle

The process of cell division occurs in different stages, each with a specific function in preparing the cell for division and ensuring proper separation of chromosomes.

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What is a genome?

All a cell's genetic information (DNA) is called the genome and is contained within chromosomes.

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What is a chromosome?

In eukaryotic cells, a chromosome consists of a complex structure of DNA and proteins (histones), each carrying a significant number of genes.

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What is a homologous chromosome pair?

Human somatic cells have 23 pairs of chromosomes (46 total), with one chromosome of each pair coming from the mother and the other from the father.

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What are somatic cells?

Somatic cells are non-reproductive cells with a diploid number of chromosomes (2n), meaning they have two sets of chromosomes.

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What are gametes?

Gametes, or reproductive cells, are haploid (n), meaning they have a single set of chromosomes. This ensures that offspring inherit a balanced set of chromosomes from both parents.

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What happens to chromosomes during interphase?

During interphase, the cell prepares for division. In S phase, DNA is replicated, leading to two copies of each chromosome (sister chromatids).

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What happens to chromosomes during mitosis?

The process of mitosis involves the condensation of chromosomes and the separation of sister chromatids, ensuring that each daughter cell receives a full set of chromosomes.

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Why is mitosis important?

Mitosis is a crucial part of growth and repair, ensuring that new cells have a complete set of genetic information.

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Chromosomal condensation in prophase

During prophase, chromosomes condense from a loose form of chromatin into tightly packed structures, making them visible under a microscope.

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Sister chromatids in prophase

Sister chromatids are identical copies of a chromosome, joined together at a specialized region called the centromere.

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Centrosome movement in prophase

Centrosomes, which contain microtubule-organizing centers, replicate during the S phase of the cell cycle. During prophase, these duplicated centrosomes move towards opposite poles of the cell.

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Mitotic spindle formation in prophase

The mitotic spindle, a structure made of microtubules, begins to form during prophase. These microtubules extend from the centrosomes towards the chromosomes.

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Kinetochores and microtubule attachment in prophase

During prophase, protein structures known as kinetochores assemble at the centromere of each sister chromatid. These kinetochores serve as attachment points for spindle microtubules, enabling the movement of chromosomes towards the metaphase plate.

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Post-mitotic Cells

Cells that have permanently stopped dividing and are arrested in the G0 phase of the cell cycle. They cannot replicate.

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Cells That Divide Upon Stimulation

Cells capable of dividing when stimulated by specific signals like growth factors, hormones, or antigens.

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Cells With High Mitotic Activity

Cells that divide frequently and are actively involved in growth and renewal, like germ cells, stem cells, and epithelial cells.

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Interphase

The period between cell divisions in a cell cycle.

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S Phase

The phase in the cell cycle where DNA replication occurs. This ensures that each daughter cell receives a complete set of genetic material.

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G1 Phase

The first stage of interphase, where the cell grows and prepares for DNA replication. It focuses on protein synthesis and organelle production.

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G2 Phase

The last stage of interphase, where the cell finishes preparing for mitosis. It focuses on final checks before cell division.

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Cell Cycle Checkpoint

The process by which the cell decides whether to divide or not. This decision is influenced by factors like cell size, nutrient availability, and growth signals.

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What is binary fission?

The process by which a prokaryotic cell (like a bacterium) reproduces by splitting into two identical daughter cells.

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How does binary fission work?

The genetic material in a prokaryote replicates, and the two copies move apart before the cell splits into two.

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What's the replication time for a bacterial cell?

The time it takes for a prokaryotic cell to complete binary fission and create a new daughter cell.

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Why is binary fission simpler than mitosis?

Prokaryotes lack a nucleus and other organized structures, which means binary fission is a less complex process than mitosis in eukaryotes.

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What is mitosis?

A specialized type of cell division used by eukaryotes to create two genetically identical daughter cells.

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What are the stages of mitosis?

The process of mitosis is divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase.

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What are sister chromatids?

Each chromosome consists of two identical sister chromatids, which are joined together at the centromere.

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What is the mitotic spindle?

The mitotic spindle is a structure made of microtubules that helps to move chromosomes during mitosis.

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Cytokinesis

The division of the cytoplasm in eukaryotic cells, following mitosis, to form two separate daughter cells.

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Study Notes

Cell Reproduction: The Cell Cycle

  • Cell division is the reproduction of cells
  • Life continuity depends on cell division
  • Unicellular organisms reproduce by cell division (e.g., binary fission)
  • Multicellular organisms use cell division for growth, development from a fertilized cell, and repair of damaged tissues
  • Cell division in humans includes: mitosis for somatic (diploid) cells and meiosis for gametes (haploid) cells
  • Mitosis conserves chromosome number by producing two genetically identical cells from a parent cell
  • Meiosis reduces the chromosome number by half to create gametes
  • Fertilization fuses male and female gametes, resulting in a zygote with the full chromosome number

Learning Objectives

  • Explain cell division's role in unicellular and multicellular organisms
  • Describe cell cycle stages, including mitosis stages
  • Describe cell cycle control through checkpoints, including the roles of cyclin-cdks, tumour suppressor genes (Rb and p53), and cdk inhibitors (CKIs)
  • Describe cancer cell characteristics related to dysregulation, including benign and malignant tumours

Cancer

  • Cancer is abnormal cell growth that proliferates uncontrollably and, sometimes, metastasizes (spreads)
  • Tight control of cell division is vital to avoid carcinogenesis

Cell Cycle

  • Mitosis is an integral part of the cell cycle
  • Mitosis produces two genetically identical daughter cells
  • Cells duplicate their genetic material (DNA replication) before division so each daughter cell receives a full copy

Cell Cycle Phases

  • The cell cycle is the series of events a cell goes through until division into two identical daughter cells
  • Stages include:
    • G1 phase: preparation for DNA replication
    • S phase: DNA replication
    • G2 phase: preparation for cell division (mitosis)
    • M phase: cell division (mitosis)
    • G0 phase: resting, non-dividing cells

Interphase

  • The period between cell divisions
  • The largest part of the cell cycle
  • The cell prepares for division
  • Includes G1, S, and G2 phases
  • Includes DNA replication (S phase)
  • The cell decides whether to proceed with division

Interphase Sub-Phases

  • G1 phase: preparation for DNA replication, protein synthesis, and organelle production (5-6 hours)
  • S phase: DNA synthesis (replication) (10-12 hours)
  • G2 phase: preparation for cell division (mitosis), protein synthesis, and organelle production (4-6 hours)

Cellular Organisation of Genetic Material

  • Genome: the complete set of genetic information (DNA) of a cell
  • DNA molecules are packaged into chromosomes, forming chromatin with DNA and proteins (histones)
  • Each chromosome carries several hundred to thousand genes
  • Human chromosomes are about 2 meters long in a cell

Chromosomal Content of Human Cells

  • Somatic cells: diploid (2n) containing 46 chromosomes (23 homologous pairs)
  • Each pair has one maternal and one paternal chromosome
  • Gametes: haploid cells (n) containing 23 chromosomes

Mitotic Phase (M Phase)

  • Mitosis: division of the nucleus
  • Cytokinesis: division of the cytoplasm
  • Mitosis consists of 5 phases (all parts of the Mitotic Phase):
    • Prophase
    • Prometaphase
    • Metaphase
    • Anaphase
    • Telophase

Mitosis Summary

  • Prophase: chromatin condenses into chromosomes, nucleolus disappears
  • Prometaphase: nuclear membrane fragments; microtubules attach to chromosomes
  • Metaphase: chromosomes align at the metaphase plate
  • Anaphase: sister chromatids separate and move to opposite poles
  • Telophase: nuclear envelopes reform; chromosomes decondense
  • Cytokinesis: division of cytoplasm into two daughter cells

Cytokinesis

  • Cytokinesis divides the cytoplasm into two daughter cells
  • Animal cells: cleavage furrow forms
  • Plant cells: cell plate forms

Prokaryotic Replication: Binary Fission

  • Prokaryotes (bacteria) reproduce via binary fission, a simpler process
  • Much faster than eukaryotic cell division
  • Bacteria replication time: 1-3 hours
  • In binary fission: bacterial chromosome replicates and daughter chromosomes move apart

Evolution of Mitosis

  • Mitosis likely evolved from bacterial cell division
  • Some unicellular eukaryotes have intermediate cell division types between binary fission and mitosis

Other

  • The cell cycle G1, S, G2 is the Interphase portion of the cell cycle and precedes the Mitotic Phase
  • Centrosomes replicate during the S phase
  • The mitotic spindle is formed from microtubules
  • Microtubules include; Astral, Kinetochore, and Polar
  • Centrosomes are involved in orienting the mitotic spindle and chromosome movement.
  • Cell-cycle checkpoints control the progression of the cell cycle.
  • Checkpoint control points monitor DNA damage, cell size, and other factors to ensure accurate cell division and prevent uncontrolled growth.

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Description

Test your knowledge on the processes of mitosis and cell division, focusing on critical phases such as prophase and cytokinesis. This quiz covers the role of chromosomes, centromeres, and various structures involved in cell reproduction. Perfect for students in biology courses.

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