Cell Membrane Transport Flashcards
Define what passive transport is
Passive transport is a type of membrane transport that does not require additional energy.
Define simple diffusion
Simple diffusion is the movement of uncharged hydrophobic solutes (CO2) from high to low concentration. Simple diffusion does not require membrane proteins (channels or carriers)
What is facilitated diffusion
Facilitated diffusion is the movement of solutes from a high to low concentration using a membrane protein (carriers or channels). Facilitated diffusion involves polar and hydrophilic solutes
What is active transport?
Active transport is the movement of substances against its electrochemical gradient. It requires the input of energy.
What are the 2 types of active transport?
Primary (direct)- uses energy directly from ATP hydrolysis
Secondary (indirect)- uses cotransporters and exchangers
What are the different types of transmembrane proteins?
Pores- always open and non-gated
Channels- gated pores that open and close to allow specific substances to pass
Carriers- bind to solutes and undergo conformational changes to transport them across the membrane
Pumps- uses ATP to move instances against their concentration gradient
What is an electrochemical gradient?
Electrical gradient- difference in charge between the inside and outside of the membrane
Chemical gradient- difference in solute concentration
What are some key points about pores
They allow facilitated diffusion
Always open
They have multiple subunits
What are some key ideas about channels
They allow facilitated diffusion
Gated ion channel
They have multiple subunits
What are the 4 types of channels and what do they do?
Voltage gated channel- respond to changes in membrane potential
Ligand gated channel- respond to binding of specific molecules (ligands)
Mechanically gated channel- respond to mechanical stimuli (e.g pressure)
Leak channel- lays slightly open to allow continuous flow of ions
What were the common properties of channels?
-Movable gate- controls opening and closing of the channel
-Sensor- detects the stimuli that triggers the gate to open/ close
-A selectivity filter- determines which substances can pass through the channel
-An open channel pore- allows passage of substances when channel s opened
What are cotransporters?
They move both solutes in the same direction
It requires a ‘driving’ solute whose energy is provided by the electrochemical gradient
What molecules can affect osmolality?
Glucose
Ions
Why do females have a lower % of body water?
Women have more adipose tissue, and fat cells contain less water leading to lower % of water
What are the components of extracellular fluid?
Blood plasma and interstitial fluid
Interstitial fluid is the fluid outside blood vessels that surrounds cells
