Cell Physiology Basics Flashcards
fundamental features of all cells
store genetic info, surrounded by plasma membrane
central dogma of molecular biology
flow of genetic info from gene to protein. proteins are the functional unit of living organisms
endomembrane system of eukaryotes
ER, Golgi, plasma membrane. constantly exchanging information and materials
biosynthetic secretory pathway
proteins and antibodies the cell is making that are being exported out of the cell into the ECF
endocytic pathway
taking stuff in from outside the cell
cytoskeleton
not just structural. intermediate filaments, microfilaments, microtubules (long rod-like proteins)
intermediate filaments
structural support to maintain shape of the cell
microfilaments
enables cell mobility that involves changing shape of cells. mostly composed of actin. involved in all muscle contraction
microtubules
components of cilia and flagella. form spindle during mitosis/meiosis. vesicular transport–how vesicles move within the cell. forms a network of tracks for the motor proteins Kinesin and Dynein
motor proteins
attach vesicles to motor proteins to speed up movement. Kinesin and dynein
Kinesin and Dynein
couple ATP hydrolysis to speed up axonal transport along microtubular highways
Kinesin
goes from body to exterior of cell
Dynein
goes from exterior to body of cell (retrograde transport)
hydrophobic effect
refers to the spontaneous self-assembly of non-polar substances that are dispersed in water. maximizes entropy
simple diffusion
anything hydrophobic can get across the lipid membrane. Gases are hydrophobic so, oxygen, can get through by simply diffusing
facilitated diffusion
impermeable solutes aided y protein carriers or channels. movement of diffusion is down the concentration gradient
active transport
pump impermeable solutes using energy. ATP or energy from another gradient is used.
Diffusion
driven by entropy, things have a tendency to fill the entire area available to them`. Net movement from HIGH to LOW concentration. Molecules want to spread out
Fick’s Law of Diffusion
Increase gradient, surface area, lipid solubility = more diffusion. The bigger something is and the thicker the membrane = slower diffusion
Channel-mediated facilitated diffusion
channel, some sort of pore. Open on both sides of the membrane and works like a door. Can be open all the time or gated. Some type of trigger causes the door to open, like phosphorylation
Carrier transport of facilitated diffusion
carriers have 2 distinct conformations. The undergo changes that reorient their “sidedness.” They have a binding site for the molecule being carried and when the molecule is bound, it will open on the other side to release the molecule. Net carrying of molecules from high->low conc. Uniporters–carry only a single solute
Simple Diffusion vs Carrier Mediated (facilitated diffusion)
Simple diffusion is directly proportional to the transmembrane concentration gradient. The Carrier mediated transport can reach a maximum where all of the available carriers are saturated
Primary Active transport
ATPase coupled ion pumps. Hydrolyzing ATP->ADP and couple that rxn to pumping up the concentration gradient (doing something thermodynamically unfavorable)
Active transporters maintain
non-equilibrium ion distributions
Sarco-endoplasmic reticulum calcium ATPase (SERCA)
Calcium ATPase present in muslce cells ER. Maintains low levels of Ca2+ by storing cytoplasmic Ca2+ into the endoplasmic reticulum
Muscle endoplasmic reticulum stores
calcium, put into ER by sarco-endoplasmic reticulum calcium ATPase (SERCA)
Plasma membrane calcium ATPase (PMCA)
on plasma membrane. pumps calcium from cytoplasm to the ECF. Want to maintain low levels of intracellular calcium
pumped
actively moving substance against its concentration gradient
Na+/K+
Uses phosphorylation as a switch. Has two conformations: E1 and E2. active transport
E1 conformation of Na+/K+ pump
accessible from the ICF (cytoplasmic fluid). High affinity for Na+, low affinity for K+. Once all binding sites for Na+ are filled, transfer Phosphate from ATP to the carrier.
E2 conformation of Na+/K+ pump
accessible from the ECF. Low affinity for Na+, high affinity for K+. Releases Na+ into ECF. Once K+ is bound, the carrier is dephosphorylated and flips back to E1 ICF open conformation
5 steps of Na+/K+ pump
In E1 conformation (1) transporter binds Na+ in cytosol (2) phosphorylation by ATP favors conformational change to E2 (3) Na+ release, K+ binds from ECF (4) Dephosphorylated favors E1 conformation (5) K+ released into ICF and the cycle can repeat
secondary active transport
still utilizing energy to pump a molecule against a gradient, but not directly using chemical energy from ATP. Using alternative gradient created by primary active transport (vast majority use sodium gradient as energy source)
Symport
secondary active transport, moving two molecules in the same direction. Ex: sodium moved in the same direction as the molecule it’s powering against gradient
Sodium Glucose transporter (SGLT)
secondary active symporter. Uses Na+ to moving down concentration gradient to pump glucose against its gradient. when sodium is bound, high affinity for gluc.
SGLT conformational changes can happen
when both Na+ and glucose are bound, or if nothing is bound.
Antiporter
molecules moving in opposite directions
metabolism
sum of all chemical reactions in a biological entity: energy metabolism and oxidative metabolism
energy metabolism
breaking down carbon fuels and making energy in the form of ATP. Transferring energy into a usable form–ATP
Glycolysis
Uses substrate level phosphorylation to produce ATP. Involves redox rxn wherein oxidation of a metabolic intermediate is coupled to the reduction of NAD+–>NADH (put an electron on it)
Glycolysis must reduce
NAD+–>NADH to continue. NAD+ is the limiting factor for glycolysis
