Lab 3
Approximate Time: 3 hours
Learning Objectives
- Understand key concepts including diffusion, osmosis, osmotic pressure, osmolarity, selective permeability, tonicity, crenation, and hemolysis.
- Identify the factors that influence a substance’s permeability through a membrane.
- Distinguish between different types of membrane transport and explain when each type is utilized.
- Determine the properties of an isotonic solution for mammalian blood cells.
- Predict outcomes for hypothetical scenarios that mimic the experiments performed in lab.
- Explain the importance of osmosis and diffusion in maintaining physiological processes.
- POPS: Students will collaborate on the Introduction section for peer editing.
Activity 1: Tonicity
Class Demonstration
You have a demonstration that has 3 semi-permeable membrane spheres in the following solutions:
- distilled water
- 0.9% NaCl
- 2.0% NaCl
The molecules in the spheres are impermeant.
Activity 1: Cell Membrane and Temperature
Active Learning through movement
Your lab professor will assign the following roles and explain the rules of the activity:
- cell Membrane Phospholipids
Before you take part of this activity, work with your group to hypothesize answers to the following questions:
- How do Phospholipids move?
- What happens to phospholipid movement when the temperature increases? What happens to them when the temperature decreases?
- 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:
- Cell Membrane Phospholipids
- Molecules that can move between phospholipids
Before you take part of this activity, work with your group to hypothesize answers to the following questions:
- What are the chemical and physical properties of molecules that can move between phospholipids in cell membranes?
- 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:
- Cell Membrane Phospholipids
- Molecules that cannot move through the membrane on their own
- Channel Proteins
- Carrier Proteins
Before you take part of this activity, work with your group to hypothesize answers to the following questions:
- What are the chemical and physical properties of molecules that cannot move through the cell membranes on their own?
- How do Channel Proteins allow a substance to cross a membrane? What substances use channel proteins for transport?
- How do Carrier Proteins allow a substance to cross a membrane? What substances use channel proteins for transport?
Activity 4: Active Transport
You Lab Professor will assign the following roles and explain the rule of the activity:
- Cell Membrane Phospholipids
- Molecules that cannot move through the membrane on their own
- Primary (Direct) Active Transporters – Carrier Proteins/Pumps
- ATP Molecules
- Secondary (Indirect) Active Transporters – Carrier Proteins/Pumps
- Na+ Cations (to power the Electrochemical Gradient)
Before you take part of this activity, work with your group to hypothesize answers to the following questions:
- What are the chemical and physical properties of molecules that can be Actively Transported?
- If a substance is going to the Bulk Transported, how will it be moving relative to its gradient?
- Why can channel proteins not be used for active transport?
- Compare (how they are the same) and Contrast (how they are different) Primary and Secondary Active Transports.
Activity 5: Bulk Transport
You Lab Professor will assign the following roles and explain the rule of the activity:
- Cell Membrane Phospholipids
- Vesicle Phospholipids
- Molecules that cannot move through the membrane on their own (without help): 3 types: small molecules, large molecules and very specific molecules (such as LDLs)
- Motor Proteins: Kinesin and Dynein
Before you take part in this activity, work with your group to hypothesize answers tot he following questions:
- What are the chemical and physical properties of molecules that can be Bulk Transported?
- If a substance is going to be Bulk Transported, how will it be moving relative to its gradient?
- Does the surface area (membrane) increase or decrease with Endocytosis?
- Compare (how they are the same) and Contrast (how they are different) Endocytosis and Exocytosis.
This Week’s focus for the POPS Project Includes:
- Introduction Section due Next Week.
Student responsible for the Materials and Methods section of your POPS project should bring it to our next lab class for peer editing. Student name is listed under the Timeline for Completion in the “Plan and Schedule Assignment”, which outlines your roles for the project.
Materials and Methods Section Guidelines:
Think of this section as step-by-step directions that detail exactly how your group will be completing your research. Here are some key points to keep in mind:
Materials List: start with a comprehensive list of materials that will be use in your research.
Detailed Explanation: provide a through description of how each material will be utilized so that a reader could replicate your research exactly as you conducted it.
Essential Details to Include:
- Participants:
Number of participants (keep identities confidential per IRB training)
Age range and ethnicities
Breakdown of genders - Study Duration and Data Collection:
How long did your study will last?
Methods of data collection (e.g.,automatic blood pressure)
Consistency in devices used (same brand or different) - Environment of Data Collection:
Where was the data collected (lab, other setting)?
Timing of data collection (same time of day, intervals between data points).
Specify whether data was collected at the beginning/end (like surveys) or on a regular schedule (weekly, daily).
If multiple people collected data, explain how you ensured accuracy and consistency. - Confounding Variables:
Include details on any confounding variables you controlled during data collection.
Ensure the order of details flows logically, like instructions for a new game. It’s a good idea to have someone unfamiliar with physiology read this section to ensure it’s easy to follow and replicate.
Please come prepared with your Materials and Methods section, as it is critical part of your research project. If you have any questions or need help, feel free to reach out!
- For additional guidance, refer to the POPS Project Materials at the end of this manual.