Text Chapter 3: Membranes

Question 1

Macromolecules that Comprise the Plasma Membrane

Answer 1

phospholipids, cholesterol, proteins

Question 2

Phospholipid Bilayer (plasma membrame)

Answer 2

forms boundary to isolate cell contents form environment, restricts passage of hydrophilic substances across the membrane

Question 3

Cholesterol (plasma membrane)

Answer 3

increases bilayer strength and flexibility, reduces membrane fluidity, reduces permeability to water-soluble substances

Question 4

Transport Proteins

Answer 4

regulates movement of water-soluble substances
Channel Proteins- have pores that allow passage of ions and small water-soluble molecules
Carrier Proteins- bind to molecules and change shape for delivery across membrane

Question 5

Receptor Proteins

Answer 5

docking site for molecules outside the cell, trigger internal cellular response

Question 6

Recognition Proteins

Answer 6

identification tags (carbohydrate chains aid in cell-cell recognition), cell-surface attachment sites

Question 7

Role of Carbohydrates when attached to Proteins and Lipids

Answer 7

carbohydrate chains aid in cell-cell recognition

Question 8

Diffusion

Answer 8

molecules move from an area of high concentration to an area of low concentration, molecules pass through the plasma membrane without the assistance of another molecule.

Question 9

Osmosis

Answer 9

diffusion of water molecules from an area of high concentration to an area of low concentration across a differentially permeable membrane

Question 10

Active Transport with Carrier

Answer 10

movement from an area of low concentration to an area of high concentration, energy and protein carrier required

Question 11

Endocytosis

Answer 11

surrounding the material with the plasma membrane, creating a vesicle that is transported into the cell, energy needed

Question 12

Receptor-Mediated Endocytosis

Answer 12

material that binds to a receptor is enclosed in a vesicle and transported into the cell

Question 13

Exocytosis

Answer 13

material enclosed in a vesicle is released from the cell when the vesicle fuses with the plasma membrane

Question 14

Hypertonic Solution

Answer 14

solute concentrations are higher in the extracellular fluid, water diffuses out of cells

Question 15

Hypotonic Solution

Answer 15

solute concentrations are lower in the extracellular fluid, water diffuses into the cells (unlike plant cells, animal cells may explode in hypotonic solutions because they don’t have a cell wall to limit cellular expansion)

Question 16

Isotonic Solution

Answer 16

solute concentrations are balanced, water movement is balanced

Question 17

Tight Junction

Answer 17

fusion of proteins from membranes adjacent to cells, form a water-tight seal between cells like a caulking around tub

Question 18

Desmosome

Answer 18

transmembrane proteins link together to bridge space between cells, act like velcro and fasten cells together

Question 19

Gap Junction (animals)

Answer 19

pairs of channels connect insides of adjacent cells (animals)

Question 20

Plasmodesmata (plants)

Answer 20

connect insides of adjacent cells (plants)

Question 21

Channel Proteins

Answer 21

have pores that allow passage of ions and small water-soluble molecules (type of transport protein)

Question 22

Carrier Proteins

Answer 22

bind to molecules and change shape for delivery across membrane (type of transport protein)

Question 23

Plasma Membrane “Fluid”

Answer 23

a double layer of phospholipids

Question 24

Plasma Membrane “Mosaic”

Answer 24

a collection of proteins

Question 25

Low Concentration —–> High Concentration

Answer 25

endocytosis, exocytosis, receptor-mediated endocytosis, active transport