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BIOL 2170 > Membranes and Cells > Flashcards

Membranes and Cells Flashcards

1
Q

what is the fluid mosaic model

A

the general structure of membranes

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2
Q

T or F: proteins float on the phospholipid bilayer

A

T

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3
Q

what part of the phospholipid is hydrophilic

A

the head

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4
Q

what part of the phospholipid is hydrophobic

A

the tail

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5
Q

why do lipids maintain a. bilayer organization spontaneously

A

helps membranes fuse during exocytosis

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6
Q

what is a phospholipid structure called in the cell

A

a vesicle

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7
Q

can membranes vary in lipid composition

A

yes

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8
Q

how do phospholipids vary

A

fatty acid, chain length, degree of saturation, phosphate head groups

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9
Q

what is the structure of the phospholipid bilayer

A

flexible and the interior is fluid allowing lateral movement of molecules

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10
Q

what does fluidity depend on

A

temperature and lipid composition
higher temp = more fluid
lower temp = less fluid

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11
Q

how to the phospholipid tail lengths affect fluidity

A

shorter tail = more fluid
longer tail = less fluid

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12
Q

what is the fluidity of saturated vs unsaturated fatty acids

A

saturated = less fluid (no double bonds)
unsaturated = more fluid (one or more double bonds)

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13
Q

where are the carbohydrates on the membrane

A

outer surface

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14
Q

what purpose to carbohydrates serve on the outer surface of the membrane

A

recognition sites for other cells and molecules

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15
Q

what type of protein is typically a transmembrane protein: span the bilayer, hydrophilic ends protrude on either sides

A

integral membrane protein

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16
Q

what type of membranes do not penetrate the bilayer and are only temporarily associated with the internal or external side of the membrane

A

peripheral membrane proteins

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17
Q

T or F: some membrane proteins can move freely within the bilayer, while some are anchored to a specific region

A

T

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18
Q

what are membrane proteins anchored by

A

cytoskeleton or lipid rafts (a defined patch of membrane with distinct components

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19
Q

FRAP experiment

A

used mouse cells to prove that membrane proteins can diffuse rapidly in the plane of a membrane

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20
Q

what is selective permeability

A

some substances can pass through, but not others (membranes have this)

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21
Q

what is passive transport

A

no outside energy required - diffusion based

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22
Q

what are the two types of passive transport

A
  1. simple diffusion
  2. facilitated diffusion
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23
Q

what is active transport

A

movement of substances across the membrane AGAINST a concentration and/ or electrical gradient and it REQUIRES ENERGY

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24
Q

what are the two types of active transport

A
  1. primary active transport
  2. secondary active transport
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25
Q

what is the NET movement from regions of greater concentration to regions of lesser concentration

A

diffusion

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26
Q

what is it called when particles continue to move, but there is no net change in distribution

A

equilibrium

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27
Q

what does diffusion rate depend on

A

diameter of molecules (larger = slower)
temperature of solution (higher temp = faster)
electrical charges (like charges repel = slow and opposite charges attract = faster)
concentration gradient (big difference = rate higher)

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28
Q

what is permeable

A

solutes move easily though membrane

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29
Q

what is impermeable

A

solutes cannot move across membrane

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30
Q

what type of diffusion: hydrophobic molecules easily pass through the lipid bilayer

A

simple diffusion

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31
Q

does water diffuse across the membrane slow or fast

A

slowly

32
Q

can electrically charged and polar molecules pass through the membrane easily

A

no

33
Q

is o2+co2 slow or quick to diffuse

A

quick

34
Q

are hydrophobic things permeable

A

yes they cross the membrane

35
Q

are hydrophilic things permeable

A

no they do not cross the membrane

36
Q

the diffusion of water across membranes (high - low)

A

osmosis

37
Q

diffusion of water from a region of _ water concentration to a region of _ water concentration

A

high
low

38
Q

what does osmosis depend on

A

the number of solute particle present, not the type of particles

39
Q

equal solute concentration (and equal water concentration)

A

isotonic solution

40
Q

higher solute concentration

A

hypertonic solution

41
Q

lower solute concentration

A

hypotonic solution

42
Q

water will diffuse from a __ solution across a membrane to a __ solution

A

hypotonic
hypertonic

43
Q

in what solution to animal cells burst

A

hypotonic

44
Q

plant cells with rigid cell walls build up internal pressure that keeps more water from entering

A

turgor pressrure

45
Q

what type of diffusion: (passive) of polar molecules requires membrane proteins

A

facilitated diffusion

46
Q

what type of proteins have a central pore lined with polar amino acids (faster)

A

channel proteins

47
Q

what type of proteins are membrane proteins that bind some substances and speed their diffusion through the bilayer (slower)

A

carrier proteins

48
Q

what are integral membrane proteins that form channels

A

ion channels

49
Q

what does it mean for an ion channel to be gates

A

can be closed or open to ion passage
-gates open when protein is stimulated to change its shape
-ligand (molecule or signal) vs voltage gated

50
Q

what exists because cells maintain an imbalance of ion concentrations across the plasma membrane

A

voltage potential

51
Q

what does rate and direction of ion movement through channels depend on

A
  1. concentration gradient
  2. distribution of electrical charge
52
Q

water can diffuse through special water channels called

A

aquaporins

53
Q

what do carrier proteins transport

A

polar molecules such as glucose across the membrane in both directions

54
Q

glucose binds to protein causing it to

A

change shape

55
Q

are proteins specific in active transport

A

yes

56
Q

what type of transport requires direct hydrolysis of ATP

A

primary active transport

57
Q

in what type of transport does energy come from an ion concentration gradient that is established by primary active transport

A

secondary active transport

58
Q

what is the sodium potassium pump an example of and where is it found

A
  1. primary active transport
  2. found in ALL animal cells and the pump is an integral membrane glycoprotein
59
Q

what are symports

A

in secondary active transport and it is where both substances are moving in the SAME direction

60
Q

what are antiports

A

in secondary active transport where substances move in opposite directions

61
Q

along the protein concentration gradient energy is released to

A

move another substance against its concentration gradient

62
Q

the first unifying theory of biology

A

cell theory

63
Q

what is cell theory

A
  1. cells are the fundamental units of life
  2. all organisms are composed of cells
  3. all cells come from preexisting cells
64
Q

what are some exceptions to the fact that cells are small

A

bird eggs, neurons, some algae and bacteria cells

65
Q

T or F: prokaryotic cells are 10x larger than eukaryotic

A

false

66
Q

why are cells small

A

they need a high surface area to volume ratio

67
Q

what determines the amount of chemical activity in the cell per unit time

A

volume

68
Q

determines the amount of substances that can pass the cell boundary per unit time

A

surface area

69
Q

what does the plasma membrane do

A

all cells are surrounded by it and it allows cells to maintain a constant internal environment (homeostasis), is a selectively permeable barrier, is important in communication and receiving signals

70
Q

all living organisms are __

A

eukaryotic

71
Q

DNA is a membrane enclosed compartment called the

A

nucleus

72
Q

what type of cell is
1. enclosed by a plasma membrane
cytoplasm consists of cytosol and suspended particles (ribosomes)
2. The DNA is contained in the nucleotide
3. ribosomes– site of protein synthesis

A

prokaryotic

73
Q

T or F: most prokaryotic cells have a rigid cell wall outside the plasma membrane

A

true

74
Q

in photosynthetic bacteria, the plasma membrane folds into the cytoplasm to form an __ system where photosynthesis occurs

A

internal membrane

75
Q

some prokaryotes swim using

A

flagella

76
Q

some bacteria have __ which is a hair like structure projecting from the surface

A

pili

BIOL 2170 (11 decks)

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