Human A&PBIO 304 · American River College ← Week 1 pre-work

BIO 304 · Week 1 · Interactive Workbook

Membrane Transport

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Part 1 of 4 · Recall

Fill in the blanks

Type the term that completes each statement, using the word bank. Pull it from memory first.

Word bank

Simple diffusionFacilitated diffusionChannel proteinOsmosisAquaporinsIsotonicHypotonicPrimary active transportNa+/K+ pumpSymport / cotransportAntiportExocytosisPhagocytosisPinocytosis

  1. small nonpolar molecules cross the lipid bilayer directly (O₂, CO₂)
  2. polar or charged solutes cross via channel or carrier proteins
  3. open pore; lets one type of ion through quickly
  4. water moves across a semipermeable membrane toward higher solute
  5. water-specific channels; explain how kidneys reabsorb so much
  6. same solute concentration as the cell; no net water movement
  7. less solute outside; cell swells, may lyse
  8. pump uses ATP directly (Na+/K+ pump, Ca2+ pump)
  9. 3 Na+ out, 2 K+ in per ATP; sets up resting potential
  10. two solutes cross in the same direction (Na+/glucose)
  11. two solutes cross in opposite directions (Na+/Ca2+ exchanger)
  12. vesicle fuses with membrane to release contents outward
  13. cell eats large particles (a macrophage swallowing bacteria)
  14. cell drinks dissolved solutes in tiny vesicles

Define it: high-yield vocabulary

Write a clear definition in your own words for each term.

  1. Selective permeability
  2. Diffusion
  3. Osmosis
  4. Facilitated diffusion
  5. Active transport
  6. Concentration gradient
  7. Hypertonic
  8. Hypotonic
  9. Isotonic
  10. Endocytosis
  11. Exocytosis

Part 2 of 4 · Anatomy lab

Draw and label

Box A. The plasma membrane

Directions

  1. Draw a horizontal section of plasma membrane: two rows of phospholipid heads (small circles) with their tails (wavy lines) facing each other inside.
  2. Label phospholipid head (polar, hydrophilic) and phospholipid tail (non-polar, hydrophobic).
  3. Draw at least 3 integral membrane proteins spanning the bilayer. Label.
  4. Draw a peripheral protein on one side. Label.
  5. Embed cholesterol molecules between the phospholipids. Label.
  6. Add carbohydrate chains on the extracellular surface attached to proteins (glycoproteins) and lipids (glycolipids). Label.
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Box B. Four transport modes side by side

Directions

  1. Draw four panels, each with a small section of membrane.
  2. Panel 1: Simple diffusion. Show O2 or CO2 passing directly through the bilayer down a gradient. Label.
  3. Panel 2: Facilitated diffusion. Show glucose passing through a channel/carrier protein, still down its gradient. Label.
  4. 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.
  5. Panel 4: Vesicular transport. Show a vesicle fusing with the membrane (exocytosis) and releasing contents. Label.
  6. Above each panel write: passive vs active, and whether ATP is required.
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Structures to label

Label each on your drawing.

  1. Phospholipid bilayer
  2. Phospholipid head (hydrophilic)
  3. Phospholipid tail (hydrophobic)
  4. Integral protein
  5. Peripheral protein
  6. Cholesterol
  7. Glycoprotein
  8. Simple diffusion
  9. Facilitated diffusion
  10. Primary active transport (Na+/K+ ATPase)
  11. Exocytosis
  12. Endocytosis

Part 3 of 4 · Physiology lab

Reason it through

A. Transport comparison table

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.

B. Synthesis

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.

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