7 Flashcards
What is the plasma membrane?
Which parts are polar and which parts are non polar?
-a phospholipid bi-layer
-heads of the lipids are polar and hydrophilic
-tails are non-polar and hydrophilic
Is the plasma membrane permeable, semi permeable, or non permeable? What does this mean?
-semipermeable
-only certain molecules can pass without the assistance of a protein
What influences a membrane’s fluidity?
Temperature. It must maintain its fluidity and The membrane must find a balance…
What helps the plasma membrane in low temperatures? How so?
Unsaturated fats
The kinks prevent tight packing of lipids, so it doesn’t get too viscous (like cold honey)
What helps the plasma membrane in high temperatures? How so?
-Saturated fats
-No kinks, so they tight packet and maintain viscosity (think warm honey)
How does cholesterol play a role in the plasma membrane?
Where is it?
-It acts as a buffer of membrane fluidity
-it is packed between lipids in the bi-layer
What are the three types of transports?
- Passive transport
- Active transport
- Bulk transport
Define passive transport and its properties
-No ATP required
-Diffusing down the concentration gradient
-diffusion and facilitated diffusion
-includes osmosis
What is facilitated diffusion?
When a protein helps diffuse the solute (high to low)
Define active transport and its properties
-It is when energy and a transport protein are required to move the solute against the concentration gradient (low to high)
-Requires ATP
Define bulk transport and its properties
Vesicles moving large molecules like fatty acids (endo in, exo out)
What can pass through the plasma membrane? How?
- Small non-polar molecules which are hydrophobic (CO2, O2) through passive transport
- Polar hydrophilic molecules can only pass with the help of a protein (active transport)
- Ions can pass but also need help. They can’t do it alone
What are the 7 types of transport proteins?
- Channel proteins
- Carrier proteins
- Ion channels
- Glycoproteins
- Sodium potassium pump
- Proton pump
- Cotransport pump
Define channel proteins and their properties
- Extends through the membrane
- It’s a channel
- Accepts specific molecules and leads them into the cell
Define carrier proteins and their properties
-It is also a channel, but it closes until it receives the molecule that wants to go in (imagine bringing food to your mouth)
-undergoes a conformational shape change and brings the molecule in
Define ion channels and their properties
-Also a carrier protein, but it is for ions.
-ions flow down the electrochemical gradient
-it is has a membrane potential (meaning that it is electrically charged)
-cations go into the cell, anions leave the cell
Define glycoproteins and their properties
- Responsible for cell to cell signaling. They receive signals and can cause shape changes to proteins (think of Venus fly trap reacting after something touches one of the sensors)
Define sodium potassium pumps and their properties
How is it powered?
- It is a Transport protein that pumps 3 sodium’s out of the cell and 2 potassium into the cell
- Doing this creates an electrochemical gradient because they are ions
- Powered by ATP
- Undergoes a shape change
Define proton pumps and their properties
- Pumps hydrogen ions out of the cell and forms membrane potential.
- Stores energy (ATP) and is always running
Define Cotransport pump and its properties
- Think of a key to a lock. Downhill diffusion of one molecule attaches to the protein and is like the “key” for the other molecule to lock on.
- Once both are locked on, they can pass through
What is diffusion? Does it need energy?
-No ATP needed
-is high to low
-certain things can just diffuse across the membrane (ex. Small non polar molecules like O2 and CO2)
What molecules can just pass through the plasma membrane?
CO2 and O2
What is facilitated diffusion? How is it different from just diffusion? Does it need ATP?
- It is diffusion that requires a channel or carrier protein
- Helps polar molecules get across the cell membrane
- No ATP required
What is Osmosis? What are its properties? Does it require ATP?
- The diffusion of water
- High to low
- No ATP
- Helps even out the concentration of solutes (not the volume)
Name the three types of osmosis occurrences or scenarios
- Hypertonic
- Hypotonic
- Isotonic
Define hypertonic. Does the cell shrivel up or swell?
- When the environment outside is more concentrated than inside the cell
- Water leaves the cell
- The cell shrivels up (think of pouring salt on a mummy)
Define hypotonic. Does the cell shrink or shrivel up?
- Happens when there is more concentration on the inside of the cell
- Water flows into the cell
- The swell swells up, burst or lyse
What is Isotonic? Does it cause the cell to swell or shrivel up?
- Both concentrations are equal
- No cells dies
- Water diffuses proportionally in and out of the cell
