The Cell Cycle and Mitosis Overview
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Questions and Answers

What phase does the replication of DNA occur during?

  • G2 Phase
  • M Phase
  • S Phase (correct)
  • G1 Phase

    • Cell checkpoints monitor the progress of the cell cycle to ensure proper chromosome alignment.

    True

    The cell cycle includes phases such as G1, S, G2, and _____.

    Mitosis

    Match the phases of the cell cycle with their functions:

    <p>G1 Phase = Cell growth and preparation for DNA synthesis S Phase = DNA replication G2 Phase = Preparation for mitosis M Phase = Cell division</p> Signup and view all the answers

    What is checked for at the G2/M checkpoint?

    <p>DNA factors and damage</p> Signup and view all the answers

    Sufficient nutrients are not required for cell cycle progression.

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

    What must be present in the environment for cell growth to continue?

    <p>favorable conditions</p> Signup and view all the answers

    The G2/M checkpoint ensures DNA _________ is complete before mitosis.

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

    What does the G2/M checkpoint verify?

    <p>Both A and B</p> Signup and view all the answers

    The cell cycle can proceed without checking for unreplicated DNA.

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

    What type of damage does the G2/M checkpoint look for?

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

    Match the following terms with their descriptions:

    <p>G2/M checkpoint = Checks for DNA replication and damage Cell growth = Requires a favorable environment Nutrient requirements = Essential for cell cycle progression Mitosis = Final stage of cell division</p> Signup and view all the answers

    During which phase do chromosomes arrive at the poles?

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

    Chromatin is formed during Telophase.

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

    What process involves the preparation of the cell for division?

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

    In the ____ phase, chromosomes speed into identical sets.

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

    Match the following phases with their descriptions:

    <p>Prophase = Chromosomes condense and become visible Anaphase = Sister chromatids separate and move to opposite poles Telophase = Chromosomes relax into chromatin Metaphase = Chromosomes align at the cell's equator</p> Signup and view all the answers

    What is true about the phase named Anaphase?

    <p>Sister chromatids are pulled apart</p> Signup and view all the answers

    Chromosomes are present in their most condensed form during Anaphase.

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

    What happens to chromosomes during Telophase?

    <p>They reach opposite poles and de-condense into chromatin.</p> Signup and view all the answers

    During ___ phase, the cell prepares for mitosis.

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

    Which structure forms during Prophase?

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

    What do MAMASANARASTRANSITIONs ensure in cell cycles?

    <p>They prevent premature progression</p> Signup and view all the answers

    Cyclin-CaK complexes are involved in promoting cell cycle progression.

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

    What activates proteins to ensure proper transitions in the cell cycle?

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

    Cancer treatment can be enhanced with CAL __________ inhibitors.

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

    What effect do cancer treatments with CAL inhibitors aim to achieve?

    <p>Stop kinase activity</p> Signup and view all the answers

    The mitotic spindle is crucial for proper chromosomal alignment during cell division.

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

    What is the role of the complex that chops up proteins into individual chains?

    <p>To ensure proper cell cycle regulation</p> Signup and view all the answers

    Match the following cancer-related terms with their definitions:

    <p>Cyclin = Regulates cell cycle progression Kinase = Enzyme that adds phosphate groups Mitosis = Process of cell division Apoptosis = Programmed cell death</p> Signup and view all the answers

    The __________ ensures the bipolar array of chromosomes is correctly aligned.

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

    What does unregulated activity of cyclin-CaK complexes lead to?

    <p>Consistent cell cycle progression despite damage</p> Signup and view all the answers

    What phase follows prophase in mitosis?

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

    Cytokinesis is the process of nuclear division in a cell.

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

    What structure forms the attachment point for chromosomes during mitosis?

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

    Cylindependent kinases are __________ that control the cell cycle.

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

    Match the stages of mitosis with their descriptions:

    <p>Prophase = Chromosomes condense and spindle forms Metaphase = Chromosomes align at the spindle equator Anaphase = Chromosomes are pulled apart into sister chromatids Telophase = Nuclear membranes reform around each set of chromosomes</p> Signup and view all the answers

    What is the main purpose of the spindle apparatus during mitosis?

    <p>To ensure chromosomes are separated correctly</p> Signup and view all the answers

    The chiasma is formed during metaphase of mitosis.

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

    Name the phase of mitosis where the nuclear envelope breaks down.

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

    The __________ furrow forms during cytokinesis to separate the two daughter cells.

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

    Match each component of cell cycle regulation with its function:

    <p>Cyclin-dependent kinases = Control progression of the cell cycle Molecular switches = Regulate enzyme activity Phosphorylation = Add phosphate groups to proteins Cell cycle checkpoints = Monitor and regulate cell cycle progression</p> Signup and view all the answers

    Which of the following is a key component in regulating the cell cycle?

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

    In anaphase, sister chromatids separate and move to opposite poles of the cell.

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

    What happens during Telophase of mitosis?

    <p>Nuclear membranes reform around each set of chromosomes</p> Signup and view all the answers

    The __________ phase is the last stage of mitosis before cytokinesis occurs.

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

    What key event defines metaphase in mitosis?

    <p>Chromosomes align at the spindle equator</p> Signup and view all the answers

    Study Notes

    The Cell Cycle

    • The cell cycle is a series of events that occur in a cell leading to its division and duplication.
    • The cell cycle progresses through distinct stages: G1 (first gap), S (synthesis - DNA replication), G2 (second gap) and M (mitosis) phases.
    • These phases are regulated by checkpoints and internal control that ensure proper DNA replication and cell division.
    • G1, S, G2 phases are collectively termed as interphase.

    Mitosis and Cytokinesis

    • M-phase includes both mitosis, nuclear division, and cytokinesis, cytoplasmic division.
    • During mitosis, the replicated chromosomes are separated and distributed into two daughter nuclei.
    • The phases of mitosis are prophase, prometaphase, metaphase, anaphase, and telophase.
    • During prophase, chromosomes condense, and the mitotic spindle begins to form.
    • During prometaphase, the nuclear envelope breaks down, and chromosomes attach to the spindle fibers via kinetochores.
    • During metaphase, the chromosomes line up at the metaphase plate, midway between the spindle poles.
    • During anaphase, sister chromatids separate and move to opposite poles of the cell.
    • During telophase, the chromosomes arrive at the poles, the nuclear envelope reforms, and the spindle fibers disappear.
    • Cytokinesis overlaps with telophase, and it involves the division of the cytoplasm to produce two daughter cells.
    • In animal cells, cytokinesis is achieved by the formation of a cleavage furrow, a contractile ring made of microfilaments that pinches the cell in two.

    Regulation of the Cell Cycle

    • The cell cycle is regulated by cyclin-dependent kinases (Cdks), enzymes that control the cell cycle by phosphorylating proteins and promoting activity.
    • The activity of Cdks is controlled by cyclins, regulatory proteins that bind to Cdks and activate them.
    • Different Cdks and cyclins are active at different stages of the cell cycle.
    • For example, the cyclin-cdk complex known as M-Cdk is activated at the G2/M checkpoint and triggers entry into mitosis.
    • Specific checkpoints within the cell cycle ensure that the cell only progresses through the cycle when all necessary conditions are met.
    • These checkpoints monitor the completion of DNA replication, the proper alignment of chromosomes, and the presence of sufficient nutrients and growth factors.

    Cell Cycle Checkpoints

    • The G1 checkpoint is often called the "restriction point" as it determines whether the cell will continue through the cell cycle. It checks for DNA damage and the availability of growth factors.
    • The G2/M checkpoint ensures that DNA replication is complete before initiating mitosis. It also detects and repairs DNA damage before the cell enters mitosis.
    • The M checkpoint occurs during metaphase and ensures that all chromosomes are properly attached to the mitotic spindle before proceeding to anaphase.

    Cancer and the Cell Cycle

    • Uncontrolled cell division is a hallmark of cancer. This is often due to mutations that disrupt the normal regulation of the cell cycle.
    • Cancer cells often have defects in genes that regulate the cell cycle, including genes that encode cyclins, Cdks, and checkpoint proteins.
    • These defects can lead to the uncontrolled proliferation of cells and the development of tumors.

    Cancer Treatment

    • Cancer treatments often target the cell cycle, aiming to disrupt the growth and proliferation of cancer cells.
    • One strategy is to use inhibitors of Cdks to block the progression of the cell cycle at specific checkpoints.
    • Specific inhibitors of different Cdks in the cell cycle have been developed and are being tested in clinical trials.
    • Other cancer treatments, including DNA-damaging agents, are also designed to disrupt the cell cycle and induce cell death.

    The Mitotic Spindle

    • The mitotic spindle is a structure made of microtubules that forms during mitosis and plays a crucial role in chromosome segregation.
    • Microtubules are long, thin, hollow cylinders made of the protein tubulin.
    • The mitotic spindle is composed of microtubules and associated proteins, including motor proteins that drive the movement of microtubules and chromosomes.
    • The mitotic spindle forms a bipolar array anchored at two poles of the cell.
    • The spindle fibers attach to the chromosomes via kinetochores, specialized protein structures located at the centromeres of replicated chromosomes.
    • The spindle fibers pull the sister chromatids apart, ensuring equal distribution of genetic material to the daughter cells.

    Cytokinesis

    • Cytokinesis is the division of the cytoplasm, which typically occurs after nuclear division (mitosis).
    • In animal cells, cytokinesis is achieved by the formation of a cleavage furrow, a contractile ring made of microfilaments made of the protein actin that pinches the cell in two.
    • In plant cells, cytokinesis occurs through the formation of a cell plate, a new cell wall that grows from the center of the cell outwards and eventually divides the cell into two.
    • Cytokinesis ensures that each daughter cell receives a complete complement of organelles and cytoplasm.

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    Cell Cycle Phases - PDF

    Description

    This quiz explores the cell cycle, including its phases such as G1, S, G2, and M, as well as the processes of mitosis and cytokinesis. Understanding these concepts is crucial for grasping how cells divide and replicate their DNA. Test your knowledge on checkpoints, stages of mitosis, and the significance of each phase.

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