membranes and transport

Question 1

THE PHOSPHOLIPID BILAYER
1. Cell membrane
2. Structure

Answer 1

1. Cell membrane
   -Responsible for homeostasis within the cell
   –Semi-permeable barrier = only allows some molecules in and others out
2. Structure
   
   • Lipids - polar hydrophilic head and non-polar hydrophobic tail
   • Carbohydrate Chain
   • Proteins
     –Marker Proteins - identifies cells (name tags)
     –Channel/Carrier Proteins - allow larger/charged molecules in or out
     –Receptor Proteins - receive cell signals

Question 2

passive and active transport
1. passive
- diffusion
- facilitated diffusion
- osmosis
2. active
- Exocytosis
- Endocytosis

Answer 2

1. passive
   
   • diffusion = random movement of molecules from high concentration to low concentration until evenly spaced out
   • facilitated diffusion = uses transport/carrier protein to move larger molecules across membrane
   • osmosis = diffusion of water through cell membrane
2. active
   
   • Exocytosis = process of elimination material from cell into external environment
   • Endocytosis = process of engulfing material from external environment into the cell

Question 3

solutions
1. Isotonic Solution
2. Hypotonic Solution
3. Hypertonic Solution

Answer 3

1. Isotonic Solution - solution with same concentration of solutes as the cell (cell stays same)
2. Hypotonic Solution - solution with less solutes than the cell (cell expands)
3. Hypertonic Solution - solution with more solutes than the cell (cell shrivels up)