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Biology 1010 > Membrane Function and Structure > Flashcards

Membrane Function and Structure Flashcards

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1
Q

Cellular membranes are ______ made from ______ and ______

A

fluid mosaics, lipids and proteins

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2
Q

the membrane structure results in it being

A

selectively permeable

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3
Q

what is passive transport

A

diffusion of a substance across the membrane

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4
Q

what transport does not need energy

A

passive transport

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5
Q

active transport

A

moves solutes against their gradients

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6
Q

most common lipid in the membrane

A

phsopolipids

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7
Q

what does selective permeability mean

A

certain molecules can pas

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8
Q

what transport needs energy

A

active transport

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9
Q

how do bulk transports move across the membrane

A

exocytosis and endocytosis

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10
Q

what is the boundary that separates a living cell from its surroundings

A

plasma membrane

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11
Q

why are membranes important for life

A

a cell must be able to separate itself from the outside environment

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12
Q

why must the cell be separate from the outside environment

A
  1. must keep its DNA and RNA from dissipating away
  2. must keep out foreign molecules that damages or destroys the cell
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13
Q

Charles Overton

A

Found that membranes were made of lipids

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14
Q

Irving Langmuir

A

made an artificial membrane

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15
Q

Gorter and Grendel

A

the phospholipid bilayer has two molecules that stick

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16
Q

Davson and Danielli

A

made the sandwich model

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17
Q

what is the sandwich model

A

sandwiched the phospholipid bilayer between two protein layers

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18
Q

Singer and Nicolson

A

Made the fluid mosaic model

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19
Q
A

Fluid Mosaic model

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20
Q
A

Sandwich Model

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21
Q

Fluid mosaic model

A

disperses the proteins
puts them in the phospholipid bilayer

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22
Q

present working model of the membrane

A

fluid mosaic membrane

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23
Q

in the fluid mosaic membrane, the proteins are

A

embedded in the phospholipid bilayer not forming a solid coat on the surface

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24
Q

what results in a stable membrane structure

A

hydrophilic portions of proteins and phospholipids are exposed to water

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25
Q

where are hydrophobic portions in the membrane

A

in the nonaqueous environment inside the bilayer

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26
Q

what does the membrane fence inside the cell

A

organically produced chemicals

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27
Q

the most common molecule in the plasma membrane

A

phospolipid

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28
Q

amphipathic molecules

A

have both a hydrophobic and hydrophilic region

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29
Q

phospholipids are considered ______ molecules

A

amphiphatic

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30
Q

protein movement in the membrane

A

laterally

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31
Q

phospholipid movement in the membrane

A

lateral and flip-flop

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32
Q

what is not randomly distributed in the membrane

A

proteins

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33
Q

how are membranes held together

A

weak hydrophobic interactions between the tails

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34
Q

what marks the difference in human and mouse cells

A

proteins

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35
Q

as temperatures cool what happens to the membrane fluidity

A

membranes go from a fluid state to a solid state

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36
Q

what does the temp for solidifying membranes depend on

A

types of lipids

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37
Q

what must membranes be to work properly

A

fluid

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38
Q

what is a membrane-like with more unsaturated fatty acids

A

more fluid than with saturated fatty acids

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39
Q

what is the primary reason we want unsaturated fatty acids

A

allows for a more efficient flow of molecules

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40
Q

impact of cholesterol on the membrane at warm temps

A

restrains movement of phospholipids and prevents the membrane from being too fluid

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41
Q

impact of cholesterol on the membrane at cool temps

A

maintains the fluidity by preventing tight packing

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42
Q

what has allowed organisms to live in temps that change

A

the ability to change lipid composition as temp changes

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43
Q

what determines most of membrane’s specific function

A

proteins

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44
Q

types of proteins in the membrane

A

peripheral proteins
integral proteins

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45
Q

peripheral proteins

A

bound to the surface of the membrane

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46
Q

integral proteins

A

penetrate the hydrophobic core and are embedded in the membrane

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47
Q

what are integral proteins that span the membrane called

A

transmembrane proteins

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48
Q

what does the hydrophobic region of an integral protein made from

A

stretches of nonpolar amino acids called alpha helices

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49
Q

what must molecules go through in the integral proteins

A

the alpha helices

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50
Q

six major functions of membrane proteins

A
  1. transport
  2. enzymatic activity
  3. signal transduction
  4. cell-cell recognition
  5. intercellular joining
  6. attachments to the cytoskeleton and extracellular matrix
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51
Q

six major functions of membrane proteins

A
  1. transport
  2. enzymatic activity
  3. signal transduction
  4. cell-cell recognition
  5. intercellular joining
  6. attachments to the cytoskeleton and extracellular matrix
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52
Q

transport

A

a protein that either shuttles a substance from one side to another by changing shape or a protein that provides a hydrophilic channel that is selective for a solute

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53
Q

enzymatic activity

A

protein built into the membrane that acts as a docking space and can change the reaction rate

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54
Q

signal transduction

A

a protein that acts as the receptor with a binding site for a molecule which can cause it to change shape to send signal into the cell

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55
Q

cell-cell recognition

A

cells that attach and build a layer for a specific purpose

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56
Q

intercellular joining

A

proteins that hook and join into junctions for physical barriers

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57
Q

attachments to the cytoskeleton and extracellular matrix

A

allows for more structure and stabilizes the location of certain membrane proteins

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58
Q

what membrane protein is more long-lasting

A

intercellular joining

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59
Q

what membrane protein is more short-lasting

A

cell-cell recognization

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60
Q

HIV example of cell surfaces being important in medicine

A
  1. HIV must bind to the surface protein CD4 and the co-receptor CCR5 to infect a cell
  2. HIV cannot enter the cell without the CCR5 receptor
  3. When the CCR5 receptor is blocked, HIV cannot enter
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61
Q

how do cells recognize each other

A

by binding to extracellular surface molecules

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62
Q

what do extracellular surface molecules often have

A

carbohydrates

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63
Q

what can membrane carbohydrates be covalently bonded to

A

glycolipids and glycoproteins

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64
Q

without the membrane carbohydrates or proteins

A

won’t be able to tell the different membranes apart

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65
Q

when do the _______ parts of the plasma membrane determine

A

asymmetrical
when its built by the ER and Golgi

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66
Q

the process of exchanging materials to the surroundings is controlled by

A

plasma membrane

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67
Q

how does the plasma membrane regulate the cell’s molecular traffic

A

by being selectively permeable

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68
Q

______ can dissolve in the lipid bilayer and pass through _____

A

hydrophobic (nonpolar) and rapidly

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69
Q

______ molecules do not cross the membrane easily

A

polar (hydrophilic)

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70
Q

______ allows the hydrophilic substances to pass across the membrane

A

transport proteins

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71
Q

channel proteins

A

transport proteins that have a hydrophilic channel that the molecules can use to pass through the membrane

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72
Q

aquaporins

A

facilitates the passage of water

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73
Q

Carrier proteins

A

transport proteins that hold their passengers and change shape in a way that shuttles them across the membrane

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74
Q

types of transport proteins

A

carrier and channel

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75
Q

Diffusion

A

tendency of molecules to spread evenly into available space

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76
Q

in diffusion, each molecule moves _______

A

randomly

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77
Q

Dynamic equilibrium

A

as many molecules cross the membrane in one direction as the other

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78
Q

substances diffuse down their

A

concentration gradients

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79
Q

diffusion is a ___________ process

A

spontaneous

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80
Q

what is an example of passive transport

A

diffusion

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81
Q

diffusion of molecules is from ____ to ___ concentration

A

high to low

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82
Q

osmosis

A

diffusion of water across a selectively permeable membrane

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83
Q

water diffuses across the membrane from ____ to the _____ solute concentration

A

lower solute concentration to the higher

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84
Q

what is the goal of osmosis

A

for the solute concentrations to be equal

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85
Q

tonicity

A

the ability of a surrounding solution to cause cells to gain or lose water

86
Q

examples of tonicity

A
  1. isotonic
  2. hypertonic
  3. hypotonic
87
Q

isotonic solution

A

the solute is the same as that inside the cell

88
Q

what do isotonic solutions do to the plasma membrane

A

there is no water movement across the membrane

89
Q

hypotonic solutions

A

the solute concentration is less than that inside the cell

90
Q

as a result of the hypotonic solution,

A

cell gains water

91
Q

hypertonic solution

A

the solute concentration is greater than inside the cell

92
Q

as a result of the hypertonic solution,

A

the cell loses water

93
Q

the direction of osmosis is determined by the

A

difference in total solute concentration

94
Q

osmotic concentration

A

total solute concentration of a solution

95
Q

if the two solutions have different concentrations and are separated by a selectively permeable membrane that allows water but not solute to pass,

A

the water would travel from the hypoosmotic solution to the hyperosmotic

96
Q

what determines how a living cell will react to changes in solute concentrations of their environment

A

whether they have a cell wall

97
Q

osmoregulation

A

the control of solute concentrations and water balance

98
Q

Too fluid membranes and they cannot

A

support the protein function

99
Q

Seen as a “Fluidity Buffer”

A

cholesterol

100
Q

Cell-cell recognition is important

A

Sorting cells into tissues and organs in animal embryo
The basis for the rejection of foreign cells by the immune system

101
Q

Supramolecular structure

A

many molecules ordered into a higher level of organization that have emergent properties beyond the individual molecules

102
Q

This is the best environment for ANIMAL CELLS

A

isotonic solutions

103
Q

what happens to animal cells in hypertonic solutions

A

The cell will lose water because the environment has more nonpenetrating solutes

Will shrivel up and die

104
Q

what happens to animal cells in hypotonic solutions

A

Water will enter the cell faster than it leaves, and the cell will burst

105
Q

This is the best environment for PLANT CELLS

A

hypotonic solutions

106
Q

Turgor pressure

A

the limit to how much the cell wall can expand before putting pressure on the cell and opposes any more water uptake

107
Q

When the turgor pressure is reached, the cell becomes

A

turgid (firm)

108
Q

what happens to plant cells in isotonic solutions

A

no net tendency for water to enter and the cell becomes flaccid (limp)
the plant wilts

109
Q

what happens to plant cells in Hypertonic solutions

A

b. Plant cell will lose water to its surroundings and shrink

110
Q

PLASMOLYSIS

A

the plasma membrane will pull away from the plant cell as it shrinks in hypertonic solutions

111
Q

What solution is 1

A

Hypotonic Solution

112
Q

What solution is 2

A

Isotonic Solution

113
Q

What solution is 3

A

Hypertonic Solution

114
Q

facilitated diffusion

A

transport proteins aid the passive movement of molecules across the plasma membrane

115
Q

is facilitated diffusion passive or active

A

passive transport

116
Q

what kinds of transport proteins are there

A

channel proteins and carrier proteins

117
Q

what do channel proteins provide

A

corridors that allow a specific molecule or ion to cross

118
Q

what kinds of channel proteins are there

A

aquaporins and ion channels

119
Q

aquaporins channels are

A

the diffusion of water

120
Q

ion channels are

A

the diffusion of ions

121
Q

gated channels are ______ that _____ or ____ with a _____

A

ion channels, open or close, stimulus

122
Q

what does a gated channel use to pass ions

A

the charge

123
Q

carrier proteins

A

undergo a subtle change in shape to transport solute-binding site across the membrane

124
Q

what triggers a carrier protein’s change in shape

A

the binding and release of transport molecule

125
Q

is the carrier proteins still diffusion

A

YES

126
Q

how do solutes move in facilitated diffusion

A

downs its concentration gradient from high to low

127
Q

does facilitated diffusion need energy

A

NO

128
Q

some transport proteins can do what

A

move solutes against their concentration gradients

129
Q

active transport

A

moves substances against their concentration gradients

130
Q

what does moving against concentration gradient mean

A

moves towards HIGHER concentration

131
Q

what transport needs energy and in what form

A

active transport needs energy in form of ATP

132
Q

how is active transport done

A

by specific proteins embedded in membranes

133
Q

what does active transport allow cell to do

A

maintain concentration gradients that differ from their surroundings

134
Q

one example of an active transport system

A

sodium-potassium pump

135
Q

where is most energy going to

A

the sodium-potassium pump,

136
Q

how many sodium ions are pumped by the sodium-potassium pump

A

3 sodium ions out of the cell

137
Q

how many potassium ions are pumped by the sodium-potassium pump

A

2 potassium ions into the cell

138
Q

what gives the membrane a charge

A

the movement of Na and K ions

139
Q

step 1 of the potassium-sodium pump

A

sodium in the cytoplasm binds to the pump

140
Q

when is the sodium affinity high with the sodium-potassium pump

A

when the protein has the original shape

141
Q

Step 2 of the sodium-potassium pump

A

the binding of sodium stimulates the phosphorylation by ATP

142
Q

Step 3 of the sodium-potassium pump

A

the phosphorylation leads to a change in protein shape

143
Q

when is the sodium affinity low with the sodium-potassium pump

A

when the protein changes shape with the addition of energy

144
Q

why is sodium released to the outside of cell

A

the reduced affinity releases it to the outside

145
Q

step 4 of the sodium-potassium pump

A

potassium binds onto the extracellular side of the pump

146
Q

what triggers the release of the phosphate group from the pump

A

when potassium from outside binds to the pump

147
Q

when is the potassium affinity high with the sodium-potassium pump

A

after the release of sodium and is still in the new shape

148
Q

what happens when the phosphate group is removed from the pump

A

restores the protein’s original shape

149
Q

when is the potassium affinity low with the sodium-potassium pump

A

when the protein’s shape is restored with the removal of the phosphate

150
Q

why is the potassium released from the sodium-potassium pump

A

the lower affinity causes it to be released inside the cell

151
Q

what kind of pump is the sodium-potassium pump

A

uniport

152
Q

membrane potential

A

the voltage difference across a membrane

153
Q

how is the voltage created across the membrane

A

the differences in the distribution of positively and negatively charged ions

154
Q

what two forces drive the diffusion of ions across a membrane

A

chemical and electrical force

155
Q

what are the two forces that drive the diffusion of ions across a membrane called

A

electrochemical gradient

156
Q

the chemical force in the electrochemical gradient

A

the ion’s concentration gradient

157
Q

the electrical force in the electrochemical gradient

A

effect of membrane potential on ion’s movement

158
Q

electrogenic pump

A

transport protein that generates voltage across a membrane

159
Q

what is the major electrogenic pump in ANIMALS

A

sodium-potassium pump

160
Q

what is the major electrogenic pump in PLANTS, FUNGI and BACTERIA

A

proton pump

161
Q

what does the proton pump do

A

helps store energy that can be used for cellular work

162
Q

what does the proton pump pump

A

hydrogen ions

163
Q

how is the proton pump used in the mitochondrion

A

it couples the chemical and electrical process to make ATP

164
Q

cotransport

A

active transport of a solute indirectly drives transport of other solutes

165
Q

how is cotransport often used in plants

A

hydrogen ion gradients to drive active transport of nutrients into the cell

166
Q

uniport

A

transports one molecule at a time

167
Q

antiport protein

A

two molecules are moved in opposite directions across the bilayer

168
Q

symport protein

A

two molecules are moved in the same direction across the membrane are

169
Q

how do small molecules and water enter or leave the cell

A

through the lipid bilayer or by transport proteins

170
Q

how do large molecules (polysaccharides and proteins) move across a membrane

A

through vesicles called Bulk Transport

171
Q

does bulk transport need energy

A

YES

172
Q

types of bulk transports

A

endocytosis and eocytosis

173
Q

exocytosis

A

transport vesicles migrate to the membrane, fuse with it and release their contents to the outside of the cell

174
Q

what is an example of exocytosis

A

secretory cells that export their products

175
Q

endocytosis

A

cell takes in macromolecules by forming vesicles with the plasma membrane

176
Q

how is endocytosis different from exocytosis

A

its the reversal and uses different proteins

177
Q

types of endocytosis

A
  1. phagocytosis
  2. pinocytosis
  3. receptor-mediated endocytosis
178
Q

phagocytosis and pinocytosis have no what

A

receptor mediation

179
Q

phagocytosis

A

engulfs a particle in a vacuole
the vacuole fuses with lysosomes to digest particles

180
Q

pinocytosis

A

extracellular fluid is “gulped” into tiny vessicles

181
Q

receptor-mediated endocytosis

A

binding of ligands to receptors that triggers vesicle formation

182
Q

receptor-mediated endocytosis is only possible when

A

ligands can bind which means only select cells can do it

183
Q

where does receptor-mediated endocytosis function the most

A

in the immune system

184
Q

how do human cells use receptor-mediated endocytosis

A

to take in cholesterol for synthesis of membranes and other steroids

185
Q

how is cholesterol carrier

A

carried by the blood by the low density lipoproteins (LDLs)

186
Q

where is cholesterol carried to

A

to the LDL binding sites and entering cells by endocytosis

187
Q

hypercholesterolemia

A

missing or defective LDL receptor proteins which means there is a high level of lipids in the blood

188
Q

how does SARS-Cov-2 enter the body

A

through the olfactory bulb

189
Q
A

uniport

190
Q
A

symport

191
Q
A

Antiport

192
Q

how are gated channels stimulated

A

electrical stimulus or when a specific substance binds to the channel

193
Q

ATP hydrolysis

A

Supplies the energy for most active transport

194
Q

The cytoplasmic side of the membrane is

A

negative

195
Q

the cytoplasmic side of the membrane favors

A

the passive transport of cations into the cell

196
Q

The extracellular side of the membrane is

A

positive

197
Q

the extracellular side of the membrane favours

A

the passive transport of anions out of the cell

198
Q

The benefit of electronic pumps

A

Help store energy that can be tapped for cellular work

199
Q

Water and solutes enter and leave the cell by diffusing through

A

a. the lipid bilayer of the plasma membrane
b. Being pumped across the membrane by transport proteins

200
Q

Receptor-mediated endocytosis is a specialized form of

A

pinocytosis

201
Q

Endocytosis or exocytosis

A

exocytosis

202
Q

Endocytosis or exocytosis

A

Endocytosis

203
Q

Pinocytosis or phagocytosis or receptor-mediated endocytosis

A

pinocytosis

204
Q

Pinocytosis or phagocytosis or receptor-mediated endocytosis

A

phagocytosis

205
Q

Pinocytosis or phagocytosis or receptor-mediated endocytosis

A

receptor-mediated endocytosis

206
Q
A

Step 3

207
Q
A

Step 4

208
Q
A

Step 5

209
Q
A

Step 6

210
Q
A

Step 1

211
Q
A

Step 2

Biology 1010 (14 decks)

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