Podcast
Questions and Answers
What is primarily responsible for the protective barrier function of the plasma membrane?
What is primarily responsible for the protective barrier function of the plasma membrane?
Which component of the extracellular matrix is most essential for providing structural support to cells?
Which component of the extracellular matrix is most essential for providing structural support to cells?
What is the main function of integrins in cellular processes?
What is the main function of integrins in cellular processes?
What role do gap junctions play in cell communication?
What role do gap junctions play in cell communication?
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Gap junctions are critical for what specific intercellular communication?
Gap junctions are critical for what specific intercellular communication?
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Which protein is primarily responsible for cell-matrix adhesion?
Which protein is primarily responsible for cell-matrix adhesion?
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Which feature characterizes the fluid mosaic model of the cell membrane?
Which feature characterizes the fluid mosaic model of the cell membrane?
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Which of the following describes the extracellular matrix (ECM)?
Which of the following describes the extracellular matrix (ECM)?
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Selectins are primarily involved in which function?
Selectins are primarily involved in which function?
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What is the primary function of integrins in cellular processes?
What is the primary function of integrins in cellular processes?
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Which cell adhesion protein helps in maintaining epithelial integrity?
Which cell adhesion protein helps in maintaining epithelial integrity?
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What is the role of the glycocalyx in cells?
What is the role of the glycocalyx in cells?
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Which of the following is NOT a function of the plasma membrane?
Which of the following is NOT a function of the plasma membrane?
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Which component is NOT a typical feature of the extracellular matrix?
Which component is NOT a typical feature of the extracellular matrix?
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What type of attachment is more common in connectives tissues?
What type of attachment is more common in connectives tissues?
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Cell-matrix adhesion is primarily facilitated by which type of membrane proteins?
Cell-matrix adhesion is primarily facilitated by which type of membrane proteins?
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Which component primarily links cells to the extracellular matrix?
Which component primarily links cells to the extracellular matrix?
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What is a primary function of gap junctions in epithelial cells?
What is a primary function of gap junctions in epithelial cells?
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Which type of junction is most associated with cell-cell adhesion?
Which type of junction is most associated with cell-cell adhesion?
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Which adherens molecule exists in various forms, such as E-cadherin and N-cadherin?
Which adherens molecule exists in various forms, such as E-cadherin and N-cadherin?
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What role do intermediate filaments play in cell adhesion?
What role do intermediate filaments play in cell adhesion?
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Which structure prevents leakage across epithelial layers?
Which structure prevents leakage across epithelial layers?
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How do integrins facilitate cell-matrix adhesion?
How do integrins facilitate cell-matrix adhesion?
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Which type of junction is primarily responsible for linking adjacent epithelial cells against mechanical stress?
Which type of junction is primarily responsible for linking adjacent epithelial cells against mechanical stress?
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Which molecule is directly involved in cell-cell adhesion in animal cells?
Which molecule is directly involved in cell-cell adhesion in animal cells?
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What is a key feature of tight junctions?
What is a key feature of tight junctions?
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Which junction is most involved in communication between cells?
Which junction is most involved in communication between cells?
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Which of the following is NOT a function of the extracellular matrix?
Which of the following is NOT a function of the extracellular matrix?
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What role do cadherins play in cellular structures?
What role do cadherins play in cellular structures?
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What form of cadherin is predominantly found in the placenta?
What form of cadherin is predominantly found in the placenta?
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Study Notes
Cell Membrane
- Functions of the plasma membrane:
- Protective barrier
- Selective transport
- Cell recognition
- Anchoring sites for cytoskeletal filaments
- Binding sites for ligands
- Interconnecting cells (junctions)
- Contains cytoplasm
Structure of Cell Membrane
- Thin film of lipids and proteins
- Held together by non-covalent interactions
- Dynamic and fluid
- Lipid bilayer (5nm)
- Impermeable to water-soluble molecules
- Membrane proteins span the bilayer and mediate functions, including transport and catalysis.
Cell Membrane Components
- Phospholipids
- Two fatty acid chains
- Polar head (with phosphate group, glycerol, and other groups)
- Nonpolar tails (hydrophobic)
- Cholesterol: embedded within the bilayer
- Proteins (integral and peripheral): embedded within or on top of the bilayer.
- Glycocalyx (cell coat): carbohydrate-rich layer, with glycoproteins and proteoglycans.
Membrane Transport
- Simple diffusion: movement of molecules across the membrane from higher to lower concentration, without energy input.
- Passive transport: movement of molecules across the membrane from higher to lower concentration, with the help of membrane proteins (e.g., channels, carriers).
- Active transport: movement of molecules against their concentration gradient, requiring energy input.
Types of Transport
- Simple diffusion
- Facilitated diffusion (using transport proteins):
- Channels: allow specific ions to pass through a pore.
- Carriers: bind to the transported molecule and undergo a conformational change to move it across the membrane.
- Active transport: uses energy to move molecules against their concentration gradient.
- Coupled transporters: use the energy from one molecule's movement down its concentration gradient to move another molecule up its gradient.
- ATP-driven pumps: use ATP hydrolysis to move molecules against their concentration gradient.
- Light-driven pumps: use light energy to move molecules against their concentration gradient (e.g., in some bacteria).
Endocytosis and Exocytosis
- Endocytosis: cellular uptake of materials via vesicles formed from the plasma membrane.
- Pinocytosis: intake of dissolved substances.
- Phagocytosis: intake of particulate substances.
- Receptor-mediated endocytosis: intake of specific molecules bound to receptors.
- Exocytosis: secretion of substances from the cell via vesicles fusing with the plasma membrane.
Prokaryotic vs. Eukaryotic Cells
- Prokaryotic cells:
- No membrane-bound organelles
- No true nucleus
- Unicellular
- Eukaryotic cells:
- Contain membrane-bound organelles
- Contain a true nucleus
- Uni- or multicellular
Organelles
- Nucleus: DNA and RNA processing
- Endoplasmic Reticulum (ER): lipid and protein synthesis
- Golgi apparatus: modification, sorting, and packaging of proteins and lipids
- Lysosomes: cellular waste removal
- Peroxisomes: fatty acid breakdown
- Mitochondria: energy production (ATP)
- Ribosomes: protein synthesis, free in cytosol or associated with ER
- Cytoskeleton: structural support and cell movement.
Protein Import and Export
- Proteins destined for other organelles or secretion are often directed by signal sequences
- Signal sequences direct proteins to the specific destination.
- Proteins may require modification inside their destination
- Proteins may be transported by vesicles to the target location.
Chromosomes
- DNA is packaged with proteins into chromosomes
- Unique structure and sequence
- DNA forms the backbone.
Cell Cycle
- A series of stages the cell undergoes for growth and reproduction
- Specific stages necessary for cell division and function
- The cell cycle involves multiple stages like G1, S, and M phases and checkpoints or control processes
- Important for accurate DNA segregation
Cellular Communication
- Cells communicate with one another through signaling molecules interacting with cell surface receptors or intracellular receptors.
- Different signaling pathways activate different intracellular response
- Signaling can affect gene expression.
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