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Membrane Flashcards

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Biology 101 flashcards
1
Q

The Functions of Membranes

A

define boundaries and serve as permeability barriers

are sites of specific functions
.
regulate the transport of solutes

detect and transmit electrical and chemical signals

mediate cell-to-cell communication

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2
Q

Composition of Plasma Membrane

A

lipids,

proteins

carbohydrates

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3
Q

most abundant lipids in membranes

A

phospholipids

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4
Q

types of Phospholipids in membrane

A

Glycerol-based phosphoglycerides
Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine
PhosphotidylEnositol (Not as abundant)

Sphingolipids
sphingomyelin

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5
Q

major classes of lipids in Membranes

A

Phospholipids (most abundant)

Glycolipids

Sterols

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6
Q

Cerebrosides

Gangliosides

A

Glycolipids

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7
Q

name the parts

A
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8
Q

effects of fatty acid composition

on membrane fluidity

A

Long-chain fatty acids: higher Tm than shorter-chain

unsaturated fatty acids: tend to have lower Tm and are more fluid

Fluidity is enhanced by increased temperature and a high degree of unsaturation of fatty acid tails

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9
Q

effects of sterols

on membrane fluidity

A

less fluid at higher temperatures

Increases fluidity at lower temperatures
prevents fatty acid chains from getting close

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10
Q
A
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11
Q
A
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12
Q

Lipid Rafts

A

Also called microdomains

localized regions of membrane lipids that are involved in cell signaling

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13
Q

Peripheral Membrane proteins

A

Associate through weak electrostatic forces and hydrogen bonding

change in pH or salt remove them

Lack discreet hydrophobic segments

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14
Q

Integral membrane proteins

A

Singlepass or multipass proteins

Hydrophobic transmembrane segments

Some are lipid-anchored proteins

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15
Q
A
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16
Q

Single-pass transmembrane protein

Key points

(Oligosaccharide chains disulfide bonds)

A

Oligosaccharide chains and disulfide bonds

are on the extracellular side

in the cytosolic domain do not form disulfide bonds because the reducing environment in the cytosol maintain these groups in their reduced (-SH) form

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17
Q

Glycocalyx

A

surface (sugary) coat of carbohydrates extending from

_glycoproteins _(integral membrane) and

_glycolipids (_oligosaccharide side chains)

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18
Q
A
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19
Q

Simple Diffusion

A

Unassisted movement down the gradient

moves solutes toward equilibrium

from regions of higher to lower free energy

limited to small, nonpolar molecules

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20
Q

Osmosis

A

diffusion of water across a

differentially permeable membrane

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21
Q

Hypertonic

A

a solution with a higher solute concentration

than inside the cell

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22
Q

Isotonic

A

a solution with an equal solute concentration

than inside the cell

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23
Q

Hypotonic

A

a solution with a lower solute concentration

than inside the cell

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24
Q

Osmosis

A
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25
Q

Facilitated Diffusion

(clases)

A

Protein-mediated movement down the gradient

not require input of energy

2 classes : Carriers and channels

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26
Q

Carrier proteins

A

transporters or permeases

bind one or more solute molecules on one side of the membrane and undergo conformational change to deliver solute to the other side of membrane

analogous to enzymes in their specificity and kinetics

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27
Q

Channel proteins

(examples)

A

form hydrophilic channels,

often transport ions

Ion channels
Porins
Aquaporins

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28
Q

Uniport

A

Carrier proteins

transport single solute

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29
Q

Cotransport

A

Carrier proteins

transport two solutes

Symport and Antiport

30
Q
A
31
Q

Ion channels

A

only participate in passive transport

transport inorganic ions

Voltage-gated
Ligand-gated
Mechanosensitive

32
Q

Porins

A

Transmembrane proteins that allow

rapid passage of various solutes

33
Q

Aquaporins

A

Transmembrane channels that allow

rapid passage of water

34
Q

Active transport

A

Protein-mediated movement up the gradient

requires energy!

has directionality

35
Q

Three major functions

of Active transport

A

Uptake of essential nutrients

Removal of secretory products and waste

Maintain nonequilibrium intracellular [] of ions

36
Q

Direct active transport

A

the accumulation of solute molecules or ions on one side of the membrane

is coupled directly to an exergonic chemical reaction (ATP hydrolysis)

Na+/K+ Pump

37
Q

Indirect active transport

A

depends on the cotransport of two solutes,

with the movement of one solute down its gradient

driving the movement of the other solute up its gradient

Na+/glucose symporter

38
Q

what is it?

A

Na+/K+ Pump

39
Q

what is it and what kind?

A

Indirect Transport:

Na+/glucose symporter

40
Q

Wha is it?

Name the parts

A

Transcellular Transport of Glucose

41
Q

explain the process involve

A

Glucose is pumped into cell by a Na+ powered glucose symporter.

Glucose passes out of cell (down its conc. gradient) by passive movement through a different GLUT in the basal and lateral membrane domains.

The Na+ gradient driving the glucose symport is maintained by the Na+ pump in the basal and lateral plasma membrane domains, which keeps the internal concentration of Na+ low

42
Q

Four types of Transport ATPases

A

P-type ATPases (P for phosphorylation)

F-type ATPases (F= factor)

V-type ATPases (V=vesicle)

ABC-type ATPases (ATP-binding cassette)

43
Q

P-type ATPases

A

(P for phosphorylation):

Reversibly phosphorylated by ATP as part of the transport mechanism.

responsible for maintaining an ion gradient across the membrane

Example: Na/K pump and proton pump in stomach

44
Q

F-type ATPases

A

(F=factor): ATP synthases.

Proton transporter found in bacteria, chloroplasts and in mitochondria..

Not only can ATP be used as an energy source to generate and maintain electrochemical gradients,

but such gradients can be used as an energy source to synthesize ATP

45
Q

V-type ATPases

A

(V=vesicle):

Pump protons into such organelles as: vesicles, vacuoles, lysosomes, endosomes, and the Golgi complex

in a phosphorylation independent manner

Structurally related to F-type ATPases

46
Q

ABC-type ATPases

A

(ATP-binding cassette):

Large superfamily. Handles a wide variety of solutes. (ions, sugars, AA, peptides and polysaccharides)

Example: Multidrug resistance transport protein found in tumor cells, may help these cells evade drug therapy.

47
Q

Cystic fibrosis transporter gene

(CFTR)

A

encodes for a chloride transporter.

Mutation in this gene causes cystic fibrosis

ABC Transporter Superfamily

48
Q

Cystic Fibrosis

A

inability of cells to transport chloride and water to body secretions

increased frequency of respiratory infections

pancreatic insufficiency

Males often are sterile

progressive lung disease is the principle cause of death

49
Q

what is happening and

which disease is it?

A

dehydrated mucus

Cystic fibrosis

50
Q

Endocytosis

and what types (3)

A

Uptake of macromolecules from the extracelluar surroundings by localized regions of plasma membrane

Phagocytosis
Pinocytosis
Receptor-mediated – binding of ligands to receptors triggers vesicle formation

51
Q

Phagocytosis

A

endocytosis of large particulate substances

52
Q

Pinocytosis

A

endocytosis of fluid and dissolved solutes

53
Q

Exocytosis

A

secretion of macromolecules by transport vesicles

54
Q

Signal transduction

A

Detection of specific signals at the cell surface

and the mechanism by which such signals are transmitted into the cell’s interior,

resulting in changes in cell behavior and/or gene expression

55
Q

Primary messenger

Second messenger

A

1-A molecule that binds to a receptor, thereby beginning the process of transmitting a signal to the cell

2-substances that transmit signals from extracellular signaling ligands to the cell interior

56
Q

chemical signals that can be received by cells

A
57
Q

types of Extracellular Signal Molecules

A

Endocrines

Paracrines

Autocrines

58
Q

Endocrines hormone

A

exerts its actions on specific target cells,

which may be some distance away

59
Q

Paracrines actions

A

those performed on nearby cells, and the location of the cells plays a role in the specificity of the response

Very important in limiting immune response to a specific location in the body

60
Q

Autocrine actions

A

messenger that acts on the cell from which is secreted,

or on nearby cells that are the same type as the secreting cells.

61
Q

If deprived of appropriate survival signals, a cell will undergo a form of cell suicide known as

A

apoptosis

62
Q

3 SIGNALING PATHWAYS BY WHICH EXTRACELLULAR LIGANDS INFLUENCE GENE EXPRESSION

A
63
Q

use intracellular gene-specific trancription factors (Receptors)

A

lipophilic hormones

steroid hormones, thyroid hormones, retinoic acid and vitamin D

64
Q

3 largest classes of cell-surface receptor proteins

A

Ion-channeled coupled receptors

G-protein-coupled receptors

Enzyme-coupled receptors

65
Q

Ion-channeled coupled receptors

A

rapid synaptic signaling between nerve cells and other electrically excitable target cells such as muscle cells.

Mediated by neurotransmitters that transiently open or close and ion channel formed by the protein to which they bind

66
Q

G-protein-coupled receptors

A

indirectly regulate the activity of a separate

plasma-membrane-bound target protein, which is generally either an enzyme or an ion channel

A trimeric GTP-binding protein mediates the interaction between the activated receptor and this target protein

67
Q

Enzyme-coupled receptors

A

Either function directly as enzymes or

associate directly with enzymes that they activate

68
Q

which cell-surface receptor proteins

A

Ion-channeled coupled receptors

69
Q

which cell-surface receptor proteins

A

G-protein-coupled receptors

70
Q

which cell-surface receptor proteins:

A

Enzyme-coupled receptors

Cell bio (3 decks)

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