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Questions and Answers
What is the primary function of tumor suppressor genes?
What is the primary function of tumor suppressor genes?
How do cancer cells typically behave in relation to growth factors?
How do cancer cells typically behave in relation to growth factors?
What happens when the p53 gene is mutated in relation to DNA-damaged cells?
What happens when the p53 gene is mutated in relation to DNA-damaged cells?
Why are cell cycle checkpoints essential in cellular processes?
Why are cell cycle checkpoints essential in cellular processes?
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Which statement about p53 protein is true?
Which statement about p53 protein is true?
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What is one primary reason why cells undergo division?
What is one primary reason why cells undergo division?
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Which phase of the cell cycle is characterized by primary growth?
Which phase of the cell cycle is characterized by primary growth?
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During which phase does the genome get replicated?
During which phase does the genome get replicated?
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What is a consequence of defects in cell division?
What is a consequence of defects in cell division?
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Mitosis results in which of the following?
Mitosis results in which of the following?
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What is the term for the complete set of genetic information in a cell?
What is the term for the complete set of genetic information in a cell?
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Which phase follows the synthesis phase in the cell cycle?
Which phase follows the synthesis phase in the cell cycle?
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What is the function of cytokinesis in the cell cycle?
What is the function of cytokinesis in the cell cycle?
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What is the primary function of kinetochores during cell division?
What is the primary function of kinetochores during cell division?
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In which phase do chromosomes condense and become visible under a light microscope?
In which phase do chromosomes condense and become visible under a light microscope?
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What structural change occurs in the nucleus during prophase?
What structural change occurs in the nucleus during prophase?
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Which of the following occurs during anaphase?
Which of the following occurs during anaphase?
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What happens to the chromosomes during telophase?
What happens to the chromosomes during telophase?
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Which phase is characterized by the centrosomes moving to opposite poles of the cell?
Which phase is characterized by the centrosomes moving to opposite poles of the cell?
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What structure forms during cytokinesis in animal cells?
What structure forms during cytokinesis in animal cells?
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During which phase do centrosomes replicate to form two centrosomes?
During which phase do centrosomes replicate to form two centrosomes?
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What is the primary purpose of mitosis in eukaryotic organisms?
What is the primary purpose of mitosis in eukaryotic organisms?
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Which cells undergo meiosis to produce gametes?
Which cells undergo meiosis to produce gametes?
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What is the chromosome consistency of daughter cells produced by mitosis?
What is the chromosome consistency of daughter cells produced by mitosis?
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How do prokaryotic cells reproduce compared to eukaryotic cells?
How do prokaryotic cells reproduce compared to eukaryotic cells?
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What role do condensins play during the mitotic process?
What role do condensins play during the mitotic process?
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What is the chromosome number of a haploid cell?
What is the chromosome number of a haploid cell?
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Which structure connects sister chromatids at the centromere?
Which structure connects sister chromatids at the centromere?
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At what stage do chromosomes align at the cell's equator during mitosis?
At what stage do chromosomes align at the cell's equator during mitosis?
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What occurs during metaphase of mitosis?
What occurs during metaphase of mitosis?
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What is the role of spindle microtubules in cell division?
What is the role of spindle microtubules in cell division?
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What happens during telophase?
What happens during telophase?
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Which statement best describes the abnormalities of cell division?
Which statement best describes the abnormalities of cell division?
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How do different types of cells affect the rate of cell division?
How do different types of cells affect the rate of cell division?
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What does the cell cycle control system direct?
What does the cell cycle control system direct?
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What is a consequence of an abnormal number of autosomal chromosomes?
What is a consequence of an abnormal number of autosomal chromosomes?
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What defines the metaphase plate during mitosis?
What defines the metaphase plate during mitosis?
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What role do cyclins play in the cell cycle?
What role do cyclins play in the cell cycle?
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Which of the following statements about checkpoints in the cell cycle is true?
Which of the following statements about checkpoints in the cell cycle is true?
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What are cyclin-dependent kinase inhibitors (CKIs) primarily responsible for?
What are cyclin-dependent kinase inhibitors (CKIs) primarily responsible for?
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How does the anaphase-promoting complex (APC) affect cell cycle progression?
How does the anaphase-promoting complex (APC) affect cell cycle progression?
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What external factor is mentioned as influencing cell division?
What external factor is mentioned as influencing cell division?
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Which of the following is a correct statement about cyclin/CDK complexes?
Which of the following is a correct statement about cyclin/CDK complexes?
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During which phase are the main checkpoints found?
During which phase are the main checkpoints found?
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What must be assessed during the G2 checkpoint?
What must be assessed during the G2 checkpoint?
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Study Notes
Cell Division and Cell Cycle
- Cell division is a vital part of the cell cycle.
- It results in genetically identical daughter cells.
- Cells duplicate their genetic material before division, ensuring each daughter cell receives an exact copy of DNA.
Functions of Cell Division
- Reproduction: Single-celled eukaryotes like amoebas divide to create new organisms.
- Growth and development: The fertilized egg cell divides to form new cells, enabling growth and development.
- Tissue renewal: Dividing bone marrow cells generate new blood cells, constantly renewing tissues.
DNA
- DNA is the genetic information (genome).
- DNA is organized into chromosomes.
Phases of the Cell Cycle
- Interphase: The normal cell activity stage, consisting of three sub-phases.
- G1 (Gap 1): Primary growth phase.
- S (Synthesis): DNA replication phase.
- G2 (Gap 2): Secondary growth phase.
- Mitotic phase: Cell division phase, with further sub-phases.
- Mitosis: Process of nuclear division. (further sub-phases Prophase, Metaphase, Anaphase, and Telophase)
- Cytokinesis: The division of the cytoplasm.
- Different cell types divide at different rates. Some cells rarely or never divide.
Mitosis and Meiosis
- Normal cells contain 46 chromosomes (diploid).
- Mitosis produces genetically identical daughter cells, also with 46 chromosomes, occurring in most cells.
- Meiosis produces haploid gametes (sperm and egg cells), containing only one set of chromosomes (23 in humans) for sexual reproduction.
Two Fundamental Cell Types
- Prokaryotic: Bacteria and other prokaryotic cells multiply by binary fission.
- Eukaryotic: Cells with a nucleus, follow the elaborate cell cycle of phases described in the information above.
Packing for the Move...
- Protein complexes (condensins) compact chromosomes for DNA duplication and division.
Structure of a Eukaryotic Chromosome
- A chromosome is composed of two sister chromatids, joined by a centromere.
Metaphase Chromosome
- The centromere, a constricted region, contains two kinetochores (protein discs).
- Kinetochores are points of attachment for microtubules, crucial in chromosome movement during cell division.
Eukaryotic Cell Cycle
- The eukaryotic cell cycle has two major phases.
- Interphase (G1, S, G2)
- Mitotic (M) phase, consisting of mitosis (and cytokinesis) which both involve a number of events
- DNA is uncondensed (chromatin) during interphase, condensed (chromosomes) during the mitotic phase
Mitosis Steps (Simplified)
- Prophase: Chromosomes condense.
- Metaphase: Chromosomes align.
- Anaphase: Sister chromatids separate.
- Telophase and cytokinesis: Nuclear envelopes reform; the cytoplasm divides.
Mitotic Division of an Animal Cell
- Visual representation of the dynamic events of mitosis.
G2 of Interphase
- Two centrosomes form from replication of a single centrosome.
- Each contains centrioles in animal cells.
- Chromosomes, duplicated in S phase, appear uncondensed (in a granular form).
Prophase
- Chromatin fibers condense into chromosomes.
- Nucleoli disappear.
- Two identical sister chromatids join.
- Mitotic spindle begins to form.
- Asters ("stars") emerge from centrosomes.
- Centrosomes move apart via elongation of microtubules.
Metaphase
- Chromosomes align on the metaphase plate. An imaginary plane that splits the cell.
- Kinetochores (on sister chromatids) attach to kinetochore microtubules.
- Spindle microtubules form from opposite poles.
Telophase
- Two daughter nuclei form.
- Nuclear envelopes form around the nuclei.
- Chromosomes decondense.
- Less condensed chromosomes.
- Mitosis, the division of one nucleus into two genetically identical nuclei is complete.
Cells Divide at Different Rates
- Cell division rates vary depending on the specific cell type and its function.
- Skin cells divide quickly.
- Red blood cells have a short lifespan.
- Other cells have much longer lifespans.
Abnormalities of Cell Division
- Defects in cell division/cell cycle can originate by chromosomal disruptions.
- Major chromosomal abnormalities normally result in spontaneous embryonic loss.
- Chromosomal disorders can arise from issues in number/placement of chromosomes.
- Cells can have extra chromosomes during division (or none), as a result.
- Abnormal chromosome numbers/structures are usually incompatible with life.
- Abnormalities can cause diseases like cancer, arising from uncontrollable cell proliferation.
Regulation of the Cell Cycle
- Control mechanisms direct the ordered events of the cell cycle.
- The cell cycle contains built-in checkpoints.
- External and internal factors influence control.
Cell Cycle Checkpoints
- Checks for proper cell size and DNA integrity.
- Ensures DNA is correctly replicated.
- Verifies correct chromosome alignment/attachment during mitosis.
Cyclin-dependent Kinases (CDKs)
- CDKs are protein kinases that drive the cell cycle by activating or deactivating other proteins.
- They require cyclins to become activated.
Cyclin Dependent Kinase Inhibitors (CKIs)
- Regulators that inhibit/control CDKs.
External Factors
- Growth factors influence cell division.
- Platelet-derived growth factor (PDGF) stimulates cells to divide.
- Cell signaling mechanisms control which cell types divide, how fast, and when.
Role of p53 in Cell Cycle Control
- The p53 protein is vital and has an essential role in controlling the cell cycle when DNA is damaged.
- p53 is a transcription factor that responds to DNA damage.
- If DNA is damaged, p53 promotes cell cycle arrest and triggers apoptosis.
Tumor Suppressor Genes
- Tumor suppressor genes normally slow cell division or induce programmed cell death (apoptosis).
- Mutations in these genes can lead to uncontrolled cell growth.
Cancer
- Cancer cells evade normal mechanisms and controls, leading to uncontrolled division and invasion of other tissues.
- Cancer cells can manufacture their own growth factors, have signaling pathway problems, or issues with their cell cycle control system.
- Cancer cells may stop dividing at random, not at the normal checkpoints.
Additional Information (Checkpoints/Mechanism)
- Specific molecular mechanisms and proteins are involved in cell cycle checkpoints to ensure accurate cell division.
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Description
Test your knowledge on the processes of cell division and the cell cycle. This quiz covers vital concepts including DNA organization, phases of the cell cycle, and functions of cell division in growth, reproduction, and tissue renewal. Perfect for students studying biology.
