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BSCI330 SPRING > exam 1 plasma membrane and plant cell wall > Flashcards

exam 1 plasma membrane and plant cell wall Flashcards

1
Q

what is the cell bounded by

A

plasma membrane

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2
Q

what is the plasma membrane composed of

A

phospholipids and sterols (cholesterols in animal cells)

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3
Q

what is the basic structure of cellular membranes

A

bilayers composed on phospholipids

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4
Q

what are lipid bilayers

A

2D fluids that allow lateral diffusion of constituents

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5
Q

what are the microdomains of the plasma membranes called

A

lipid rafts

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6
Q

what are leaflets

A

layers of the bilayer

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7
Q

what do they two leaflets have

A

an asymmetric distribution of phospholipids

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8
Q

what is the plasma membrane

A

a regulated cell boundary - “wall” with windows and doors that can be opened/closed in regulated fashion

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9
Q

what is the main purpose of the plasma membrane

A

prevent water from getting from one side to another

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10
Q

why can steroid hormones diffuse freely through the plasma membrane

A

highly hydrophobic

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11
Q

how can water pass through membrane

A

channels

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12
Q

what are the most abundant lipids in plasma membranes

A

phospholipids

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13
Q

what is the polarity of phospholipids

A

amphipathic - polar head group and two nonpolar hydrocarbon tails

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14
Q

what increases membrane fluidity of phospholipids

A

one tail is saturated (no double-bonds) and the other is unsaturated (one cis double-bond = bent fatty acid tail)

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15
Q

what is the charge of phospholipids

A

net charges are zero

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16
Q

what are sterols

A

important lipid component of membranes

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17
Q

why are sterols important for structural stability of membrane

A

contain rigid ring structures that stiffen portions of phospholipids

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18
Q

what is the major sterol of animal cell membranes

A

cholesterol

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19
Q

what are the major sterols of plant cell membranes

A

phytosterols

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20
Q

what is the major sterol of fungi

A

ergosterol (useful target for antifungal drugs)

21
Q

why can phospholipids spontaneously self-assemble into lipid bilayer membranes

A

because they are amphiphilic

22
Q

what do polar head groups of phospholipids associate with

A

water on the “outsides” of the membrane

23
Q

what do hydrocarbon tails of phospholipids associate with

A

each other on the “inside” of the membrane

24
Q

what is a lipid micelle

A

a lipid molecule in a conical shape

25
Q

what is a lipid bilayer

A

the shape of the lipid is planar/cylindrical

26
Q

what form of phospholipid bilayer is energetically favorable

A

a sealed (sphere-looking) compartment formed by phospholipid bilayer

27
Q

what does the Fluid Mosaic Model describe

A

the properties of the plasma membrane

28
Q

what does it mean that the plasma membrane is a fluid

A

molecules are able to move past each other

29
Q

what does it mean that the plasma membrane is a mosaic

A

it’s made up of lots of little pieces (i.e. not continuous)

it has discrete regions (neighborhoods)

30
Q

why is it difficult for molecules to diffuse from one region to another

A

regions have different lipid and protein compositions

31
Q

what are lipid rafts

A

a type of microdomain that is a region highly concentrated in cholesterol, which makes them stiffer

32
Q

what is lateral diffusion

A

molecules can move past each other

33
Q

what is the plasma membrane derived from

A

the ER membrane

34
Q

what is the symmetry of the plasma membrane

A

asymmetric, which provides voltage across the membrane

35
Q

what do the proteins in the plasma membrane allow for

A

molecules to cross the membrane (molecular transport)

signal transduction

anchorage to cytoskeleton

interaction with other cells/extracellular matrix

36
Q

what are peripheral membrane proteins

A

proteins bound to the membrane surface

37
Q

what are integral membrane proteins

A

proteins inserted into membrane interior

38
Q

how do integral membrane proteins interact with leaflets

A

may span both leaflets via a transmembrane region, or may be anchored via attachment of lipid groups that insert into one leaflet

39
Q

what are plant cells surrounded by

A

the plant cell wall

40
Q

what does the plant cell wall do

A

separates inside and outside of plasma membrane of plant cell

41
Q

what is the major component of the plant cell wall

A

cellulose, a polymer of glucose that provides tensile strength comparable to steel

42
Q

what is tensile strength

A

resistance to stretching

43
Q

what is lignin

A

waterproofing

44
Q

what is pectin

A

provides resistance to compression

45
Q

what are components of the plant cell wall

A

pectin and lignin

46
Q

Animals lack a cell wall. What will happen if animal cells are placed in a highly hypotonic environment?

A

they will expand until they burst OR nothing - animal cells are capable of regulating water flow in and out

47
Q

what is turgor pressure

A

the hydrostatic pressure resisted by the cell wall, which builds up when water flows into a cell

48
Q

what is the purpose of turgor pressure

A

allows plant cells to be rigid

49
Q

how does turgor pressure help with growth

A

it can force the cell to elongate and grow in specific directions

BSCI330 SPRING (24 decks)

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