BSC1010 Lecture 7
Chp 7- Plasma Membranenoanimation
Page 1: Structure of the Plasma Membrane
The plasma membrane consists of a double layer of phospholipids.
Contains proteins, cholesterol, and other molecules.
Page 2: Membrane Properties
Membrane fluidity is enhanced by the presence of phospholipids and proteins.
Most lipids and some proteins can drift laterally within the membrane.
The membrane is selectively permeable, regulating the traffic of substances into and out of the cell.
Page 3: Role of Cholesterol
Cholesterol molecules are integral to the fluidity of the membrane.
They help maintain membrane stability.
Page 4: Selective Permeability
The plasma membrane acts as a barrier to substances, allowing certain molecules to pass while blocking others.
Page 5: Selective Permeability (Reiteration)
This selective permeability is integral for maintaining homeostasis within the cell.
Page 6: Types of Membrane Proteins
There are two main types of membrane proteins:
Peripheral proteins: Not embedded in the lipid bilayer.
Page 7: Integral Proteins
Integral proteins penetrate the hydrophobic core of the lipid bilayer (transmembrane proteins).
Contact with the lipid core involves hydrophobic regions (nonpolar amino acids) and hydrophilic regions (polar amino acids).
Page 8: Functions of Membrane Proteins
Various functions include:
Transport
Intercellular joining
Enzymatic activity
Cell-cell recognition
Signal transduction
Attachment to the cytoskeleton and extracellular matrix (ECM).
Page 9: Membrane Carbohydrates
Membrane carbohydrates are branched oligosaccharides with fewer than 15 sugar units, varying by species and cell type.
Page 10: Membrane Synthesis
Membranes are synthesized in the endoplasmic reticulum (ER) and Golgi apparatus.
Page 11: Passive Transport Overview
Passive transport does not expend energy; molecules follow their concentration gradient.
Simple diffusion involves constant movement of molecules in liquid and gas states.
Page 12: Passive Transport Indicators
Passive transport involves molecules moving according to their energy and concentration gradients.
Page 13: Simple Diffusion Visual
Diffusion illustrated with solute molecules, showing net diffusion until equilibrium is reached.
Page 14: Diffusion Examples
Simple diffusion includes diffusion of one solute and diffusion of two solutes, demonstrating net movements towards equilibrium.
Page 15: Simple Diffusion Mechanism
Simple diffusion occurs with lipid-soluble molecules like O2 and CO2 across cell membranes.
Page 16: Water Diffusion
Water molecules can diffuse across a semi-permeable membrane.
Page 17: Concentration of Solutions
Concentration is the amount of solute mixed with a solvent (e.g., solute=sugar, solvent=water).
Concentration can be measured in various ways.
Page 18: Tonicity Definitions
Tonicity: The relative solute concentration of one solution compared to another;
Hypertonic: higher solute concentration.
Hypotonic: lower solute concentration.
Isotonic: equal solute concentrations with equilibrium in water movement.
Page 19: Comparing Solutions
Example comparing concentrations of solutions in a beaker and a bag; categorization into hypertonic and hypotonic solutions based on solute concentrations.
Page 20: Sugar Solution Comparison
Comparing concentrations of sugar solutions in a beaker and a bag, noting net movement of water based on solutions' tonicities.
Page 21: Isotonic Solutions
Examples illustrating isotonic solutions with no net movement of water.
Page 22: Water Molecules in Solutions
Hypertonic solutions attract more water molecules, while hypotonic solutions have more free water molecules.
Page 23: Movement of Water Molecules
Free water molecules move from areas of higher concentration to lower concentration for equilibrium.
Page 24: Osmosis Overview
Osmosis is the diffusion of water across a selectively permeable membrane, a special type of passive transport.
Continues until the two solutions reach isotonic states.
Page 25: Water Diffusion Representation
Demonstrates the flow of water across a semi-permeable membrane (similar to Page 16).
Page 26: Red Blood Cell in Isotonic Solution
An animal cell in isotonic conditions experiences no net water movement.
Page 27: Effects of Tonicity on Red Blood Cells
Red blood cells in hypertonic solutions lose water, shrivel, and may die; in hypotonic solutions, they gain water, swell, and could burst.
Page 28: Cellular Response to Tonicity
In hypertonic environments: cells lose water.
In hypotonic environments: cells gain water.
Page 29: Plant Cell Tonicity Effects
Comparison of plant cell responses to hypertonic, hypotonic, and isotonic conditions, illustrated with terms:
Turgid: normal state in hypotonic.
Flaccid: state in isotonic.
Plasmolyzed: in hypertonic.
Page 30: Plant Cell Tonicity Visualization
Similar representation of plant cell's response to changes in water concentration in different tonicities.
Page 31: Lipid-Soluble Molecules
Reiteration of the diffusion process for lipid-soluble molecules such as O2 and CO2 across membranes.
Page 32: Facilitated Diffusion
Facilitated diffusion is passive movement of molecules down their concentration gradient via transport proteins, including channel and carrier transport proteins.
Page 33: Water Transport Mechanism
Water movement via aquaporins within facilitated diffusion frameworks.
Page 34: Active Transport Overview
Active transport requires energy (ATP) to move ions/molecules against their concentration gradient, utilizing protein pumps.
Page 35: Example of Active Transport
Sodium-potassium pump is an example of a protein pump requiring energy.
Page 36: Transport Process Overview
Summary of transport processes:
Diffusion, facilitated diffusion (both forms of passive transport), and active transport requiring energy.
Page 37: Exocytosis
Exocytosis: transport method where substances are secreted out of the cell via vesicles.
Examples: neurotransmitters, insulin.
Page 38: Endocytosis Types
Endocytosis is the process by which cells internalize substances, including:
Pinocytosis: cellular drinking.
Phagocytosis: cellular eating.
Receptor-mediated endocytosis.
Page 39: Pinocytosis and Phagocytosis
Pinocytosis involves vesicle formation around a droplet of extracellular fluid (nonspecific).
Phagocytosis involves engulfing large particles or organisms into a vacuole for digestion.
Page 40: Receptor-Mediated Endocytosis
This process is highly specific; substances bind to receptors on the membrane, leading to endocytosis in coated pits.
Page 41: Final Summary of Active Transport
Active transport encompasses several processes: pumps, exocytosis, endocytosis (including pinocytosis, phagocytosis, receptor-mediated), each requiring energy.