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3.2 Lab Protocol

Approximate Time: 3 hours

Learning Objectives

  1. Understand key concepts including diffusion, osmosis, osmotic pressure, osmolarity, selective permeability, tonicity, crenation, and hemolysis.
  2. Identify the factors that influence a substance’s permeability through a membrane.
  3. Distinguish between different types of membrane transport and explain when each type is utilized.
  4. Determine the properties of an isotonic solution for mammalian blood cells.
  5. Predict outcomes for hypothetical scenarios that mimic the experiments performed in lab.
  6. Explain the importance of osmosis and diffusion in maintaining physiological processes.
  7. POPS: Students will complete the “Understanding the Steps of Scientific Research” assignment individually, using the research article presented to the lab instructor last week.

 

Activity 1A: Tonicity 

Class Demonstration

You have a demonstration that has 3 semi-permeable membrane orbies in the following solutions:

  1. distilled water
  2. 0.9% NaCl
  3. 2.0% NaCl

The molecules in the orbies are impermeant.

Activity 1B: Cell Membrane and Temperature

Active Learning through movement

Your lab professor will assign the following roles and explain the rules of the activity:

 

  1. cell Membrane Phospholipids

Before you take part of this activity, work with your group to hypothesize answers to the following questions:

  1. How do Phospholipids move?
  2. What happens to phospholipids movement when the temperature increases? What happens to them when the temperature decreases?
  3. Why is it important to maintain homeostasis of temperature?

Activity 2: Simple Diffusion

Your Lab Professor will assign the following roles and explain the rule of the activity:

  1. Cell Membrane Phospholipids
  2. Molecules that can move between phospholipids

Before you take part of this activity, work with your group to hypothesize answers to the following questions:

  1. What are the chemical and physical properties of molecules that can move between phospholipids in cell membranes?
  2. What factors can affect the speed of the molecules moving through the membrane?

 

Activity 3: Facilitated Diffusion

Your Lab Professor will assign the following roles and explain the rule of the activity:

  1. Cell Membrane Phospholipids
  2. Molecules that cannot move through the membrane on their own
  3. Channel Proteins
  4. Carrier Proteins

Before you take part of this activity, work with your group to hypothesize answers to the following questions:

  1. What are the chemical and physical properties of molecules that cannot move through the cell membranes on their own?
  2. How do Channel Proteins allow a substance to cross a membrane? What substances use channel proteins for transport?
  3. How do Carrier Proteins allow a substance to cross a membrane? What substances use channel proteins for transport?

 

Activity 4: Active Transport

Your Lab Professor will assign the following roles and explain the rule of the activity:

  1. Cell Membrane Phospholipids
  2. Molecules that cannot move through the membrane on their own
  3. Primary (Direct) Active Transporters – Carrier Proteins/Pumps
  4. ATP Molecules
  5. Secondary (Indirect) Active Transporters – Carrier Proteins/Pumps
  6. Na+ Cations (to power the Electrochemical Gradient)
      1. What are the chemical and physical properties of molecules that can be Actively Transported?
      2. If a substance is going to the Bulk Transported, how will it be moving relative to its gradient?
      3. Why can channel proteins not be used for active transport?
      4. Compare and Contrast Primary and Secondary Active Transport.

 

Activity 5: Bulk Transport

Your Lab Professor will assign the following roles and explain the rule of the activity:

    1. Cell Membrane Phospholipids
    2. Vesicle Phospholipids
    3. Endocytosis – molecules that cannot move through the membrane on their own: 3 types: small molecules, large molecules, and very specific molecules (such as LDLs)
    4. Motor Proteins: Kinesin and Dynein

Before you take part in this activity, work with your group to hypothesize answers to the following questions:

        1. What are the chemical and physical properties of molecules that can be Bulk Transported?
        2. If a substance is going to be Bulk Transported, how will it be moving relative to its gradient?
        3. Does the surface area (membrane) increase or decrease with Endocytosis?
        4. Compare (how they are the same) and Contrast (how they are different) Endocytosis and Exocytosis.

 

This Week’s POPS Project Focus:

  • The first POPS assignment, “Understanding the Steps of Scientific Research”, is due at the end of lab.
  • Work with your group this week to start completing the “POPS Project Schedule Assignment”, which is due at the end of lab next week.

 

 

 

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Human Physiology Laboratory Manual Copyright © 2024 by Kristen Taylor is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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