Ch 5 Membranes

Question 1

Tight junctions:

Answer 1

Second type of junction between adjacent cell, preventing material leaking between cells

Question 2

Cellular membranes play a role in which of the following cell functions?

Answer 2

anchoring the cytoskeleton
protein sorting
cell and nuclear division
cell signaling

Question 3

What are the three molecular components of cellular membranes?

Answer 3

carbohydrates
proteins
phospholipids

Question 4

The plasma membrane contains lipids proteins and carbohydrates it is often described

Answer 4

Mosaic model

Question 5

• Peripheral membrane protein:

Answer 5

Noncovalent associations form with phospholipids or other membrane proteins

Question 6

• Transmembrane protein:

Answer 6

A segment of amino acids is inserted into the phospholipid bilayer.

Question 7

• Lipid-anchored protein:

Answer 7

A lipid molecule is covalently attached to an amino acid side chain of the membrane protein

Question 8

____ are involved in many different cellular functions including cell compartmentalization and the selective uptake of ions and molecules

Answer 8

Biological membranes

Question 9

The three main types of macromolecules that comprise the plasma membrane are

Answer 9

• Lipids, Carbohydrates, and proteins

Question 10

Most phospholipids move freely within a semifluid membrane

Answer 10

laterally along the plane of the membrane in two dimensions

Question 11

The double bonds in unsaturated lipids create ______ in the nonpolar tails, making it more difficult for neighboring lipids to interact.

Answer 11

kinks

Question 12

membrane fluidity is increased when membrane lipids

Answer 12

shorter nonpolar tails.

Question 13

Transmembrane protein flip-flop does not occur spontaneously because it would be energetically

Answer 13

unfavorable

Question 14

all cells are surrounded by a _______ permeable plasma membrane, meaning that the membrane allows the passage of some molecules and ions but not others.

Answer 14

• semi

Question 15

the reasons why it is more appropriate to describe membranes as semifluid

Answer 15

• phospholipids usually move in two dimensions

- molecules move laterally within the membrane leaflet

Question 16

What types of transport require a transport protein?

Answer 16

• Facilitated diffusion

- Active transport

Question 17

the presence of a double bond in a phospholipid tail makes the membrane more fluid because

Answer 17

• it prevents phospholipids from packing tightly

Question 18

Transmembrane proteins do not flip flop across bilayer leaflets because

Answer 18

hydrophilic protein regions would pass through the hydrophobic bilayer interior.

Question 19

order the solutes from highest membrane permeability at the top to lowest at the bottom

Answer 19

• oxygen gas
• water
• glucose
• potassium ions

Question 20

The plasma membrane of a cell is considered to be

Answer 20

• selectively permeable.

Question 21

A term that describes a situation in which the concentration of a solute is higher on one side of a membrane than the other is

Answer 21

transmembrane gradient

Question 22

Diffusion

Answer 22

movement of a substance from a region where concentration is high to region where concentration is low

Question 23

Facilitated diffusion

Answer 23

movement from concentration high to a concentration is low through a passageway provide transport protein

Question 24

Active transport

Answer 24

Movement from region is concentration low to region concentration is high to aid transport protein and source of energy.

Question 25

A solution in which the solute concentration on both sides of the membrane is equal is classified as

Answer 25

isotonic

Question 26

Membrane fluidity is increased when membrane lipids

Answer 26

shorter nonpolar tails.

Question 27

When the concentration of solutes outside the cell is higher than that intra-cellularly, the solution is said to be __________ relative to the inside of the cell

Answer 27

hypertonic

Question 28

phospholipid bilayer are an effective barrier to many charged or polar solutes because of their _____ interior region

Answer 28

nonpolar

Question 29

 osmosis, water moves from areas of

Answer 29

low solute concentration to areas of high solute concentration.

Question 30

When the solute concentration is higher inside the cell relative to outside the cell, the outside solution is said to be:

Answer 30

hypotonic

Question 31

a term that describes a situation in which the concentration of a solute is higher on one side of a membrane than other other

Answer 31

transmembrane gradient

Question 32

Proteins that assist in the movement of substances across membranes can be classified into two types based on how they move solutes across the membrane: _____ and _____

Answer 32

Channels and Transporters

Question 33

When the concentrations of dissolved particles (solutes) on both sides of the plasma membrane are equal, the two solutions are said to be 

Answer 33

isotonic

Question 34

Unlike transporters, _____ proteins provide an open passageway all the way across the plasma membrane

Answer 34

channel

Question 35

solution whose solute concentration is higher than the concentration of solutes inside

Answer 35

hyertonic

Question 36

transporter proteins bind their solutes in a hydrophilic pocket and then undergo a ______ change that switches the exposure of the pocket from one side of membrane to the other

Answer 36

conformational

Question 37

When the concentration of solutes outside the cell is lower than that intra-cellularly, the solution is said to be _________ relative to the inside of the cell

Answer 37

hypotonic

Question 38

______ active transport involves a pump that uses energy from ATP to transport solutes against a gradient.

Answer 38

primary

Question 39

what are the categories of proteins that assist in the movement of molecules and ions across membranes

Answer 39

- transporters | - channels

Question 40

___active transport involves the use of a pre-existing gradient to drive the active transport of another solute.

Answer 40

Secondary

Question 41

How do transporters differ from channel proteins?

Answer 41

Transporters must change conformation to allow solutes to cross the membrane.

Question 42

transporter proteins transport solutes across the membrane via

Answer 42

- conformational change triggered by solute binding

Question 43

In the 1940s, studies of animal cells suggested that the import of ______ is coupled to the export of ______.

Answer 43

K+ and Na+

Question 44

Which of the following types of transport involves pumping ions against a gradient using ATP as a source

Answer 44

primary active transport

Question 45

The sodium/potassium phase transports Na+ and K+ ions against their gradients using the energy from____

Answer 45

ATP

Question 46

In osmosis, water moves from areas of

Answer 46

low solute concentration to areas of high solute concentration.

Question 47

In multicellular organisms, intercellular channels such as gap junctions in animals and plasmodesmata in plants

Answer 47

- allow the movement of substances between adjacent cells.

Question 48

IN animals functions form channels between cells that allow cells to communicate with one another.

Answer 48

gap

Question 49

In a plasmodesma, the ______ of one cell is continuous with that of another cell.

Answer 49

plasma membrane

Question 50

The processes that are coupled across cell membranes

Answer 50

- the export of Na+ ions | - the import at K+ ions

Question 51

vesicular movement of large molecules into cells is called _____, and vesicular movement of large molecules out of cells is called ______

Answer 51

- endocytosis | - exocytosis

Question 52

the cells of multicellular organisms also may have ______ that allow the movement of substances between adjacent cells

Answer 52

intercellular channels

Question 53

he three types of endocytosis are receptor-mediated endocytosis

Answer 53

- phagocytosis - pinocytosis - Receptor-Mediated Endocytosis

Question 54

What do gap junctions do in animals?

Answer 54

Provide passageways for intercellular transport

Question 55

Cell ______ are specialized structures within multicellular animals that physically adhere cells to each other.

Answer 55

junctions

Question 56

What organelle in adjacent cells is connected by the central tubules in plasmodesmata?

Answer 56

- smooth endoplasmic reticulum

Question 57

Select the types of anchoring junctions found in animals.

Answer 57

- hemidesmosomes - adherens junctions - focal adhesions - desmosomes

Question 58

The primary difference between endocytosis and exocytosis is

Answer 58

the direction of transport.

Question 59

he two types of anchoring junctions that connect cells to the extracellular matrix are

Answer 59

- hemidesmosomes - focal - adhesions

Question 60

 multicellular animals, cells are linked to one another by

Answer 60

cell junctions.

Question 61

which of the following cell junctions prevent material from passing between adjacent cells of animals?

Answer 61

- tight junctions

Question 62

The four types of anchoring junctions in humans are

Answer 62

adherens junctions, desmosomes, hemidesmosomes, cell-matrix adhesion complexes.

Question 63

Which of the following anchoring junctions bind to actin filaments in the cytoskeleton?

Answer 63

- Focal adhesions | - Adherens junctions

Question 64

Head

Answer 64

site where ATP binds and is hydrolyzed

Question 65

Hinge

Answer 65

Site bends in response to ATP binding and hydrolysis

Question 66

Tail

Answer 66

Region attached to other proteins or to other cellular molecules.