A countercurrent system is a system in which the inflow runs parallel to, counter to, and in close proximity to the outflow for some distance. This occurs for both the loops of Henle and the vasa recta in the renal medulla

TLS Online TPP Program

#Id: 8321

#Unit 2. Cellular Organization

Elongation phase

short oligomer rapidly increases in length by the addition of actin monomers to both of its ends, causing filament elongation

TLS Online TPP Program

#Id: 8322

#Unit 2. Cellular Organization

Steady-state phase

G-actin monomers exchange with subunits at the filament ends, but there is no net change in the total length of filaments.

TLS Online TPP Program

#Id: 8323

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 8324

#Unit 2. Cellular Organization

The rate of addition of monomers is given by

rate constant kon (M–1 sec–1 )

The rate of loss is given by koff (sec–1)

TLS Online TPP Program

#Id: 8325

#Unit 2. Cellular Organization

Critical concentration (Cc)

minimal concentration of monomers at which filaments form

TLS Online TPP Program

#Id: 8326

#Unit 2. Cellular Organization

The two ends of microfilament polymerize at different rates:

fast-growing end - plus end

slow-growing end - minus end