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F22 - ANP1105 > 2 - September 16 membrane - Pg. 63-82 > Flashcards

2 - September 16 membrane - Pg. 63-82 Flashcards

1
Q

Most membrane phospholipids are —-

A

unsaturated

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2
Q

how does unsaturated phospholipids help the membrane?

A

kink in the tail creates more space = increased membrane fluidity

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3
Q

chemical make up of glycolipids

A

lipids with sugar groups attached

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4
Q

where are glycolipids located?

A

outer plasma membrane

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5
Q

glycolipids account for only —% of total membrane lipids

A

5

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6
Q

the sugar group makes the molecule —-

A

polar

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7
Q

20% of the membrane lipid is?

A

cholesterol

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8
Q

what is the purpose of cholesterol? how does it achieve this?

A

hydrocarbon rings wedge between the phospholipid tails to stabilize the membrane and decrease the mobility of the phospholipids and fluidity of the membrane

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9
Q

what are integral proteins? where are they located?

A

firmly in the lipid bilayer, usually spanning across the whole membrane from both sides, consist of both hydrophobic and hydrophilic regions

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10
Q

functions of transmembrane proteins?

A

involved in transport by acting as a channel or act as carriers

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11
Q

peripheral proteins

A

loosely attached to the integral proteins and can be removed without membrane disturbance

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12
Q

peripheral proteins function

A

helps support membrane from the cytoplasmic side

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13
Q

some times peripheral proteins are

A

enzymes or motor proteins, or used to link cells

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14
Q

lipid rafts importance and function

A

important components of cell membranes - involved in essential cellular processes, including endocytosis, exocytosis and cellular signalling

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15
Q

what are lipid rafts made up of

A

enriched in cholesterol, glycophospholipids and receptors.

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16
Q

glycocalyx is a ——–rich area at the cell surface

A

carbohydrate

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17
Q

glycocalyx on each cell surface is enriched by both

A

glycoproteins and glycolipids

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18
Q

the glycocalyx provides what to help in cell-to-cell recognition

A

highly specific biological markers

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19
Q

another name for selectively permeable membrane

A

differentially permeable membrane

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20
Q

selectively permeable membrane definition

A

membrane that’s selectively about what substances can penetrate - allows some but not others

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21
Q

passive process definition

A

substances move across the membrane without any energy input from the cell

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22
Q

active process definition

A

cell provides metabolic energy, usually ATP, to help move substances across the membrane

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23
Q

selective permeability is a characteristic of what kind of cell?

A

healthy and intact

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24
Q

severe damage to a cell creates what kind of imbalance?

A

homeostatic

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25
Q

what are the two main types of passive transport?

A

diffusion and filtration

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26
Q

diffusion

A

tendency of molecules/ions to move from an area of higher concentration to lower concentration area down or along their concentration gradient

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27
Q

the greater the difference in concentration between two areas, the —– collisions occur and the —– the net diffusion of the particles

A

more and faster

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28
Q

what is the driving force behind diffusion?

A

kinetic energy of the molecules

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29
Q

speed of diffusion is based off of

A

molecule size and temperature

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30
Q

what are the 3 things that need to be met for a molecule to pass by the plasma membrane?

A

1 - lipid soluble
2 - small enough to pass through membrane channels
3 - or assisted by a carrier molecule

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31
Q

simple diffusion definition

A

direct diffusion of non polar and lipid soluable substances

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32
Q

facilitated diffusion

A

when a larger molecule either binds to protein carriers or moves through water filled protein channels

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33
Q

types of diffusion through plasma membrane

A

simple diffusion, carrier-mediated facilitated diffusion, channel-mediated facilitated diffusion, osmosis

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34
Q

carriers are

A

transmembrane integral proteins that are specific for transporting certain polar molecules or classes of molecules that are too large for membrane channels alone

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35
Q

alterations to the shape of the carrier allows for shielding the molecule from ?

A

non polar regions of the membrane

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36
Q

substances using carrier mediated facilitated diffusion more down, — —- —-, just as in simple diffusion

A

its concentration gradient

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37
Q

glucose transport in the body is typically —– into the cells

A

unidirectional

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38
Q

carrier mediated facilitated diffusion definition

A

when carriers bind to large substances to help cross through the membrane - carrier helps protect substance from non polar region of the membrane

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39
Q

channel-mediated facilitated diffusion analogy

A

channel acts as a bridge over water than can open and close

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40
Q

channel-mediated facilitated diffusion channels are —— due to ——— and ——— that line the channel

A

selective, pore size, charges of amino acids

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41
Q

channels definiton

A

transmembrane proteins that transport substances, like water or ions, through aqueous channels from one side of the membrane to the other

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42
Q

leakage channels are

A

always open to allow ions or water to mov according to concentration gradients

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43
Q

gated channels are

A

controlled (open or closed) by chemical or electrical signals

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44
Q

channels can be

A

inhibited by certain molecules, show saturation, tend to be specific

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45
Q

In channel-mediated facilitated diffusion, substances moving through also follow ?

A

concentration gradient

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46
Q

rate of diffusion is ——- through simple diffusion because?

A

uncontrollable , lipid solubility of membrane is not immediately changeable

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47
Q

rate of diffusion is —— in facilitated diffusion because

A

controllable , permeability of membrane is altered through regulating the activity or number of individual carriers/channels

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48
Q

osmosis

A

diffusion of a solvent through a selectively permeable membrane

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49
Q

even though water is highly ————, it passes through the lipid bilayer via ——

A

polar , osmosis

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50
Q

aquaporins (AQPs)

A

transmembrane proteins that created water specific channels to allow free and reversible movement of water

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51
Q

Aquaporins are believed to be present in all cell types but are most abundant where?

A

red blood cells and cells that are involved in water balance i.e. kidney tubule cells

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52
Q

osmosis occurs whenever

A

the water concentration differs on two sides of a membrane

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53
Q

as solute concentration increases, water concentration?

A

decreases

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54
Q

what is the membrane type in osmosis

A

selective permeable membrane - hence why water is moving to higher solute concentration since the solutes cannot

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55
Q

(a solution’s) osmolarity is

A

the total concentration of all solute particles in a solution

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56
Q

what would happen if two equal volumes of aqueous solution, but different osmolarity solutions were to be separated by a membrane that is permeable to all molecules?

A

net diffusion of both solute and water molecules occurs, each moving down their own concentration gradient. water and concentration would be equal

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57
Q

what would happen if two equal volumes of aqueous solution, but different osmolarity solutions were to be separated by a membrane that is impermeable to solutes particles?

A

water alone moves to reach equilibrium and the water volumes would be different

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58
Q

hydrostatic pressure

A

The force exerted by a fluid pressing against a wall

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59
Q

in living cells, net water entry ends when equilibrium of what two things?

A

hydrostatic pressure and osmotic pressure

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60
Q

the higher the amount of non-penetrating solutes in a cell, the higher the osmotic pressure and the greater the hydrostatic pressure must be to?

A

resist further net water entry

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61
Q

Hydrostatic Pressure is found in

A

any type of homogenous fluid

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62
Q

osmotic pressure and hydrostatic pressure is different in plant cells than living because of?

A

the rigidity of cells - plant cells have more rigidity than living cells. Living cells die/pop if the pressure is too much

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63
Q

osmotic imbalances cause animal cells to —– or ——-

A

swell or shrink

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64
Q

swelling or shrinking of the cell occurs until ?

A

equilibrium of solutes is reached on both sides of the plasma membrane or until the membrane stretches and breaks

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65
Q

tonicity

A

the ability of a solution to change the shape or tone of cells by altering the cells’s internal water volume

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66
Q

tono =

A

tension

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67
Q

are intracellular proteins able to diffuse through the plasma membrane?

A

no

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68
Q

isotonic

A

same tonicity - solutions have same concentrate as non-penetrating solutions and cell shape is maintained

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69
Q

hypertonic solutions

A

higher concentration of non-penetrating solutes than seen in the cell - cell shape shrinks due to water loss

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70
Q

hypotonic solutions

A

have less non-penetrating solutes than cell, therefore cell swells due to osmosis and water going to the cell

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71
Q

what is the most extreme example of a hypotonic solution?

A

distilled water

72
Q

what happens to cells placed in distilled water?

A

usually die because no solutes in distilled water, so water continuously enters the cell

73
Q

a solutions osmolarity is based off of

A

total solute concentration

74
Q

tonicity is based off of

A

how the solution affects cell volume which depends on (1) solute concentration & (2) solute permeability of plasma membrane

75
Q

what are 2 processes that are not selective?

A

simple diffusion and osmosis

76
Q

what process is often highly selective?

A

facilitated diffusion

77
Q

what energy source does simple diffusion, osmosis and facilitated diffusion use?

A

kinetic energy

78
Q

facilitated diffusion is similar to simple diffusion but the diffusing substance ?

A

Is either attached to a lipid-soluable membrane protein carrier, or moves through a membrane channel

79
Q

active transport requires carrier proteins to combine —- and —– with transported substances

A

specifically and reversibly

80
Q

facilitated diffusion follows concentration gradients because?

A

its using genetic energy

81
Q

active transport (or solute pumps) move solutes how and where?

A

uphill, against the concentration gradient by using energy

82
Q

active transport moves solutes, which is the most important type?

A

ions

83
Q

active transport is distinguished according to their?

A

source of energy

84
Q

primary active transport, the energy comes from

A

directly from hydrolysis of ATP

85
Q

in secondary active transport, the energy comes

A

indirectly by the energy stored in ionic gradients created by primary active transport pumps

86
Q

why are secondary active transports called coupled systems?

A

they move more than one substance at a time

87
Q

symport system

A

the two transported substances move in the same direction

88
Q

anti port systems

A

the transported substances ‘wave to each other’ as they cross the membrane in different directions

89
Q

what does the hydrolysis of ATP result in?

A

phosphorylation of the transport protein = protein changes shape in a way that ‘pumps’ the bound solutes across the membrane

90
Q

what types of systems does primary active pump consist of?

A

calcium-hydrogen and sodium-potassium pump

91
Q

what is the name of the ‘pump’ (carrier) of sodium-potassium pump?

A

NAK atpase

92
Q

in the body the concentration of K inside the cell is —- times higher than that outside the cell

A

10

93
Q

Na is —– times higher on the outside of the cell than the inside the cell

A

10

94
Q

why is the ion concentration of K and Na important?

A

for excitable cells like muscle and nerve cells to function normally & for cells to maintain normal fluid volume

95
Q

why does the NA-K pump almost always is an anti porter?

A

because of the slow but continuous leakage of Na-K through leakage channels in the membrane

96
Q

the Na-K pump does what exactly as an anti porter?

A

drives Na out the cell against the concentration gradient and pumps K back in

97
Q

ions diffuse according to

A

electrochemical gradients

98
Q

what two things need to be in mind when speaking of gradient?

A

electrical and concentration gradient

99
Q

The electrochemical gradient is a combination of the

A

concentration gradient and the electrical potential

100
Q

the electrochemical gradient maintained by Na-K pump underlies?

A

most of the secondary active transport of nutrients and ions

101
Q

the maintenance of the secondary active pump for nutrient and ions is essential for

A

cardiac, skeletal muscle and neuron function

102
Q

active transport system provides a way for cells to be?

A

very selective in cases where substances can’t pass by diffusion

103
Q

secondary active transport

A

transport of a solute in the direction of its increasing electrochemical potential coupled to the facilitated diffusion of a second solute (usually an ion) in the direction of its decreasing electrochemical potential

104
Q

how does the electro gradient and concentration gradient fuel secondary transport?

A

concentration gradient pushes the Na from outside to the inside due to high and low concentration then the electrical potential wants to go from more positive side to the negative side to balance it out

105
Q

Na electrochemical gradient is what is used to provide

A

energy

106
Q

vesticular transport

A

fluids containing large particles and macromolecules are transported across cellular membrane inside membranous sacs called vesicles

107
Q

exocytosis

A

the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell

108
Q

endocytosis

A

the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane, and bringing it into the cell

109
Q

which direction does vesicle transport move substances?

A

inside and outside

110
Q

what are other tasks for vesicular transport besides molecules

A

transcytosis and vesicular trafficking

111
Q

how is vesicular transport energized?

A

by ATP, but sometimes by GTP

112
Q

transcytosis definition

A

moving substances into, across and then out the cell

113
Q

vesicular trafficking

A

moving substances from one area (or membraneous organelle) in the cell to another

114
Q

all forms of vesicular transport involve what two things?

A

an assortment of protein-coated vesicles of 3 types and (usually) are mediated by membrane receptors

115
Q

what is the main route for endocytosis and transcytosis

A

protein-coated vesicles

116
Q

what is the name of the sorting vesicle that the uncoated vesicle fuses with?

A

endosome

117
Q

clathrin

A

acts in both selecting the cargo and deforming the membrane to produce the vesicle

118
Q

where is transcytosis common?

A

endothelial cells lining blood vessels

119
Q

what are the three types of endocytosis that use clathrin-coated vesicles

A

phagocytosis, pinocytosis, receptor-mediated endocytosis

120
Q

phagocytosis

A

cell engulfs large material (like debris or bacteria) and forms pseudopods around it and enclosed the membrane around it.

121
Q

what is a phagosome

A

endocytotic vesicle - the cell with engulfed materials with pseduopods

122
Q

what happens once the phagosome is formed?

A

fuses with a lysosome for the contents to be digested

123
Q

what if there’s nothing digestible for the lysosome and phagosome?

A

material is ejected from cell by exocytosis

124
Q

pinocytosis is also called

A

fluid-phase endocytosis

125
Q

pinocytosis is a daily routine for

A

most cells, especially ones that absorb nutrients like cells in the intestines

126
Q

pinocytosis

A

the cell membrane folds and creates small pockets and captures the cellular fluid and dissolved substances and forms into a tiny vesicle

127
Q

what’s the purpose of pinocytosis

A

clearing extracellular fluids and as part of immune surveillance

128
Q

receptor-mediated endocytosis is used mainly for

A

specific endocytosis and transcytosis

129
Q

the receptors in RM-endocytosis are

A

plasma membrane proteins that bind to specific substances

130
Q

EM - endocytosis

A

Extracellular substances bind to specific receptor proteins that allows ingestion and concentrate of specific substances (ligands) in protein-coated vesicles

131
Q

what happens to the ligands once they’re in the vesicle

A

released in the cell or they’re combined with lysosomes to be digested

132
Q

caveolae

A

tubular/flask-shaped inpocketings of the plasma membrane seen in many cell types and used for a unique kind of receptor mediated endocytosis

133
Q

caveolae provides

A

sites for cell signalling and cross talk between signalling pathways

134
Q

what is the most important thing to remember about coat proteins in general?

A

they play a significant role in all forms of endocytosis

135
Q

exocytosis

A

vesicular transport protein processes that eject substances from inside the cell to the outside by enclosing substance in membrane vesicle which fuses to plasma membrane to rupture and kick the substance out

136
Q

how does exocytosis get stimulated?

A

through cell-surface signal

137
Q

what does exocytosis account for?

A

hormone secretion, neurotransmitter release, mucus secretion

138
Q

secretory vesicle

A

enclosed protein-coated membraneous sac involved in exocytosis

139
Q

voltage

A

electrical potential energy resulting from the separation of oppositely charged particles

140
Q

what are the oppositely charged particles in cells?

A

ions

141
Q

what is the barrier that keeps ions apart?

A

plasma membrane

142
Q

resting membrane potential

A

resting state of plasma membrane, ranges from -50 to -1000 mV

143
Q

voltage only exists

A

at the membrane

144
Q

the negative before the voltage number indicates what

A

the inside of the cell is negative compared to the outside

145
Q

how does the resting membrane potential come about and maintained? short answer*

A

diffusion causes implantes that polarize the membrane and active transport processes maintain the membrane potential

146
Q

resting membrane potential is mainly determined by

A

concentration gradient of potassium and by differential permeability of the plasma membrane to K and other ions

147
Q

the loss of K is due to the fact that the membrane at it’s resting potential is

A

semi permeable to K via leakage channels, which allows it to flow out, but not other anion proteins creating the interior more negative but then K is attracted to the negative so it makes its way back in

148
Q

which of Na or K is more responsible to resting membrane potential and why

A

K because the membrane is more permeable to k when resting although Na still does play a role

149
Q

resting membrane potential is based off a ——– number of K ions that it actually doesn’t cause ?

A

small, a change in ion concentration in a major way

150
Q

the rate of active transport is equal to and depends on

A

the rate of Na diffusion into a cell

151
Q

each ‘turn’ of the Na-K pump, how much of each is exchanged?

A

3 Na out, 2 K in

152
Q

the ATP -dependent Na-K pump maintains bother

A

membrane potential and osmotic balance

153
Q

regardless if cells interact with this directly or indirectly, what is always involved

A

glycocalyx

154
Q

what are the two families that glyxocalyx molecules fall into

A

cell adhesion molecules and plasma membrane receptors

155
Q

a group of membrane proteins, voltage-gated channel proteins are important for

A

cells that respond to electrical signals

156
Q

what are CAM’s

A

cell adhesion molecules

157
Q

what are the key role of CAM’s

A

embryonic development, wound repairing, immunity

158
Q

membrane receptors

A

integral proteins and glycoproteins that serve as binding sites - function in contact signalling and chemical signalling

159
Q

contact signalling

A

cells come together and touch as a form of recognizing one another

160
Q

why is contact signalling important

A

for normal development and immunity

161
Q

most plasma membrane receptors are involved in?

A

chemical signalling

162
Q

ligands

A

chemicals that bind specifically to plasma membrane receptors

163
Q

ligands includes most

A

neurotransmitters, hormones and paracrines

164
Q

paracrines

A

chemicals that acts locally and are rapidly destroyed

165
Q

paracrines example

A

responses to allergens or blood clotting

166
Q

why do different cells respond differently to the same ligand?

A

the target cell response depends on the internal machinery that the receptor is linked to, not the specific ligand it’s binding to

167
Q

what happens when ligand binds to a membrane receptor?

A

the receptor’s structure changes and cell proteins are altered in some way

168
Q

g protein-linked receptors

A

exert their effect indirectly through G protein

169
Q

what’s a g-protein

A

a regulatory molecule that acts as a middle man or a relay, to either activate or deactivate, a membrane bound enzyme or ion channel

170
Q

second messengers

A

intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers, typically caused by G protein-linked receptors

171
Q

what are the two important second messengers

A

cyclic AMP and ionic calcium

172
Q

what do cyclic amp and ionic calcium do

A

typically activate protein kinase enzymes which transfer phosphate groups from ATP to other proteins

173
Q

the protein kinase enzyme can do what

A

trigger a whole series of enzymes that bring out desired cellular activity

174
Q

G protein signalling system is involved in

A

neurotransmission, smell, vision and hormone action

175
Q

NO (nitric acid) molecule is important for

A

signalling

176
Q

in electrical signalling, certain plasma membrane proteins acts as

A

channel proteins that open or close channels based on membrane potential changes

F22 - ANP1105 (11 decks)

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