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Questions and Answers
What is the primary factor that influences the rate of diffusion, according to Fick's Law?
Which of the following is NOT a characteristic of unassisted membrane transport diffusion?
What type of hormones can move into cells passively?
What is the term for the movement of water down its own concentration gradient through a semipermeable membrane?
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What is the term for the difference in concentration of non-penetrating solutes between two solutions?
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What is the formula for the rate of diffusion, according to Fick's Law?
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What happens to a cell in a hypotonic solution?
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What is the function of membrane-spanning proteins in carrier-mediated transport?
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What is the maximum rate of transport by a carrier protein?
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Which type of transport involves the movement of a substance from high to low concentration?
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What happens to the carrier protein after the solute molecule binds to it in facilitated diffusion?
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What is the purpose of GLUT4 in adipose muscles?
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What is the primary function of the cell membrane as a physical barrier?
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What is the main characteristic of the fluid mosaic model of the cell membrane?
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What is the function of intrinsic proteins in the cell membrane?
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What is the purpose of cholesterol in the cell membrane?
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What is the function of glycoproteins in the cell membrane?
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What type of protein is aquaporin?
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What is the function of cell adhesion molecules (CAMs) in the cell membrane?
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What is the term for the entire structure of cells, tissues, organs, and systems that make up an organism?
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What is the term for the process of cells working together to provide signals on what needs to happen?
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What is the function of the phospholipid bilayer in the cell membrane?
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What is the effect of acetylcholine binding to its receptor on the voltage-gated ion channel?
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What is the purpose of the Na+/K+ ATPase pump in generating the resting membrane potential?
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What is the equilibrium potential of K+ (Ek+)?
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What is the general mechanism of second messenger pathways?
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What is the primary mechanism by which sodium ions are transported out of the blood?
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What is the purpose of leak channels for Na and K ions?
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Which type of transport involves the movement of molecules down their concentration gradient?
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Why is the equilibrium potential for Na+ lower than for K+?
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What is the primary function of Na+/K+ ATPase in the kidney?
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Which type of vesicular transport involves the non-selective uptake of extracellular fluid?
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What is the primary function of exocytosis in the cell?
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Which type of cell communication involves the direct contact of plasma membranes between cells?
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What is the primary function of lipid-soluble chemical messengers in signal transduction?
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What is the primary function of ion channels in the cell?
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Which type of ion channel is always open and allows for the leakage of ions into and out of the cell?
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What is the primary function of ligand-gated ion channels in the cell?
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Study Notes
Passive Transport
- Passive transport occurs without energy input, allowing substances to move from high to low concentration
- Types of passive transport:
- Diffusion: movement of substances from high to low concentration
- Osmosis: movement of water molecules from high to low concentration
Facilitated Diffusion
- Facilitated diffusion is a type of carrier-mediated transport
- Carrier proteins bind to specific substances and transport them across the membrane
- Characteristics:
- Specificity: each carrier protein binds to specific substances
- Saturation: finite number of carrier proteins, leading to saturation
- Competition: multiple substances competing for same carrier protein
- Examples:
- GLUT4: facilitates glucose transport into adipose and muscle cells
- Insulin stimulates GLUT4 insertion into cell membrane
Active Transport
- Active transport moves substances from low to high concentration, requiring energy input
- Examples:
- Iodine uptake in thyroid gland cells
- Sodium-potassium pump (Na+/K+ ATPase) maintains ion balance
Cell Membrane Structure
- Fluid mosaic model: flexible and dynamic structure with integral and peripheral proteins
- Components:
- Phospholipids: amphipathic molecules forming bilateral layer
- Cholesterol: maintains fluidity and stability
- Carbohydrates: attached to lipids or proteins, functioning as identity markers
- Functions:
- Physical barrier
- Homeostasis maintenance
- Mechanical barrier
- Adhesion between cells
- Cell signaling
Membrane Proteins
- Types:
- Intrinsic (integral): spanning the membrane
- Extrinsic (peripheral): attached to one side of the membrane
- Functions:
- Aquaporins: water channels
- Ion channels: selective ion transport
- Carrier molecules: facilitated diffusion
- Receptors: binding specific molecules
- Enzymes: performing physiological activities
- Cell adhesion molecules (CAMs): adhering cells together
Cell-Cell Adhesions
- Cell-cell adhesions form tissues, organs, and systems
- Extracellular matrix (ECM) components:
- Proteins
- Polysaccharides
- GAGs
- Functions:
- Adhesion
- Signaling
- Mechanical support
Second Messenger Pathways
- Second messenger relays signals inside the cell
- Amplifies initial response through a signaling cascade
- Two major pathways:
- Cyclic AMP
- Ca2+/DAG
Membrane Potential
- Plasma membrane is polarized electrically, with a potential difference across the membrane
- Generation of RMP (-70mV) due to unequal distribution of Na+, K+, and anions
- Membrane potential is the capacity to do work, measured in millivolts (mV)
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Description
Learn about the crucial functions of the cell membrane, including its role as a physical barrier, maintaining homeostasis, and facilitating exchange of nutrients and wastes. Discover how it responds to environmental changes and signals, and how it knows when to produce an enzyme.