Goal 2 - The Plasma Membrane Notes
The Plasma Membrane (pages 175-178)
Cells need to maintain balance
Plasma Membrane is a flexible boundary between a cell and its environment
How does plasma membrane maintain homeostasis?
Selectively Permeability – membrane allows some molecules to pass through while keeping other out. Per – means through Meare – means to glide. Thus materials move easily (glide) though the permeable membrane
Water moves easily through plasma membrane, Sodium and calcium ions allowed in only at certain times through certain channels
Cells need to maintain balance
- Homeostasis = is the process of maintaining balance in a cells environment.
- Cells need nutrients (glucose, amino acids, and lipids) to function.
Plasma Membrane is a flexible boundary between a cell and its environment
- Allows nutrients into the cell no matter what the external conditions are.
- Too much of any nutrient or ion (salt) can be harmful to cell, if levels are too high excess removed by the plasma membrane.
- Waste leaves the cell through the plasma membrane.
How does plasma membrane maintain homeostasis?
Selectively Permeability – membrane allows some molecules to pass through while keeping other out. Per – means through Meare – means to glide. Thus materials move easily (glide) though the permeable membrane
Water moves easily through plasma membrane, Sodium and calcium ions allowed in only at certain times through certain channels
Structure
Review
Lipid = glycerol + 3 fatty acids
Phospholipids are formed when a phosphate group replaces one of the fatty acids
Plasma membrane is a phospholipids bilayer – 2 layers of phospholipids.
Water is polar (remember likes attract, thus polar attracts polar, and nonpolar attracts nonpolar)
Phosphate group heads are polar – attract water and can interact with the water environment found both inside and outside the cell.
Fatty acids non-polar tails are attracted to each other in the bi layer (remember nonpolar substances avoid water)
Other Components in the Plasma Membrane
Lipid = glycerol + 3 fatty acids
Phospholipids are formed when a phosphate group replaces one of the fatty acids
- Glycerol backbone + 2 fatty acids + phosphate group
Plasma membrane is a phospholipids bilayer – 2 layers of phospholipids.
Water is polar (remember likes attract, thus polar attracts polar, and nonpolar attracts nonpolar)
Phosphate group heads are polar – attract water and can interact with the water environment found both inside and outside the cell.
Fatty acids non-polar tails are attracted to each other in the bi layer (remember nonpolar substances avoid water)
Other Components in the Plasma Membrane
- Cholesterol – keep the fatty acids tails from sticking together.
- Transport Proteins – Move needed substances or waste materials through the membrane. Helps regulate what comes in and goes out.