Plasma Membrane Structure

Question 1

How do cells closely regulate what enters them and what they secrete?

Answer 1

Plasma membrane

Question 2

Biological membranes are 2-dimensional, fluid structures within which lipid and protein molecules diffuse freely. Term that commonly describes the plasma membrane.

Answer 2

Fluid mosaic model

Question 3

Which part of the plasma membrane is hydrophobic and hydrophilic?

Answer 3

Hydrophobic tails

Hydrophilic heads- interact with aqueous intracellular and extracellular surroundings

Question 4

Knowing the structure of the plasma membrane which molecules can diffuse easily and which ones would require help?

Answer 4

Small and non polar molecules can diffuse easily.

Large and polar molecules require help

Question 5

What are the main structure of plasma membrane?

Answer 5

1. Lipids

2. Functional Proteins

Question 6

Three main classes of lipids

Answer 6

1. Phospholipids
2. Sterols
3. Glycolipids

Question 7

What is the predominant component of the lipid bilayer? Responsible for insideness and outsideness of the plasma membrane.

Answer 7

Phospholipid

Question 8

The phospholipid is amphipathic which means?

Answer 8

It has a polar head (ex. Phosphate-negatively charged)and non polar tail (alkanes-non polar)
Therefore, they have very different behavior

Question 9

What is the second main lipid component of the plasma membrane? Give an example of this lipid.

Answer 9

Sterol- ex. Cholesterol

Question 10

Modulates fluidity of plasma membranes and has a characteristic four-ring structure

Answer 10

Cholesterol

Question 11

Similar to phospholipid but with carbohydrate instead of phosphate group in one end

Answer 11

Glycolipid

Question 12

Sphingomyelin tends to cluster with cholesterol molecules to form what structures?

Answer 12

Lipid rafts

Question 13

Glycolipids can have what two backbones?

Answer 13

Glycerol and sphingosine

Question 14

Glycolipids are involved in what two processes?

Answer 14

Cell signaling and adhesion

Question 15

Proteins that are actually embedded within the plasma membrane

Answer 15

Integral proteins- most are transmembrane proteins

Question 16

Transmembrane protein domains

Answer 16

Hydrophilic cytosolic domain, hydrophobic domain, hydrophilic extracellular domain

Question 17

Examples of transmembrane proteins

Answer 17

Proton pumps, ion channels, and G-protein coupled receptors

Question 18

These proteins are covalently bound to single or multiple lipid molecules that anchor the protein within the membrane without the protein contacting the membrane.

Answer 18

Lipid-anchored

Question 19

Example of lipid-anchored proteins

Answer 19

G proteins- intracellular membrane-bound structures that help coordinate the signaling cascade initiated by the G protein-coupled receptors.

Question 20

These proteins are found within the cytoplasm and are temporarily attached to integral proteins or are associated with peripheral regions of the lipid bilayer.

Answer 20

Peripheral proteins

Question 21

These proteins tend to interact with biological membrane only temporarily before resuming their functions pan within the cytoplasm. This category includes some enzymes and hormones

Answer 21

Peripheral Proteins

Question 22

Proteins can be glycosylated which refers to the addition of what chains to a peptide chain?

Answer 22

Oligosaccharide

Question 23

Example of glycoproteins or glycosylated proteins that is relevant to the plasma membrane

Answer 23

1. Major Histocompatibility complex

2. The antigens involved in the ABO blood type system

Question 24

Membrane glycoproteins are often involved in what processes?

Answer 24

Cell recognition and communication

Question 25

Lipid bilayer enclosing a spherical space. These laboratory-derived structures are used by researchers to deliver material to target cells and to test cell membrane permeability.

Answer 25

Liposomes or lipid vesicles

Question 26

An aggregate composed of a single layer of lipids in aqueous solution, where the hydrophilic head is in contact with the solvent while the hydrophobic tail region is sequestered in the center.

Answer 26

Micelle

Question 27

Can reduce the surface tension of a solution

Answer 27

Surfactants

Question 28

What kind of biologically relevant molecule is formed through an esterification reaction

Answer 28

Phospholipids

Question 29

T or F. Amphipathic molecules can be used as surfactants to reduce solution surface tension

Answer 29

True.

Question 30

T or F. Liposomes are lipid bio layers and micelles are lipid monolayers, both of which contain membrane proteins.

Answer 30

False. Micelles do not contain membrane proteins, only liposomes do.

Question 31

Move phospholipids from the inner leaflet to the outer leaflet

Answer 31

Floppases

Question 32

Move phospholipids from the outer leaflet to the inner leaflet

Answer 32

Flippases

Question 33

Enzymes responsible for bidirectional movement of gathering phospholipids
Vertical translation

Answer 33

Scramblase

Question 34

The degree to which phospholipids can move around laterally

Answer 34

Membrane fluidity

Question 35

Lower temperature equals more or lower fluidity?

Answer 35

Lower fluidity like how butter is more solid at lower temp

Question 36

What molecule is the mediator of membrane fluidity and prevents it from going to extremes?

Answer 36

Cholesterol

1. Promotes membrane fluidity at colder temp
2. Tripping the phospholipids at higher temp- reduces membrane fluidity

Question 37

Saturated vs. Unsaturated

No carbon-carbon double bonds- very linear and regular

Answer 37

Saturated

Question 38

Saturated vs Unsaturated

Contain at least one double bond and very often more- cis conformations cause it to be a lot less linea

Answer 38

Unsaturated

Question 39

Saturated characteristics

Answer 39

Very stackable- all linear
High melting point
Makes membrane less fluid

Question 40

Unsaturated characteristics

Answer 40

Less stackable
Lower melting points
Makes plasma membranes more fluid

Question 41

T or F. Glycoglycerolipids and sphingolipids differ from each other in the type of carbohydrate group attached

Answer 41

False. They differ from each other in their backbone molecule