B2.1 Membranes & Transport Flashcards
Phospholipid
molecule creating the cell membrane (lipid bilayer)
Permeability
Ability of the membrane to pass something through
On what does permeability very often depend?
size and polarity
Describe the ease with which the polar molecules pass through the membrane (polarity of bilayer)
polar molecules are attracted to polar phospholipid heads but pulled away by non-polar phospholipid tails
Describe the ease with which the non-polar molecules pass through the membrane
they are attracted to non-polar phospholipid tails and can easily pass through the membrane
Simple diffusion
movement from high to low concentration with no need of energy or help from other structures
2 examples of molecules that enter the membrane through simple diffusion
oxygen and carbon dioxide (small, non-polar)
Phospholipid heads are polar/non-polar?
polar
Phospholipid tails are polar/non-polar?
non-polar
What are integral membrane proteins?
they are embedded into cell membrane
What are peripheral membrane proteins?
they are attached to the surface of the membrane
What is transmembrane protein?
type of integral protein that goes all the way through cell membrane
Characteristics of peripheral membrane proteins?
-they are hydrophilic
-attached to the surface
Characteristics of integral proteins
-have hydrophobic parts
-embedded in membrane
What are the functions of membrane proteins?
-cell regonition
-transport
-enzymatic activity
Osmosis
water movement through membrane
What are aquaporins?
integral membrane protein channels that allow water across membrane
Which organ have high amout of aquaporins?
kidneys
What is facilitated diffusion?
passive movement of molecules through the protein channel
What is active transport?
energy is used to move particles across membrane against the concentration gradient (e.g. pump proteins)
In what ratio the pump transports K+/Na+ ions?
3 Na+/2K+
How Na/K pump gets energy?
from hydrolysis of ATP
How Na/K pump moves?
-open for Na ions inside the cell
-hydrolysis of ATP
-releases Na outside and open for K
-K binds
-release of gained phosphate
-releases K inside and opens for Na
What are glycoproteins?
protein bound with sugar
