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What is the cell cycle?
What is the cell cycle?
A series of steps that a cell takes to replicate itself, turning one cell into two identical cells.
What are the main phases of the cell cycle?
What are the main phases of the cell cycle?
Which phases are included in interphase?
Which phases are included in interphase?
Mitosis is divided into 5 phases.
Mitosis is divided into 5 phases.
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What happens during G1 phase?
What happens during G1 phase?
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What is the role of DNA polymerase in the cell cycle?
What is the role of DNA polymerase in the cell cycle?
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What occurs during the G2 phase?
What occurs during the G2 phase?
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What are labile cells?
What are labile cells?
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What are permanent cells?
What are permanent cells?
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Cytokinesis occurs before mitosis.
Cytokinesis occurs before mitosis.
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Which phase of mitosis involves chromatin condensing into chromosomes?
Which phase of mitosis involves chromatin condensing into chromosomes?
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Match the following cell cycle checkpoints with their function:
Match the following cell cycle checkpoints with their function:
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What is cell senescence?
What is cell senescence?
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What is the cell cycle?
What is the cell cycle?
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Which of the following are phases of the cell cycle?
Which of the following are phases of the cell cycle?
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What happens during the S Phase?
What happens during the S Phase?
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What checks if a cell is ready to enter the S phase?
What checks if a cell is ready to enter the S phase?
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Stable cells continuously divide.
Stable cells continuously divide.
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What are sister chromatids?
What are sister chromatids?
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During which stage of mitosis do chromosomes line up along the metaphase plate?
During which stage of mitosis do chromosomes line up along the metaphase plate?
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What do motor proteins dynein and kinesin do?
What do motor proteins dynein and kinesin do?
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What is the purpose of the M checkpoint?
What is the purpose of the M checkpoint?
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Cells in the G0 phase actively divide.
Cells in the G0 phase actively divide.
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What are telomeres?
What are telomeres?
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What does the G2/M checkpoint ensure?
What does the G2/M checkpoint ensure?
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What happens during the G1 phase of the cell cycle?
What happens during the G1 phase of the cell cycle?
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What is the key activity that occurs during the S phase?
What is the key activity that occurs during the S phase?
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Cells spend the majority of their time in the S phase.
Cells spend the majority of their time in the S phase.
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Which phase follows the S phase in the cell cycle?
Which phase follows the S phase in the cell cycle?
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During mitosis, sister chromatids separate during _____ phase.
During mitosis, sister chromatids separate during _____ phase.
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What is interphase?
What is interphase?
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What is the role of telomeres in cell division?
What is the role of telomeres in cell division?
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Which type of cells replicate only when stimulated by growth factors?
Which type of cells replicate only when stimulated by growth factors?
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What happens during Cytokinesis?
What happens during Cytokinesis?
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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What are the two main parts of the cell cycle?
What are the two main parts of the cell cycle?
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What are the three phases of interphase?
What are the three phases of interphase?
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During the G1 phase, the cell increases its organelles and synthesizes __________.
During the G1 phase, the cell increases its organelles and synthesizes __________.
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Which of these cells are classified as labile or proliferative cells? (Select all that apply)
Which of these cells are classified as labile or proliferative cells? (Select all that apply)
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Stable cells remain in a resting state until a strong stimulus is present.
Stable cells remain in a resting state until a strong stimulus is present.
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What is the name of the process where a cell divides its nucleus to form two identical daughter cells?
What is the name of the process where a cell divides its nucleus to form two identical daughter cells?
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During __________, the chromosomes align at the center of the cell.
During __________, the chromosomes align at the center of the cell.
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What are the phases of mitosis in order?
What are the phases of mitosis in order?
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Cytokinesis is the division of the nucleus.
Cytokinesis is the division of the nucleus.
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What are the protective caps at the ends of chromosomes called?
What are the protective caps at the ends of chromosomes called?
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The G1/S checkpoint ensures that DNA is __________.
The G1/S checkpoint ensures that DNA is __________.
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What is the role of motor proteins during mitosis?
What is the role of motor proteins during mitosis?
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What proteins regulate the cell cycle?
What proteins regulate the cell cycle?
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Cells that exit the cell cycle after differentiation are called __________.
Cells that exit the cell cycle after differentiation are called __________.
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The G2 phase lasts longer than the S phase.
The G2 phase lasts longer than the S phase.
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Study Notes
Introduction
- The cell cycle is a series of steps that a cell takes to replicate itself, turning one cell into two identical cells
- The cell cycle is essential for growth and development
- The cell cycle consists of interphase and mitosis
- Interphase is divided into G1, S, and G2 phases
- Mitosis is divided into prophase, metaphase, anaphase, and telophase
Cell Basics
- Cells are the basic unit of all living things
- All eukaryotic cells have a cell membrane, a nucleus, and cytoplasm
- The cell membrane is a phospholipid bilayer surrounding the cell
- The nucleus contains the genetic material (DNA) in the form of chromatin
- Chromatin is DNA wrapped around histone proteins
Interphase
- Interphase prepares the cell for mitosis
- G1 phase is the first phase of interphase
- In G1, the cell increases its number of organelles and synthesizes proteins and enzymes for DNA replication
- G1 is also the phase where the cell repairs any DNA damage
- Most cells spend the majority of their time in G1
- The S phase is the second phase of interphase
- In S, DNA replication occurs
- DNA polymerase enzymes replicate the DNA with high accuracy
- S phase usually takes about 6 hours
- The G2 phase is the third phase of interphase
- The main function of G2 is cell growth, increasing the cytoplasm and cellular components
- This ensures that each daughter cell receives equal amounts of cytoplasm after division
- The three phases of interphase (G1, S, and G2) are important for preparing the cell for mitosis.
Types of Cells
- Labile cells (proliferative cells) are constantly replicating
- Examples of labile cells include skin cells, epithelial cells of the GI tract, and hematopoietic stem cells
- Stable cells can replicate when stimulated
- Examples of stable cells include liver cells, kidney tubule cells, and alveolar cells
- Permanent cells cannot enter the cell cycle after they have differentiated
- Examples of permanent cells include neurons, skeletal muscle cells, and cardiac muscle cells
G1/S checkpoint
- A checkpoint occurs between G1 and S phase to ensure DNA is ready for replication.
Mitosis
- Mitosis is the division of the nucleus
- It ensures that each daughter cell receives a complete copy of the parent cell's DNA
- Mitosis is divided into four phases: prophase, metaphase, anaphase, and telophase
- Cytokinesis, the division of the cytoplasm, typically occurs at the end of telophase. It is not typically considered a separate phase of mitosis.
Prophase
- Prophase is the first phase of mitosis
- During prophase, the chromatin condenses into chromosomes
- Each chromosome consists of two identical sister chromatids held together by a centromere
Cell Cycle Stages
-
Interphase is characterized by loose chromatin within the nucleus, replicated DNA (4n) and is divided into three sub-phases:
- G1: Cell growth occurs as proteins and organelles are synthesized.
- S: DNA replication occurs, resulting in two identical copies of each chromosome.
- G2: Cell continues to grow and prepares for mitosis.
-
Prophase:
- Chromatin condenses into visible chromosomes.
- Nuclear envelope starts to break down.
- Microtubule organization centers (MTOCs) form with centrioles.
-
Metaphase:
- Nuclear envelope is fully dissolved.
- MTOCs migrate to opposite poles of the cell.
- Microtubules (polar microtubules) connect to chromosomes at the kinetochore, a protein structure on the centromere.
- Chromosomes align at the metaphase plate, a central plane in the cell.
-
Anaphase:
- Sister chromatids separate, pulled apart by shortening polar microtubules.
- Each sister chromatid, now a chromosome, moves towards the opposite pole.
- Motor proteins (dynein and kinesin) assist with the movement.
-
Telophase:
- Chromosomes reach opposite poles and decondense back into chromatin.
- Nuclear envelope reforms around each set of chromosomes.
- Cytokinesis, the division of the cytoplasm, begins, forming a cleavage furrow.
Chromosomes and Sister Chromatids
- A chromosome consists of tightly packed chromatin (DNA and histone proteins) with two arms: a short arm (top) and a long arm (bottom).
- The ends of the chromosome are called telomeres, and the center is called the centromere.
- Sister chromatids are two identical copies of a chromosome connected by a centromere. They are formed during DNA replication in the S phase.
Cytokinesis
- Cytokinesis completes cell division by dividing the cytoplasm into two daughter cells.
- A contractile ring (cleavage furrow) formed from actin and myosin proteins pinches the cell membrane, separating the cytoplasm.
- Daughter cells receive an equal amount of cytoplasm, organelles, and chromosomes.
G0 Phase (Quiescent Phase)
- Some cells, after division, enter the G0 phase, where they are not actively dividing.
- They can remain in this phase indefinitely or be stimulated to re-enter the cell cycle (G1) by various stimuli.
Cell Cycle and Differentiation
- Cell Cycle: Is the process that cells go through to divide.
- Mitosis: Is a type of cell division that creates two identical daughter cells.
- Neurons, Cardiac Muscle, and Skeletal Muscle: These cells are considered post-mitotic, meaning they don't proliferate after they've reached their maturity.
- Telomeres: These are the ends of chromosomes, shortening with each round of DNA replication.
- Cell Senescence: A state where cells irreversibly exit the cell cycle, often linked to shortened telomeres and aging.
Cell Cycle Checkpoints
- G1/S Checkpoint: Ensures cell size is adequate and all necessary nutrients are available before entering the S phase.
- G2/M Checkpoint: Ensures DNA replication was completed without errors before entering mitosis.
- M Checkpoint (Metaphase Checkpoint): Ensures chromosomes are correctly attached to spindle fibers and aligned before entering anaphase to ensure equal division.
Additional Notes
- G2 Phase: Takes approximately two hours.
- DNA Polymerase: The enzyme responsible for copying DNA during replication. Highly accurate, but not perfect.
- ATM Genes: These genes produce proteins which read DNA to identify errors and potential damage.
- APC Proteins and Securin: Proteins involved in regulating the M checkpoint.
The Cell Cycle
- The cell cycle is the process by which a cell replicates itself, creating two identical daughter cells.
- This process is essential for growth, development, and tissue repair.
Phases of the Cell Cycle
- The cell cycle is divided into two main phases: interphase and mitosis.
- Interphase is the longest phase and prepares the cell for division.
- It is further divided into three stages: G1, S, and G2.
- During G1, the cell grows and synthesizes proteins and organelles.
- The S phase focuses on DNA replication, creating two identical copies of each chromosome.
- In G2, the cell continues to grow and prepares for mitosis.
- Mitosis is the division of the nucleus, ensuring each daughter cell receives a complete copy of the parent cell's DNA.
- Mitosis is divided into four phases: prophase, metaphase, anaphase, and telophase.
- Cytokinesis, the division of the cytoplasm, typically occurs after telophase.
Interphase
- During interphase, the cell replicates its DNA and organelles, ensuring each daughter cell receives a full set of genetic material and cellular components.
Mitosis
- Mitosis is the process of nuclear division, dividing the replicated DNA equally into two daughter cells.
- It ensures genetic continuity between generations of cells.
Prophase
- Chromatin condenses into visible chromosomes, each consisting of two identical sister chromatids held together by a centromere.
- The nuclear envelope breaks down, allowing microtubules to access the chromosomes.
- Centrioles migrate to opposite poles of the cell and microtubules begin to form the mitotic spindle.
Metaphase
- Chromosomes fully condense and align at the metaphase plate, a central plane within the cell.
- Microtubules attach to the kinetochore, a protein structure on the centromere of each chromosome.
Anaphase
- Sister chromatids separate, pulled apart by shortening polar microtubules.
- Motor proteins help with the movement of chromosomes towards opposite poles.
- Each sister chromatid, now considered a chromosome, is pulled to opposite poles.
Telophase
- Chromosomes reach the poles of the cell and decondense back into chromatin.
- The nuclear envelope reforms around each set of chromosomes.
- Cytokinesis, the division of the cytoplasm, begins, forming a cleavage furrow, eventually separating the two daughter cells.
Cytokinesis
- Cytokinesis completes cell division by separating the cytoplasm into two daughter cells.
- A contractile ring (cleavage furrow) pinches the cell membrane, dividing the cytoplasm.
- Each daughter cell receives an equal amount of cytoplasm, organelles, and chromosomes.
Chromosomes and Sister Chromatids
- A chromosome consists of tightly packed chromatin (DNA and histone proteins) with two arms: a short arm (top) and a long arm (bottom).
- The ends of the chromosome are called telomeres, and the center is called the centromere.
- Sister chromatids are two identical copies of a chromosome connected by a centromere.
- They are formed during DNA replication in the S phase.
Cell Cycle Checkpoints
- These checkpoints monitor the cell cycle, ensuring proper progression and preventing errors that could lead to uncontrolled cell growth or cancer.
- G1/S Checkpoint: Ensures the cell size is adequate, required nutrients are present, and DNA is undamaged before entering the S phase.
- G2/M Checkpoint: Ensures DNA replication is complete without errors before entering mitosis.
- M Checkpoint (Metaphase Checkpoint): Ensures chromosomes are correctly attached to spindle fibers and aligned before entering anaphase, ensuring equal division of genetic material.
Variations in Cell Cycle Progression
- Some cells enter the G0 phase after division, where they do not actively divide.
- They can remain in this phase indefinitely or be stimulated to re-enter the cell cycle by various stimuli.
- Differentiated cells, like neurons, cardiac muscle cells, and skeletal muscle cells, reach a stage of maturity where they no longer replicate (post-mitotic).
Cell Senescence and Telomeres
- Telomeres, the ends of chromosomes, shorten with each round of DNA replication.
- Cell senescence is a state where cells permanently exit the cell cycle, often linked to shortened telomeres and aging.
The Cell Cycle and Its Stages
- The cell cycle is a process where a cell replicates itself.
- The cell cycle is crucial for controlled cell growth and reproduction.
- It's divided into two main phases: interphase and the M phase (mitosis).
- Interphase is further divided into G1, S, and G2 phases.
- G1 phase is the cell growth phase.
- G1 phase is crucial for proteins and enzymes.
- G1 phase also allows DNA repair.
- S phase is when DNA replication takes place, creating two copies of the genetic material.
- This is done by DNA polymerase enzymes (types 1 and 3).
- S phase includes checkpoints to ensure accurate DNA replication.
- G2 phase also involves cell growth and prepares for cell division.
- G2 phase also includes necessary DNA repair to ensure successful mitosis.
Cell Cycle Checkpoints
- The G1/S checkpoint ensures the cell has the resources to replicate.
- There are checkpoints to ensure proper spindle fiber attachment to chromosomes.
- The M checkpoint ensures all chromosomes are attached to spindle fibers before anaphase.
Types of Cells and Their Division
- Labile cells continuously divide and include skin, gut cells, and hematopoietic stem cells.
- Stable cells can divide when stimulated by growth factors, like liver, kidney, and alveolar cells.
- Permanent cells don't divide after maturation, including neurons, skeletal, and cardiac muscle cells.
Mitosis and its Stages
- Mitosis is nuclear division, resulting in two identical daughter cells.
- It is divided into four stages: prophase, metaphase, anaphase, telophase.
- Prophase involves chromatin condensing into visible chromosomes.
Chromatin and Chromosomes
- Chromatin is composed of DNA and histone proteins.
- Chromatin condenses into chromosomes in prophase.
- Chromosomes consist of condensed chromatin, DNA, and histone proteins.
- The centromere is the constricted region of a chromosome that serves as the attachment point for spindle fibers.
- Telomeres protect the ends of chromosomes.
- Two copies of a chromosome, linked at the centromere, are called sister chromatids.
Microtubule Organization Center (MTOC) and Spindle Fibers
- MTOCs organize microtubules, which form spindle fibers.
- Centrioles are located within MTOCs.
- Spindle fibers extend from MTOCs to chromosomes, helping with separation.
- Polar microtubules extend from the cell poles.
- Kinetochore microtubules attach to the kinetochore of chromosomes.
- Astral microtubules extend outwards from the poles of the cell.
Motor Proteins
- Dynein and kinesin are motor proteins that move chromosomes along spindle fibers during mitosis.
- Dynein moves chromosomes towards the minus end of the microtubules.
- Kinesin moves chromosomes towards the plus end of the microtubules.
The G0 Phase
- The G0 phase is a resting phase where cells do not actively divide.
- Cells in the G0 phase can re-enter the cell cycle if stimulated.
Cell Cycle and Aging
- Some cells are post-mitotic and do not divide after formation, including neurons, skeletal and cardiac muscle cells.
- Telomeres shorten with each DNA replication cycle.
- Cell senescence is the irreversible exit of the cell cycle often triggered by shortened telomeres.
Important Proteins and Genes
- The G2/M checkpoint involves ATM genes that produce proteins to detect DNA defects.
- The M checkpoint utilizes APC and Securin proteins for ensuring proper chromosome alignment.
Cell Cycle Phases
- The cell cycle is a series of events that takes place in a cell leading to its division and duplication of its DNA (DNA replication) to produce two daughter cells.
- G1 Phase (Gap 1): Cell growth and preparation for DNA replication. Increased organelle production, protein synthesis, and DNA damage repair.
- S Phase (Synthesis): DNA replication occurs, resulting in two identical DNA molecules. This process is called the semi-conservative model because each new DNA molecule consists of one original strand and one newly synthesized strand.
- G2 Phase (Gap 2): Continued cell growth and preparation for mitosis. Increases cytoplasm volume, preparing the cell for division into two identical cells.
Interphase
- G1, S, and G2 phases collectively constitute interphase, representing the preparation for cell division.
Mitosis
- The process of cell division that results in two genetically identical daughter cells.
- Prophase: Chromatin condenses into visible chromosomes. The nuclear envelope breaks down. Microtubule Organizing Centers appear, composed of centrioles.
- Metaphase: Chromosomes line up at the center of the cell (equator) along the spindle fibers.
- Anaphase: Sister chromatids separate and move to opposite poles of the cell.
- Telophase: The nuclear envelope reforms around each set of chromosomes, the chromosomes uncoil, and the cytoplasm divides.
- Cytokinesis: The division of the cytoplasm, typically occurs during telophase.
Types of Cells
- Labile (Proliferative) Cells: Continuously replicate throughout life. Examples include epithelial cells of skin, GI tract, urinary tract, and hematopoietic stem cells in the red bone marrow.
- Stable Cells: Replicate only when stimulated by specific growth factors. Examples: Hepatocytes (liver cells), kidney tubules, alveolar (lung) cells.
- Permanent Cells: Do not replicate after differentiation. Examples: Neurons (nervous tissue), skeletal muscle, cardiac muscle.
G1/S Checkpoint
- A control mechanism that monitors the cell's readiness for DNA replication before the S phase.
DNA Replication
- The process by which the DNA in a cell is copied, resulting in two identical DNA molecules.
- Replication Bubble: Structure formed during DNA replication.
Chromatin
- The complex of DNA and histone proteins found in the nucleus.
Cell Cycle Phases
- Interphase: Chromatin is loose within the nucleus. DNA replicates, going from 2n to 4n chromatin.
- Prophase: Chromatin condenses. The nuclear envelope breaks down. Microtubule Organizing Centers appear, composed of centrioles.
- Metaphase: Microtubule organizing centers move to opposite poles of the cell. Polar microtubules connect to the kinetochore of chromosomes on the metaphase plate (the mid-line of the cell).
- Anaphase: Sister chromatids are pulled apart by microtubules towards opposing poles, producing chromosomes.
- Telophase: Chromatin becomes less condensed. Nuclear envelope reforms. Cytokinesis occurs: a constriction (cleavage) furrow forms and pinches the cell in two.
Key Terms
- Chromatin: DNA and histone proteins.
- Chromosome: Condensed chromatin with two arms, a short arm, and a long arm. Ends of the chromosome are called telomeres. The center is the centromere.
- Sister Chromatids: Two identical copies of a chromosome that are attached at the centromere.
- Kinetochore: A protein structure on the outside of a chromosome that anchors microtubules (the "hooks").
- Motor Proteins: Proteins that can move along microtubules. Dynein & Kinesin move chromatids towards microtubule organizing centers.
- Cytokinesis: Division of the cytoplasm to form two distinct cells.
Cell States
- Proliferative cells (e.g., epithelial cells): Cells that can continuously reenter the cell cycle.
- Quiescent cells (G0 Phase): Cells that are at rest and not actively dividing. Can return to the cell cycle with a specific stimulus.
Cell Cycle and Checkpoints
- Neurons, skeletal muscle cells, and cardiac muscle cells do not proliferate once they are fully developed.
- Telomeres, the protective caps at the ends of chromosomes, shorten with each DNA replication.
- Shortened telomeres can lead to cell senescence, where cells irreversibly exit the cell cycle and no longer divide.
- The G2 phase of the cell cycle, lasting about 2 hours, prepares the cell for mitosis.
- The G2/M checkpoint ensures there were no errors in DNA replication using the ATM (Ataxia Telangiectasia Mutated) genes.
- The M checkpoint, occurring at metaphase, ensures chromosomes are properly aligned at the metaphase plate before separation. This checkpoint utilizes proteins such as APC (Anaphase Promoting Complex) and securin.
Cell Cycle
- The cell cycle is the process of cell replication. It is essential for cellular growth.
- The cell cycle has two phases: interphase and mitosis.
- Interphase has three sub-phases: G1, S, and G2.
- During G1, the cell grows and synthesizes proteins and enzymes while repairing any DNA damage.
- The S phase focuses on DNA replication, using enzymes like DNA polymerase 1 and 3. This replication ensures the creation of two identical DNA molecules.
- G2 involves cell growth and preparing for mitosis.
- Mitosis divides the nucleus, producing two genetically identical daughter cells.
- Mitosis has four stages: prophase, metaphase, anaphase, and telophase.
- In prophase, chromatin condenses into chromosomes.
- In metaphase, chromosomes align at the center, forming the metaphase plate.
- In anaphase, sister chromatids separate and move towards opposite poles.
- In telophase, the nuclear envelope reforms around each chromosome set.
- Cytokinesis follows telophase, physically dividing the cytoplasm, creating two daughter cells.
Cell Types and Cell Cycle Behavior
- Labile cells constantly cycle through the cell cycle.
- Examples: epithelial cells of the skin, GI tract, urinary tract, and hematopoietic stem cells.
- Stable cells usually remain in a resting state but can be stimulated to enter the cell cycle.
- Examples: hepatocytes, renal epithelial cells, and alveolar cells.
- Permanent cells exit the cell cycle after differentiation and do not divide.
- Examples: neurons, skeletal muscle cells, and cardiac muscle cells.
DNA Replication
- DNA replication creates an exact copy of the DNA molecule, ensuring that each daughter cell receives a complete copy of genetic information.
- This process is remarkably accurate and has a low error rate.
Checkpoints
- The cell cycle has checkpoints to regulate and ensure error-free cell division.
- The G1/S checkpoint verifies that DNA is undamaged and sufficient proteins and enzymes are present.
- The cell cycle is regulated by complex interactions of proteins, enzymes, and genes.
Chromatin and Chromosomes
- During cell division, chromatin condenses into chromosomes.
- Chromosomes consist of DNA and histone proteins.
- Each chromosome has a short arm and a long arm.
- Chromosome ends are called telomeres.
- The center of a chromosome is called the centromere.
- Sister chromatids are two identical copies of a replicated chromosome.
Nuclear Envelope
- The nuclear envelope breaks down during cell division.
- Nuclear envelope proteins are phosphorylated and then degraded by proteases.
- The nuclear envelope reforms during telophase.
Microtubule Organization Centers (MTOCs)
- MTOCs form during cell division and contain centrioles.
- MTOCs form the microtubule spindle, which separates chromosomes.
- Microtubules attach to the kinetochore, a protein structure on the centromere of chromosomes.
Stages of Mitosis
- Prophase: Chromatin condenses, the nuclear envelope breaks down, and MTOCs move to opposite poles.
- Metaphase: Microtubules attach to kinetochores, and chromosomes align on the metaphase plate.
- Anaphase: Sister chromatids separate and are pulled apart towards opposite poles.
- Telophase: The nuclear envelope reforms, microtubules disappear, and the cytoplasm divides.
Cytokinesis
- Cytokinesis is the division of the cytoplasm.
- It occurs through the formation of a cleavage furrow composed of actin and myosin proteins.
The Cell Cycle
- The cell cycle has two major phases: interphase and mitosis.
- Interphase involves cell growth and DNA replication.
- Mitosis involves cell division, yielding two identical daughter cells with the same number of chromosomes.
- Interphase has three sub-phases: G1, S, and G2.
- Cell cycle regulation involves proteins called cyclins and cyclin-dependent kinases.
- Cells may enter a resting phase called G0 where they do not divide.
Motor Proteins
- Motor proteins move chromosomes along microtubules.
- Examples include dynein and kinesin.
- Dynein moves chromosomes towards opposite poles.
- Kinesin moves chromosomes towards the MTOC.
Organelles
- Organelles are distributed evenly between daughter cells during cytokinesis.
- Examples include ribosomes, mitochondria, and the Golgi apparatus.
Cell Cycle Checkpoints
- G1/S checkpoint: Regulates the transition from G1 to S, ensuring DNA integrity and adequate proteins.
- G2/M checkpoint: Regulates the transition from G2 to M. It uses proteins like ATM to check for DNA damage.
- M checkpoint (Spindle checkpoint): Regulates the transition from metaphase to anaphase, ensuring proper chromosome alignment.
Telomeres and Aging
- Telomeres protect the ends of chromosomes.
- Telomeres shorten with each DNA replication.
- Cellular senescence occurs when a cell can no longer divide due to telomere shortening.
Other Key Information
- Neuron, skeletal muscle, and cardiac muscle cells are examples of cells that do not divide after differentiation.
- The G2 phase lasts about 2 hours.
- The S phase lasts about an hour.
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Description
Test your knowledge on the cell cycle, including its phases such as interphase and mitosis, as well as the fundamental components of eukaryotic cells. This quiz will challenge your understanding of cellular replication and the key roles of each phase.
