Unit 1.3a Flashcards
Movement of Molecules Across Membranes
What is the cells (plasma) membranes purpose?
To control the entry and exit of material in and out of the cell
What’s the cell (plasma) membrane made from?
Proteins and Phospholipids
What part of a phospholipid is hydrophilic?
The Head
What part of a phospholipid is hydrophobic?
It’s Tail
What part of the phospholipid is attracted to water?
The hydrophilic head
Is the phospholipid head or tail polar?
The head is polar (charged)
What two types of proteins are found with the plasma membrane?
Integral + Peripheral
Where could you find integral proteins?
Inside the membrane
Where could you find peripheral proteins?
On the surface of the membrane
What attaches integral proteins to the membrane?
Hydrophobic R group interact with the inside of the membrane creating strong hydrophobic interactions
What does transmembrane mean?
An integral protein that spans the whole width of the plasma membrane
What region a of the plasma membrane do transmembrane proteins interact with?
Hydrophobic region
What region of the plasma membrane do peripheral proteins interact with?
Hydrophilic region
How do peripheral proteins stick to the outside of the plasma membrane?
The peripheral proteins have hydrophilic R groups on their surface so therefore bind to the plasma membrane via hydrogen OR ionic bonding
Do peripheral proteins ever attach themselves to integral?
Yes they can interact with each other
What can’t get through the plasma membrane?
Ions and uncharged polar molecules
What can get through the plasma membrane? (+example)
Small molecules can diffuse through
- O2 CO2
What does facilitated diffusion involve?
Passive transport via. transmembrane proteins
What are the two types of transport membranes?
Channel + Transporter
What is a channel protein?
Multi-sub unit proteins that form water-filled pores from one end of the membrane to the other. This allows molecules to pass through.
How are channel proteins highly selective?
As majority are channel gated and change conformation to allow or prevent molecules from passing.
What are the two types of channels?
Ligand gated and voltage gated
How do ligand gated channels work?
Controlled by the binding of signal molecules
How do voltage-gated channels work?
Controlled by changes in the ion concentration
How do transport proteins move substances in and out if the cell membrane?
By binding to the substance that is being transported and undergoing a conformational change that allows the solute to move across the membrane
Which protein uses active transport?
The pump protein
How does a pump protein work?
Transfers molecules against the concentration gradient
What is required to transfer solute against the concentration gradient (make the conformational change occur)?
Source of Metabolic Energy
How do pumps produce their own metabolic energy?
Hydrolysing ATP directly
What is ATPases?
The enzyme that hydrolyses ATP in the pump protein
