2b- Cell membrane transport Flashcards
(85 cards)
1
Q
in
A
Food
- carbohydrates
- sugars,
- proteins
- amino acids
- lipids
- salts
- O2
- H2O
2
Q
out
A
Waste
- ammonia
- Salts
- CO2
- H2O products
3
Q
Permeability of plasma membrane
A
- Differentially (selectively) permable
4
Q
Materials allowed to pass
A
Water, oxygen, carbon dioxide
5
Q
prevents other from passing
A
Protein, Carbohydrates
6
Q
Factors that determine how a substance may be transported across a plasma membrane:
A
- Size
- Polar or nonpolar
- Charge
7
Q
- 2nd law of Themodynamics
- governs biological systems
– universe tends towards disorder (entropy)
A
Passive diffusion
8
Q
movement from high to low concentration
A
Passive diffusion
9
Q
Are the molecules are able to diffuse across a phospholipid bilayer at significant rates by using passive diffusion.
A
Only small, relatively hydrophobic
10
Q
Gases
A
- Oxygen
- carbon dioxide
11
Q
Water molecules
A
- rate slow due to polarity
12
Q
Lipid
A
Steroid Hormones
13
Q
lipid soluble molecules
A
- Hydrocarbons
- alcohols
- some vitamins
14
Q
small nonecharged molecules
A
- NH3
15
Q
Why is diffusion important to cells and humans?
A
- Cell respiration
- Alveoli of lungs
- Capillaries
- Red Blood Cells
- Medications: time
release capsules
16
Q
Diffusion through protein channels which do not interact with hydrophobic interior
- no energy needed
A
Facilitated diffusion
17
Q
with help
A
facilitated
18
Q
fast transportation
A
Open channel
19
Q
two kinds of proteins
A
- Carrier proteins
- Channel proteins
20
Q
bind specific molecules, undergo conformational change to release molecule
A
Carrier proteins
21
Q
example of carrier protein
A
Glucose transporters
22
Q
- form open pores for free diffusion
- found in gap junctions
A
Channel proteins
23
Q
Molecules will randomly move through the pores in ____ ____
A
Channel proteins
24
Q
do not extend through the membrane
A
Some carrier proteins
25
Other carrier proteins ____ ___ to move materials across the cell membrane
change shape
26
How do molecules move through the plasma membrane by facilitated diffusion?
* Channel and Carrier proteins are specific:
* Channel Proteins allow ions, small solutes, and water to pass
* Carrier Proteins move glucose and amino acids
* Facilitated diffusion is rate limited, by the number of
proteins channels/carriers present in the membrane.
27
- provide corridors allowing water molecules to cross the membrane.
- Allow for fast transpor
- water channels
- protein pores used during osmosis
Aquaporins
28
is the diffusion of water across a differentially permeable membrane.
Osmosis
29
is the pressure that develops in a system due to osmosis.
Osmotic pressure
30
Different concentration
Hypertonic
Hypotonic
Isotonic
31
more solute, less water
Hypertonic
32
less solute, more water
Hypotonic
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equal solute, equal wate
Isotonic
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- animal cell immersed in mild saltsolution
- volume of cell is stable
- no net movement of water
isotonic
35
a cell in fresh water
- Gains water, swell & can burst
Hypotonic
36
plant cell in hypotonic
turgid
37
a cell in salt water
- lose water and die
Hypertonic
38
plant cells in hypertonic
Plasmolysis = wilt
39
Water regulation in Paramecium
Contractile vacoule
40
Examples of Osmosis in Cells and Humans
Cells:
- Removes water produce by cell respiration
Human:
- Large intestine cells transport water to bloodstream
- Kidney cells form urine
41
regulates the opening/closing of the channel
Member potential (voltage)
42
permit the free passage of ions and small polar molecules through the outer membranes of bacteria.
Porins
43
mediate the passage of ions across plasma membranes.
Ion channels
44
channels open in response to the binding of neurotransmitters or other signaling molecules.
Ligand-gated
45
channels open in response to changes in electric potential across the plasma membrane
Voltage-gated
46
open or close depending on the presence or absence of a physical or chemical stimulus.
Gated channels
47
Examples of voltage gated channels
- K+ voltage-gated channels
- Na+ voltage gated channels
48
regulates opening/closing of the channel
Membrane potential
49
exist as either open or close depending on the membrane voltage. It has only an activation gate.
K+ voltage-gated channels
50
- opens when the membrane potential depolarizes
- It has activation and
inactivation gates
Na+ voltage gated channels
51
Cells may need to move molecules against concentration gradient
- costs energy = ATP
Active transport
52
Importance active transport
- Bring essential molecules
- Rid cell of unwated molecules
- Maintain internal conditions
53
2 groups of active transport
- Primary active transport
- Secondary active transport
54
Two substances are transported in the same direction across a
plasma membrane.
Symporter
55
Two substances are transported across the membrane in opposite directions across the plasma membrane.
Antiporter
56
transport only a single molecule using the facilitated diffusion of glucose.
Uniport
57
uses active transport to move two molecules in opposite directions.
Antiport
58
- moving things out.
- Transport of large molecules
Vesicle formation
59
Substance transported in Exocytosis
- Neurotransmitters
- Hormones
- Digestive enzymes
60
Exocytosis of Proteins
- Vesicle formation -> Golgi body -> ER
61
Vesicles form as a way to transport molecules out of a cell
Exocytosis
62
susbtance transported in exocytosis
Neurotransmitters, hormones and digestive enzymes.
63
Vesicles form as a way to transport molecules
into a cell.
Endocytosis
64
Types of endocytosis
- Phagocytosis
- Pinocytosis
- Receptor mediated endocytosis
65
Large,particulate matter (Bacteria, viruses, and aged or dead cells).
Phagocytosis
66
Liquids and small particles dissolved in liquid
Pinocytosis
67
Ligandreceptor complexes trigger infolding of a clathrin pit that forms a vesicle containing ligands
Receptor mediated endocytosis
68
Substance/Products transported by Receptor mediated endocytosis
- Some Vitamins
- Certain Hormones
- Antibodies
69
Most common form of
endocytosis
Pinocytosis
70
pinocytosis is also called
Cell drinking
71
Examples of pinocytosis
- Intestinal cells
- Kidney cells
- Plant root cells
72
a form of pinocytosis, provides a mechanism for the selective uptake of specific macromolecules.
Receptor-mediated endocytosis
73
Example of materials transported by Receptor mediated endocytosis
- Uptake of cholesterol by animal cells
if with receptors in the surface
- Hormones, Cholesterol
74
are specialized regions of the plasma membrane where specific cell surface receptors are found
Clathrin-coated pits
75
a membrane associated GTP-binding protein, assists in the budding off of pits from the plasma membrane.
Dynamin
76
Clathrin occupied space
About 1-2% of the surface area of plasma membranes
77
What does clathrin formes
forming invaginated pits
78
___ assembles into a ____ structure that ____ the membrane
- Clathrin
- basketlike
- distorts
79
located at the periphery of the cell, that fuse with clathrin-coated vesicles which have shed their coats
Endosomes
80
Important features of early endosomes
- Maintain acidic internal pH as the result of the action of a membrane H+ pump
81
is the major fate of membrane proteins taken up by receptor-mediated endocytosis
Recycling to the plasma membrane
82
is a phenomenon where receptor-ligand complexes are removed from the plasma membrane
Receptor-down regulation
83
are phagosomes fused to lysosomes, contain lysosomal acid hydrolases that digest the ingested material
Phagolysosomes
84
Does not move chloride ions causing sticky mucus to build up on the out side of the cell
- Mutant CFTR channel
85
moves chloride ions to the outside of the cell
- Normal CFTR channel
