Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

AAA BIO108: General Physiology > 2a. Cell Membrane Structure > Flashcards

2a. Cell Membrane Structure Flashcards

(95 cards)

Start Studying
1
Q

What is a cell membrane?

A
  • Acts as a boundary
  • Controls what enters and leaves cell
  • Regulates chemical composition
  • Maintains homeostasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is cell membrane call the gateway to the cell?

A

cell’s outer membrane acts as a gate, preventing intruders from invading the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the importance of the cell membrane?

A

main role is to provide protection to the cell from its surroundings. It controls the passage of some solutes and water into and out of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The cell membrane in unicellular organisms is

A

flexible and allows to
move

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Studies of the red blood cell plasma
membrane provided ____

A

the first evidence that
biological membranes consist of lipid bilayers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The role of the cell membrane in the plant cell is ____

A

to separate the cytoplasm of the cell from its cell wall.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Sandwich model was proposed by?

A

Danielli and Davson

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

3 Plasma Membrane Model

A
  1. Sandwich Model
  2. Unit Membrane Model
  3. Fluid Mosaic Model
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is fluid mosaic model?

A

Phospholipid bilayer with proteins partially or fully imbedded, seen with freeze-fractured membrane via electron micrographs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is sandwich model?

A

2 layers of globular proteins with phospholipid inside to make a layer and then join 2 layers together to make a channel for molecules to pass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Who proposed unit membrane model?

A

Robertson

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the outer layer of PPL bilayer?

A

glycoprotein coat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is unit membrane model?

A
  1. Outer layer of protein with phospholipid bilayer inside,
  2. believed all cells same composition,
  3. does not explain how some molecules pass through or the use of
    proteins with nonpolar parts
  4. used transmission electron microscopy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Who proposed fluid mosaic model?

A

Singer and Nicolson

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Process on how to verify the correct membrane model?

A

1) Rapidly freeze specimen
2) Use special knife to cut membrane in half
3) Apply a carbon + platinum coating to the surface
4) Use scanning electron microscope to see the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

According to the electron micrograph which membrane model is correct?

A

Fluid-Mosaic Model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What model is the Basic paradigm of biological
membrane structure

A

Fluid-mosaic model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The lattice becomes ____ at
the transition temperature.

A

frozen crystalline gel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The lipids in a membrane are organized into a
_____

A

liquid crystalline lattice.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What composes in FM model freeze-fracture?

A

there is a P face and E surface, extracellular surface of membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What composes in FM model section?

A

bimolecular lipid leaflets (trilaminar)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The Plasma Membrane is composed of two layers of lipids. Why is this important?

A

Having lipids in the plasma membrane means that at least a portion of the membrane repels the water that constantly surrounds it. Allowing
too much water inside the cell could cause the cell to burst.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

2 Layers of the FM Model

A
  1. Fluid
  2. Mosaic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the fluid in FM Model

A

plasma membrane has consistency of olive oil at body temperature, due to unsaturated phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
What happens to the PPL and proteins in the fluid layer
move around freely within the layer, like it’s a liquid.
20
Describe the mosaic layer of FM Model
1. proteins form a collage that differs on either side of membrane and from cell to cell (greater than 50 types of proteins)
21
Describe the protein span of the mosaic layer
2. proteins span the membrane with hydrophilic portions facing out and hydrophobic portions facing in.
22
describe the mosaic pattern of the FM Model
3. mosaic pattern produced by scattered protein molecules when membrane is viewed from above.
23
What happens if it in low temperature?
hydrocarbons are tightly packed and in gel phase
24
What happens if it in higher temperature?
moves to fluid phase, bilayer "melts", movement is allowed
25
Formation of sphere is ____?
energetically favorable
26
Describe the sphere in energetically unfavorable?
planar phospholipid bilayer with edges exposed to water
27
Describe the sphere in energetically favorable?
sealed compartment formed by phospholipid bilayer
27
planar lipid bilayers spontaneously ___
form vesicles
28
What is the surroundings of the sphere bilayer?
water inside and outside
29
it is a harsh ionic detergent
SDS (sodium dodecyl sulfate)
30
a gentler non-ionic detergent and commonly used solubilizing agents
Triton X-100
30
What happens when you put SDS in the bilayer?
SDS will intercalate first with the phospholipids and will increase the hydrophilicity of the membrane promoting a leak first and complete disruption eventually
30
What is the difference between triton X-100 and SDS in terms of effects?
Triton-X-100 is a non-ionic detergent suitable for gently solubilizing proteins without denaturing them, while SDS is an anionic detergent that denatures proteins
31
What happens when you have detergent in the bilayer?
lysing cells to extract protein and other cellular organelles or to permeabilize the living cell membrane for transfection
32
What are integral membrane proteins?
Integral membrane proteins are embedded in the lipid bilayer and can be removed only by disrupting the bilayer.
33
how does detergent remove protein membrane?
These amphipathic molecules disrupt the bilayer by forming mixed phospholipid-detergent micelles.
34
Process to isolate a protein from its membrane
1. detergent micelles + monomers added to the membrane 2. they will be solubilized membrane proteins 3. will now became lipid-detergent micelles 4. purification of NaK pump 5. Removal of detergent micelles + monomers 6. Addition of phospholipids (mixed with detergent) 7. functional protein incorporated into phospholipid vesicle
34
Scheme to Study a Membrane Protein (3)
Solubilization, Purification, and Reconstitution in Liposomes
35
Membrane Proteins Can Be Solubilized by?
Detergents That Disrupt the Membrane
36
Structure of the Plasma Membrane (9)
1. extracellular matrix 2. glycoprotein 3. carbohydrate 4. glycolipid 5. cytoplasm 6. cholesterol 7. proteins 8. phospholipid 9. microfilaments of cytoskeleton
37
Membrane movement
1. lateral movement (frequent) > flexion > rotation 2. flip-flop (rare)
38
movement of phospholipids
1. Most of the lipids and some proteins drift laterally on either side. 2. Phospholipids do not switch from one layer to the next.
39
Movement of lipids and proteins in the cell membrane
not fixed in position but constantly moving.
40
While the lipids can move both laterally and rotate 360 degrees
flip-flop diffusion
40
The proteins move laterally within the cell membrane
lateral diffusion
41
Cholesterol affects ____
fluidity
42
Cholesterol at colder temperature
it maintains fluidity by not allowing phospholipids to pack close together.
42
Cholesterol at body temperature (2)
1. it lessens fluidity by restraining the movement of phospholipids 2. reduce permeability to small mol
43
our body needs some cholesterol to make _____
hormones, vitamin D, and substances that help you digest foods
43
The Planar Rings of Cholesterol Make the Membranes what? (3)
1. More Rigid 2. Less Permeable 3. Resistant to Low Temperature Crystalization
44
a waxy, fat-like substance that's found in all the cells in your body.
cholesterol
45
plant membrane have no cholesterol but have
sterols
46
A major membrane component in animal cells
cholesterol
47
Cholesterol stabilizes the cell membrane by ____
forming interactions with the phospholipid tails and heads This makes their structure more rigid and helps provide stability
48
Paracrystalline state (solid)
a. heat produces thermal motion of acyl side chains (solid --> fluid transition) b. (fluid state) lateral diffusion in plane of bilayer c. transbilayer diffusion
49
Classification of membrane proteins
1. peripheral membrane proteins 2. integral membrane proteins 3. transmembrane proteins
50
proteins that dissociate from the membrane following treatments with polar reagents that do not disrupt the phospholipid bilayer.
peripheral membrane proteins
51
Integral membrane proteins
can be released only by treatments that disrupt the phospholipid bilayer.
51
can be released only by treatments that disrupt the phospholipid bilayer.
integral membrane proteins
51
span the lipid bilayer with portions exposed on both sides of the membrane.
Transmembrane proteins
52
Peripheral MP
proteins that dissociate from the membrane following treatments with polar reagents that do not disrupt the phospholipid bilayer.
53
Transmembrane proteins
span the lipid bilayer with portions exposed on both sides of the membrane.
54
6 types of membrane proteins
1. transport protein 2. receptor protein 3. enzymatic protein 4. cell recognition protein 5. attachment proteins 6. intercellular junction proteins
55
channel for lipid insoluble molecules and ions to pass freely through
Channel Proteins
56
bind to a substance and carry it across membrane, change shape in process
carrier proteins
57
Bind to chemical messengers (Ex. hormones) which sends a message into the cell causing cellular reaction
receptor proteins
58
Carry out enzymatic reactions right at the membrane when a substrate binds to the active site
enzymatic proteins
59
Glycoproteins (and glycolipids) on extracellular surface serve as ID tags (which species, type of cell, individual).
cell recognition proteins
60
are short branched chains of less than 15 sugars
Carbohydrates
61
Attach to cytoskeleton (to maintain cell shape and stabilize proteins) and/or the extracellular matrix
attachment proteins
61
protein fibers and carbohydrates secreted by cells and fills the spaces between cells and supports cells in a tissue.
extracellular matrix
62
Extracellular matrix can influence the ____
activity inside the cell and coordinate the behavior of all the cells in a tissue.
63
types of cell junction (2)
–Tight junctions –Gap junctions
63
Bind cells together
intercellular junction proteins
64
Transmembrane Proteins of opposite cells attach in a tight zipper-like fashion; No leakage
tight junction
64
Examples of tight junctions
Ex. Intestine, Kidneys, Epithelium of skin
65
Describe the tight junction in epithelial cells
TJ bar the movement of dissolved materials from the lumen through the spaces in between
66
Cytoplasmic plaques of two cells bind with the aid of intermediate filaments of keratin; allows for stretching
desmosomes
67
Examples of desmosomes
stomach, bladder, heart
68
a transmembrane protein that binds with other cadherins to form junctions known as desmosomes between cells
desmogleins
69
Channel proteins of opposite cells join together providing channels for ions, sugars, amino acids, and other small molecules to pass.
gap junctions
70
allows communication between cells
gap junctions
71
only intercellular junctions in plants between walls of 2 adjacent plant cells
plasmodesmata
71
examples of gap junctions
heart muscle, animal embryos
72
the motion of protein molecules under the influence of an electric field that is applied across the fluid that they are dispersed in
mobility of membrane proteins
73
Many Membrane Proteins Move _____
Freely in the Plane of the Membrane
74
(FRAP)
Fluorescence Recovery After Photobleaching
74
fusion of membrane protein process
1. cell fusion creates heterocaryon
75
2 types of transport protein
1. channel protein 2. carrier protein

AAA BIO108: General Physiology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions