Chapter 5: Membranes, The Interface Between Cells and their Environment Flashcards
Permeable
Allowing something to pass through.
Impermeable
Things cannot pass through.
Semi- or Selective Permeable
Only specific things can pass through.
The plasma membrane is made up of…?
Phospholipid bilayer
The head of the phospholipid is…
Hydrophilic, and faces out.
The legs of the phospholipids are…
Hydrophobic, and faces in.
Cholesterol
Helps stiffen the plasma membrane at high temps
Helps with fluidity at low temps.
Membrane structure results in…
Selective permeability.
What are the six membrane proteins?
Transport
Enzyme
Junction
Attachment
Glycoproteins
Receptor
Transport Proteins
Allows specific ions or molecules to enter or exit the cell.
What are the two types of transport proteins?
Channel and Carrier
What is the difference between Channel and Carrier proteins?
Channel proteins do not require energy.
Carrier proteins require ATP energy which changes their shape.
Enzyme Proteins
Grouped
Carry out Reactions
1. Start Reactions
2. Stop Reactions
3. Speed up chemical reactions
4. Slow down chemical reactions
Attachment Proteins
HELPS SUPPORT THE MEMBRANE.
COORDINATES EXTERNAL AND INTERNAL CHANGES.
Attach to the extracellular matrix and cytoskeleton.
Receptor Proteins
Cell communication!
Signaling molecules bind to receptor proteins.
Receptor proteins relay the message by activating other molecules inside the cell.
Junction Proteins
Form intercellular junctions that attach adjacent cells.
Glycoproteins
Serves as ID tags.
May be recognized by membrane proteins of other cells.
Glycocalyx
What are the two main categories of transport across the plasma membrane?
Passive and Active
Passive Transport
Does not require cellular enery.
Active Transport requieres?
Cellular energy (ATP)
What are the three types of passive transport?
Diffusion, Selective Permeable and Osmosis.
Diffusion
Substances move from an area of HIGH concentration to an area of LOW concentration.
Concentration Gradient
Occurs when the concentration of substances is higher in one area than another.
What affects the rate of diffusion?
Temperature
Molecular Size
Concentration
Pressure
Selective Permeable Diffusion
Water can move freely through the membrane, but the membrane regulates the passage of solutes.
Osmosis
Movement of WATER across a selectively permeable membrane.
Going from low solute to high solute.
Moving down its own concentration gradient.
Active Transport
Moves substances against their concentration gradient.
Requires ATP energy
Tonicity
The ability of a solution to cause a cell to gain or lose water.
Depends on the concentration on both sides.
Dictates the direction of diffusion.
Isotonic Solution
Solute concentration is the SAME as that inside the cell; no net water movement across the plasma membrane.
Hypertonic Solution
Solute concentration is GREATER than that inside the cell; the cell loses water.
Hypotonic Solution
Solute concentration is LESS than that inside the cell; the cell gains water.
Solute
Dissolved substances (dissolved in water)
Facilitated Diffusion
(Three Points)
- Does not require energy
- Relies on the concentration gradient
- Does NOT require transport proteins.
Passive Transport
(three points)
What makes it different from Facilitated Diffusion?
- Does not require energy.
- Relies on the concentration gradient.
- A solute moves through a membrane transport Protein **
Aquaporin
A channel that makes it possible for water to rapidly diffuse into and out of certain cells.
Electrogenic Pump
A transport protein that generates a voltage across the membrane.
What is the major electrogenic pump of animal cells?
Sodium-Potassium pumps
What is the major electrogenic pump for plants, fungi and bacteria?
Proton Pump
Cotransport
Occurs when active transport of solute indirectly drives transport of other solutes.
Endocytosis
Used to import substances useful to the livelihood of the cell.
Exocytosis
Used to export bulky molecules, such as proteins or polysaccharides.
What are the three types of Endocytosis?
Phagocytosis
Pinocytosis
Receptor-Mediated Endocytosis
Phago-
to eat
Phagocytosis
“Cell eating” large items (such as food, and other cells) are brought into cells in a vacuole.
Pino-
To drink
Pinocytosis
“Cell drinking” fluid is brought into the cell vesicles.
Receptor-Mediated Endocytosis
Specific molecules bind to receptors and then enter the cells in vesicles.
