1.3 a) Movement of Molecules Across Membranes

Question 1

The ___ ___ model describes the structure of the plasma membrane.

Answer 1

fluid mosaic

Question 2

The cell membrane is comprised of a bilayer of ___ molecules and a patchwork of ___ molecules.

Answer 2

phospholipid, protein

Question 3

Phospholipid molecules have ___ heads and ___ tails.

Answer 3

hydrophilic, hydrophobic

Question 4

What gives the membrane its fluid quality?

Answer 4

the constantly moving phospholipids

Question 5

Membrane proteins can be classified as ___ or ___.

Answer 5

integral or peripheral

Question 6

Integral membrane proteins react extensively with the ___ region of the phospholipids in the ___ ___.
Which region of phospholipids is hydrophobic?

Answer 6

hydrophobic, plasma membrane.
The tail, you cutesie

Question 7

Regions of ___ R groups allow strong interactions that hold ___ membrane proteins within the phospholipid bilayer.

Answer 7

hydrophobic, integral

Question 8

Some integral membrane proteins are ___ proteins.

Answer 8

transmembrane

Question 9

Peripheral membrane proteins have ___ R groups on their surface that make ___ and ___ bond interactions (primarily) with the surface of the membrane - aka the (head/tail) of the phospholipid molecules.

Answer 9

hydrophilic, ionic, hydrogen, heads

Question 10

To reiterate; peripheral membrane proteins ___ to the membrane through ___ and ___ bond interactions.

Answer 10

bind, ionic, hydrogen

Question 11

Many peripheral membrane proteins interact with the surface of ___ ___ ___.

Answer 11

integral membrane proteins

Question 12

What is the phospholipid bilayer a barrier to?

Answer 12

ions and most uncharged particles

Question 13

Name 2 small molecules that are able to pass through the membrane by simple diffusion.

Answer 13

oxygen and carbon dioxide

Question 14

What is diffusion?

Answer 14

The movement of molecules across a membrane, down their concentration gradient

Question 15

Facilitated diffusion is the ___ transport of substances across the membrane through specific ___ proteins.

Answer 15

passive, channel

Question 16

Different cell types have different ___ and ___ proteins, allowing them to perform their specialised functions.

Answer 16

channel, transporter

Question 17

Channel proteins are highly ___.

Answer 17

selective

Question 18

Channels are multi-___ proteins, with the ___ arranged to form a ___ that extends through the membrane.

Answer 18

subunit, subunits, pore

Question 19

Since water diffuses very slowly across the membrane, most water travels through the membrane protein ___.

Answer 19

aquaporin

Question 20

Some channel proteins are gated, and can change their ___ to allow or ___ diffusion.

Answer 20

conformation, prevent

Question 21

Name the two types of gated channels.

Answer 21

Ligand gated and voltage gated.

Question 22

Ligand gated channels are controlled by…

Answer 22

the binding of signal molecules

Question 23

Voltage gated channels are controlled by ___ in the ___ of different ___.

Answer 23

changes, concentration, ions

Question 24

Transporter proteins undergo ___ changes to transport ___ across the ___.

Answer 24

conformational, substances/molecules/solutes, membrane

Question 25

Transporter proteins alternate between two conformations, so that the ___ site is sequentially ___ on one side of the bilayer, and then the other.

Answer 25

binding, exposed

Question 26

Active transport uses ___ proteins that transfer substances across the membrane against the ___ ____.

Answer 26

pump, concentration gradient

Question 27

Pump proteins are ___ proteins with an ___ ___ attached.

Answer 27

transporter, energy source

Question 28

The conformational change of the ___ protein in active transport requires energy which comes from the ___ of ___.

Answer 28

pump, hydrolysis of ATP

Question 29

ATP is hydrolysed into… by enzymes called…

Answer 29

ATP + Pi, ATPases

Question 30

Some pump proteins that carry out active transport can ___ the ATP directly, without the need for ____ enzymes.

Answer 30

hydrolyse, ATPase

Question 31

The ATP required for active transport provides energy for…

Answer 31

the conformational change of the pump
(although in passive transport, pumps still change their conformation, but since the molecules are being transported down their concentration gradient, ATP is not required for this)

Question 32

One example of a pump protein that does not utilise ATPases is…

Answer 32

the Sodium-Potassium Pump (Na-K pump)

Question 33

(Hydrophobic/Hydrophilic) signalling molecules can diffuse through the membrane.

Answer 33

hydrophobic (think O2 and CO2 can diffuse directly- and are hydrophobic, and steroid hormones also can (oestrogen and testosterone))