Cell Cycle: G0 and G1 Phases
45 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What characterizes the G0 phase of the cell cycle?

  • Cells continue to metabolize but cannot divide. (correct)
  • Cells are preparing for mitosis.
  • Cells are completely inactive.
  • Cells divide rapidly.

    • Which of the following cells are examples of terminally differentiated cells that remain in G0?

  • Eye cells (correct)
  • Stem cells
  • Lung cells
  • Liver cells

    • Which type of cell is known to be able to be called out of the G0 phase?

  • Mature cardiac cells
  • Stem cells (correct)
  • Mature blood cells
  • Mature nerve cells

    • Recent research indicates that brain cells can continually turn over in which area of the brain?

    <p>Hippocampus</p> Signup and view all the answers

    What is the primary function of the hippocampus in relation to cell turnover?

    <p>Storing long-term memories and aiding in learning</p> Signup and view all the answers

    What occurs during the G2 phase of the cell cycle?

    <p>Proteins related to microtubules are produced and the cell grows.</p> Signup and view all the answers

    What happens to the chromosomes during the G2 phase?

    <p>They remain as loosely packed chromatin fibers.</p> Signup and view all the answers

    Why does the transport demand increase as the cell grows during G2?

    <p>The volume increases more rapidly than the surface area.</p> Signup and view all the answers

    What indicates the readiness of a cell to enter the M phase?

    <p>The cell has completed the G2 phase.</p> Signup and view all the answers

    Which of the following is a significant activity that occurs during the G2 phase?

    <p>Protein synthesis occurs, especially for microtubules.</p> Signup and view all the answers

    What is the primary role of the hippocampus?

    <p>Storing long-term memories</p> Signup and view all the answers

    What happens to one of the daughter cells after mitosis and cytokinesis in G₀ phase?

    <p>It becomes a specialized blood cell</p> Signup and view all the answers

    During which phase does DNA replication occur?

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

    What structural feature connects sister chromatids?

    <p>Centromere</p> Signup and view all the answers

    What type of cells can hematopoietic stem cells produce?

    <p>Red blood cells, white blood cells, and platelets</p> Signup and view all the answers

    What is the primary function of mitosis in the cell cycle?

    <p>Division of the cell's nucleus</p> Signup and view all the answers

    Which stage directly follows prophase in mitosis?

    <p>Prometaphase</p> Signup and view all the answers

    During which phase do the chromosomes align at the cell's equatorial plane?

    <p>Metaphase</p> Signup and view all the answers

    What is the purpose of cytokinesis in the cell cycle?

    <p>Division of the cytoplasm</p> Signup and view all the answers

    How many distinct stages are typically identified in mitosis?

    <p>4 or 5</p> Signup and view all the answers

    What is the longest phase of mitosis?

    <p>Prophase</p> Signup and view all the answers

    Which structure forms during prophase to assist in chromosome movement?

    <p>Mitotic spindle</p> Signup and view all the answers

    What happens to the nuclear envelope during prophase?

    <p>It dissolves.</p> Signup and view all the answers

    Which of the following best describes the process of kinetochores forming?

    <p>Happens during prometaphase.</p> Signup and view all the answers

    What are centrosomes comprised of?

    <p>Two centrioles</p> Signup and view all the answers

    What happens during the G1 stage of the cell cycle?

    <p>Cells increase in size.</p> Signup and view all the answers

    Which characteristic is true about the G0 phase?

    <p>Cells perform specialized functions but cannot divide.</p> Signup and view all the answers

    Which of the following cell types is an example of being in the G0 phase?

    <p>Eye cells</p> Signup and view all the answers

    What is a key feature of cells during the G1 stage regarding DNA replication?

    <p>DNA is not replicated and remains in chromatin form.</p> Signup and view all the answers

    Why might cells enter the G0 phase?

    <p>Due to lack of growth factors or nutrients.</p> Signup and view all the answers

    What occurs during the breakdown of the nuclear envelope?

    <p>It allows mitotic spindles to connect with the kinetochores.</p> Signup and view all the answers

    Which structure forms around the centromeres during prometaphase?

    <p>Kinetochore</p> Signup and view all the answers

    What are the fibers that connect chromosomes to the spindle apparatus called?

    <p>Kinetochore microtubules</p> Signup and view all the answers

    Which of the following options is NOT a component of the mitotic spindle?

    <p>Nuclear envelope</p> Signup and view all the answers

    What is the primary role of the kinetochores during prometaphase?

    <p>To anchor the chromosomes to the spindle fibers</p> Signup and view all the answers

    What is located at the poles during metaphase?

    <p>Centrosomes</p> Signup and view all the answers

    What structure is prominent in a replicated chromosome?

    <p>Centromere region</p> Signup and view all the answers

    Which of the following connects to the kinetochores during cell division?

    <p>Kinetochore microtubules</p> Signup and view all the answers

    During which phase do chromosomes align at the metaphase plate?

    <p>Metaphase</p> Signup and view all the answers

    Which component is crucial for the separation of sister chromatids during mitosis?

    <p>Spindle fibers</p> Signup and view all the answers

    What occurs during the G1 phase of the cell cycle?

    <p>Cell growth</p> Signup and view all the answers

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

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

    During which stage of mitosis do chromosomes align at the cell equator?

    <p>Metaphase</p> Signup and view all the answers

    What process follows mitosis to ensure the formation of daughter cells?

    <p>Cytokinesis</p> Signup and view all the answers

    What is represented by the notation '2n = 6' for a parent cell?

    <p>Total number of chromosomes in the diploid state</p> Signup and view all the answers

    Study Notes

    G0 Phase

    • Cells in G0 are alive, metabolically active, but cannot divide.
    • Some cells enter G0 temporarily; others are terminally differentiated and remain there.
    • Examples of cells that typically remain in G0 include eye cells, mature nerve cells, mature blood cells, and mature cardiac cells. Damage to these cells is usually irreparable.
    • Liver cells and stem cells can be recalled from G0.
    • Recent research indicates that neurogenesis (the birth of new neurons) occurs in the hippocampus throughout life, contrary to previous beliefs.

    G1 (First Gap) Phase

    • Cell increases in size.
    • Proteins and organelles are synthesized.
    • DNA replication does not occur in this phase; DNA remains as chromatin.
    • Some cells remain in G1 for extended periods (e.g., neurons, muscle cells).
    • Cells in G1 possess totipotency (ability to differentiate into any cell type), a crucial concept in cloning.
    • Cells may enter a quiescent phase called G0 due to lack of growth factors or nutrients.

    S (Synthesis) Phase

    • DNA replication occurs, creating two identical sister chromatids joined at the centromere.
    • Centrosomes are duplicated.
    • Entry into S phase usually commits the cell to completing the rest of the cell cycle.

    G2 (Second Gap) Phase

    • Further cell growth and protein synthesis occurs, particularly proteins needed for microtubule formation.
    • Chromosomes are replicated but remain as loosely packed chromatin fibers.
    • The cell prepares for mitosis – the demand on transport mechanisms increases.

    Mitosis

    • Mitosis is the division of the cell's nucleus (karyokinesis).
    • It's divided into four (or five) distinct stages: prophase, prometaphase, metaphase, anaphase, and telophase. Prometaphase is sometimes considered part of prophase.
    • Nearly 2 trillion human cells divide daily.

    Prophase

    • Longest phase of mitosis.
    • Chromosomes condense and become visible.
    • The nuclear envelope dissolves.
    • The mitotic spindle begins to form, centrosomes separate and migrate to opposite ends of the cell. Each centrosome has two centrioles.

    Prometaphase

    • Kinetochores form at the centromeres, providing attachment sites for spindle fibers.
    • The nuclear envelope fragments. This allows the spindle fibers to connect with the kinetochores and subsequently move the chromosomes.

    Metaphase

    • Chromosomes align at the cell's equator (metaphase plate).
    • Centrosomes are positioned at opposite poles of the cell.

    Anaphase

    • Sister chromatids separate and move to opposite poles of the cell

    Telophase

    • Chromosomes arrive at the poles and begin to decondense.
    • Nuclear envelopes reform around each chromosome set.
    • The mitotic spindle disassembles.

    Cytokinesis

    • Cytoplasm divides, resulting in two genetically identical daughter cells.

    Chromosome Structure

    • A chromatid is a single strand of a replicated chromosome.
    • Two sister chromatids are connected at the centromere.

    Hippocampus

    • Region of the brain involved in long-term memory and learning. Displays continual neurogenesis.

    Hematopoietic Stem Cells

    • Found in bone marrow and blood.
    • Can differentiate into all types of blood cells (red blood cells, white blood cells, platelets).

    Cell Differentiation & Examples

    • During a cell's life cycle, cells can differentiate – that is, become specialized into cells that perform different jobs in the body.
    • Examples of terminally differentiated cells that usually can’t divide include: eye cells, nerve cells, blood cells, and heart cells.
    • Other cells are able to exit the cell cycle temporarily and re-enter (such as liver cells, stem cells, and some other adult cells).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Explore the cellular processes of the G0 and G1 phases in this quiz. Understand the characteristics of cells in G0, including their metabolic activity and the implications of being terminally differentiated. Delve into the significance of the G1 phase, where cells increase in size and prepare for division without DNA synthesis.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser