the DYNAMIC CELL...
some estimates of number of chemical reactions in cells and
speed of molecular movements inside of cells...
- bacterial ribosomes add new aa's @ rate 20
bacteria have ≈ 15,000 ribosomes = 300,000 aa/sec or some 1,000 proteins/sec
- eukaryotic ribosomes @ 2 aa/sec
eukaryotes have over 1 million ribosome = 6,500 proteins/sec
over 500 molecules pass through each of the 3000–4000
nuclear pores every second
individual cell of the body make and use on average 10 million ATP/sec
typical enzyme may catalyze 2,500 reactions/sec
a single phospholipid in 1 min may travel breadth of cell
mitochondria in each cell are replaced about every 10 days
Cell Biology animations by john kyrk
Scale of Cell
(obviously small, but)
consider that gravity is probably inconsequential...
instead, electrostatic attractions between molecules and the kinetic energy of motion
are the dominant energy forces
here events take nanseconds and speed is measured in чm/sec
- flagella can move bacteria thru water at 60 cell lengths/sec = 120 чm/sec (0.0004ft/sec)
- Alexander Popov - WR 50M free moves at 1.26 body lengths/sec (7.6 ft/sec)
- cheetah, fastest animal known, = 25 body lengths/sec (115ft/sec)
Cells are truly dynamic...
Thousands of chemical reactions occur each second,
molecules constantly enter and exit across the plasma membrane,
thousands of proteins are constantly being made,
cell vesicles move along protein fibers of cytoskeleton,
cytoskeleton, itself, grows and shrinks continually,
cells move as a whole flagella or cilia, or cell crawling,
and motor proteins convert ATP into movement...