Cell Membrane, Membrane Transport, and Membrane Potential 2

Question 1

What is the role of transport proteins?

Answer 1

move hydrophilic substances across the plasma membrane
-allow things unable to cross the membrane by themselves to cross

Question 2

What are the three types of transport proteins?

Answer 2

channels
carriers
active transporters

Question 3

What are channels?

Answer 3

transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and cytoplasm

Question 4

What is able to cross through channels?

Answer 4

ions

Question 5

What is the function membrane channels?

Answer 5

facilitated diffusion of ions into and out of the cells
(passive and does not require energy)

Question 6

Are channels specific?

Answer 6

they can be
-Ca2+ channels, Na+ channels, Cl- channels

Question 7

Are channels saturable?

Answer 7

no

Question 8

What are open channels?

Answer 8

channels that are always open and ions freely flow through facilitated diffusion
-creates “leak currents”

Question 9

What are gated channels?

Answer 9

spend most of their time in the closed state, and will open only when stimulated

Question 10

What are the three types of gated channels?

Answer 10

chemically gated, mechanically gated, and voltage gated

Question 11

What is allosteric modulation?”

Answer 11

changing something with noncovalent binding

Question 12

What is covalent modulation?

Answer 12

changing something with covalent binding

Question 13

What are ligand gated channels?

Answer 13

channels that have a ligand that binds without covalent binding and changes confirmation

Question 14

What are phosphorylated gated channels?

Answer 14

channels that open when they are phosphorylated with a covalent bond

Question 15

What causes voltage gated channels to open?

Answer 15

change in membrane potential

Question 16

What causes pressure gated channels to open?

Answer 16

stretching of the membrane

Question 17

What are carriers?

Answer 17

transmembrane proteins that move hydrophilic building blocks across the membrane via facilitated diffusion

Question 18

Are carriers open on both sides of the membrane?

Answer 18

no
-if there were open on both sides it would hurt the integrity of the membrane and allow all things to cross without any control

Question 19

What is the process of carriers working?

Answer 19

-molecule that needs to be transported enters one side of the carrier and binds to a specific spot
-transition state causes both sides of the carrier to be closed
-the other side of the carrier opens and allows the molecule the exit through the other side of the membrane

Question 20

What are active transporters?

Answer 20

transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane via active transport

Question 21

What is active transport?

Answer 21

moving of molecules against the concentration gradient

Question 22

What are structural proteins?

Answer 22

forms cell to cell attachments that hold adjacent epithelial cells together

Question 23

What are tight junctions?

Answer 23

cell to cell junctions that prevent intercellular movement of fluid and dissolved substances

Question 24

What are desmosomes?

Answer 24

structural support that does not restrict intercellular movement
-just maintains the cells integrity so the cells do not come apart

Question 25

What are gap junctions?

Answer 25

two ion channels on adjacent cells that create a channel between two cells -allows for ions to flow between cells -allow for rapid cell to cell communication

Question 26

What are enzymes?

Answer 26

integral, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell or inside cell

Question 27

What are the steps of enzyme function in the cell membrane?

Answer 27

-ligand binds noncovalently -transmembrane protein changes shape -the change in shape causes a change in function

Question 28

How long does it take for a protein to be made?

Answer 28

2 hours

Question 29

Because it takes so long to make a protein, what happens?

Answer 29

many proteins are synthesized in advance and stored in an inactive form, activated when they are needed

Question 30

What does the interaction between substance and protein binding site follow?

Answer 30

the mass action model

Question 31

Where are carbohydrates attached to the membrane?

Answer 31

on the extracellular surface

Question 32

What are proteins with carbohydrates bound called?

Answer 32

glycoproteins

Question 33

What are lipids with carbohydrates bound called?

Answer 33

glycolipids

Question 34

What is the sugar coating of the cell membrane called?

Answer 34

glycocalyx

Question 35

Why is the glycocalyx important?

Answer 35

plays important role in enabling cells to identify and interact with each other

Question 36

What are four characteristics of membrane structure?

Answer 36

selectively permeable barrier, mosaic, dynamic, and fluid

Question 37

What substances are higher in the extracellular fluid?

Answer 37

-Na+ -Ca++ -Cl- -HCO3- -glucose

Question 38

What substances are higher in the intracellular fluid?

Answer 38

-K+ -Mg++ -phosphates -pH -proteins

Question 39

What is passive transport?

Answer 39

movement across the membrane that does not require energy -down gradient (concentration, pressure, and electrical)

Question 40

What are the types of passive transport?

Answer 40

diffusion osmosis bulk flow

Question 41

What is active transport?

Answer 41

movement across the membrane that does require energy -against concentration gradients

Question 42

What are the types of active transport?

Answer 42

active transporters and bulk transport

Question 43

What is random thermal motion?

Answer 43

molecules in a fluid are continuously and randomly bouncing around

Question 44

What is the rate of movement directly related to?

Answer 44

temperature

Question 45

What is the rate of movement inversely related to?

Answer 45

mass

Question 46

What is diffusion?

Answer 46

movement of stances other than water down a gradient

Question 47

When does net movement of diffusion stop?

Answer 47

at equilibrium

Question 48

What does passive transport move toward?

Answer 48

equilibrium

Question 49

What is the driving force of diffusion?

Answer 49

gradient

Question 50

What alters the flow of diffusion?

Answer 50

membrane resistance

Question 51

If a membrane has high permeability what is the net flux?

Answer 51

there is a high net flux