Chapter 5: Membrane, Structure, Synthesis And Transport

Question 1

phospholipid bilayer

Answer 1

Framework of the membrane

Question 2

Fluid-mosaic model

Answer 2

Membrane is considered a mosaic of lipid, protein, and carbohydrate molecules

Question 3

Transmembrane proteins

Answer 3

Regions are physically embedded in the hydrophobic portion of the phospholipid bilayer

Question 4

Lipid-anchored protein

Answer 4

An amino acid of the protein is covalently attached to a lipid

Question 5

Peripheral or extrinsic membrane proteins

Answer 5

Noncovalently bound either to the integral membrane proteins that project out from the membrane or to polar head groups of phospholipids

Question 6

20% - 30% of all genes encode ____.

Answer 6

Transmembrane proteins

Question 7

Transmission electron microscopy (TEM)

Answer 7

Dye binds tightly to the polar head groups of phospholipids but not to the fatty acid chains

Question 8

Freeze fracture microscopy (FFEM)

Answer 8

Specialized form of TEM used to analyze the interior of the phospholipid bilayer

Question 9

lipid rafts

Answer 9

group of lipids floats together as a unit within the large sea of lipids in the membrane
contains high concentration of cholesterol and unique member proteins

Question 10

factors affecting fluidity

Answer 10

longer fatty acid tail –> less fluid
presence of double bonds –> more fluid
presence of cholesterol –> more fluid at cold temperatures

Question 11

lipid exchange proteins

Answer 11

extract lipid from one membrane for insertion in another

Question 12

glycosylation

Answer 12

process of covalently attaching a carbohydrate to a protein or lipid

Question 13

glycolipid

Answer 13

carbohydrate to lipid

Question 14

glycoprotein

Answer 14

carbohydrate to protein

Question 15

N-linked glycosylation

Answer 15

attachments of carbohydrate to nitrogen atom

Question 16

O-linked glycosylation

Answer 16

addition of carbohydrate to oxygen atom, occurs in Golgi

Question 17

passive transport

Answer 17

requires no input of energy

Question 18

passive diffusion

Answer 18

diffusion of a solute through a membrane without transport protein

Question 19

facilitated diffusion

Answer 19

diffusion of a solute through a membrane with the aid of a transport protein

Question 20

active transport

Answer 20

requires energy, up against a gradient

Question 21

phospholipid bilayer barrier

Answer 21

barrier to hydrophilic molecules and ions due to hydrophobic interior

Question 22

rate of diffusion

Answer 22

depends on chemistry of solute and its concentration

Question 23

transmembrane gradient

Answer 23

concentration of a solute is higher on one side of a membrane than the other

Question 24

ion electrochemical gradient

Answer 24

both an electrical and chemical gradient

Question 25

isotonic

Answer 25

equal water and solute concentrations on either side of the membrane

Question 26

hypertonic

Answer 26

solute concentration is higher (and water concentration is lower) on one side of the membrane

Question 27

hypotonic

Answer 27

solute concentration is lower (and water concentration is higher) on one side of the membrane

Question 28

osmosis

Answer 28

water diffuses through a membrane from one area with more water to an area with less water

Question 29

crenation

Answer 29

shrinkage of a cell in a hypertonic solution

Question 30

osmotic lysis

Answer 30

swelling and bursting of a cell in a hypotonic solution

Question 31

turgor pressure

Answer 31

pushes plasma membrane against cell wall, maintains shape and size

Question 32

plasmolysis

Answer 32

plants wilting because water leaves plant cells

Question 33

contractile vacuole

Answer 33

takes up water and discharges it outside the cell to prevent osmotic lysis

Question 34

aquaporin

Answer 34

forms a channel that allows water to pass through a membrane, can also be closed to slow diffusion

Question 35

transport proteins

Answer 35

transmembrane proteins that provide a passageway for the movement of ions and hydrophilic molecules across membranes

Question 36

channels

Answer 36

forms an open passageway for the direct diffusion of ions or molecules across the membrane

Question 37

transporter

Answer 37

conformational change transports solute across a membrane

Question 38

uniporter

Answer 38

transports single molecule or ion

Question 39

symporter or cotransporter

Answer 39

two or more ions or molecules transported in the same direction

Question 40

antiporter

Answer 40

two or more ions or molecules transported in opposite directions

Question 41

active transport

Answer 41

movement of solute across a membrane against its gradient from a region of low concentration to higher concentration

Question 42

primary active transport

Answer 42

uses a pump to directly use energy to transport solute

Question 43

secondary active transport

Answer 43

uses a different gradient, uses a preexisting gradient to drive transport

Question 44

Na+/K+ ATPase

Answer 44

actively transports Na+ and K+ against the gradient using the energy from ATP hydrolysis

Question 45

electrogenic pump

Answer 45

exports one net positive charge

Question 46

exocytosis/endocytosis

Answer 46

used to transport large molecules such as proteins and polysaccharides

Question 47

exocytosis

Answer 47

material inside the cell packaged into vesicles and excreted into extracellular medium

Question 48

endocytosis

Answer 48

plasma membrane invaginates to form a vesicle that brings substances into the cell