1/22: Cell Membrane, Membrane Transport, and Membrane Potential II

Question 1

What is the function of transport proteins?

Answer 1

Move hydrophilic substances across the plasma membrane of cell

Question 2

What are the three types of transport proteins?

Answer 2

1. Channels
2. Carriers
3. 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 are two functions of channels?

Answer 4

1. Facilitated diffusion of ions into and out of cell (passive; does not require energy)
2. Can be somewhat specific (Ca+ channel Cl- channel, cation channel, etc)

Question 5

Are channels saturable?

Answer 5

No

Question 6

What are two types of channels?

Answer 6

Open channels
Gated channels

Question 7

What are open channels?

Answer 7

Always open and ions freely flow through via facilitated diffusion

Question 8

What do open channels create?

Answer 8

“Leak currents” - currents happening all the time

Question 9

Where do gated chanels spend most of their time?

Answer 9

In the closed state

Question 10

When do gated channels open?

Answer 10

When stimulated

Question 11

What are the three types of gated channels?

Answer 11

a. Chemically gated
b. Mechanically gated
c. Voltage gated

Question 12

What are four types of ion channel gating mechanisms?

Answer 12

A. ligand-gated
B. phosphorylation-gated
C. Voltage gaated
D. stretch or pressure gated

Question 13

What two things are used for covalent modulation?

Answer 13

1. Kinases
2. Phosphatases

Question 14

What are the functions of kinases and phosphatases

Answer 14

Kinase - attach covalent modulator
Phosphatase - remove covalent modulator

Question 15

What are carriers?

Answer 15

Transmembrane proteins that move hydrophilic building blocks across the plasma membrane

Question 16

What kind of transport do carriers use?

Answer 16

Facilitated diffusion (passive; doesn’t require energy)

Question 17

What are properties of carriers?

Answer 17

1. Specificity
2. Saturation
3. competition

Question 18

What are active transporters?

Answer 18

Transmembrane proteins that move ions and hydrophilic building blocks across the plasma membrane via active transport (Active; requires energy)

Question 19

What kind of transport do active transporters use?

Answer 19

Active transport; requires energy

Question 20

What are properties of active transporters?

Answer 20

1. Specificity
2. Saturation
3. Competition

Question 21

What are structural proteins?

Answer 21

Form cell to cell attachments that hold adjacent epithelial cells together

Question 22

What are the three types of attachments (cell to cell junctions) that are held together by structural proteins?

Answer 22

1. Tight junctions
2. Desmosomes
3. Gap junctions

Question 23

What are tight junctions?

Answer 23

Prevents intercellular movement of fluid and dissolved substances

Question 24

What do desmosomes provide?

Answer 24

Structural support

Question 25

What are the functions of gap junctions?

Answer 25

Cell to cell communication via ions

Question 26

What are types of enzyme classifications?

Answer 26

Integral membrane proteins Transmembrane proteins Peripheral membrane proteins

Question 27

What are the functions of enzymes?

Answer 27

Catalyzing specific chemical reactions either on the extracellular surface of cell or inside cell

Question 28

What are properties of enzymes?

Answer 28

1. Specificity 2. Saturation 3. Competition

Question 29

How long does it take to synthesize proteins?

Answer 29

approx. 2 hours

Question 30

How are proteins synthesized and stored?

Answer 30

Synthesized in advanced; stored in an inactive form, activated when needed

Question 31

What does proteins storage provide a means for?

Answer 31

Immediate protein regulation

Question 32

Interaction between substance and protein binding site follows the ________

Answer 32

Mass action model

Question 33

Where are carbohydrates attached?

Answer 33

To the EC surface of membrane lipids and proteins (glycocalyx)

Question 34

What do carbohydrates play an important role in?

Answer 34

Enabling cells to identify and interact with eachother

Question 35

Because of the selectively permeable membrane, what do we find?

Answer 35

Concentrations of various extracellular and intracellular components vary

Question 36

What is higher in the extracellular fluid?

Answer 36

Na Ca Cl HCO3- Glucose

Question 37

What is higher in the intracellular fluid?

Answer 37

K+ Mg+ Phosphates Amino acids pH Proteins