Cell + Molec III Flashcards
1
Q
What is a liposome
A
A lipid-only artificial membrane vesicle
2
Q
What things can pass easily through the PM
A
hydrophobic things, gasses, small uncharged molecules
3
Q
3 main ions and their concentrations INSIDE the cell
A
Sodium; 5-15
Chlorine; 5-15
Potassium; 140mM
4
Q
3 main ions and their concentrations OUTSIDE the cell
A
Sodium; 145
Chlorine; 110
Potassium; 5mM
5
Q
What is membrane potential
A
the difference in voltage
6
Q
3 types of transmembrane exchange mechanisms
A
simple diffusion; small nonpolar molecules
Channel and transporter mediated; still passive, transporter binds and channels don’t
Active transport; against diffusion (requires E)
7
Q
What channels are for osmosis
A
Aquaporins
8
Q
What is a tetramer and what is normally in a tetramer?
A
4 channels, Aquaporins are in a tetramer
9
Q
What directs Osmosis?
A
Nonpermeable solutes
10
Q
What do gradient pumps do?
A
couple the movement of molecules along their concentration gradient
11
Q
The sodium-Potassium pump
A
maintains sodium and K+ gradients, 3Na go out, 2k+ go in – 30% of ATP use in cells
12
Q
steps of the Na - K+ pump
A
1) binds Na+ in cytosol
2) ATP phosphorylation
3) conformation releases sodium
4) Extracellular k+ binds
5) dephosphorylation
6) k+ released and original conformation achieved
13
Q
Na+-glucose symporter
A
Sodium goes into cell along with glucose (which is going against its concentration gradient)
14
Q
What is a uniport
A
a transporter that only moves one type of molecule
15
Q
What is a synapse
A
junction b/w two neurons or a neuron and a cell
16
Q
What maintains resting membrane potential
A
Na+/K+ pump and K+ leak channels
17
Q
What is resting membr potential?
A
-60mV
18
Q
What is an Action Potential?
A
local changes in membrane potential propagating down an axon
from -60 to +40mV (depolarization)
19
Q
What is the threshold for an AP?
A
-40mV
20
Q
3 states of V-gated k+ channels
A
open, closed, inactivated
21
Q
How does hyperpolarization come about?
A
Voltage-Gated K+ channels open after a delay with depolarization
22
Q
How wide is the synaptic cleft?
A
20nm
23
Q
What happens in the presynaptic neuron after the AP?
A
Ca++ Channels open, causing NTS to release via exocytosis
24
Q
what can inhibit depolarization?
A
Cl- or letting K+ out of the cell
25
Catabolism and Anabolism
breaking down and releasing energy vs
building molecules and storing it (biosynthesis)
26
Oxidation
a form of catabolism where you release energy, sometimes by adding oxygen
27
Cellular respiration
the stepwise-oxidation of food molecules to get Energy released
28
3 stages of cellular respiration
digestion
glycolysis (6-C glucose to pyruvate and acetyl CoA)
complete oxidation in mitochondria (citric acid cycle)
29
2 activated carriers
NADH and FADH2
30
What are the reduced forms of the two activated carriers we cover
NAD+
FAD
31
5 steps of gycolysis
1. 1 glucose
2. initial input of 2 ATP
3. 1, 6-C split to 2, 3-C G3P
4. produces 2 NADH, 4 ATP by substrate-level
phosphorylation: rxn coupled with ADP
phosphorylation
5. 2 pyruvate
32
We have two pyruvate after glycolysis.... now what>?
it gets PUMPED into the mitochondrial matrix
then it goes into the pyruvate dehydrogenase complex
1. breaks pyruvate into CO2 + 2-C
acetyl group (–COCH3)
2. produces acetyl CoA = acetyl
group + activated carrier,
coenzyme A (modified
nucleotide)
3. produces NADH
net total
(4NADH + 2ATP)
33
What is the purpose of the citric acid cycle>?
to turn the acetyl groups into carbon dioxide
34
Citric acid cycle
1. 2-C acetyl group + 4-C oxaloacetate
= 6-C citrate
2. 2 carbons oxidized to 2 CO2,
produces 2 NADH, GTP (guanosine
triphosphate), 4-C succinate
3. rxn produces FADH2
4. rxn produces more NADH,
oxalacetate
(2x per glucose)
35
what is the net products after the citric acid cycle?
10NADH, 2FADH, 2ATP, 2GTP, 6CO2
36
How are fatty acids processed for e and what does it make?
They're coupled with CoA, you put ATP into the process, but get FADH2 NADH
37
what is oxidative phosphorylation?
ATP synthesis from the proton gradient made by the ETC powered by activated carriers
38
What inhibits glycolysis?
ATP
39
anabolic pathway
building molecules with E to store it
example; glucogenesis
40
Glucose storage molecules
starch: in plants (cellulose too for cell walls)
glycogen: in animals; branching
41
how long to animal energy stores last?
glycogen; 1 day
fat; as fat droplets; 1 months worth (2x as much energy as glycogen/g)
42
2 steps of oxidative phosphorylation
1. proton gradient made in intermembrane space
2. protons flow down gradient through ATP synthase (chemiosmotic coupling)
43
what are the 3 steps to cell signaling
1reception
2trasduction
3response
44
what do extracellular signaling molecules bind to>?
receptors
45
Endocrine signaling
long distance; signaling cell secretes hormones into circulatory system
46
paracrine signaling
signal secreted into extracellular fluid e.g. histamine
47
neuronal signaling
neurotransmitter secreted to target cell at synapse
48
contact dependent signaling
membrane bound signal to receptor of adjacent cell
49
transduction
reception induces intracellular signaling molecules
50
examples of fast and slow cellular responses to signaling
fast; modifying something like phosphorylating
slow; changing gene expression like turning off or on protein synthesis
51
what is the intracellular signaling pathway
a cascade of proteins, polypeptides, small and hydrophilic molecules, etc. that activate some effector for a response.
52
benefits to the intracellular signaling pathway
relays information
amplifies response
integrates with other pathways
feedback; self regulates
distributes; branches for multiple responses
RAIFD
53
Where does the citric acid cycle take place?
w/in the inner membr. of the mitochndria
54
Difference b/w inner and outer membranes of the mitochondria
outer; wide porins and highly permeable
inner; only ions and can only pass thru specific transporters
55
how does the ETC function?
NADH andFADH2 have high energy electrons that are given up to respiratory enzyme complexes. Ea has a higher electron affinity than the previous one and these pump protons
56
What is the final electron acceptor in the ect
oxygen
57
what is the proton motive force
gradient toward matrix due to membrane potential and pH gradient
58
how much atp do NADH and FADH produce
2.5 and 1.5 respectively
59
What converts the proton gradient into atp?>
ATP synthase
60
What's different about respiration in anaerobic conditions?
glycolysis ends with lactate
61
what are the two series of reactions in chloroplasts?
light rxns and the carbon fixation cycles
62
Carbon fixation reactions are made up by;
calvin cycle; makes sugar
no second one lol
63
Mesophyll cells
make up green tissue in plants; these have chloroplasts
64
what is the space within a thylakoid?
thylakoid space
65
What captures light? What harvests it?
photosystems and antenna complexes (photosystems have antenna complexes and a rxn center complex)
66
what does the special pair do>?
captures light
67
PSII vs PS1
PSII: first one; the electron for the ETC is gotten from water splitting enzyme
PSI passes electron to second ETC for making NADPH and is catalyzed by NADP+ reductase
68
first 3 steps of carbon fixation
carbon fixation
1.) 3, 5-C ribulose and 1, 5-C RuBP each are combined with CO2 by RuBisCO
2.) 3 new 6-C are split into 6, 3-C
sugar formation
3.) E from ATP and 6NADPH are used to reduce 6, 3-C to G3Ps (also 6, 3-C)
69
last 3 steps of Carbon Fixation
4.) 1G3P used to make something like glucose
Regeneration
5.) 5 remaining G3p go into regeneration
6.) 3 ATP used to convert 5, 3-C G3p into RuBp (3, 5-C)
70
lyso v endo vs peroxisomes
digestion, sorting, lipid metabolism + toxin digestion
71
How did the endomembrane system origninate>
invagination of PM, lumen derived from exterior
72
Mitochondria and chloroplast origin
via endosymbiosis
73
Cell signaling; what goes where and comes from what?
extracellular signaling molecule from a signaling cell results in intracellular signaling molecules
74
3 stages in cell signaling
1 reception (ligand binds to receptor)
2 transduction (intracellular molecules are induced)
3 response (change in cell)
75
endocrine signaling
signaling molecules (hormones) secreted to circulatory system and are the broadest ranging ones
76
paracrine signaling
local mediator signaling; sectreted into ecf
77
autocrine
signals self
78
neuronal signaling
NTS secreted to sp target cell at synapse
79
contact-dependent signaling
membrane bound signal to receptor adjacent to cell
80
fast and slow cellular responses
modifying something that already exists vs changing gene expression
81
intracellular signaling pathway
cascade that activate effectors for a response
82
multistep pathway advantages
relays signal
amplifies it
integrates signals and decisions
feedback (self regulating)
distributes more responses
83
all receptor types
ion-channel-coupled receptors
G-protein coupled receptors
enzyme-coupled receptors
84
3 types of proteins used in intracellular signaling pathways
molecular switches, protein kinases (and phosphatases), and GTP-binding proteins
85
what does epinephrine do?
breaks down glucose in skeletal muscle
86
epidermal growth factor?
triggers activation of genes involving cell cycle
87
epinephrine pathway
GPCR activated by epinephrine
GPCR activates G-protein
G-protein activates adenylyl cyclase
adenylyl cyclase makes cAMP out of ATP
PKA activated by cAMP, phosphorylates other kinases and proteins
88
G-protein steps for epinephrine
1 --- inactive, binds GDP in alpha
2 --- signal molecule activates GPCR
3 --- binds G-protein, alpha releases GDP
4 --- G-protein released activated by GTP
5 --- dissociation of activated alpha and activated beta gamma
89
two parts of enzyme coupled receptors
ligand binding domain and intracellular active site
90
What does EGFR bind?
epidermal growth factor, and its a type of enzyme coupled receptors
91
how do RTK get activated? What are they?
when they bind to each other (dimer)
receptor tyrosine kinase; phosphorylates itself and has binding sites for other proteins
92
what do RTKs do? (pathway)
activate Ras (with help of Ras-GEF), which activate MAP-kinase signaling module
activates MAP kinase pathway
MAPKKK
MAPKK
MAPK
93
nuclear lamina
protein on the inside of the nuclear envelope for support
94
what marker is used for importing proteins into the nucleus
nuclear localization signal: it binds to and recognized by nuclear import receptors on cytosolic fibrils
whole process powered by GTP
95
Process of getting proteins into mitochondria and chloroplasts
1) precursor proteins with N-terminus signal sequence
2) bound by import receptor protein
3) guides to outer membrane protein translocator unfolded
4) aligns with inner protein translocator
5) chaperone proteins help refold protein
6) signal sequence cleaved
96
how are proteins are imported into the ER as they are synthesized?
SRP recognizes ER signal sequence of protein getting translated. guides ribosome to protein translocator
97
secretory protein vs endocytic pathway
ER to Golgi to PM or Lysosome
and
PM to lysosome to digest
98
clathrin
coat protein used for: PM to GOLGI
99
vesicle budding process
1. cargo receptors bind cargo molecules that have transport signals
2) adapting binds cargo receptors and clathrin
3) forms pit 4) dynamin rings the buds neck and pinches off coated vesicle
5) clathrin removed
100
Microtubules
25nm -- made of beta and alpha tubulin subunit
distinct ends
microtunules organized at the centrosome
