cell transport across plasma membrane Flashcards
(168 cards)
1
Q
where is Na+ most abundant
A
outside the cell
2
Q
where is K+ most abundant
A
inside the cell
3
Q
what are Na+ ions balanced by
A
Cl- ions
4
Q
what are K+ ions balanced by
A
charges of organic molecules
5
Q
what is a voltage difference
A
small excesses of positive or negative charge on two sides of plasma membrane
6
Q
membrane potential
A
the voltage difference across the membrane
7
Q
resting membrane potential
A
the steady exchange of anions and cations across the membrane for a cell at rest
8
Q
what creates membrane potential
A
ion channels
9
Q
how do ion channels create membrane potential
A
ion channels create openings for passive movement of inorganic ions
10
Q
which channel is responsible for the resting membrane potential
A
K+ leak channels
Na+-K+ pumps also contribute
11
Q
what is the range of the charge of resting membrane potential in animal cells (mV)
A
-20 to -200 mV
12
Q
AT REST, what is the plasma membrane most permeable to
A
K+
13
Q
Most channels in the cell are what kind of channels?
A
ion channels
14
Q
what do ion channels do
A
facilitate passage of select inorganic ions
15
Q
ion channels vs. pores
A
- ion selectivity
- open/closure state
16
Q
(T/F) ion channels are continuously open
A
FALSE
ion channels fluctuate between closed and open conformations
17
Q
(T/F) most ion channels are gated
A
TRUE
18
Q
what kind of gate ion channels are there
A
- ligand-gated
- voltage gates
- mechanically gated
- always open (leak channels)
19
Q
voltage-gated ion channels
A
controlled by changes in the voltage across the membrane
moves down concentration gradient
20
Q
ligand gated ion channels
A
controlled by the binding of a molecule
- polar substance more concentrated on outside
- binding of stimulus molecule (ligand) causes pore to open
- polar substance can diffuse across membrane
21
Q
mechanically gated ion channels
A
controlled by physical stimuli
ex. light, sound waves, pressure, stretch, touch, vibration
moves down concentration gradient
22
Q
what is a neuron made up of
A
cell body, axon, dendrites
23
Q
what does an electric signal consist of
A
changes in the membrane potential across neuron’s plasma membrane
24
Q
(T/F) liposomes are impermeable to most water-soluble molecules
A
TRUE
25
what do membrane transport proteins do
facilitate the passage of selected small water-soluble molecules
26
what affects diffusion rate
molecule's size and solubility
27
(T/F) lipid bilayers are impermeable to ions and most uncharged polar molecules
TRUE
only small nonpolar molecules can pass through
28
what are the two classes of membrane proteins
1. transporter
2. channel
29
transporter protein
transfer small organic molecules/inorganic molecules
30
channel proteins
form tiny hydrophilic pores and allow substances to pass by diffusion
31
passive vs. active transport
active transport requires energy/ATP
32
downhill movement
molecules flow from a region of high concentration to low concentration
33
passive transport
requires no energy
downhill movement
--> moves solute down its gradient
change conformation to mediate transport
34
active transport
requires energy
uphill movement
-->against concentration/electrical gradient
35
transport of uncharged molecule
movement direction determined ONLY by concentration gradient
36
transport of charged molecule
both concentration gradient and membrane potential exert forces
37
electrochemical gradient
net driving force moving a charged solute
force from membrane potential + force from concentration gradient
38
osmosis
diffusion of water across membranes
39
what channels do water molecules diffuse through
diffuse rapidly through aquaporin channels in the plasma membrane of some cells
40
what are aquaporin channels responsible for
water reabsorption in kidneys
41
3 types of proteins for active transport
- uniporter : transports one substance in one direction
- symporter : transports 2 different substances in the same direction
- antiporter : transports 2 different substances in opposite directions
42
uniporter
transports one substance in one direction
43
symporter
transports 2 different substances in the same directionan
44
antiporter
transports 2 diff substances in opposite directions
45
3 types of energy sources in active transport
- ATP (primary at)
- electrochemical gradient (secondary at)
- light
46
what is plasma membrane made of
thin fatty film studded w proteins and coated with carbs
47
plasma membrane functions
- cell communication
- import/export of molecules
- cell growth
- motility
48
phospholipid structure
hydrophilic head, hydrophobic tails
49
saturated vs. unsaturated fatty acid
saturated = no double bond
50
triacyglycerol
main constituents of animal fats and plant oils
--> completely hydrophobic
51
amphipathic
both hydrophilic and hydrophobic parts
52
first law of thermodynamics
total amt of energy in the universe must always be the same
53
what do all animals live off of
energy stored in chemical bonds of organic molecules
54
where does energy ultimately come from
the sun
55
photosynthesis
process that converts the electromagnetic energy in sunlight into chemical-bond energy in organic molecules
56
how is energy extracted from organic molecules
gradual oxidation
57
oxidation
addition of oxygen atoms to a molecule
58
second law of thermodynamics
in the universe, the degree of disorder can only increase
entropy: measure of a system's disorder
59
how do cells follow the second law of thermodynamics
disorder increases when useful energy that could be harnessed to do work (free energy) is dissipated as heat
60
Gibbs free energy (G)
amount of energy available in a molecule to do work in a system when the temp and pressure are uniform
61
what is free energy measured in
joules
62
how can chemical reactions in a cell cause disorder
1. by breaking apart a long chain of molecules or by disrupting an interaction that prevents bond rotations
2. charges of bond energy of the reacting molecules can cause heat to be released
63
formula for free energy change
A+B --> C+D
(delta)G = free energy (C+D) - free energy (A+B)
64
what does delta G represent
amt of disorder created when a reaction involving these molecules takes place
65
what does a negative delta G represent
disorder of the universe increases
66
what does delta G at 0 mean
system is at equilibrium
67
standard free change
delta G^0
used to predict the outcome of a reaction
68
endergonic reactions
reaction with a positive change in free energy
69
exergonic
reaction with a negative change in free energy --> release energy
spontaneous reactions
reaction product has a lower free energy level = more stable
70
are exergonic or endergonic reactions energetically favorable
exergonic
71
endergonic reactions
require energy, can store energy in bonds
non-spontaneous
reaction product has a higher free energy level than substrate
72
transferable chemical group/readilt transferable election
as a readily transferable chemical group or as readily transferable electrons
73
what are the most important activated carriers
ATP, NADH, NADPH
74
what is the most widely used activated carrier
ATP
75
what group does ATP carry
phosphate
76
what group does NADH, NADPH, FADH2 carry
electrons and hydrogens
77
what group does acetyl CoA carry
acetyl group
78
what group does carboxylated biotin carry
carboxyl group
79
what group does S-adenosylmethionine carry
methyl group
80
what group does uridine diphosphate glucose carry
glucose
81
what do enzymes do
act as catalysts and lower activation energy
82
2 sets of metabolic pathways
catabolic and anabolic
83
catabolic metabolism
process of cellular respiration
84
anabolic metabolism
process of photosynthesis
85
where do light-reactions take place
thylakoid membrane
86
where does the carbon-fixation take place
stroma
87
how to light reactions convert light energy into chemical energy
form of ATP and reduced electron carrier NADPH
88
carbon fixation reactions
light-independent reactions --> use ATP, NADPH, and CO2 to produce carbohydrates
89
what is light
electromagnetic radiation
90
photons
particles of light
91
shorter wavelength = ?
greater energy
92
what light do chlorophylls absorb
light of blue and red wavelengths
93
photosystem
complex of proteins and pigments in thylakoid membrane
94
2 parts of the photosystem
- antenna system
- reaction center
95
what does the antenna system do
pigments absorb light energy and transfer it to chlorophyll a in the reaction center
96
what are electrons from chlorophylls in the reaction center transferred to
electron acceptor
97
where are electrons transported in photosynthesis
thylakoid membrane
98
what provides electrons for chlorophylls in the reaction center
water molecules split to provide electrons
99
protons are transferred from the stroma to where?
interior of the thylakoids
100
what do the light reactions of photosynthesis lead to the production of
- ATP
- NADPH
- O2
101
carbon fixation
uses ATP and NADPH to convert CO2 into sugar
102
what does carbon fixation consume ATP/NADPH to form
glyceraldehyde-3-phosphate
103
glyceraldehyde-3-phosphate (G3P)
3 CO2 + 9 ATP + 6 NADPH
104
glycolysis
converts glucose --> 2 pyruvate and some ATP
anaerobic
105
cellular respirationg
uses O2 to convert 1 pyruvate --> 3 CO2
106
fermentation
converts pyruvate into lactic acid or ethanol
107
oxidizing agent
reactant that becomes reduced
108
when do redox reactions occur
during the formation of a salt
109
between glucose and O2, which is the REDUCING agent
glucose
110
key electron carrier in redox reactions
coenzyme NAD+
111
aerobic metabolic process
- glycolysis
- pyruvate oxidation
- citric acid cycle
- electron transport/ATP synthesis
112
anaerobic metabolic processes
- glycoysis
- fermentation
113
where does glycolysis take place
cytoplasm, 10 steps
114
net result of glycolysis
2 pyruvate + 2 ATP + 2 NADH
115
3 phases of glycolysis
- energy consuming phase --> requires ATP
- cleavage phase
- energy-releasing phase --> produce ATP and NADH
116
what pathways does cellular respiration include
- pyruvate oxidation
- citric acid cycle
- ETC/ATP synthesis
117
where does cellular respiration take place
in the mitochondria
118
where does pyruvate oxidation occur
mitochondrial matrix
119
results of one citric acid cycle
2 CO2 + 3 NADH + 1 GTP + 1 FADH2
** cycles operates 2 times for 1 glucose
120
what is the starting point for the citric acid cycle
acetyl coa
121
citric acid cycle
8 reactions, acetyle group oxidized to 2 CO2
122
step 8 of citric acid cycle
oxidation of malate, NAD+ --> NADH, malate --> oxaloacetate
123
results of the oxidation of 1 glucose
- 6 CO2
- 10 NADH
- 2 FADH2
- 4 ATP
124
oxidative phosphorylation
2 steps:
- electron transport : electrons from NADH and FADH2 pass through respiratory chain --> create concentration gradient
- chemiosmosis" protons diffuse back to mitochondrial matrix --> ATP is made
125
where does proton pumping create an electrochemical gradient
inner mitochondrial membrane
126
electron transfers cause movement of protons where?
matric to intermembrane space
127
what kind of motor is the mitochondrial ATP synthase
rotary motor
128
results of lactate fermentation
2 lactate + 2 ATP
129
results of ethanol fermentation
2 ethanol + 2 CO2 + 2 ATP
130
how does the cycle of fermentation regulate itself
NADH gives up its electrons in the cytosol and converts back into NAD+ that glycolysis can use
131
metabolites
regulatory molecules
132
3 types of endocytosis
- receptor-mediated endocytosis (specific intake)
- pinocytosis (fluid)
- phagocytosis (particles)
133
2 types of exocytosis
release of large molecules
release of small molecules
134
2 types of membrane proteins
- integral : extend through lipid bilayer
- peripheral: interact with integral membrane proteins
135
how are integral proteins removed
can only be removed by disrupting the bilayer with detergents
136
(T/F) distribution of membrane proteins is asymmetrical
TRUE
137
transmembrane protein
integral protein that extends all the way through the phospholipid bilayer
138
how does an integral membrane protein cross the lipid bilayer
as an a helix
139
how do plasma membrane proteins move in the bilayer
laterally
140
how do cells confine particular proteins to localized areas
- binding meshwork of proteins inside cell
- binding proteins on surface of another cell
- diffusion barriers
- binding extracellular matrix molecules
141
membrane domains
functionally specialized regions
142
cell cortex
framework of proteins that support cell membrane
143
sugar coating on cell curface
carbohydrate layer/glycocalyx that functions in cell recognition and adhesion
144
3 types of cell junctions that connect adjacent cells
- desmosomal adhesion
- tight junctions
- gap junctions
145
desmosomal junctions
cell structure specialized for cell=cell adhesion
randomly arranged on lateral sides of cell
tissues faced with mechanical stress
146
tight junctions
protein complex between 2 cells that creates a seal to prevent leakage of content through membranes
147
gap junctions
allow intracellular flow of ions and molecules between cytoplasms
148
cell theory
- cells are the fundamental units of life
- all living organisms are composed of cells
- all cells come from preexisting cells
149
bright-field microscopy
light passes directly through cells
details not distinguished
150
phase contrast microscopy
contrast increased by emphasizing differences in refractive index
enhances light and dark regions in cell
151
differential interference contrast microscopt
2 beams of polarized light are used
looks as if cell is casting a shadow on one side
152
stained bright-field microscopy
stain enhances contrast, reveals details not otherwise visible
153
fluroescence microscopy
natural substance in cell that binds to a specific material is stimulated by a beam of light
154
confocal microscopy
fluorescence materials are used --> adds sustem of focusing both stimulating and emitted light
2D image
155
scanning electron microscopt (SEM)
electrons are directed to the surface of the sample where they cause other electrons to be emitted
156
nuclear lamina
involved in most nuclear activities
157
rough ER
site of protein synthesis
158
smooth ER
site of glycogen degredation, lipid/steroid synthesis, calcium ion storage
159
golgi apparatus
site of protein modification and sorting
adds carbs to proteins
160
lysosomes
site of macromolecule digestion
161
mitochondria
sites of energy transformation
162
chloroplasts
site of photosynthesis in plants
163
chromoplasts
make/store red, yellow, orange pigments
164
leucoplasts
store starch
165
peroxisomes
accumulate toxic peroxides
166
vacuols
storage compartment in plants
167
what happens at the nerve terminal
electric signal is converted to chemical signal
168
what happens at a synpase
chemical signal converted into electrical signal
