2.08 Membranes and Transport System Flashcards Preview

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Flashcards in 2.08 Membranes and Transport System Deck (104)
1

Vesicles surrounded by a lipid bilayer with an aqueous interior

Liposomes

2

Tested as red cell substitute, to deliver encapsulated drugs and as vectors for gene therapy

Liposomes

3

Membranes lipids are composed of _______

Phospholipid
Glycolipid
Cholesterol

4

2 types of membrane proteins

Integral protein
Peripheral protein

5

Permanently bound, fixed in the membrane

Integral protein

6

Do not penetrate the hydrophobic layer of membrane

Peripheral protein

7

___ are asymmetrically distributed in the membranes

Lipids

8

ATP-dependent lipid class of transporters specific for phosphatidylserine and phosphatidylethanolamine

Flippase

9

Outward directed ATP-dependent transporter; non-specific for phospholipid

Floppase

10

Most membrane lipid and protein can freely move through the membrane plane

Lateral mobility

11

Fluidity of membrane depends on ____ and ___

Temperature
Lipid composition

12

Temperature at which membrane starts to become fluid from gel-like consistency

Transition temperature

13

Interactions between hydrophobic tails ____ fluidity

Decrease

14

Increase in fluidity , ___ in permeability to water and other small hydrophilic molecules

Increase

15

Membrane allows adjustments of cell compositions and functions

Selectivity

16

Steroid, amphipathic, found in animal cells, found in both leaflets of bilayer

Cholesterol

17

Major lipid component of cell membrane, amphipathic, phosphatidylcholine, sphingomyelin

Phospholipid

18

Cholesterol (increases/decreases) fluidity if the temperature is below the transition temperature

Increases
It interferes with the interaction of hydrocarbon fails of fatty acids

19

As the fluidity increases, the permeability to water and other small hydrophilic molecules ______

Increases

20

As the concentration of unsaturated fatty acids in the membrane increases, fluidity _____

Increases

21

Cholesterol (increases/decreases) fluidity if the temperature is above the transition temperature

Decreases
It limits the disorder because cholesterol is more rigid than the hydrocarbon tails of the fatty acids

22

Contains choline head group and glycerophosphoric acid
Precursor of sphingomyelin

Phosphatidylcholine

23

Contains predominantly the longer chain fatty acids, with carbon length of 24
Serves in signal transduction and insulation of nerve fibers

Sphingomyelin

24

Least common of the membrane lipids
Always found on the leaflet membrane

Glycolipid

25

Involved in the cell identity

Glycolipid

26

Penetrate bilayer or span membrane

Integral protein

27

2 types of integral protein

Transmembrane protein
Covalently tethered integral protein

28

Single pass or multiple pass

Transmembrane protein

29

Integral proteins are synthesized in ____

RER

30

Functions of integral proteins

Enzymatic
Receptor
Transport
Communication
Adhesion

31

Proteins that do not penetrate the whole membrane
Not covalently linked to other membrane compounds

Peripheral proteins

32

Peripheral proteins are synthesized in ____ and ____

Cytoplasm (cytoplasmic-inner- side)
ER and exocytosed (extracellular-outer-side)

33

____ play a role in cell-to-cell recognition

Membrane carbohydrates (oligosaccharides)

34

Specialized region in the membrane that play a role in signaling
Composed of cholesterol and sphingomyelin

Lipid rafts

35

Little caves
Groups of integral protein that contain caveolin
Transcellular pathway or signaling process

Caveolae

36

Intercellular juction that serves as barrier to prevent the molecules and ions to move freely between cells

Tight junctions

37

Constitutive, regulated

Exocytosis

38

Preferably at clathrin coated pits

Endocytosis

39

Processes involved in the cell membrane

Exocytosis
Endocytosis
Phagocytosis/pinocytosis
Small solute movement

40

Allow direct flow of molecules from one cell to another

Gap junction

41

Movement across biological membrane, does not require energy

passive diffusion

42

Tendency of the molecules of any substance to spread out in available space

Diffusion

43

Movement may be random or directional
Across permeable membrane

Diffusion

44

Molecules with limited permeability can diffuse though bilayer with the aid of ____

Transported protein

45

Solutes move down a gradient of electrochemical potential in combination with a carrier

Facilitated diffusion

46

Movement of water

Osmosis

47

Enzymes couple net solute movement across a membrane to ATP hydrolysis

Active Transport

48

In active transport, Km for carrier loading is asymmetrical. It is ____ on the side of the membrane toward which active transport occurs

Higher

49

Transport system is an ATPase

Primary active transport

50

Utilizes the Na+ electrochemical gradient

Secondary active transport

51

4 Primary active transporters

P-type
V-type
F-type
ATP-binding casette transporter

52

De/phosphorylated during the transport of Na, K, Ca

P-type

53

Proton pumps responsible for acidification of the interior of lysosomes, endosomes, Golgi vesicles and secretory vesicles

V-type

54

Present in mitochondria, translocate protons at the expense of ATP hydrolysis

F-type

55

Catalyze ATP-dependent vectorial movement of diverse substances

ABC transporter

56

Multidrug resistance family
Sulfonylurea receptor
Cystic fibrosis transmembrane conductance regulator

ABC transporter

57

Atypical ABC transporter
Indirectly regulates ____ channels

Sulfonylurea receptor; Potassium

58

Utilize a secondary structure of energy such as transmembrane electrochemical gradient of either sodium or hydrogen

Secondary active transport

59

Involves interaction with the solute and changing shape

Carrier transport protein

60

Allows the solute to pass through without binding and changing shape

Channel transport protein

61

Ion carriers or channels produced by microorganisms

Ionophores

62

Carriers exhibit _____ with respect to solute concentration

saturation kinetics

63

Carriers will only recognize a specific structure

Stereospecificity

64

Characteristics of carrier protein

Saturation kinetics
Stereospecificity
Susceptible to inhibition
Susceptible to hormonal control
Influence of insulin on the GLUT
Influence of aldosterone on the Na-K transporter

65

Transport rate mediated by carrier is (faster/slower) than the transport with no catalyst

Faster

66

Transport rate mediated by carrier is (faster/slower) than w/ channels

Slower

67

Too large to move across the membrane
Transmembrane proteins with fixed topology

Carrier proteins

68

Classes of carrier protein

Uniport
Symport
Antiport

69

Facilitated diffusion
Carriers mediate transport of a single solute

Uniport

70

GLUT 1
Valinomycin

Uniport

71

Large integral protein
Predicted via hydropathy plots to have 12 transmembrane helices

GLUT1

72

Carrier for potassium; reversibly binds a single potassium ion

Valinomycin

73

Can undergo conformational change associated with bound substate
Mediate net solute transport

Uniport

74

Carriers bind 2 dissimilar solutes (substrate) and transport them together across a membrane

Symport

75

In symport, transport of the 2 solutes is _____

Obligatorily coupled

76

glucose-sodium symport

Symport

77

A gradient of 1 substrate, usually an ion, may drive uphill transport of cosubstrate

Symport

78

Carrier exchange one solute for another across a membrane

Antiport

79

ADP/ATP exchanger

Antiport

80

Small, very hydrophobic intrinsic membrane proteins with several highly conserved AA sequences

Aquaporin

81

Allow water molecules to enter cell

Aquaporin

82

Caused by mutation in the gene encoding for aquaporin (AP-2)

Nephrogenic diabetes insipidus

83

Usually consists of large protein complexes with multiple transmembran alpha-helices

Cellular channels

84

Form of allosteric regulation.

Control of channel gating

85

Conformational changes associated with channel opening may be regulated by

Voltage
Binding of ligand
Membrane stretch

86

An unusual peptide, with alternating D and L amino acids

Gramicidin channels

87

Channels cycle between open and closed conformations

Ion channels

88

Many ions flow through a channel, each it opens

Ion channels

89

Higher transport rates for ____

Channels

90

The membrane itself wraps around particle and pinches off a vesicle inside the cell

Endocytosis

91

Type of endocytosis in which an entire cell is engulfed

Phagocytosis

92

Type of endocytosis in which external fluid is engulfed

Pinocytosis

93

The material to be transported binds to certain specific molecules in the membranes

Receptor-mediated endocytosis

94

Large molecules that are manufactured in the cell are released through cell membrane

Exocytosis

95

Causes short-limbed dwarfism
Cartilage is not converted to bone through bone ossification

Achondroplasia

96

Achondroplasia is due to mutation of ___

Fibroblast Growth Factor 3

97

Genetic mutation in the low density lipoprotein receptor

Familial hypercholerostemia

98

Autosomal recessive disease that leads to chronic lung inflammation, infertility in males and pancreatic insuffiency

Cystic fibrosis

99

Cystic fibrosis is due to gene mutation in ___ , an ABC transporter, which acts as a chloride ion channel

Cystic Fibrosis Transmembrane Regulator

100

Autosomal recessive disorder copper excretion
Accumulation of copper in the body

Wilson disease

101

Wilson disease is caused by defect in the ____, encodes for ATP-dependent P-type ATPase that transports copper ions from the liver to the bile canaliculi

ATP7/B Gene

102

Happens when cancer cells interact with oligosaccharides in glycoproteins and glycolipids in the cell membrane (selectin, integrin)

Metastasis of cancer cells

103

Leads to polyuria
Water is not reabsorbed in the kidneys

Nephrotic Diabetes Mellitus

104

____ in the apical membrane does not respond to vasopressin >> does not allow permeability in the collecting duct cells, thus preventing water reabsorption that leads to polyuria

Aquaporin-2