1A. What you will draw
Cells live or die by what they let in and out. Today you'll draw the membrane in detail and the four major transport modes that operate across it.
BIO 304 . WEEK 1 . FRIDAY . LAB WORKBOOK
Membrane Transport
How material crosses the plasma membrane: passive, active, and vesicular pathways.
Print this page. You will draw your own diagrams from the directions below, then hand-label the structures listed. Drawing by hand is the integrity mechanism for this course.
Part 1 of 2
Anatomy Lab
Box A. The plasma membrane
Directions
- Draw a horizontal section of plasma membrane: two rows of phospholipid heads (small circles) with their tails (wavy lines) facing each other inside.
- Label phospholipid head (polar, hydrophilic) and phospholipid tail (non-polar, hydrophobic).
- Draw at least 3 integral membrane proteins spanning the bilayer. Label.
- Draw a peripheral protein on one side. Label.
- Embed cholesterol molecules between the phospholipids. Label.
- Add carbohydrate chains on the extracellular surface attached to proteins (glycoproteins) and lipids (glycolipids). Label.
Draw here. Sketch by hand.
Box B. Four transport modes side by side
Directions
- Draw four panels, each with a small section of membrane.
- Panel 1: Simple diffusion. Show O2 or CO2 passing directly through the bilayer down a gradient. Label.
- Panel 2: Facilitated diffusion. Show glucose passing through a channel/carrier protein, still down its gradient. Label.
- Panel 3: Primary active transport. Draw the Na+/K+ ATPase with 3 Na+ leaving the cell, 2 K+ entering, and ATP being consumed. Show the gradient: against concentration.
- Panel 4: Vesicular transport. Show a vesicle fusing with the membrane (exocytosis) and releasing contents. Label.
- Above each panel write: passive vs active, and whether ATP is required.
Draw here. Sketch by hand.
1C. Structures to label (12)
After you finish each drawing, label every structure below directly on your sketch.
- Phospholipid bilayer
- Phospholipid head (hydrophilic)
- Phospholipid tail (hydrophobic)
- Integral protein
- Peripheral protein
- Cholesterol
- Glycoprotein
- Simple diffusion
- Facilitated diffusion
- Primary active transport (Na+/K+ ATPase)
- Exocytosis
- Endocytosis
Part 2 of 2
Physiology Lab
2A. Transport comparison table
Fill in the table below. Use a short phrase per cell. After the table, answer the two follow-up questions.
| Property | Simple diffusion | Facilitated diffusion | Primary active transport | Endocytosis |
|---|---|---|---|---|
| Uses a membrane protein? | ||||
| Moves with or against gradient? | ||||
| Requires ATP directly? | ||||
| Typical molecule transported | ||||
| Rate-limiting factor |
Why are large polar molecules unable to cross the membrane by simple diffusion, while small non-polar molecules can?
Secondary active transport (e.g., glucose-Na+ symporter) does not directly consume ATP. Explain how it still depends on ATP, indirectly.
2B. Synthesis questions
Answer each in 2 to 4 sentences. Use the language from this week's lecture and your drawings as evidence.
1. Red blood cells placed in a 0.45% NaCl solution swell and lyse. Explain using tonicity terms (hypertonic, isotonic, hypotonic). Predict what would happen in a 3% NaCl solution.
2. Ouabain blocks the Na+/K+ ATPase. Predict the effect on a cell's resting Na+ and K+ concentrations over time, and on its ability to perform secondary active transport.
3. Cystic fibrosis is caused by a defective chloride channel (CFTR). Predict the effect on the watery secretions of the airways, and explain why patients develop thick mucus.
3. What to submit
Complete both the Anatomy Lab (your own drawings, hand-labeled, plus the structures list) and the Physiology Lab (activity and synthesis questions). Photograph or scan every page and upload to Canvas before the deadline listed on the schedule. Hand-drawn, hand-labeled work is the integrity mechanism for this course. Typed or AI-generated diagrams are not accepted.