Download Cell Interactions - Manasquan Public Schools

The Working Cell
Energy,
Homeostasis &
Transport
Ch 5
Interaction categories
–Cell to external environment
–Cell to cell
The lipid bilayer
• Fluid mosaic model
Major functions of proteins
Cell membrane
Structure = Function
• Phospholipid Bi-layer structure
– Polar Phosphate head
• Phosphate + glycerol group
– Nonpolar fatty acid tails
What may enter?
• Depends on
– Size
– Polarity
– concentration
– Needs of cell
Terms to know
• Diffusion
• Osmosis
• Concentration
gradient
• Equilibrium
2 types of transport
Movement is known as transport
• Passive transport
Examples: diffusion, osmosis,
facilitated diffusion, gated
channels
• Active transport
• Moves particles from low
concentration to high
• Up the concentration gradient
• Cellular NRG (ATP) is required
• Stops when cell has
accomplished what it needs
(not necessarily equilibrium)
Ex: pumps, endocytosis
(phago & pino), and
exocytosis
Passive transport examples…
Gated channels & Facilitated diffusion
– use solute-specific protein channels
How do cells respond to environmental changes?
What does osmosis look like in cells?
Solutions – solute + solvent
relative terms - hypertonic, hypotonic,
isotonic
Who’s THIRSTY?
How cells deal with osmosis?
osmoregulation
• Too much fluid in
– Turgid (plant cells)
– Cytolysis (animal cells)
• Too much fluid out
– Plasmolysis (plant cells)
– Crenate (animal cells)
Cells can regulate what they bring in or excrete
• Active transport
– Ex: pumps, endocytosis (phago & pino),
and exocytosis
Big particles (use NRG)
• Endocytosis
–Pinocytosis
–Phagocytosis
• Exocytosis
“Pumping ions” is like pumping iron
• Sodium potassium pump
• Proton (H+) pump
Combinations of both…
• Coupled channels - both types of transport
– Glucose can diffuse (passive transport) into cell
when attached to a sodium ion ( active transport)
Homeostasis
• Problems with organelles
Pompe’s disease, TaySach’s, liver disease
• Transport issues
– endocrine system
– Cholesterol, diabetes
• Feedback mechanisms &
enzyme regulation help
maintain the balance
Feedback Mechanisms