Module 1: Background slides

Question 1

What are the two main roles of a membrane?

Answer 1

Isolate cells from their environment

Organize intracellular pathways into subcellular compartments

Question 2

What are the two main types of membrane proteins?

Answer 2

Integral membrane proteins

and

Peripheral membrane proteins

Question 3

Define integral membrane proteins

Answer 3

1. Tightly bound to membrane

2. Embedded in bilayer OR go all the way through

Question 4

Define peripheral membrane proteins

Answer 4

1. Weaker association with the lipid bilayer

2. May be held by glycolipid anchor to membrane

Question 5

What are the three main types of membrane transport

Answer 5

1. Passive diffusion
2. Facilitated diffusion
3. Active transport

Question 6

What types of molecules can utilize passive diffusion?

Answer 6

Lipid-soluble molecules

Question 7

What types of molecules can utilize facilitated diffusion?

Answer 7

Hydrophillic molecules

Question 8

What are two things required for facilitated diffusion?

Answer 8

1. Concentration gradient

2. Protein transporter

Question 9

What are the three types of proteins used in facilitated diffusion?

Answer 9

a. Ion channels
b. Permeases
c. Porins: used for larger molecules

Question 10

What are the two types of active transport?

Answer 10

Primary and secondary active transport

Question 11

Define primary active transport

Answer 11

ATP is used to drive an ion up its conc. Gradient

Question 12

Define secondary active transport

Answer 12

Use of another molecules conc gradient to go against its own

Question 13

What are three ways to distinguish between types of transport across the membrane?

Answer 13

i. Direction of transport
ii. Nature of carriers
iii. The role of energy

Question 14

What are the three types of ion channels

Answer 14

Voltage gated
Ligand gated
Mechanically gated

Question 15

What are two factors that guide selectivity of ion channels?

Answer 15

i. Ion-selective binding sites

ii. Conformational changes

Question 16

What role does the Na+/K+ ATPase play?

Answer 16

Transports 3 Na+ out of the cell while shunting 2 K+ into the cell using the power of ATP

Question 17

What two uses does a membrane potential play for a cell?

Answer 17

Provides cell with energy for cell-cell communication and membrane transport

Question 18

How significant is ion movement during (de)polarization events?

Answer 18

a. In general small numbers of ions move in and out of the cell during hyper- and depolarization
b. Therefore, no significant effect on ion conc. in the short term

Question 19

What is Ohms Law?

Answer 19

V=IR

Question 20

Define current clamp recording

Answer 20

Membrane potential is free to vary, but can be influenced by applying current

Question 21

Define voltage clamp recording

Answer 21

a. Membrane potential is held constant by applying current through an electrode

Question 22

What are the three types of electrodes present in voltage clamp recording?

Answer 22

i. Reference (ground electrode)
ii. Clamp electrode (injects current)
iii. Sensing electrode (sensing voltage in the neuron

Question 23

Define single channel recording - patch clamp

Answer 23

a. A glass pipette is fused to a tiny region of the membrane

b. The pipette is used as an electrode to record currents flowing through one of several individual channel proteins

Question 24

Whcih portion of the voltage-gated Na+ channels is responsible for sensing voltage and moving toward the extracellular surface of the cell, causing the channel to change conformation?

Answer 24

S4 domain