Biol 2404 3.2

Front 1

Plasma Membrane Functions

Back 1

- provides physical isolation from the extracellular fluid, so that the cytoplasm is kept different from extracellular fluid

- controls molecules that enter and exit the cell

- has receptors that allow the cell to recognize molecules and other cells in the surrounding environment

Front 2

Structure of the plasma membrane is described by what model?

Back 2

Fluid Mosaic Model

Front 3

What is the plasma membrane composed of?

Back 3

Lipids and Proteins

Front 4

Bilayer of phospholipids

Back 4

The basic component of the plasma membrane

Front 5

What does bilayer mean?

Back 5

That the phospholipids lie in two distinct layers

Front 6

Hydrophilic

Back 6

Polar heads: water-loving

Front 7

Hydrophobic

Back 7

Non-polar tails: water-hating

Front 8

What's inserted in the phospholipid bilayer?

Back 8

Cholesterol Molecules

Front 9

What keeps the membrane fluid and flexible?

Back 9

Phospholipid and Cholesterol Molecules

Front 10

What does cholesterol prevent?

Back 10

Close packing of phospholipids at low temperatures

Front 11

Transmembrane Proteins

Back 11

some proteins span through the width of the membrane

Front 12

Surface Proteins

Back 12

Other proteins are partially embedded on the inside or on the outside of the membrane

Front 13

2 arrangements of proteins associated with plasma membrane

Back 13

Transmembrane Proteins & Surface Proteins

Front 14

3 types of proteins in the plasma membrane

Back 14

Receptor Proteins, Channel Proteins, Carrier Proteins

Front 15

Receptor Proteins

Back 15

Allow specific extracellular molecules to bind them and trigger a response (a change) in the cell's activity

Front 16

Channel Proteins

Back 16

Form a channel (a pore) that allows water, ions, and other solutes to travel through the membrane, bypassing its lipid portion

Front 17

Carrier Proteins

Back 17

Different from channel proteins as they first bind and then transport solutes across the plasma membrane. Change shape as the molecule binds to them and open toward the other side of the cell and release the molecule

Front 18

Where are carbohydrates found?

Back 18

Outer surface of the membrane

Front 19

Cell-to-cell identification

Back 19

Prevents the immune system from attacking the body's own cells and tissues - Glycoproteins, Gylcolipids

Front 20

Permeability

Back 20

the "leakiness" of the plasma membrane. reflects the ease with which dissolved materials can cross the plasma membrane

Front 21

What are the factors that affect whether a molecule can cross a membrane?

Back 21

Size & shape, electric charge, & lipid solubility

Front 22

What does passive force use?

Back 22

Concentration gradient for substance to transport it. Moves it from higher to lower concentration. moving the substance down

Front 23

What does active force use?

Back 23

Uses ATP as an energy source to transport the substance. Moves from lower to higher. Moves up 'against' the concentration gradient

Front 24

Passive Transport

Back 24

Any type of transport that uses passive force

Front 25

Active Transport

Back 25

Any type of transport that uses the active force

Front 26

Kinds of Passive Transport

Back 26

Diffusion, Osmosis, Facilitated Diffusion

Front 27

Kinds of Active Transport

Back 27

Active transport (solute pumping), Vesicular Transport (Endocytosis and exocytosis)

Front 28

What do all solutions contain?

Back 28

A solute (solid) and a solvent (liquid)

Front 29

What happens when a solute is mixed with a solvent?

Back 29

The molecules move randomly and take up available space

Front 30

What is diffusion?

Back 30

The movement of solute molecules from an area of higher to lower concentration; DOWN the concentration gradient

Front 31

What can lipid soluble molecules do?

Back 31

Diffuse through the plasma membrane easily as they are able to diffuse through the lipid portions of the membrane

Front 32

What do ion and water soluble substances do?

Back 32

They're not lipid soluble so they must pass through the membrane channels to enter the cytoplasm

Front 33

What is an example of diffusion in the body?

Back 33

Transport of respiratory gases between the lungs and blood

Front 34

What is osmosis?

Back 34

Diffusion of water (solvent) across a selectively permeable membrane. Occurs from higher to lower concentration of water

Front 35

Three Characteristics of Osmosis

Back 35

1. Diffusion of water molecules across a selectively permeable membrane

2. Occurs across a selectively permeable membrane that is freely permeable to water, but not freely permeable to all solutes

3. Water flows from low solute concentration to high solute concentration

Front 36

Osmotic Pressure

Back 36

The force with which pure water moves into a solution as a result of its solute concentration

Front 37

What happens when the concentration of solutes is higher in a solution?

Back 37

The higher its osmotic pressure is

Front 38

Tonicity

Back 38

The ability of an extracellular solution to cause a cell to gain or lose water; based on the concentration of solutes

Front 39

Hypertonic Solution

Back 39

Solution with higher solutes

Front 40

Hypotonic Solution

Back 40

Solution with lower solutes

Front 41

Isotonic Solution

Back 41

If solutes are equal in both solutions

Front 42

When does osmosis always occur?

Back 42

From a hypotonic to a hypertonic solution

Front 43

2 types of carrier-mediated transport processes

Back 43

Facilitated Diffusion & Active Transport

Front 44

What do membrane proteins bind to?

Back 44

Specific ions and molecules and carry them across the membrane

Front 45

What can carrier mediated transport processes be?

Back 45

Passive (no ATP required) or Active (ATP dependent)

Front 46

What does facilitated diffusion use?

Back 46

Carrier proteins to passively move larger molecules, like glucose and amino acids down their concentration gradient. Insoluble in lipids and too large to pass through membrane channels

Front 47

What does an exchange pump do?

Back 47

Move two ions in opposite direction.

Ex. sodium-potassium exchange pump

Front 48

Active transport always involves carrier protein called what?

Back 48

Pump

Front 49

Vesicular Transport

Back 49

Moves substances either into or out of cell in small membrane sacs called vesicles

Front 50

What does vesicular transport require?

Back 50

Energy from ATP

Front 51

2 major categories of vesicular transport

Back 51

1. Endocytosis: vesicles enter into cells

2. Exocytosis: vesicles exit the cells

Front 52

What does endocytosis involve?

Back 52

The packaging of extracellular materials in a vesicle at the cell surface for import into the cell

Front 53

3 major types of endocytosis

Back 53

1. Receptor-mediated Endocytosis: molecules bind to receptors on the surface, and the membrane pinches off to for a vesicle

2. Pinocytosis: 'cell drinking; is the formation of vesicles filled with fluid

3. Phagocytosis: 'cell eating' is the formation of vesicles containing large particulate matter

Front 54

How does exocytosis occur?

Back 54

The reverse of endocytosis

1. Vesicles form inside the cell and travel to the plasma membrane

2. The membrane of the vesicle fuses with the plasma membrane of the cell

3. The membrane ruptures and contents of the vesicle are released outside the cell