Exam 1 Lec 3 Membrane

Question 1

Where water is found?

Answer 1

• Blood
• Cytosol
• Interstitial fluid

Question 2

66% of water in our body can be founded in:

Answer 2

Cytosol

Question 3

The content of interstitial fluid is going to determine _____________________.

Answer 3

what is permeable to the site

Question 4

Environment of the interstitial fluid: (6)

Answer 4

• Concentration of salt, and other electrolytes
• Concentration of energy-riched molecules
• Concentration of oxygen and carbon dioxide
• Concentration of waste product
• pH
• Temperature

Question 5

Cells vary in ______ and _______.

Answer 5

shape; function

Question 6

Two types of membrane proteins: _________ and _________. They function in ________, __________, and ________ _________.

Answer 6

peripheral; integral; junctions; transport; chemical signaling

Question 7

Cell-to-cell junctions: (3)

Answer 7

• Desmosomes
• Tight junctions
• Gap junctions

Question 8

Desmosomes

Answer 8

Provide rigidity for neighboring, resist a lot of pulling and pushing, make sure neighboring cells are anchored together

Question 9

Tight junctions; name the type of protein that is specific for gap junctions

Answer 9

Push cells very close to each other to minimize the interstitial space in between them to prevent paracellular pathways; in parts of body where lots of movement occur; to ensure permeability is through the cells, but not between the cells

*Occludin

Question 10

Have a very high control over ___________ pathway; whereas cannot control over ___________ pathway, like leaking

Answer 10

transcellular; paracellular

Question 11

Gap junctions; name the type of protein that is specific for gap junctions

Answer 11

Openings between neighboring cells; facilitates exchanges between neighboring cells; promotes synchronized moves

*Connexon (6 subunits of connexin)

Question 12

Where can we find

a) demosomes
b) tight junctions
c) gap junctions

Answer 12

a) skin/muscle
b) digestive system/urinary system
c) heart/lungs/brain

Question 13

Diffusion can occur through _______________, and _______________.

Answer 13

lipid bilayer; ion channels for specific ions

Question 14

The ______ lipid-soluble the molecule, the _____ rapidly it diffuses

Answer 14

more; more

Question 15

How does water move across the membrane?

Answer 15

• Through lipid bilayer

- Through aquaporins

Question 16

Osmosis is passive or active transport; water diffuse from _____ concentration of solute to ______ concentration of solute

Answer 16

Passive; high; low

Question 17

Types of solution that direct water movement:

Answer 17

Isotonic, hypertonic (water out; cell shrink), and hypotonic (water in; cell burst)

Question 18

Polar and charged substances do not diffuse across the lipid portion of the lipid. (T/F)

Answer 18

T

Question 19

List 4 gating mechanisms for the channels:

Answer 19

• Voltage gated
• Stretched gated
• Phosphorylation gated
• Ligand gated

Question 20

Voltage-gated channel

Answer 20

By charge:

• extracellular positive, cytoplasm negative -> close
• extracellular negative, cytoplasm positive -> open

*brain cells

Question 21

Stretch gated channel

Answer 21

By stretching:

• loosen -> close
• tighten -> open

*skin cells, hair cells in the ear

Question 22

Phosphorylation gated channel

Answer 22

ATP/ phosphate in the cytoplasm -> open
without -> close

*nervous system cells; muscles

Question 23

Ligand gated channel

Answer 23

lock and key, aka receptor gated channel

*nervous system cells; muscles

Question 24

Voltage-, ligand-, stretch-, and phosphorylation-gated channels are all by ________ diffusion.

Answer 24

simple

Question 25

Passive transport, aka ___________ transport, are ______________ proteins of quaternary structure creating a pore for substance pathway. Also included _______ _______.

Answer 25

channel; transmembrane; carrier proteins

Question 26

Channel transport requires input of energy. (T/F)

Answer 26

F; channel transport is another name for passive transport

Question 27

_________ transport is highly specific. It is used to transport larger molecules, or against the concentration gradient. It is ______ than ion channels.

Answer 27

Mediated; slower

Question 28

2 types of mediated transports:

Answer 28

- Active transport (needs energy) | - Facilitated diffusion (does not need energy)

Question 29

Facilitated diffusion

Answer 29

From high to low concentration; does not require energy; can become saturated

Question 30

Ion channels are facilitated diffusion. (T/F)

Answer 30

F

Question 31

In active transport (2):

Answer 31

- Requires energy | - Against concentration gradient

Question 32

Active transport has three types of transporters:

Answer 32

- Uniport transporters (1 solute, 1-way) - Symport transporters (2 solutes, 1-way) (Na+/Glu) - Antiport transporters (2 solutes, 2-way) (Na+/K+ pump)

Question 33

2 types of active transport:

Answer 33

- Primary active transport | - Secondary active transport

Question 34

Primary active transport: | Give an example

Answer 34

- Requires ATP - Also known as pumps - Only cations (Na+, K+, Ca2+, etc.) pass through *Na+/K+ pump

Question 35

Na+/K+ pump

Answer 35

3 Na+ out | 2 K+ in

Question 36

Why Na+/K+ pump called primary active transport?

Answer 36

Because it requires ATP to bind directly to the protein for it to work

Question 37

Secondary active transport: | Give an example

Answer 37

- Does not require ATP - Use chemical gradient of one ion to move another ion *Na-glucose cotransporter

Question 38

Na-glucose cotransporter

Answer 38

- Uses the energy of Na to move the glucose against its concentration gradient - Na is along concentration gradient; glucose is agaisnt - For this to occur, Na concentration must remain low at all times (this is done by the sodium-potassium pump)

Question 39

2 types of endocytosis:

Answer 39

- Phagocytosis | - Pinocytosis

Question 40

Endocytosis

Answer 40

Plasma membrane invaginates toward the cell interior while surrounding the materials to be transported

Question 41

Exocytosis

Answer 41

Materials packaged in vesicles are secreted from the cell

Question 42

How does G-protein cascade work? (8 steps)

Answer 42

1. Messenger binds to the receptor and activates it 2. Receptor activates G-protein (which is normally unactiviated when binding with GDP) 3. G-protein binds to alpha subunit 4. Alpha subunit translocates 5. Alpha subunit G-protein activates adenelyl cyclase (AC) 6. AC converts ATP to cAMP 7. cAMP activates protein kinase A (PKA) 8. PKA phosphorylates other proteins to generate cellular response