Plasma Membrane Transport (2.4) Flashcards
1
Q
State the 2 major bulk transport mechanisms
A
- Endocytosis
2. Exocytosis
2
Q
Describe the type of substance transported across the cell membrane via osmosis
A
Water
3
Q
Describe the type of substances transported across the plasma membrane via simple diffusion
A
Hydrophobic molecules
4
Q
Provide 3 examples of substances transported across the plasma membrane via simple diffusion
A
- Water
- Oxygen
- Carbon dioxide
5
Q
Describe the type of substances transported across the plasma membrane via facilitated diffusion
A
Hydrophilic molecules
6
Q
Provide 4 examples of substances transported across the plasma membrane via facilitated diffusion
A
- Glucose
- Amino acids
- Sodium ions
- Potassium ions
7
Q
Describe concave plasmolysis
A
Contraction of the protoplasm and plasma membrane -> results in pocket formation
Points of attachment between cell wall and protoplasm remain
8
Q
Outline solution reversibility of concave plasmolysis
A
Hypotonic solutions
9
Q
Describe flaccidity
A
Loss of turgor due to the lack of net water movement between the plant cell and environment
10
Q
State solution type associated with flaccidity
A
Isotonic solution
11
Q
State cell type associated with flaccidity
A
Plant cells
12
Q
Describe protoplasm
A
Fluid lining the contents of a cell
including cytoplasm and cell membrane
13
Q
Describe cytolysis
A
Bursting of cell due to influx of water
14
Q
State solution type associated with cytolysis
A
Hypotonic solution
15
Q
State cell type associated with cytolysis
A
Animal cells
16
Q
Describe plasmolysis
A
Shrinking of the protoplasm away from the cell wall
17
Q
State solution type associated with plasmolysis
A
Hypertonic solution
18
Q
State cell type associated with plasmolysis
A
Plant cells
19
Q
Describe turgidity
A
State of being turgid (especially due to high fluid content)
20
Q
State solution type associated with turgidity
A
Hypotonic solution
21
Q
State cell type associated with turgidity
A
Plant cells
22
Q
Describe hydrostatic (or turgor) pressure
A
Pressure exerted by fluid against the plant cell wall
23
Q
Describe ‘particle size’ as a factor affecting the rate of diffusion
A
The smaller the particles, the faster the rate of diffusion through a membrane
24
Q
Describe ‘temperature’ as a factor affecting the rate of diffusion
A
The higher the temperature, the higher the rate of diffusion
25
State the 3 main factors which affect the rate of diffusion across the plasma membrane
- Concentration
- Temperature
- Particle size
26
Describe 'concentration' as a factor affecting the rate of diffusion
The greater the concentration gradient the faster the rate of diffusion
27
Name the process by which proteins change shape to bind to specific molecules which cross the plasma membrane
Conformation
| carrier proteins
28
Describe the process used by carrier proteins to transport molecules across the cell membrane
Process: Conformation
Protein changes shape to allow specific molecules to bind and cross membrane
Protein is restored to original shape once molecule crosses
29
Describe the structure of channel proteins which allows for the transport of molecules across the cell membrane
Specific for substance (don't bind)
| Function like pores which open/close
30
Describe channel proteins
A type of protein found on the plasma membrane that is involved in facilitated diffusion
31
Describe carrier proteins
A type of protein found on the plasma membrane that is involved in facilitated diffusion and active transport
32
State the 2 major membrane transport proteins employed in facilitated diffusion
- Channel proteins
| - Carrier proteins
33
Describe crenation
Cell shrinks due to efflux of water
34
State solution type associated with crenation
Hypertonic solution
35
State cell type associated with crenation
Animal cells
36
Outline the effect of turgor pressure on cell water uptake
Prevents further water uptake in plant cells
37
Describe convex plasmolysis
Plasmolysed cell becomes a spherical protoplast which completely detaches from the cell wall
38
State 2 types of plasmolysis in plant cells
- Concave
| - Convex
39
Outline solution reversibility of convex plasmolysis
Irreversible
40
State the major membrane transport protein employed in active transport processes
Carrier proteins
41
Outline what active transport allows a cell to do
Enables cells to maintain internal concentrations of small solutes which differ from concentrations in its' environment
42
Describe active transport
Movement of a molecule across the cell membrane with the expenditure of energy
43
Describe passive transport
Movement of a molecule across the cell membrane without the expenditure of energy
44
Describe endosmosis
Net water influx
45
Describe the osmotic gradient
Difference in concentration between solutions on either side of a semi-permeable membrane
46
Describe osmolarity
Concentration of a solution expressed as the total number of solute particles per litre
47
State the major type of molecule that can diffuse across the plasma membrane via simple or facilitated processes
Small polar molecules
| very slowly throughout simply diffusion
48
State the 2 major types of molecules that cross the plasma membrane via facilitated diffusion
1. Small ions
| 2. Large, polar, water-soluble molecules
49
State the permeability of small, uncharged molecules across the plasma membrane
Permeable
50
State 2 examples of large, polar, water-soluble molecules
1. Amino acids
| 2. Glucose
51
Describe hypertonic solution
Solution with a higher concentration of solute
| low concentration of free water molecules
52
Describe hypotonic solution
Solution with the lower concentration of solute
| high concentration of free water molecules
53
Describe isotonic solution
Solutions being compared have equal concentrations of the solutes
54
Diffusion occurs because of the...?
Concentration gradient
55
State the transport classification of simple diffusion
Passive
56
State the transport type of facilitated diffusion
Passive
57
State 2 types of molecules that cross the plasma membrane via simple diffusion
1. small, uncharged molecules
| 2. lipid-soluble, non-polar molecules
58
Define osmosis
Movement of free water molecules through a semipermeable membrane from a region of higher free water concentration to a lower free water concentration
59
Describe the polarity of the water molecule
Electrons are not shared equally between the O and H molecules
There is greater concentration of electrons at the O end making O (negatively charged) and H (positively charged)
60
State the permeability of large, polar, water-soluble molecules across the plasma membrane
Non-permeable
| pass through protein carriers
61
State 2 examples of small, uncharged molecules
- Oxygen
| - Carbon dioxide
62
State 3 examples of lipid-soluble, non-polar molecules
- Steroids
- Alcohol
- Chloroform
63
State 2 examples of small polar molecules
- Water
| - Urea
64
State 3 examples of small ions
- Potassium (K+)
- Sodium (Na+)
- Chloride ion (Cl-)
65
State the permeability of small, polar molecules across the plasma membrane
Permeable/selectively permeable
66
State the permeability of lipid-soluble, non-polar molecules across the plasma membrane
Permeable
67
State which organelle synthesises secretory proteins providing an exact location
Ribosomes bound to the RER
68
Describe transport vescicles
Vesicles that move form one part of the cell to another
69
Describe the path of the secretory protein through the Golgi Apparatus
Moves from one cisternae to the next, carried by vesicles
70
State to what face transport vesicles from the Golgi fuse to during exocytosis
Transport vesicles fuse to the 'cis' face of the Golgi
71
Describe the process that occurs when the secretory vesicle and plasma membrane contact one another
Specific proteins alter the arrangement of the phospholipids enabling membrane fusion
72
List the 5 basic stages of secretory protein exocytosis and briefly outline the major stages
1. RER ribosomal synthesis of secretory protein
2. Protein introduced to transport vesicles
3. Transport vesicles fuse to 'cis' face
4. Secretory vesicles carry protein from 'trans' face
5. Secretory vesicle fuses to plasma membrane (exocytosis)
73
Describe the 2 faces of the plasma membrane
1. Cytoplasmic
| 2. Extracellular
74
Describe endocytosis
Cell takes in particles from outside the cell by engulfing it within the plasma membrane to form a vesicle
75
Describe exocytosis
Movement of materials out of a cell via a vesicle
| Vesicles fuse with membrane and contents released into extracellular fluid
76
Describe 'cis' face of the Golgi Apparatus
The side of the Golgi facing the nucleus
| usually near endoplasmic reticulum
77
Describe the 'trans' face of the Golgi Apparatus
Side of the Golgi facing the plasma membrane
78
Describe secretory vesicles
Vesicle that buds from the Golgi Apparatus and contains material to be secreted from cell
(via exocytosis)
79
List the 3 types of endocytosis
1. Phagocytosis
2. Pinocytosis
3. Receptor-mediated endocytosis
80
State whether or not bulk transport requires the expenditure of energy
Yes. Bulk transport requires energy. It is an active transport process.
81
State the bulk transport process employed in the movement of material from the extracellular fluid into the cellular cytoplasm
Endocytosis
82
State the major cellular function of endocytosis
Take in materials in bulk by forming new vesicles from the plasma membrane
83
State the 2 major cellular functions of exocytosis
- Protein secretion
| - Release of cellular waste and lysosomal breakdown products
84
Describe phagocytosis
Engulfment of solid materials in which the plasma membrane surrounds the material, forming a phagosome
85
Describe pinocytosis
Engulfment of a liquid in which the plasma membrane surrounds the substance, forming a vesicle
86
Describe phagosome
Vacuole in cell cytoplasm that contains a phagocytosed particle
87
Describe phagocyte
Cells capable of engulfing pathogens or foreign particles to destroy them
88
Describe pseudopodia
Temporary protrusion of cell cytoplasm that has the capacity to take up food or other particulate matter
89
Describe receptor-mediated endocytosis
Transport of substances into a cell in which a receptor binds to a molecule to trigger its' entry into the cell
90
Describe 2 major types of phospholipid movement within the phospholipid bilayer and relative frequency
- Later movement
(approx. 1-^7 times/second)
- Transverse movement
(once per month)
91
Describe polar molecule
```
Water soluble
(slight charge)
```
92
Describe non-polar molecule
```
Water insoluble
(no charge)
```
93
State the 3 types of passive transport across membranes
- Diffusion
- Facilitated diffusion
- Osmosis
94
Describe a reason supporting the fact that the phospholipid bilayer is impermeable to charged atoms or molecules
Ions have a surrounding shell of water and are consequently too large to move across the membrane via the phospholipid bilayer
(move through protein channels)
95
State whether molecules move up or down the concentration gradient in diffusion
Down the concentration gradient
96
State 3 chemical properties which affects the way molecules cross the plasma membrane
- Size
- Charge
- Polarity
97
Describe exosmosis
Net water efflux
98
Describe solvent
The substance in which a solute dissolves to form a solution
99
Describe solute
A substance that is dissolved in a solvent to form a solution
100
Describe concentration gradient
The difference in concentration of a solute between one region and another. (E.g. across membrane)
101
Describe simple diffusion
Passive movement of a solute from a region of higher concentration to an area of lower concentration
102
Describe facilitated diffusion
Molecules move down the concentration gradient across the plasma membrane by carrier proteins or channel proteins
103
Describe cytoplasm
Jelly like substance surrounding the nucleus (not including the cell membrane)
104
Compare and contrast cytoplasm and protoplasm
Protoplasm is the content of the cell including the cell membrane, cytoplasm and the cell nucleus whereas cytoplasm is the jelly like substance surrounding the nucleus, within the cell membrane.
105
State whether or not most hydrophobic molecules can dissolve in the lipid bilayer and move freely without the aid of membrane proteins
Yes.
106
Describe the relationship between polar and non polar molecules and hydrophobic/hydrophilic classification
Polar molecules - hydrophilic
| Non-polar molecules - hydrophobic
107
Describe the function of a porin
Acts as a protein channel to allow movement of ions/water soluble/polar molecules across the cell membrane
