The Cell Membrane
(Part 1)
(Part 1)
What 2-word term describes the structure of the cell membrane?
phospholipid bilayer
What is the major function of the cell membrane?
to regulate what moves into and out of the cell
What is diffusion?
movement of molecules from high concentration to low concentration
What is osmosis?
diffusion of water
What is active transport?
a form of transport that DOES require energy
Define concentration
the amount of solute dissolved in a given quantity of solution
The cell membrane is “selectively permeable.” What does this mean?
the membrane only allows certain substances to pass through
What is passive transport?
a form of transport that does NOT require energy
What is an isotonic solution?
a solution that has the same concentration as the cell -OR- a solution that has an equal amount dissolved solute as the cell
What type of energy is needed to power active transport?
ATP
The cell membrane is “fluid.” What does this mean?
membrane is flexible and/or proteins can move around in the membrane
What type(s) of substances can pass through the cell membrane easily?
small, nonpolar molecules
Describe equilibrium.
when the concentration of molecules is equal throughout a solution
What prevents plant cells from bursting when placed in water?
cell wall
In the bonds between the phosphates.
Why does a cell membrane form a sphere shape?
what role does a choldesterol do to a membrane in low temperatures?
Increases fluidity by preventing the lipids from packing as tightly
What is facilitated diffusion?
when a transport protein helps big and/or polar molecules to diffuse across the membrane
What will happen to a cell in a hypotonic solution AND why?
The cell will swell. The solution has a lower concentration than the cell, so water will go into the cell.
What is the main difference between primary and secondary active transport??
Primary directly relies on ATP while secondary relies on ATP to create a gradient that can then facilitate diffusion
What do hydrophilic and hydrophobic mean?
hydrophilic = water loving
hydrophobic = water fearing
What role does a cholesterol do to a membrane in high temperatures?
It increases the rigidity by making the membrane denser
Name all 3 types of passive transport we have talked about in this unit.
Diffusion, Osmosis, Facilitated Diffusion
What will happen to a cell in a hypertonic solution AND why?
The cell will shrink. The solution has a higher concentration than the cell, so water will leave the cell.
In what direction do molecules move during active transport?
from low to high concentration -OR- against the concentration gradient