VCU Exam 3 Flashcards
cell signaling
a signaling cell initiates communication by receptor activation (binding the signaling molecule to the receptor molecule) which triggers a cascade of events (signal transduction) that leads to a response. Termination of cell signaling allows the cell to receive other signals.
endocrine signaling
travels through the blood stream (longest distance)
paracrine signaling
from one cell to a nearby cell (up to 20 cells away) important in embryonic development
initiates cell division, growth or differentiation
juxtacrine signaling
adjacent molecules. both signal molecule and receptor molecule are transmembrane and physically joins the 2 cells together
autocrine signaling
one cell is both signaling and responding. receptors is polar and on the outside for large molecules and nonpolar and interior for small molecules
G-protein coupled receptors
Adrenaline (ligand) is the signaling molecule, binds to transmembrane receptor at ligand binding site and the receptor changes shapes (conformational change).
G Protein activated- GDP is released and replaced with GTP, Alpha subunit will release from beta and gamma subunits.
G protein binds to another transmembrane protein/enzyme and this enzyme converts ATP to cyclic AMP (cAMP)
cAMP binds to PKA, and activates PKA acts an enzyme (signal amplification)
PKA can phosphorylates many protein target in the heart which results in the response- heart contraction and heart rate increase.
Termination- adrenaline concentration go below threshold and detach from the receptor, g-protein replaces dephosphorylates GTP back into GDP, G-protein detaches from enzyme and reattaches to beta and gamma sub units.
signal amplification
one adrenaline molecule can cause the production of lots of cAMP
receptor kinases
dymer has 2 kinases, activated by signal molecule (ligand) binding to both kinases, kinases phosphorylates, and the kinases join together
ligand gated channels
nerve cells to muscle cell or to other nerve cell.
muscle cell receptors are gated and closed
nerve cell carry acetylcholine in vesicles that will bind with the plasma membrane of a nerve cell and release acetylcholine.
acetylcholine will bind to the ion channel on the muscle cell and open that channel.
Na+ (sodium) flows into the muscle cell through the opened channel and cause contraction
catabolic pathway
net release of energy
Large molecule broken down to small molecules (glucose->ATP) ATP is formed from glucose being broken down into CO2 and H2O
oxidation and reduction reactions
Oxidation- loss of electron
Reduction- gain of electron
LEO the lion says GER
hydrogen travels with electrons
stages of cellular respiration
stage 1: glycolysis
stage 2: pyruvate oxidation to acetyl CoA (in mitochondria)
stage 3: citric acid cycle
stage 4: oxidative phosphorylation (inside membrane of mitochondria)
glycolysis
carbohydrate-breaking down (glucose->pyruvate) (10 steps outside of mitochondria) 1 glucose makes 2 pyruvates
Step 1 Glucose-> ATP-> ADP Glucose 6-phosphate Step 2 Glucose 6 phosphate->fructose 6-phosphate Step 3 Fructose 6-phosphate-ATP-ADP->fructose1, 6-bisphosphate Steps 1-3 is Energy consuming phase Step 4 Fructose 1, 6-bisphosphate splits in to glyceraldehyde 3 phosphate and dihydroxyacetone 3 phosphate- cleavage Step 5 Dihydroxyacetone 3 phosphate->glyceraldehyde 3 phosphate Step 6 glyceraldehyde 3 phosphate gains a phosphate group and oxidize 1,3 bisphosphogycerate gain 2 NADH Step 7 1,3 bisphosphogycerate- ADP-> gain 2 ATP 3 bisphosphogycerate Step 8 2 bisphosphogycerate Step 9 Phosphoenolpyruvate Step 10 Phosphoenolpyruvate loses a phosphate-> gain 2 ATP pyruvate
Total= 2 NADH, 2 ATP, 2 pyruvate
pyruvate oxidation to acetyl CoA
Step 1
Pyruvate enters mitochondria matrix and loses a carbon in the form of CO2
Step 2
NAD+ picks up electron from pyruvate-> NADH
Step 3
CoA->Acetyl CoA
Total= 2NADH (per glucose), 2 Acetyl CoA (per glucose)
citric acid cycle
Step 1
Acetyl CoA joins with oxaloacetate, water is used up to break CoA (facilitates the joining of acetyl to oxaloacetate-> Citrate
Step 2
Citrate loses a water molecule -> cis-aconitate
Step 3
cis-aconitate gives of CO2 and NAD+ gains an electron NADH
Step 4
Alpha ketoglutarate- loses a CO2 and NAD+ gains an electron NADH
Temporary addiction of CoA
Step 5
Succlnyl CoA- phosphate group attaches and kick off CoA
Step 6
GDP takes phosphate group from Succlnyl to form GTP, then ADP comes and takes the phosphate from GTP to form ATP
Step 7
Succinate is oxidized, FAD-> FADH2
Step 8
Fumarate gains a water molecule
Step 9
Malate is oxidixed- NAD+-> NADH
Step 10
Returns back to oxaloacetate
Total for citric acid cycle:
6 NADH, 2 ATP, 2 FADH2/ glucose
Acetyl CoA-> NADH, FADH2(electron carriers)
