Podcast
Questions and Answers
Which of these tissues is classified as labile?
Which of these tissues is classified as labile?
What is the main difference between embryonic stem cells and tissue stem cells?
What is the main difference between embryonic stem cells and tissue stem cells?
Which of these tissues is considered to be permanent?
Which of these tissues is considered to be permanent?
Which of these locations is NOT a source of adult stem cells?
Which of these locations is NOT a source of adult stem cells?
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Which of these is NOT a characteristic of labile tissue?
Which of these is NOT a characteristic of labile tissue?
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Which type of growth is characterized by an increase in the size of individual cells?
Which type of growth is characterized by an increase in the size of individual cells?
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What is the primary function of cellular differentiation?
What is the primary function of cellular differentiation?
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Which of the following is the best example of multiplicative growth?
Which of the following is the best example of multiplicative growth?
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What is the key characteristic of morphogenesis?
What is the key characteristic of morphogenesis?
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What process involves the selective expression of genes to produce a cell with a specialized function?
What process involves the selective expression of genes to produce a cell with a specialized function?
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What two processes does morphogenesis involve?
What two processes does morphogenesis involve?
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Which of the following is a physiological condition that can increase cell proliferation?
Which of the following is a physiological condition that can increase cell proliferation?
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How can cell growth be achieved in a tissue context?
How can cell growth be achieved in a tissue context?
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What is the primary role of the G1/S checkpoint in the cell cycle?
What is the primary role of the G1/S checkpoint in the cell cycle?
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Which of the following correctly describes the cell cycle phase where DNA is synthesized?
Which of the following correctly describes the cell cycle phase where DNA is synthesized?
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What happens if DNA damage is beyond repair during the cell cycle?
What happens if DNA damage is beyond repair during the cell cycle?
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Cyclins and CDKs interact to regulate what aspect of the cell cycle?
Cyclins and CDKs interact to regulate what aspect of the cell cycle?
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Which of the following correctly defines asymmetric division of stem cells?
Which of the following correctly defines asymmetric division of stem cells?
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What is the function of cyclin-dependent kinase inhibitors (CDKIs)?
What is the function of cyclin-dependent kinase inhibitors (CDKIs)?
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How do CDKs acquire their ability to phosphorylate proteins?
How do CDKs acquire their ability to phosphorylate proteins?
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What is the primary purpose of maintaining cell populations?
What is the primary purpose of maintaining cell populations?
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Flashcards
Embryonic Stem Cells
Embryonic Stem Cells
Present in the inner mass of the blastocyst, they have virtually limitless self-renewal capacity and can differentiate into any cell type in the body.
Tissue (Adult) Stem Cells
Tissue (Adult) Stem Cells
Found within differentiated tissues, they can only produce cells that are constituents of that particular tissue.
Labile Cells
Labile Cells
Cells that continuously proliferate throughout life, having a short lifespan and rapid turnover. They are susceptible to the toxic effects of radiation and drugs due to their high turnover rate.
Stable Cells
Stable Cells
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Permanent Cells
Permanent Cells
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Growth
Growth
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Multiplicative Growth
Multiplicative Growth
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Auxetic Growth
Auxetic Growth
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Differentiation
Differentiation
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Morphogenesis
Morphogenesis
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Cell Proliferation
Cell Proliferation
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Apoptosis
Apoptosis
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Microenvironment Signals
Microenvironment Signals
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Cell Cycle
Cell Cycle
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G1 (Gap 1) Phase
G1 (Gap 1) Phase
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S (Synthesis) Phase
S (Synthesis) Phase
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G2 (Gap 2) Phase
G2 (Gap 2) Phase
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M (Mitosis) Phase
M (Mitosis) Phase
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G1/S Checkpoint
G1/S Checkpoint
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G2/M Checkpoint
G2/M Checkpoint
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Stem Cells
Stem Cells
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Study Notes
Cell Turnover
- The presentation is on cell turnover, detailing growth, differentiation, and morphogenesis, as well as cell cycle, stem cells, and tissue types.
- The presentation was given by Dr N Buthelezi, Department of Anatomical Pathology, on 20/01/2025.
Growth, Differentiation and Morphogenesis
- Growth is the increase in size due to tissue synthesis.
- Types of growth include:
- Multiplicative: Increase in cell number via mitosis, occurs in all tissues during embryogenesis.
- Auxetic: Increase in individual cell size (e.g., skeletal muscle).
- Accretionary: Increase in intercellular components (e.g., bone, cartilage).
- Combined: A combination of the above types.
- Differentiation is the development of a cell's specialized function or morphology, distinguished from its parent cell.
- Gene expression is selective during differentiation, producing cells with specialized functions.
Morphogenesis
- Morphogenesis is a complex process creating the form and structure of organs (e.g., limbs, facial features).
- It involves growth and differentiation, cell movement relative to each other, and apoptosis to remove unwanted structures during embryogenesis.
Maintaining Cell Populations
- Cell proliferation is essential for:
- Development
- Maintaining steady-state tissue homeostasis
- Replacing dead/damaged cells
- Cell population size depends on proliferation rate and apoptosis (cell death).
- Cell proliferation can be stimulated by physiological or pathological conditions.
- Physiological examples include endometrial tissue changes during the menstrual cycle or thyroid tissue during pregnancy.
- Pathological examples include after cell death or tissue injury.
Cell Cycle
- The cell cycle is a series of events leading to cell division.
- Phases include:
- G1: Presynthetic growth phase
- Restriction point
- G1/S checkpoint
- S: DNA synthesis
- G2: Premitotic growth phase
- G2/M checkpoint
- M: Mitosis
Cell Cycle Regulation
- The cell cycle is controlled by activators (cyclins) and inhibitors (CDKIs):
- Cyclins
- Cyclin-dependent kinases (CDKs)
- Cyclin-dependent kinase inhibitors (CDKIs)
- CDKs phosphorylate proteins, controlled by cyclin levels, which wax and wane.
Cell Cycle Checkpoints
- Checkpoints ensure cells with genetic imperfections do not replicate.
- G1/S checkpoint monitors DNA integrity before replication.
- G2/M checkpoint ensures accurate genetic replication before mitosis.
- Damaged DNA beyond repair triggers apoptosis or senescence.
Cyclin-Dependent Kinase Inhibitors
- p21 (CDKN1A), p27 (CDKN1B) and p57 (CDKN1C) broadly inhibit CDKs.
- p15 (CDKN2B), p16 (CDKN2A), p18 (CDKN2C) and p19 (CDKN2D) selectively affect CDK4 and CDK6.
Stem Cells
- Stem cells are undifferentiated, able to differentiate into various cell types.
- Properties include:
- Self-renewal: Maintain stem cell pool.
- Asymmetric division: One daughter cell differentiates, the other remains undifferentiated, maintaining self-renewal capacity.
- Types of stem cells:
- Embryonic stem cells (most undifferentiated, present in the inner mass of the blastocyst, virtually unlimited self-renewal capacity, totipotent - can differentiate into any cell type).
- Tissue (adult) stem cells (found within differentiated tissues, produce cells specific to that tissue, protected within stem cell niches).
- Labile: Continuously proliferate in postnatal life, short lifespan, rapid turnover (e.g., hematopoietic cells, skin, lining cells of the digestive tract).
- Stable: Divide infrequently under normal conditions but can rapidly divide when cells are lost (e.g., liver cells, endocrine glands, bone, renal tubules).
- Permanent: Active stem cells do not persist long into postnatal life, cells cannot be replaced when lost (e.g., neurons, cardiac muscle cells, photoreceptors).
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Description
This quiz explores the concepts of cell turnover, growth, differentiation, and morphogenesis. It covers various types of growth, the role of stem cells, and the cell cycle, providing a comprehensive understanding of tissue formation and specialization. Perfect for students in anatomical pathology or related fields.