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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
what is the NET movement from regions of greater concentration to regions of lesser concentration
diffusion
26
what is it called when particles continue to move, but there is no net change in distribution
equilibrium
27
what does diffusion rate depend on
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)
28
what is permeable
solutes move easily though membrane
29
what is impermeable
solutes cannot move across membrane
30
what type of diffusion: hydrophobic molecules easily pass through the lipid bilayer
simple diffusion
31
does water diffuse across the membrane slow or fast
slowly
32
can electrically charged and polar molecules pass through the membrane easily
no
33
is o2+co2 slow or quick to diffuse
quick
34
are hydrophobic things permeable
yes they cross the membrane
35
are hydrophilic things permeable
no they do not cross the membrane
36
the diffusion of water across membranes (high - low)
osmosis
37
diffusion of water from a region of _ water concentration to a region of _ water concentration
high low
38
what does osmosis depend on
the number of solute particle present, not the type of particles
39
equal solute concentration (and equal water concentration)
isotonic solution
40
higher solute concentration
hypertonic solution
41
lower solute concentration
hypotonic solution
42
water will diffuse from a __ solution across a membrane to a __ solution
hypotonic hypertonic
43
in what solution to animal cells burst
hypotonic
44
plant cells with rigid cell walls build up internal pressure that keeps more water from entering
turgor pressrure
45
what type of diffusion: (passive) of polar molecules requires membrane proteins
facilitated diffusion
46
what type of proteins have a central pore lined with polar amino acids (faster)
channel proteins
47
what type of proteins are membrane proteins that bind some substances and speed their diffusion through the bilayer (slower)
carrier proteins
48
what are integral membrane proteins that form channels
ion channels
49
what does it mean for an ion channel to be gates
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
what exists because cells maintain an imbalance of ion concentrations across the plasma membrane
voltage potential
51
what does rate and direction of ion movement through channels depend on
1. concentration gradient 2. distribution of electrical charge
52
water can diffuse through special water channels called
aquaporins
53
what do carrier proteins transport
polar molecules such as glucose across the membrane in both directions
54
glucose binds to protein causing it to
change shape
55
are proteins specific in active transport
yes
56
what type of transport requires direct hydrolysis of ATP
primary active transport
57
in what type of transport does energy come from an ion concentration gradient that is established by primary active transport
secondary active transport
58
what is the sodium potassium pump an example of and where is it found
1. primary active transport 2. found in ALL animal cells and the pump is an integral membrane glycoprotein
59
what are symports
in secondary active transport and it is where both substances are moving in the SAME direction
60
what are antiports
in secondary active transport where substances move in opposite directions
61
along the protein concentration gradient energy is released to
move another substance against its concentration gradient
62
the first unifying theory of biology
cell theory
63
what is cell theory
1. cells are the fundamental units of life 2. all organisms are composed of cells 3. all cells come from preexisting cells
64
what are some exceptions to the fact that cells are small
bird eggs, neurons, some algae and bacteria cells
65
T or F: prokaryotic cells are 10x larger than eukaryotic
false
66
why are cells small
they need a high surface area to volume ratio
67
what determines the amount of chemical activity in the cell per unit time
volume
68
determines the amount of substances that can pass the cell boundary per unit time
surface area
69
what does the plasma membrane do
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
all living organisms are __
eukaryotic
71
DNA is a membrane enclosed compartment called the
nucleus
72
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
prokaryotic
73
T or F: most prokaryotic cells have a rigid cell wall outside the plasma membrane
true
74
in photosynthetic bacteria, the plasma membrane folds into the cytoplasm to form an __ system where photosynthesis occurs
internal membrane
75
some prokaryotes swim using
flagella
76
some bacteria have __ which is a hair like structure projecting from the surface
pili

BIOL 2170 (11 decks)

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