Unit 1 KA3 Flashcards
What does the fluid mosaic model consist of?
plasma membrane consists of proteins and phosholipids
How and why does the phospholipid bilayer hold together?
Regions of hydrophobic R groups allow strong hydrophobic interactions that hold integral membrane proteins within the phospholipid bilayer
What are the functions of membrane proteins?
proteins that are embedded into cell membrane
- active transport proteins
- channel forming proteins
- enzymes
- receptors
- attachment proteins for the cell’s cytoskeleton
Some integral membrane proteins are…
transmembrane proteins
What are Peripheral membrane proteins?
They have hydrophillic R groups on their surface
bound to surface of membranes
by ionic and hydrogen bond interations
they can react with surfaces of integral membrane protiens
Phospholipid bilayer
what can pass through, what is it a barrier to?
- barrier to ions and most uncharged polar molecules
- small molecules can pass through by simple diffusion
Integral proteins
penetrate hydrophobic interior
folded
hydrophobic R groups form strong interactions
Facilitated diffusion
passive transport of substances across thr membrsne through specific transmembrane proteins
Transport proteins
use method of facillitated diffusion
Channel proteins
use facilitated diffusion
mulit-subunit proteins
Ligand-gated channels
controlled by binding of signal molecules
chemical stimulus
correct signal molecule opens gate
Voltage-gated channels
controlled by changes in ion concentration
Transporter proteins
><
bind to specific substance to be transproted and undergo a conformational change to transfer the solute across the membrane
each side of bilater is exposed as it alternates conformation
Protein pumps
uses active transport
against conc. gradient
needs a source of metabolic energy
some proteins hydrolyse ATP for conformational change
What combines together to form the electrochemical grandient that determines the transport of the solute?
when the solute is carrying a net charge
The concentration gradient + electrical potential difference
Membrane potential
also known as electrical potential difference
This is created when there is a difference in electrical charge on the 2 sides of the membrane
What hydrolase ATP?
ATPases
What do transporter proteins do when coupled to an energy source (ATP)
Mediate active transport
Concentration grandient
definition
Difference in conc. of a solute across the plasma membrane
Where do ion pumps get the energy they use?
Also give an example of an ion pump
Sodium-Potassium Pump
They use energy from hydrolysis of ATP to establish and maintain ion gradients
In terms of the Na-K pump what does it do?
Transports ions against a steep conc. gradient using energy directly fro ATP hydrolysis
Actively transports Na+ out of cell and K+ in
What is the process of Na-K pump
- High affinity from Na+ inside cell
- binding occurs
- phosporylation by ATP
- conformation change
- Affinity for Na+ decreases
- Na+ released out of cell
- K+ bind out of cell
- Dephosphorylation
9.Conformational changes
10.K+ taken in cell
11.. Affinity returns to start
For each ATP hydrolysed how many Na+ and K+ are involved?
What is the mneumonic
3 Na+ OUT
2 Ka+ IN
Where in the body does the Na-K pump drive the active transport of glucose?
small intestine epithelial
How do Na+ enter cell in small intestine?
DOwn the concentration gradient
At the same time as Na+ what is transported in the small intestine?
Glucose is pumped into the cell via active transport
What and how transports Na+ and glucose in the small intestine?
A glucose transporter is responsible for this glucose symport and transports Na+ and glucose at the same time and in the same direction
