-
Graphic Objective 3.
Linst and classify the components of the plasma membrane. as defined by the fluid-mosaic model.Cassify membreane proteins as peripheral or interal.
-
Define permeability
tells how easily a substance can cross the plasma membrane.
-
What is differential permeability
is what defines a cell.
-the cell lets some things pass (water and cell nutrients must be allowed into the cell)
-the cell does not let other things pass(guts of the cell should not leak out)(toxic substances should not leak in)
-
What can pass through the cell membrane?
Small uncharged moleculeslipid-soluble substances (fat-soluble)gases
-
What can't pass through the cell membrane?
charged ionswater-soluble molecules
-
Only ______ and ________ can move across the cell membrane without help.
Water; Gases
-
The random motion of small particles or even molecules in a liquid or gas is called
Brownian motion
-
Physical principles underlying diffusion.
Molecules in a gas or liquid can move around.
The warmer the tempertature, the more movement.
The smaller the molecule, the more movement.
This random movement is seen as diffusion: over time, the concentration of the substance will become equal in all parts of the system.
-
Graphic objective 13 module 4
Discuss the physical principles underlying osmosis
-
Passive Transport
No energy needed
-
Facitlitated diffusion
protein channels or carriers in the cell membrane facilitate the diffusion of substances.
-
What has to be escorted, even if the concentration is higher outside than inside.
Larger and charged molecules
-
What are the critical steps in the facilitated diffusion of glucose?
Step 1: Gluscose fits into "pocket" of glucose transporter.
Step 2: Protein changes shape, closing glucose pocket.
Step 3: Glucose transporter changes shape again, forces glucose into cytoplasm.
-
What is Active Transport?
Requires energy. Is used to move an ion against its concentration gradient.
-
Energy sources for active transport?
ATP
Pre-existing storage of energy in a concentration gradient.
-
When molecules are moved against their concentration gradient (from low concentration to high), energy is required.
Active Transport
-
Na+ is _______ outside, ________ inside.
high; low
-
K+ is _______ outside, _________ inside.
low; high
-
Na+/K+ pump moves both
against their concentration gradients (Na+ moves out, K+ moves in), splits ATP for energy to do this (ATPase).
-
Three Na+ ions rest in a pocket of the pump. Thes Na+ ions are expelled as _______ is split into ____ + _______, releasing the nergy needed to drive the pump. Then, two K+ ions _______ outside the cell and these are ________ inside the cell.
ATP; ADP; phosphate; bind; released
-
Since three positive charges are pumped out for every two allowed in, the cell is made more negative inside by the pump. We call this pump
electrogenic
-
Na+/K+ ATPase (Na+/K+ pump)
Na+ gradient: high outside cell, low inside.
K+ gradient: low outside cell, high inside.
Pump wants to move both against their gradients.
ATP is used as energy source.
3 Na+ bind to pocket in pump protein
-
Na+/K+ ATPase
Step 2:
3 Na+ expelled from cell.
ATP split to ADP + P + energy
-
Na+/K+ ATPase
Step 3:
K+ pocket exposed
P released
-
Na+/K+ ATPase
Step 4:
2 K+ enter cell.
Pump is reset to bind 3 more Na+
-
What is an Antiport System?
It is a form of Active transport.When two ions move in opposite directions to drive the pump.
-
What is a Symport System?
It is a form of Active transport.
A molecule and an ion move in the same direction to drive the pump.
|
|
