Structure and Function Of Plasma Membranes (Chapter 5) Flashcards
(18 cards)
What is the Membrane Structure?
-Phospholipids arranged in a bilayer
-Proteins and cholesterol inserted in the lipid bilayer
What are the 4 components of a cell membrane?
- Phospholipid bilayer
-Transmembrane proteins
-Surface Proteins
-Cell surface markers
Phospholipids
-Glycerol , a 3- carbon molecule
-2 fatty acids attached to the glycerol (nonpolar and hydrophobic)
-Phosphate group attached to the glycerol (polar and hydrophilic)
Facts about phospholipids and membranes
-Saturated fatty acids make the membrane less fluid than unsaturated fatty acids
-Long fatty acids make the membrane less fluid than short fatty acids.
-Most membranes also contain sterols that act as fluidity buffers.
Simple diffusion is
An example of passive transport
Facilitated Diffusion is
An example of Active transport
What is Simple Diffusion?
No energy is required,and hydrophobic molecules move in response to their concentration gradient.
The net diffusion of water across a membrane toward a higher solute concentration
Osmosis
Osmotic Pressure is
The force needed to stop the osmotic flow
Hypertonic, Hypotonic, and Isotonic
-Hypertonic solution has a higher osmotic force
-Hypotonic solution has a lower osmotic force
-Isotonic solutions have the same osmotic force.
What is Facilitated Diffusion?
Molecules that cannot cross membrane easily may move through proteins.
-Channel Proteins
-Carrier Proteins.
Usually specific to a particular ion or may be gated
Ion channels
Can help transport both ions and other solutes, such as some sugars and amino acids AND must bind to the molecules they can transport.
Carrier Proteins
What are the 3 different types of carrier proteins?
-Uniporters: move one molecule at a time
-Symporters: move two molecules in the same direction
-Antiporters: move two molecules in opposite directions
What is Active Transport?
Requires energy - ATP is used directly or indirectly to fuel active transport
- Requires the use of highly selective carrier proteins
This pump is an anti porter that moves 3 Na+ ions out of the cell and 2 K+ ions into the cell for each ATP that is hydrolyzed
Sodium - Potassium Pump
What is Indirect (Secondary) Active Transport?
A symporter is used to pump a molecule against its concentration gradient, by using the energy released during the “downhill” movement of another molecule that was previously pumped against its concentration gradient.
What are the types of Bulk Transport?
-Endocytosis: movement of substances into the cell
-Phagocytosis- cell takes in particulate matter
-Pinocytosis- cell takes in only fluid
-Receptor-mediated endocyotsis: specific molecules are taken in after they bind to a receptor.
-Exocytosis
-Movement of materials out of the cell
-Used in plants to export cell wall material
- Used in animals to secrete hormones, neurotransmitters
