Membrane Structure

Question 1

_________ is a barrier to prevent the contents of cells from escaping & mixing with molecules in the surrounding environment & it also allows nutrients to come in & waste to leave

Answer 1

The plasma membrane

Question 2

_________ is responsible for the structure of all cell membranes

Answer 2

Lipid bilayer

Question 3

__________ form bilayer in water

Answer 3

Membrane lipids

Question 4

The types of lipids found in cell membranes are _____________

Answer 4

Phospholipids

Question 5

Phospholipids

Answer 5

Have a phosphate - containing hydrophillic head linked to a pair of hydrophobic hydrocarbon tails

Question 6

Amphipathic

Answer 6

Molecules with both hydrophillic & hydrophobic parts

Question 7

Phospolipids are __________

Answer 7

Amphipathic

Question 8

What are the two conflicts that happens with amphipathic molecules?

Answer 8

1. The hydrphillic head is attracted to water
2. The hydrophobic tail shun water

Question 9

A ________ fixes the conflict in amphipathic molecules where in a ________ the hydrophilic head faces water & the hydrophobic tails are shield from water

Answer 9

Bilayer

Question 10

When a _________ is form the ________ is quickly fixed (They are self - sealing the amphipathic molecules)

Answer 10

Free edge (tear in the bilayer)

Question 11

The lipid bilayer is a ___________

Answer 11

Flexible 2-D fluid

Question 12

____________ spontaneously close in on themselves to form sealed compartments called lipidosomes

Answer 12

Phospholipids bilayers

Question 13

The _______ of a lipid bilayer depends on its composition

Answer 13

Fluidity

Question 14

The fluidity of a cell membrane

Answer 14

Is the ease that the lipid molecules move within the bilayer

Question 15

How _______ a lipid is depends on its phospholipid composition mostly on how packed the hydrocarbon tails are

Answer 15

Fluid

Question 16

The closer & more packed the hydrocarbon tails the __________ the bilayer is

Answer 16

Less fluid

Question 17

What are the two major properties that affect how tightly hydrocarbons will pack?

Answer 17

1. Their length
2. The number of double bonds they contain

Question 18

The ________ the hydrocarbon tails are they are less likely to interact with one another which increases the fluidity of the bilayer

Answer 18

Shorter

Question 19

_____________ can form closed, spherical liposomes

Answer 19

Pure Phospholipids

Question 20

A hydrocarbon tail that contains a __________ is unsaturated

Answer 20

A double bond

Question 21

A hydrocarbon tail that contain _________ is saturated

Answer 21

Single Bonds

Question 22

Lipids bilayers that contain large amount of _________ are more fluid than those with small amounts

Answer 22

Double bonds

Question 23

_________ stiffens cell membranes & prevents light packing of phospholipids

Answer 23

Cholesterol

Question 24

Membrane assembly begin in the __________

Answer 24

ER (Endoplasmic retriculum)

Question 25

In ___________ phospholipids are formed in the ER (The cytosolic surface)

Answer 25

Eukaryotic cells

Question 26

Phospholipids make it to the otherside of the layer by enzymes called \_\_\_\_\_\_\_\_\_\_

Answer 26

Scramblase

Question 27

Scramblase

Answer 27

Transporter protein that moves randomly selected phospholipids from outer to the inner membrane at the side time moving an inner to the outer membrane

Question 28

The ________ membrane contains flippases

Answer 28

Gogi membrane

Question 29

Flippases (Flip Flop movement)

Answer 29

Moves specific phospholipids from the outer side into the inner side of the membrane

Question 30

\_\_\_\_\_\_\_\_\_\_ helps establish & maintain the asymmetric distribution of the phospholipids characteristic of animal cell membranes

Answer 30

Flippases

Question 31

\_\_\_\_\_\_\_\_\_ have a variety of functions

Answer 31

Plasma membrane proteins

Question 32

\_\_\_\_\_\_\_\_\_\_\_\_\_\_ associate with the lipid bilayer in different ways

Answer 32

Membrane proteins

Question 33

A ___________ chain usually crosses the lipid bilayer as an alpha helix

Answer 33

Polypeptide

Question 34

\_\_\_\_\_\_\_\_\_\_ are alpha helix because the hydrocarbon side chains are exposed on the outside of the helix where they contact the hydrophobic lipids tails

Answer 34

Polypeptides

Question 35

Integral membrane proteins

Answer 35

Are permanently bound

Question 36

Peripheral membrane proteins

Answer 36

Are temporarily bound

Question 37

Transmembrane proteins

Answer 37

Type of integral membrane proteins & external through the lipid bilayer

Question 38

\_\_\_\_\_\_\_\_\_\_\_ bound to other membrane proteins

Answer 38

Peripheral membrane

Question 39

The backbone of a polypetide chain is \_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 39

Hydrophilic

Question 40

A ____________ polypeptide chain usually crosses the lipid bilayer as an alpha helix

Answer 40

Transmembrane

Question 41

The __________ is reinforced by the underlaying cell cortex

Answer 41

Plasma Membrane

Question 42

What are some roles of membrane proteins?

Answer 42

1. Some transport substances across the lipid bilayer 2. Some anchor the membrane to molecules on the outside and inside of the cell 3. Some detect chemical signals on the outside and relay them into the cell’s interior 4. Some act as enzymes to carry out a reaction near the membrane.