Topic 5, membrane transport

Question 1

What type of molecules are highly permeable?

Answer 1

Hydrophobic

O2, CO2, N2, steroid hormones

Question 2

Rank types of molecules in order of permeability

Answer 2

Hydrophobic, small uncharged polar (H2O, urea, glycerol), Large uncharged polar (Glucose, sucrose),
Ions (Impermeable)

Question 3

What are the four types of transport?

Answer 3

Passive ones: simple diffussion, facilitated diffusion with channel, facillatated with carrier
Active transport.

Question 4

Example of simple diffusion

Answer 4

High concentration to low, Unassisted. small nonpolar molecules like water and CO2

Question 5

What if the membrane is impermeable to dissolved solute?

Answer 5

What is OSmosis, Dan

Question 6

Three states for plants and animals cells

Answer 6

animal: crenation (if in hypertonic solution), normal in isotonic, Lysed in hypotonic.

Plant: plasmolyzed if in hypertomic, flaccid in isotonic, turgid in hypotonic

Question 7

What three factors determine the ability for something to diffuse?

Answer 7

Size.
Polarity.
Charge.
All key words

Question 8

Why is facillated diffussion necessary?

Answer 8

So things can diffuse at a reasonable rate.

Question 9

What do the lines look like for rates of diffussion, facilitated vs linear. why?

Answer 9

FacilITATED= hyperbolic
simple= linear

why? bc the transport proteins havea maximum capacity of what they can handle at one time.

Question 10

Another name for carrier proteins

Answer 10

Permeases

Question 11

types of carrier proteins (3 specific, two umbrella)

PLUS 3 facts

Answer 11

Uni ports= one guy
Coupled Transport= 2 types of solute.
symports or antiports.

carrier proteins are highly specific.

transport velocity has an upper limit

Question 12

how do carrier proteins work?

Answer 12

Binding of transported molecules changes the shape of the transporter.

note in glucose transport, molecles is quickly modified to GLUT1 to prevent it from leaving throught the carrier protein.

Question 13

Are channel proteins selective?

Answer 13

They may display a very high degree.
They may be gated (selectively opened and closed) via ATP but still considered passive diffussion
FOR IONS

Question 14

Explain cystic fibrosis and the link to

Answer 14

Cftr is the channel protein for Cl- in our airways. Usually Cl- is released, then water and sodium follow it (bc charge and osmosis). This keeps the mucus hydrated.
in cystic fibrosis,

Question 15

Porins structure

Answer 15

Forms beta barrel hydrophilic channel

and contain transmembrane helices

Question 16

Types of active transport? (2)

Answer 16

Direct

indirect

Question 17

What is the difference between direct and indirect active transport?

Answer 17

Drect transport is directly linked to exeronic chemical reactions.
For example, ATP hydrolysis may drive it.

Indirect active transport utilyzes an exhisting concentration gradient to drive the transport of another solute up its gradient with coupled transport.

Question 18

P-type ATPases

what does P stand for?

How many P-type pumps do humans have?

Answer 18

P=phosphoryl group

transporter temporarily and reversibly phosphorylated during transport

About 70

Question 19

What are the main types of transport pumps? (ATPases) (4)

Answer 19

P-type
V-type
F-type
ABC-type

Question 20

What does the V n V pumps stand for?

defining features

Answer 20

V=vacuole

pump protons into organellar compartments, especially lysosomes to maintain acidity.

Pump is not phosphorylated

Question 21

F-type ATPases

What are the two componants?

defining features

Answer 21

F=factor
This is ATPsynthase in the ETC

Fo=
Mobile: transmembrane pore for protons. 10 c subunits. ONe can bind at a time, and each proton bound rotates the ring 1/10 of a turn.
Static: one a and two b subunits. a is a proton channel that is stuck in the membrane, immobile. b subunit form the peripheral stalk. attach to a subunit and F1.

F1
mobile: gamma and e. the rotating stalk, movement comes from c ring.
Static: alt a and b subunits (3 of each). immobalized by sigma subunit. The part that binds to ATP is here.

Can either pump protons or make ATP

Question 22

ABC Transporters

How many domains. Config?

how many in human genome?

Role? Name one specific

Answer 22

4 domains in each protein.
2 that span the membrane, and 2 ATP binding cassettes
config, mem, cas, mem, cas. with connective strands inbetween.

at least 70

Multidrug resistance of cancers

CFTR- cystic fibrosis transport (Cl-)

Question 23

Indirect active transport.

defining features.

Are the symporters or antiports?

Answer 23

link energetically fav with energetically unfav

one solute moves down concentration gradient, while a second goes up.

can be either sym or anti

Question 24

Na+ and glucose

symporter or anti?

Answer 24

symporter.

2 NA+ bind, then glucose., transported inside cell. Na+ released. pumped out with Na-K pump to maintain gradient.
glucose released inside cell.

Question 25

Baceriorhodopsin

Answer 25

retinal embedded in protein, when light hits it, retinal changes to a form with one cis double bond. (Usually all trans)

light-driven proton pump.

not dependent on eTC