Plasma Membrane

Question 1

ICF (5 things)

Answer 1

• intracellular fluid: fluid inside cells
• 40% body weight
• 2/3 body water
• maintains shape of cell
• moves across membrane via osmosis

Question 2

ECF (4 things)

Answer 2

• extracellular fluid: fluid outside cells
• 20% body weight
• 1/3 body water
• made up of: ISF, plasma volume and lymph, and transcellular fluid

Question 3

Plasma volume and lymph (three things)

Answer 3

• in blood and lymphatic vessels
• 1/4 ECF
• 5% body weight

Question 4

How is plasma volume and lymph separated from ISF?

Answer 4

separated by capillary wall

Question 5

Where do the exchange between plasma, lymph, and ISF occur?

Answer 5

capillary beds

Question 6

Transcellular fluid (three things)

Answer 6

• in specialized areas
• very small % of body weight
• stable volume

Question 7

Examples of transcellular fluid

Answer 7

• cerebral spinal fluid

- aqueous humor

Question 8

Where is most of the body weight?

Answer 8

ICF

Question 9

Most important cation in ICF?

Answer 9

K+

Question 10

Important cation for cell function?

Answer 10

Ca2+

Question 11

Most important anion in ISF?

Answer 11

Cl-

Question 12

Important ECF buffer

Answer 12

HCO3-

Question 13

What do proteins act like in the ICF?

Answer 13

act as major anions

Question 14

What does the cell membrane separate?

Answer 14

ICF and ECF

Question 15

Functions of the cell membrane

Answer 15

• regulate exchange w/ environment
• cell communication
• structural support

Question 16

How does cell membrane regulate exchange w/ environment?

Answer 16

provides permeability barrier and highly selective filter

Question 17

How does cell membrane help w/ cellular communication?

Answer 17

receptors and signal transduction pathways for hormones and neurotransmitters

Question 18

Cell membrane contains:

Answer 18

adhesion molecules and surface antigens

Question 19

Adhesion molecules allow for:

Answer 19

• anchoring
• tissue organization
• intracellular communication
• cell shape

Question 20

Types of junctions (3 types)

Answer 20

• gap
• tight
• anchoring

Question 21

Major adhesion molecules (4 of them)

Answer 21

• cadherins
• integrins
• immunoglobulin superfamily CAMs
• selectins

Question 22

Cadherins:

Answer 22

• cell-cell junctions
• adherens junctions
• desmosomes
• Ca2+ dependent

Question 23

Integrins:

Answer 23

• mostly found in cell-matrix junctions

- help w/ cell signaling

Question 24

Example of immunoglobulin superfamily CAMs and its function

Answer 24

nerve cell adhesion molecules (NCAM): responsible for nerve cell growth during nervous system development

Question 25

Selectins:

Answer 25

temporary cell-cell adhesion

Question 26

Surface antigens function

Answer 26

important for recognition of "self" vs. "nonself"

Question 27

Model of plasma membrane structure

Answer 27

fluid mosaic model

Question 28

Plasma membrane is made of

Answer 28

lipids (50%), proteins (50%), and carb

Question 29

Phospholipids:

Answer 29

- core structure - organized in bilayer - have polar head and nonpolar tail

Question 30

Why are phospholipids of plasma membranes amphipathic?

Answer 30

has polar (hydrophilic) phosphate head and nonpolar (hydrophobic) tails

Question 31

Orientation of phospholipids in plasma membrane?

Answer 31

polar heads on the outside and nonpolar fatty acyl tail chains are on the inside

Question 32

Nonpolar tail of plasma membrane forms what?

Answer 32

permeability barrier to H2O soluble molecules

Question 33

Cholesterol

Answer 33

- hydrocarbon ring structure | - about 20% of total membrane lipid

Question 34

Functions of cholesterol in plasma membrane

Answer 34

- stabilizes membrane at body temp (37 C) - increases membrane fluidity - reservoir of precursor molecules for steroid hormones

Question 35

Protein types:

Answer 35

- integral / intrinsic | - peripheral / extrinsic

Question 36

Integral / intrinsic proteins:

Answer 36

- 70% of membrane proteins - embedded in membrane - transmembrane protein: spans membrane completely

Question 37

Functions of integral / intrinsic proteins:

Answer 37

- carriers - enzymes - channels - receptors

Question 38

Peripheral / extrinsic:

Answer 38

- either on outside or inside of plasma membrane | - often are enzymes

Question 39

T/F: phosphatases remove phosphate group from protein.

Answer 39

T

Question 40

T/F: kinases remove phosphate group from protein.

Answer 40

F

Question 41

Carbohydrates:

Answer 41

- 2-3% of membrane lipid - glycoproteins: made of carb and proteins - glycolipids: made of carb and phospholipids

Question 42

Functions of glycoproteins / glycolipids:

Answer 42

- cell-cell communication - structural stability - immune response

Question 43

Example of membrane transporters

Answer 43

- carriers | - channel proteins

Question 44

T/F: Carriers change conformation

Answer 44

T

Question 45

Channel proteins form:

Answer 45

- open channels | - closed channels

Question 46

Types of gated channels:

Answer 46

- mech - voltage - chem

Question 47

Structural proteins are found in:

Answer 47

- cell junctions | - cytoskeleton

Question 48

Membrane enzymes:

Answer 48

- activated by membrane receptors | - functions in: metabolism and signal transfer

Question 49

Functions of membrane receptors:

Answer 49

- receptor mediated endocytosis - signal transfer - open and close chem gated channel

Question 50

Order of concentration of ions in ECF (highest to lowest)

Answer 50

Na+, Cl-, K+

Question 51

Order of concentration of ions in ICF (highest to lowest)

Answer 51

K+, Na+, Cl-