Cell + Molec III Flashcards
What is a liposome
A lipid-only artificial membrane vesicle
What things can pass easily through the PM
hydrophobic things, gasses, small uncharged molecules
3 main ions and their concentrations INSIDE the cell
Sodium; 5-15
Chlorine; 5-15
Potassium; 140mM
3 main ions and their concentrations OUTSIDE the cell
Sodium; 145
Chlorine; 110
Potassium; 5mM
What is membrane potential
the difference in voltage
3 types of transmembrane exchange mechanisms
simple diffusion; small nonpolar molecules
Channel and transporter mediated; still passive, transporter binds and channels don’t
Active transport; against diffusion (requires E)
What channels are for osmosis
Aquaporins
What is a tetramer and what is normally in a tetramer?
4 channels, Aquaporins are in a tetramer
What directs Osmosis?
Nonpermeable solutes
What do gradient pumps do?
couple the movement of molecules along their concentration gradient
The sodium-Potassium pump
maintains sodium and K+ gradients, 3Na go out, 2k+ go in – 30% of ATP use in cells
steps of the Na - K+ pump
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
Na+-glucose symporter
Sodium goes into cell along with glucose (which is going against its concentration gradient)
What is a uniport
a transporter that only moves one type of molecule
What is a synapse
junction b/w two neurons or a neuron and a cell
What maintains resting membrane potential
Na+/K+ pump and K+ leak channels
What is resting membr potential?
-60mV
What is an Action Potential?
local changes in membrane potential propagating down an axon
from -60 to +40mV (depolarization)
What is the threshold for an AP?
-40mV
3 states of V-gated k+ channels
open, closed, inactivated
How does hyperpolarization come about?
Voltage-Gated K+ channels open after a delay with depolarization
How wide is the synaptic cleft?
20nm
What happens in the presynaptic neuron after the AP?
Ca++ Channels open, causing NTS to release via exocytosis
what can inhibit depolarization?
Cl- or letting K+ out of the cell
Catabolism and Anabolism
breaking down and releasing energy vs
building molecules and storing it (biosynthesis)
Oxidation
a form of catabolism where you release energy, sometimes by adding oxygen
Cellular respiration
the stepwise-oxidation of food molecules to get Energy released
3 stages of cellular respiration
digestion
glycolysis (6-C glucose to pyruvate and acetyl CoA)
complete oxidation in mitochondria (citric acid cycle)
2 activated carriers
NADH and FADH2
What are the reduced forms of the two activated carriers we cover
NAD+
FAD
5 steps of gycolysis
- 1 glucose
- initial input of 2 ATP
- 1, 6-C split to 2, 3-C G3P
- produces 2 NADH, 4 ATP by substrate-level
phosphorylation: rxn coupled with ADP
phosphorylation - 2 pyruvate
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)
What is the purpose of the citric acid cycle>?
to turn the acetyl groups into carbon dioxide
Citric acid cycle
- 2-C acetyl group + 4-C oxaloacetate
= 6-C citrate - 2 carbons oxidized to 2 CO2,
produces 2 NADH, GTP (guanosine
triphosphate), 4-C succinate - rxn produces FADH2
- rxn produces more NADH,
oxalacetate
(2x per glucose)
what is the net products after the citric acid cycle?
10NADH, 2FADH, 2ATP, 2GTP, 6CO2
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
what is oxidative phosphorylation?
ATP synthesis from the proton gradient made by the ETC powered by activated carriers
What inhibits glycolysis?
ATP
anabolic pathway
building molecules with E to store it
example; glucogenesis
Glucose storage molecules
starch: in plants (cellulose too for cell walls)
glycogen: in animals; branching
how long to animal energy stores last?
glycogen; 1 day
fat; as fat droplets; 1 months worth (2x as much energy as glycogen/g)
2 steps of oxidative phosphorylation
- proton gradient made in intermembrane space
- protons flow down gradient through ATP synthase (chemiosmotic coupling)
what are the 3 steps to cell signaling
1reception
2trasduction
3response
what do extracellular signaling molecules bind to>?
receptors
Endocrine signaling
long distance; signaling cell secretes hormones into circulatory system
paracrine signaling
signal secreted into extracellular fluid e.g. histamine
neuronal signaling
neurotransmitter secreted to target cell at synapse
contact dependent signaling
membrane bound signal to receptor of adjacent cell
transduction
reception induces intracellular signaling molecules
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
what is the intracellular signaling pathway
a cascade of proteins, polypeptides, small and hydrophilic molecules, etc. that activate some effector for a response.
benefits to the intracellular signaling pathway
relays information
amplifies response
integrates with other pathways
feedback; self regulates
distributes; branches for multiple responses
RAIFD
Where does the citric acid cycle take place?
w/in the inner membr. of the mitochndria
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
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
What is the final electron acceptor in the ect
oxygen
what is the proton motive force
gradient toward matrix due to membrane potential and pH gradient
how much atp do NADH and FADH produce
2.5 and 1.5 respectively
What converts the proton gradient into atp?>
ATP synthase
What’s different about respiration in anaerobic conditions?
glycolysis ends with lactate
what are the two series of reactions in chloroplasts?
light rxns and the carbon fixation cycles
Carbon fixation reactions are made up by;
calvin cycle; makes sugar
no second one lol
Mesophyll cells
make up green tissue in plants; these have chloroplasts
what is the space within a thylakoid?
thylakoid space
What captures light? What harvests it?
photosystems and antenna complexes (photosystems have antenna complexes and a rxn center complex)
what does the special pair do>?
captures light
