Lecture 7: Membranes, Composition and Function

Question 1

Plasma membrane

Answer 1

Plasma membrane has selective permeability to maintain differences in composition between the inside and outside of the cell (cell homeostasis)

Question 2

Selective permeabiltiy

Answer 2

molecules can pass through membrane through transporters or ion channels

• lipid soluble molecules can pass
• O2, N2 and CO2 (gases) can pass membrane

Question 3

Order of cell

Answer 3

Organism> Organ> Tissues > Cell > Organelle

Question 4

Membranes are:

Answer 4

• asymmetric
• proteins can move laterally
• form specialized compartments within cell for ex. organelles

Question 5

Cilia

Answer 5

• detect sound

- borders hair cells around ear

Question 6

Intercalated discs

Answer 6

• heart

- allow electron coupling of cells

Question 7

Synapse

Answer 7

site of chemical communication between adjacent cells

Question 8

Cholesterol

Answer 8

-mostly resides within plasma membrane but smaller amounts are found within mitochondrial, Golgi complex and nuclear membranes

Question 9

Membrane fluidity

Answer 9

the kink in the tail of the unsaturated fatty acid increases membrane fluidity

Question 10

What increases plasma membrane fluidity?A.Phospholipids with unsaturated fatty acids.
B.Phospholipids with saturated fatty acids.
C. Glycolipids
D.Surrounding water molecules.

Answer 10

A.Phospholipids with unsaturated fatty acids.

Question 11

Ions are

Answer 11

Hydrophilic or lipophilic and need ion channels to pass membrane

Question 12

The permeability coefficient

Answer 12

measures the ability of a molecule to diffuse across a permeability barrier

Question 13

The drug prednisone is a corticosteroid that is used to treat many inflammatory diseases including asthma
The lipid bilayer permeability coefficient of prednisone is:
A.Equal to that of water. B.Lower than that of water.
C.Higher than that of water.

Answer 13

C.Higher than that of water.

This drug is has rings which make is hydrophobic so its harder to pass through the membrane than water

Question 14

Active transport

Answer 14

Movement of molecules against concentration gradient using energy

Question 15

Simple diffusion

Answer 15

molecules diffuse through the lipid bilayer

- driven by the transmembrane gradient of substrate

Question 16

Facilitated diffusion

Answer 16

movement of molecules with the aid or a protein, transporter or ion channel

Question 17

Uniport

Answer 17

transport a single species across membrane in one direction

Question 18

Symport

Answer 18

transport a two species across membrane in the same direction

Question 19

Antiport

Answer 19

transport a two species across membrane in the opposite direction

Question 20

Aquaporins

Answer 20

• water channels
• always open
• cells regulate water movement

Question 21

Ion channels

Answer 21

• permeability of a channel depends on charge, the extent of hydration and size
• maybe always open
• often active transporters

Question 22

The concentration of sodium Na+ is:
A.higher inside than outside the cell?
B.equal between the inside and outside of the cell?
C.higher outside than inside the cell

Answer 22

C.higher outside than inside the cell

3 Na+ out for every 2 K+ in

Question 23

Sodium potassium pump

Answer 23

-Powered by ATP
-2K+ into cell
3Na+ out of cell
-net +1 increase in charge outside

Question 24

Weak acid

Answer 24

pH>pKa Ionized form charged

pH

Question 25

Weak base

Answer 25

pH>pKa Unionized form uncharged | pH

Question 26

Fluid base pinocytosis

Answer 26

random and nondirected

Question 27

Absorptive endocytosis

Answer 27

selective and occurs in coated pits

Question 28

Gap Junctions

Answer 28

-allow direct flow of molecules from one cell to another

Question 29

Exocytosis

Answer 29

releasing of hormones out of cell

Question 30

peripheral vs integral proteins

Answer 30

Integral proteins are embedded in the whole bilayer | Peripheral proteins is only located in the inner or outer surface of the phospholipid bilayer

Question 31

Mosaic

Answer 31

constant fluid movement in membrane | -Proteins and phospholipids can move laterally in the membrane

Question 32

The majority of cholesterol resides | within

Answer 32

plasma membranes - smaller amounts are found within mitochondrial, Golgi complex, and nuclear membranes

Question 33

What other ways regulate fluidity and permeability?

Answer 33

The hydroxyl group of the cholesterol faces water and the tail inside away from water

Question 34

So how other molecules are transported through the membrane?

Answer 34

``` -Large molecules bind to receptors - Glucose binds to a specific ping-pong receptor -Ions are transported via pumps or ion channels ```

Question 35

Molecules with low membrane permeability are

Answer 35

hydrophilic or lipophobic

Question 36

Molecules with high membrane permeability are

Answer 36

hydrophobic or lipophilic

Question 37

The lipid bilayer permeability coefficient of prednisone is: A. Equal to that of water. B. Lower than that of water. C.Higher than that of water

Answer 37

C.Higher than that of water

Question 38

(GLUT) Glucose transporter

Answer 38

- facilitated transport | - helps to transport insulin through the membrane (cell)

Question 39

“AQUAPORINS”

Answer 39

``` water channels - always open -Cells regulate water movement by controlling # of aquaporin proteins inserted into the plasma membrane ```

Question 40

P (in P-type) transporter

Answer 40

``` signifies phosphorylation (these proteins autophosphorylate). - Ca2+ ATPase (SR); Na+ -K + -ATPase (PM) ```

Question 41

F (in F-type) transporter

Answer 41

signifies energy coupling factors | -mt ATP synthase of oxidative phosphorylation

Question 42

V (in V-type) transporter

Answer 42

signifies vacuolar | -The ATPase that pumps protons into lysosomes and synaptic vesicles

Question 43

ABC transporter

Answer 43

signifies ATP-binding cassette transporter (all have two nucleotidebinding domains and two transmembrane segments) -CFTR protein (PM); MDR-1 protein (PM)

Question 44

Uionized vs ionized as far as diffusion

Answer 44

Unionized forms can diffuse across cell membranes | Ionized forms will be have low lipid solubility and will be harder to cross cell membranes

Question 45

Diffusion of weak acid and weak base drugs through | plasma membrane depend on

Answer 45

pH

Question 46

A caveolae

Answer 46

is an invagination in the plasma membrane. The protein caveolin appears to play an important role in the formation of caveolae and occurs as a dimer

Question 47

Cystic fibrosis causes

Answer 47

Mutations in the gene encoding the CFTR protein, a Cl– transporter