Campbell Biology Ch 7

Front 1

Generally describe a cell membrane.

Back 1

1) 7-8 nanometers thick
2) phospholipid (amphipathic) bilayer
3) held together by hydrophobic (core) interactions
4) rich in hydrophobic and hydrophilic proteins

Front 2

Describe the fluid mosaic model of a cell membrane.

Back 2

1) proteins penetrate and imbedded in membrane
2) nonpolar amino acids interact with the hydrophobic core
3) polar and charged amino acids interact with water outside
4) contains other lipids such as cholesterol
5) sugars attached (oligosaccarides) to surface (short chain)

Front 3

Explain membrane fluidity

Back 3

1) consistency of salad oil
2) phospholipids and proteins move laterally (2micrometers/sec)
-essential for:
1) proper permeability
2) functioning of membrane proteins
-influencing factors
1) temperature (up, more fluid; down less fluid)
2) unsaturated fatty acids, more fluid; saturated acids, less fluid
3) cholesterol prevents drastic changes (buffer)

Front 4

Describe the mosaic of proteins in a cell membrane.

Back 4

diverse set of proteins with specific orientations
1) integral: imbedded
2) peripheral: weakly attached to surface
3) primary structure of protein dictates it's disposition within membrane

Front 5

Name the membrane proteins/functions.

Back 5

1) signal transduction
2) intercellular joining (junction proteins)
3) attachment to cytoskeleton
4) cell to cell recognition
5) enzymatic
6) transport

Front 6

Describe the permeability of a pure phospholipid bilayer.

Back 6

most nutrients are polar and charged
1) small, nonpolar molecules pass easily
2) small, polar molecules partially blocked
3) large, polar molecules totally blocked
4) charge substances totally blocked

Front 7

Describe passive transport

Back 7

diffusion: random movements toward equilibrium
1) down the concentration gradient (high to low)
2) thermal energy involved because of movement
3) net movement
-two types
1) simple (no outside help): small nonpolar substances (O, CO2)
2) facilitated (uses transport protein): polar and charged
both are specific

Front 8

Describe the two proteins involved in facilitated diffusion

Back 8

transport proteins for polar and charged substances
1) channel protein: integral membrane protein
-contains hydrophilic pore that recognizes one type of solute
-static
-examples: ion channels, aquaporins
2) carrier protein: integral membrane protein
- changes shape to allow one type of solute to pass
-examples: monosaccarides, amino acids

Front 9

Describe active transport.

Back 9

1) up the concentration gradient (low to high)
2) requires input of energy
3) requires carrier protein
-two types: used to concentrate ions
1) primary: ion pumps, driven directly by ATP
-examples: Na+/K+ pump
2) secondary: cotransport, driven by diffusion of an ion (energy source is ion gradient), indirectly requires ATP
-example: Na+ driven glucose transport protein

Front 10

Describe vesicle-mediated transport (bulk transport).

Back 10

how macromolecules, particles (LDL), and small cells cross the membrane
-two types:
1) exocytosis/secretion
2) endocytosis
-phagocytosis: one cell swallows another
-receptor mediated endocytosis: involves receptor proteins