Physiology Lec 2

Question 1

4 functions of a membrane

Answer 1

1. physical isolation 2. regulation of exchange 3. communication 4. structural support

Question 2

How does a membrane provide phyical isolation

Answer 2

surrounds cytoplasm and separates intracellular from extracellular

Question 3

How does a membrane regulate exchange?

Answer 3

controls exchange of ions, nutrients, watse and products between membrane

Question 4

How does a membrane facilitate communication

Answer 4

membrane proteins enable the cell to recognize and respond to molecules in environment

Question 5

How does a membrane provide structural support?

Answer 5

contains membrane bound proteins that attach to the cytoskeleton, adjacent cells, and extracellular matrix

Question 6

What’s the most common type of glycolipid in the outermembrane?

Answer 6

antigens

Question 7

2 categories membrane proteins?

Answer 7

1. peripheral 2. imtegral

Question 8

Define peripheral proteins

Answer 8

1. loosely bound to surface of membrane, cell surface identiy marker (like antigens)

Question 9

Define integral proteins

Answer 9

penetrate lipid bilayer (across whole membrane), transmembrane protein, transport proteins (channels, permeasse (pumps)

Question 10

What are the 6 major functions of membrane proteins

Answer 10

1. transport 2. enzymatic activity 3. signal tranduction 4. cell-cell recognition 5. intercellular joining 6. attachment to the ECM

Question 11

What bond holds the membrane together?

Answer 11

non-covelent

Question 12

Where is the hydrophillic structure of the membrane lipid?

Answer 12

head

Question 13

Where is the hydrophobic end of a phospholipid?

Answer 13

tail

Question 14

What’s the total mass of a membrane to a whole cell?

Answer 14

50%

Question 15

Structures found in the membrane (3)

Answer 15

phosphlipids, cholesterol, glycolipids

Question 16

Bacteria (prokaryotes) lack which common component in their bilayer?

Answer 16

cholesterol

Question 17

How does cholesterol affect the membrane?

Answer 17

helps stiffen and stabilize the bilayer. Less fluid. Less permeable.

Question 18

What replaces the effect of cholesterol in prokaryotes?

Answer 18

cell wall

Question 19

Which direction can phospholipids move (and not move)?

Answer 19

horizontally, not usually transversely (flip).

Question 20

Which 2 factors determine membrane fluidity

Answer 20

1. temperature 2. composition

Question 21

Cholesterol blurs the distinctin between which two states of the membrane?

Answer 21

gel and fluid state

Question 22

Which 2 phospholipids are confined to the outer membrane?

Answer 22

1. phospatidylcholine and sphingomyelin

Question 23

Which 2 phospholipids are confined to the inner monolayer?

Answer 23

phosphatidyethanolamine and phosphatidylserine

Question 24

Which layer are glycolipids found in?

Answer 24

outer monolayer

Question 25

What are the functions of glycolipids

Answer 25

1. protection 2. cell recognition 3. electrical impulses

Question 26

Example of enzymatic activity function (of membrane)?

Answer 26

hydrolase

Question 27

Example of signal transduction

Answer 27

vasopressin receptor

Question 28

Example of cell-cell recognition?

Answer 28

major histocompatibility complex proteins.

Question 29

Example of intercellular joining?

Answer 29

desmocollin

Question 30

What do desmosomes do?

Answer 30

hold neighboring cells together and transmit force from cell to cell.

Question 31

Example of desmosome?

Answer 31

epithelia, heart muscle

Question 32

What are tight junctions?

Answer 32

Prevent lateral diffusion of proteins in the bilayer and regulate pericellular permeability. They maintain cell polarity.

Question 33

Example of tight junction?

Answer 33

epithelia

Question 34

What are gap junctions?

Answer 34

intercellular membrane that connects cytoplasm of cells and allows ion and molecule exchange.

Question 35

Examples of cells with gap junctions?

Answer 35

heart muscle, smooth muscle, epithelia

Question 36

The membrane is ______ permeable

Answer 36

selectively

Question 37

Which molecules cannot cross the membrane?

Answer 37

Na, K, Ca2+, Cl-, Aminos, Sugar

Question 38

Which molecules can cross the membrane?

Answer 38

Water, CO2, fatty acids, small nonpolar molecules, steroid hormones

Question 39

Define passive transport

Answer 39

no energy required. Diffusion. Flows down concetration gradient

Question 40

What is the difference between the unidirectional movements in the two directions?

Answer 40

net flux

Question 41

Which factors increase the rate of diffusion

Answer 41

^ concentration gradient, ^ surface area of membrane ^ membrane permeability, ^ temperature

Question 42

Which factors decrease the rate of diffusion

Answer 42

^ molecular weight, ^ distance of two concentrations

Question 43

What’s the name of the law that determines diffusion properties?

Answer 43

Flick’s Law

Question 44

What is the Van Hoff Equation?

Answer 44

all non-permeable solutes in a solution exert osmotic pressure, which depends on molecular concetration ,and temperature

Question 45

What is the van Hoff Equation (actual equation)?

Answer 45

pie=RCT (r is gas constant, C is molar concentration)

Question 46

When concentration difference and temperature are high, osmotic pressure is ….

Answer 46

higher

Question 47

What is osmolarity?

Answer 47

concetration of solutes in a solution.

Question 48

What happens to a cell whose plasma membrane is weak and not expandable?

Answer 48

^ in extracellular osmolarity, v cell size …. v extracellular osmolarity ^ cell size.

Question 49

Isotonic?

Answer 49

2 solutions haveequal solutes

Question 50

Hypertonic?

Answer 50

one with higher solute and one with a lower solvent

Question 51

Hypotonic?

Answer 51

One has a lower solute, and one has a higher solvent.