Cell Cycle Quiz: Interphase and Mitosis
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Questions and Answers

What happens during the S phase of the cell cycle?

  • The cell prepares for mitosis.
  • Cellular energy is focused on growth.
  • The cell size increases significantly.
  • Chromosomes are duplicated. (correct)

    • Which checkpoint mechanism ensures readiness for DNA synthesis?

  • Metaphase checkpoint
  • S checkpoint
  • G1 checkpoint (correct)
  • G2 checkpoint

    • What occurs during the G2 phase of the cell cycle?

  • Chromosomes are actively being duplicated.
  • The cell stops synthesizing DNA.
  • Cell growth is maximized.
  • The cell prepares to divide. (correct)

    • What is the duration of Interphase in the cell cycle?

    <p>Approximately 90% of the cell cycle. (B)</p> Signup and view all the answers

    What happens at the Metaphase checkpoint during mitosis?

    <p>The cell checks if it is ready to complete cell division. (D)</p> Signup and view all the answers

    What is the primary function of the cell cycle?

    <p>To distribute cellular components evenly during cell division (B)</p> Signup and view all the answers

    What does the 'Interphase' of the cell cycle correspond to?

    <p>The phase of growth and DNA replication (C)</p> Signup and view all the answers

    Which cell types are noted to be unable to divide?

    <p>Heart cells, nerve cells, eye lens cells (B)</p> Signup and view all the answers

    What is indicated by the G0 state in the cell cycle?

    <p>Cells have left the cycle and are resting (C)</p> Signup and view all the answers

    What is the significance of the cell cycle in unicellular organisms?

    <p>It reproduces the entire organism (A)</p> Signup and view all the answers

    What process underlies the function of generating two identical daughter cells?

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

    What is the primary role of the G1 phase in the cell cycle?

    <p>Cell growth and preparation for DNA replication. (B)</p> Signup and view all the answers

    During which phase do cells replicate their DNA?

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

    Which of the following statements about DNA replication is true?

    <p>DNA replication is semiconservative. (A)</p> Signup and view all the answers

    What is the function of the centrosome during the cell cycle?

    <p>It organizes microtubules and assists in cell division. (B)</p> Signup and view all the answers

    What characterizes the leading strand during DNA replication?

    <p>It is synthesized continuously in the 5' to 3' direction. (A)</p> Signup and view all the answers

    Which of the following is NOT a feature of DNA replication?

    <p>It is a single-enzymatic process. (C)</p> Signup and view all the answers

    During the S phase, what happens to the duplicated chromosomes?

    <p>They are held together by a centromere. (D)</p> Signup and view all the answers

    What is the first step of DNA replication?

    <p>Initiation of DNA synthesis. (C)</p> Signup and view all the answers

    What are the internal control mechanisms that influence cell cycle progression primarily responding to?

    <p>Cues from both inside and outside the cell (A)</p> Signup and view all the answers

    At which checkpoint does the cell cycle typically stop in response to DNA damage?

    <p>G2–M transition checkpoint (A), G1 checkpoint (C)</p> Signup and view all the answers

    Which factor is most likely to increase the activity of Cdks and cyclins?

    <p>Presence of growth factors (A)</p> Signup and view all the answers

    What is a primary function of cyclins in the cell cycle?

    <p>To regulate Cdk activity (C)</p> Signup and view all the answers

    During which specific phase do the chromosomes condense and the nuclear envelope break down?

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

    What essential role does CDK (Cyclin-Dependent Kinase) play in the cell cycle?

    <p>Phosphorylating target proteins to drive cell cycle progression (D)</p> Signup and view all the answers

    What occurs at the G2–M transition checkpoint?

    <p>DNA damage is assessed (B)</p> Signup and view all the answers

    Which phase of the cell cycle is characterized by the synthesis of DNA?

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

    What is the primary function of cyclins in cell cycle regulation?

    <p>They activate cyclin-dependent kinase enzymes. (D)</p> Signup and view all the answers

    How do cancer cells typically differ from normal cells in terms of growth factor requirements?

    <p>Cancer cells can make their own growth factors. (A)</p> Signup and view all the answers

    What role does Maturation Promoting Factor (MPF) play in the cell cycle?

    <p>It promotes the transition from G2 phase to mitosis. (D)</p> Signup and view all the answers

    Which cyclins are involved in the G1 phase of the cell cycle?

    <p>Cyclin D and Cyclin E. (D)</p> Signup and view all the answers

    What abnormal characteristic may cancer cells have regarding cell cycle control systems?

    <p>An abnormal cell cycle control system. (B)</p> Signup and view all the answers

    Which of the following statements about the cell cycle is true?

    <p>Cell growth and division lead to two genetically identical daughter cells. (A)</p> Signup and view all the answers

    What is a key difference between cyclins and cyclin-dependent kinases (cdks)?

    <p>Cyclins activate cdks, which are responsible for cell cycle regulation. (B)</p> Signup and view all the answers

    Why is the concentration of cyclins described as cyclic?

    <p>Cyclin levels fluctuate in a regulated manner during the cell cycle. (A)</p> Signup and view all the answers

    What is the primary function of the kinetochore during cell division?

    <p>To pull sister chromatids apart (D)</p> Signup and view all the answers

    During which phase of mitosis do chromosomes line up in the center of the cell?

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

    What occurs during the anaphase of mitosis?

    <p>Separation of sister chromatids (B)</p> Signup and view all the answers

    Which checkpoint prevents progress past metaphase until all kinetochores are attached to microtubules?

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

    What is the main event during telophase?

    <p>Formation of the nuclear envelope (B)</p> Signup and view all the answers

    Which process directly follows mitosis in the cell cycle?

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

    What role does the cell cycle control system serve?

    <p>To direct the sequential events of the cell cycle (C)</p> Signup and view all the answers

    What are daughter cells formed from mitosis expected to do next?

    <p>Begin G1 phase to grow (C)</p> Signup and view all the answers

    Which structure organizes the spindle fibers during cell division?

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

    What characterizes interphase G2 stage?

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

    Study Notes

    Course Details

    • Course title: The Human Body PJ1311
    • Topic: The Cell Cycle and its Control
    • Lecturer: Dr Lamia Kandil
    • Lecturer of Pharmacy Practice, PhD, FHEA
    • MB138
    • Email: [email protected]
    • vevox.app ID: 102-353-245

    Kandil Lectures

    • 3 lectures on Genomics
      • Introduction to Genomics
      • The central dogma of life (Transcription, Translation)
      • Cell cycle and control mechanism

    The Cell Cycle

    • All cells are derived from pre-existing cells
    • Cell cycle: ordered series of events preparing for cell division
    • Functions of the cell cycle
      • Copying cellular components & DNA duplication
      • Dividing the cell evenly into daughter cells
    • "Cell cycle": alternating "growth" and "division" of the cell.
    • Cell division is a part of the cell cycle.

    Why Cell Division Occurs

    • In unicellular organisms, division of one cell reproduces the entire organism (reproduction)
    • Multicellular organisms depend on cell division for
      • Growth (increase in numbers)
      • Maintaining and repairing cells (e.g., liver, skin)
    • Not all cells divide
      • Some cells can't divide (e.g., eye lens, nerve, heart cells). These cells are maintained.

    Cell Cycle Basic Function

    • "Growth" activity corresponds to "Interphase"
    • Cell growth and copying of chromosomes in preparation for cell division (mitosis and cytokinesis)
    • "Division" activity corresponds to "M phase"

    Stages of the Cell Cycle

    • Interphase (G1, S, G2)
      • G1: Cell growth, normal cell function, organelle duplication, proteins synthesis. G1 checkpoint
      • S: DNA replication
      • G2: Continued growth, organelles and proteins synthesis. G2 checkpoint
    • Mitosis (prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis)
      • Prophase: Chromosomes condense, nuclear membrane breaks down, spindle forms
      • Prometaphase: Chromosomes attach to spindle microtubules. Nuclear envelope fragments
      • Metaphase: Chromosomes align at the metaphase plate
      • Anaphase: Sister chromatids separate and move to opposite poles
      • Telophase: Chromosomes decondense, nuclear envelopes reform.
      • Cytokinesis: Cytoplasm divides, producing two daughter cells. Note: Mitosis doesn't include cytokinesis

    Interphase Details

    • Interphase: about 90% of the cell cycle
      • G1 phase: First gap, cell growth
      • S phase: Synthesis, DNA replication (longest phase)
      • G2 phase: Second gap, cell prepares to divide

    G1 Phase Details

    • First stage of cell growth after cell replication occurs.
    • Preparation of chromosomes for replication
    • Duplication of cellular components (cytoplasm and organelles).
    • Cell carries out its usual metabolic activities
    • G1 checkpoint (restriction point): Cell commits to division or exits from the cell cycle.

    S Phase Details

    • Instructions for making cell parts are encoded in DNA
    • Each new cell needs a complete set of DNA molecules
    • DNA must be copied (replicated) before cell division.

    DNA Replication

    • DNA replication is semiconservative.
    • Watson and Crick base pairing is maintained during replication.
    • Synthesis of new DNA strands occurs in the 5' to 3' direction.
    • DNA replication is a multi-enzymatic process initiated when a primer is required. Several enzymes and proteins (Replisome) are involved in the initiation process.
    • Enzymes involved in DNA replication: - Helicase, Binding protein, Primase, DNA polymerase, DNA polymerase I, Ligase
    • Replication of DNA: Base pairing allows each strand to serve as a template for a new strand.

    Stages of DNA Replication

    • The initiation phase
    • Elongation phase (Leading and Lagging strand synthesis)
    • Termination phase

    S Phase - Duplicated Chromosomes

    • Duplicated chromosomes are called chromatids
    • Chromatids are held together by a centromere

    S Phase - Centrosome Duplication

    • Centrosome is near the nucleus in animal cell
    • Contains microtubule organizing center (MTOC) and two centrioles
    • Protein surrounding centrioles that migrate to poles before cell division.

    Mitosis

    • Mitosis: process separating chromosomes in the cell nucleus into two identical sets in two nuclei
    • During mitosis, pairs of chromosomes condense.
    • Sister chromatids attach to fibers that pull them to opposite sides of the cell.
    • Cytokinesis follows mitosis.

    Phases of Mitosis

    • Prophase
    • Prometaphase
    • Metaphase
    • Anaphase
    • Telophase
    • Cytokinesis

    Prometaphase (Late Prophase)

    • Nuclear membrane and nucleolus break down
    • Chromosomes continue condensing and become clearly visible
    • Spindle fibers attach to the chromosomes at the centromere

    Telophase

    • Prophase is essentially reversed.
    • Sister chromatids are at opposite poles
    • Nuclear envelope forms around each set of sister chromatids and chromosomes condense
    • Nucleolus reappears and interphase cellular functions resume

    Cytokinesis

    • Cytoplasm division
    • Divides the cell into two daughter cells (cytoplasm, organelles)
    • Cytokinesis begins in telophase and ends shortly thereafter (part of M phase but not mitosis)

    Daughter Cells of Mitosis

    • Have the same number of chromosomes as the parent cell.
    • Identical to each other
    • Must grow in size (G1 of Interphase) to become mature
    • Ready to enter a new cell cycle

    Cell Cycle Control System

    • The sequential events of the cell cycle are controlled by a cell cycle control system, similar to a clock
    • Controlled by internal and external controls
    • Checkpoints in the clock where the cell cycle stops until a go-ahead signal is received.

    Cancer Cells

    • Cancer cells do not respond normally to the body's control mechanisms.
    • They may not need growth factors to grow and divide
    • They may make their own growth factors
    • They may convey a growth factor's signal without the presence of the growth factor
    • May have an abnormal cell cycle control system

    Cyclins and Cyclin-Dependent Kinases (Cdks)

    • Cyclins: family of proteins activating cyclin-dependent kinase (Cdk) enzymes. Examples: Cyclin A, Cyclin B, Cyclin D, Cyclin E
    • Cyclin-Dependent Kinases (Cdks): Family of protein kinases regulating cell cycle, including cdk1, cdk2, cdk4, cdk6
    • Maturation Promoting Factor (MPF): Heterodimeric protein composed of cyclin B & cyclin-dependent kinase (CDK1), promoting entrance into mitosis (M phase) from G2 phase, phosphorylating multiple proteins needed during mitosis.

    Important Videos (URLs)

    • List of URLs for videos provided for further learning.

    Important Cell Cycle Checkpoints

    • G1 checkpoint: Cell growth, DNA damage, adequate resources.
    • G2 checkpoint: DNA replication, damage.
    • M checkpoint (spindle checkpoint): Ensures all chromosomes are properly attached to the spindle fibers in metaphase before anaphase.

    Purpose of Cell Cycle in Eukaryotic Cells

    • Main purpose: Cell division. Additional minor purposes are DNA replication and cell growth.

    Phase of Cell Cycle and DNA Replication

    • S phase is responsible for DNA replication.

    Phase of Cell Cycle and Chromosome Condensation and Breakdown of Nuclear Envelope

    • Prophase is the stage where chromosomes condense, and the nuclear envelope breaks down.

    Molecule Responsible for Driving Cell Cycle Progression

    • CDK (Cyclin-Dependent Kinase) phosphorylates target proteins.

    G2 Checkpoint Function

    • Checks for DNA damage and repairs it. This checkpoint ensures the cell only goes into mitosis if DNA is undamaged and properly replicated.

    Cancer and Normal Cell Cycle Control

    • In cancer, the normal control mechanisms of the cell cycle are lost or disrupted.

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    Related Documents

    The Cell Cycle and Its Control PJ1311 PDF

    Description

    Test your knowledge about the cell cycle, including its phases such as S phase, G2 phase, and checkpoints during mitosis. This quiz covers critical processes and concepts that define how cells replicate and division occurs, essential for maintaining life in both unicellular and multicellular organisms.

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