Lecture 6 - Membrane transport - LC2024WT1 POST

Page 1: Cells and Neurons

• Cell of the Day: Mouse brain neurons

  • Human brain contains approximately 86 billion neurons.

  • Learning induces the formation of new connections, specifically dendritic spines, which influence neuronal activity.

  • Neurons have a cell membrane embedded with various protein pumps and pores that generate electrical activity, known as action potentials.

Page 2: Membrane Transport and Concentration Gradient

• Understanding Concentration Movement:

  • The concept of transport demonstrates that molecules move from high to low concentrations.

  • Humorous dialogue indicates a desire to move against the concentration gradient without needing ATP, which suggests alternative transport mechanisms.

Page 3: Academic Weaponry 101

• Event:

  • Date: September 25th, 5:30-7:45 PM

  • Location: SWNG 121

  • Strategies for study presented by professors and TAs for various science courses, including:

    • SCIE 113 Scientific Writing segment

    • UBC Academic Integrity Hub presentation

    • Tips on habit building and time management from upper-year students.

  • RSVP information available via QR code.

Page 4: Midterm Exam Schedule

• Rescheduled Midterm:

  • New Date: Tuesday, October 22, at 7 PM

  • Reason: To prevent conflict with the PHYS 117 midterm, which affected 20-30% of the class.

  • Important for students to adjust their study schedules accordingly.

Page 5: MLM1 Test Protocol

• Test Details:

  • Date: September 20, 2024

  • Access via Canvas Tutorial page.

  • Ensure all other windows are closed and devices stored away.

  • Academic Integrity Pledge required; the test will not count without it.

  • Memory aid submission required with name and student ID noted.

  • Canvas test available at 12:02 PM, closing at 12:22 PM.

  • It’s crucial to save and submit answers before the timer ends.

Page 6: Access for Evening Tutorials

• Building Access:

  • FNH is locked at 5 PM.

  • Students with tutorials post-5 PM have access programmed into their UBC ID cards.

  • Use the card reader at the main entrance off East Mall for access.

Page 7: Lipid Bilayer Formation

• Behavior of Lipids in Aqueous Environment:

  • When a lipid bilayer forms:

    • A. Lipid molecules gain increased motional freedom.

    • B. Water molecules also gain greater motional freedom.

Page 10: Membrane Proteins

• Integral and Peripheral Proteins:

  • Integral membrane proteins or transmembrane proteins: cross the lipid bilayer.

  • Peripheral membrane proteins: do not span the bilayer and associate with it on one side.

Page 11: Protein Embedding in Membranes

• Learning Objective:

  • Identify protein embedding in bilayers (hydrophilic and hydrophobic groups).

  • Predict which amino acids in a transmembrane protein interact with fatty acyl tails of lipids.

Page 13: Membrane Transport Learning Objectives

• Prior Knowledge Required:

  • Distinguish between diffusion and osmosis.

• Target Goals:

  • Predict molecule permeability across membranes based on size and charge.

  • Compare transport types: simple diffusion, facilitated diffusion, and active transport (energy/requirements).

Page 15: Concepts of Diffusion

• Diffusion Defined:

  • Movement of molecules due to kinetic motion from high to low concentration.

  • At equilibrium, there is no net movement, but molecules continue to move randomly.

  • Energetically favorable for molecules to diffuse from high to low concentrations, increasing entropy.

Page 16: Osmosis

• Osmosis Defined:

  • Water diffuses from lower solute concentration to higher solute concentration.

  • Requires a membrane that allows water passage but not solutes.

Page 17: Membrane Transport Types

• Transport Types:

  • Materials can move via simple diffusion or facilitated diffusion (no energy).

  • Active transport requires energy and involves protein transporters to move against concentration gradients.

Page 19: Channel and Carrier Proteins

• Channel Proteins:

  • Can be open or gated, facilitating the selective movement of specific molecules (e.g., ions).

  • Provides a hydrophilic passageway for faster transport compared to carrier proteins.

• Carrier Proteins:

  • Are gated and undergo conformational changes to transport specific molecules.

Page 22: Experiment A Overview

• Experiment Details:

  • Monitor glucose movement in/out of a cell over time.

  • Initial ratio of glucose concentrations is assessed.

Page 24: Glucose Transport Observations

• Transport Prediction:

  • If facilitated diffusion occurs, the glucose concentration inside the cell will equal that outside over time.

Page 26: Experiment A Graph Analysis

• Graph Analysis:

  • Show the start/end ratio of glucose concentration from greater than 1 to equal 1.

Page 29: Active Transport Considerations

• Question:

  • Identify which molecules would require active transport and the reasoning behind this.

Page 32: Graphing Activity

• Graphing illustrates glucose movement and relation to transport types (active vs facilitated diffusion), aiming to demonstrate movement from a region of high concentration to low concentration.

Page 38: Upcoming Tasks

• Next Steps:

  • Prepare for MLM1 test and attend tutorials.

  • Complete readings/videos for quizzes and activities due in the next weeks.

Page 50: Amino Acid Transport Analysis

• Transport Activity Statements:

  • Analyze statements related to amino acid transport focusing on ratios observed in Experiment B, including whether energy is required for transport.