Ch3 Membranes Flashcards
Fluid Mosaic Model
Used to model how biomolecules are combined to form a structure (like cell membrane)
3 components of Biomembrane
Which is the main
- Phospholipid bilayer (MAIN)
- Proteins
- Carbohydrates
Each membrane has
A unique composition of lipids and proteins suited for its functions
Glycoproteins and glycolipids
Sugars linked to proteins and sugars linked to phospholipids on the outside of the membrane
Membrane is fluid due to
Kinetic/thermal energy that causes motion in the phospholipids
Cholesterol
Rigid molecule
Integrates itself in the phospholipid bilayer
Hydrophobic-Interacts w tails
Membrane fluidity increases as Cholesterol
Cholesterol decreases
Less rigidity and structure
Membrane fluidity increases as unsaturated fatty acids
Increase.
Cause the tails to be bent, and allows for more fluidity
Membrane fluidity increases as temperature
Increases
More energy more movement more fluidity
3 kinds of membrane proteins
1.Integral Proteins
2.Peripheral Membrane Proteins
3.Glycoproteins
Integral proteins
Embedded in the membrane. Amphipathic
Can be in just 1 side or go all the way through
Transmembrane protein
When a integral protein goes all the way through the membrane
Peripheral membrane protein
Loosely bound to inside of membrane
Often bound to integral membrane proteins
Helps give structure to the cell
Glycoproteins
Proteins with carbohydrates covalently bonded
Biomembranes are
Asymmetrical
6 functions of MP
1.transport
2.enzymatic activity
3.signal transduction
4.cell-cell recognition
5.intercellar joining
6.Attatchment to cytoskeleton+extracellular matrix
Signal transduction
Protein acts as a receptor. Signal molecule binds and relays message to inside the cell.
Cell-Cell recognition
Glycoproteins/lipids act as molecular markers for the immune system
(Tcells)
Intracellular joining
Physical linking of the plasma membrane of adjacent cells
Attatchment to cytoskeleton and extracellular matrix serves
Many different functions including cell shape
Permeable
Substance that can pass
Impermeable
Substance that can not pass
Permeability is controlled
By the opening and closing of specific channels
What 2 factors influence permeability
- Solubility of molecule in lipids
Lipid soluble-Pass Freely - Size of the molecule Smaller=more permeable
Lipid soluble molecules are
Hydrophobic
Non polar or uncharged
Pass freely through membrane
Lipid insoluble molecules
Hydrophillic
Polar or charged
Do not pass freely through membrane
Passive transport
High to low energy/conc
Favored by entropy/can be spontaneous
No energy is required
2 kinds of passive transport
(One has 2 names)
Simple diffusion
Carrier mediated/Facilitated diffusion
2 kinds of Facilitated diffusion
Aka
Channel proteins- Provides Hydrophillic pathways to allow water/small ions to pass freely
Carrier Proteins- (oyster) undergo subtle changes in protein conformation/shape -allows translocation of specific molecule
Simple diffusion
Occurs until
Molecules go from high to low conc
Until equilibrium is reached
Movement still occurs but equally
Large molecules diffuse
Slower than small ones
Diffusion can only occur if
The membrane is PERMEABLE to the molecule
Hydrophobics can diffuse
Through the membrane directly
Hydrophilics must
Use other channels to cross the membrane
Osmosis
Diffusion of water across membranes
Most membranes are freely permeable to
Water
The concentration of water and concentration of solute
Are inversely proportional. As one increase the other decreases.
Tonicity
Predicts the
Used to describe the solute in a solution relative to the solute in a typical cell.
Predicts the magnitude + direction of osmosis
Isotonic
Equal amount of solute inside and outside the cell
Hypertonic
Concentration of solute is greater outside the cell than inside the cell. Cause cell to be shriveled
Hypotonic
Concentration of solute inside the cell is greater than the concentration outside of the cell
Causes cell to be lysed/burst open
Terms for tonicity for plant cells
Isotonic Flaccid
Hyper- Plasmolyzed
Hypo- Turgid
Primary active transport
Ex?
Directly used energy from an ATP molecule
Ex. Protein pumps/ Sodium Potassium pump ATPase
How does the sodium potassium pump work
For every 1 ATP molecule,
1) In the cytoplasm, low NA high K. 3 NA and ATP bind.
2) ATP hydrolizes. Phosphate attaches to protein.
3. Protein configuration changes. Low affinity for NA. They are released
4. Protein now has high K affinity. 2 Ks from outside bind. Phosphate falls off
5. Pump returns to original shape.
6.2 Ks are released
Cycle continues.
3 NA 2 K
Membrane potential
Difference in electrical potential between interior and exterior of membrane.
Inside- negative
Outside- positive
A protein pump is
Active transport
Secondary active transport
Uses STORED energy from HC, so that when a driving ion like H goes from HC-LC, that energy is used to drive a 2nd molecule against its gradient
Secondary active transport is aka
Cotransport
Small, hydrophobic molecules use ____ while large Hydrophillic molecules and ions use ____
Simple diffusion
Facilitated diffusion
MACRO molecules move across the membrane in
2 ways
Membrane bound vessels
Exocytosis- molecules moving out of the cell
Endocytosis- molecules moving into the cell
3 kinds of endocytosis
Phagocytosis
Pinocytosis
Receptor-Mediated Endocytosis
Phagocytosis
Some or all cells
LARGE molecules brought into the cell
“Cell eating”
Some cells
Pinocytosis
Some or all cells
Small molecules brought into the cell
“Cell drinking”
ALL cells
Receptor mediated endocytosis
Selectively bringing LARGE molecules into the cell.
The cell membrane become the exterior of the vessel after a canyon is formed
The interior is called the lumen
Hat is the job of the bio membrane
The separate compartments
