How many ribosomes/signaling molecules are in a cell?
How do genes regulate each other?
How rapidly does a protein move from one end of the cell to another?
What fraction of transcription factors is bound to DNA?
What are the speed limits for biochemical reactions?
How are polarities and developmental gradients set up?
Not: Gene X causes Y
But: 20% faster diffusion of gene X extends the gradient by $20\mu m$
Dimensions and units
Dimensions
length
weight
energy
current
force
temperature
....
Units:
length: meters, miles, feet, Angstrom
weight: grams, stones,
energy: Joules, calories
current: ampere
force: Newton
temperature: Celsius, Kelvin
....
Dimensions describe the nature of a quantity
Units are conventions to measure them
Comparing quantities
Only quantities of the same dimension can be compared: length $X$ is greater than length $Y$ etc. There is no sense is which length $X$ can be greater than weight $Y$.
Units are conventions -- there is nothing fundamental about them.
Some unit systems are more convenient than others.
Everyday units are often inconvienent for biological processes
We can pick units to make things as simple as possible
Aim: Enable you to reason quantitatively about biological problems!
Wikipedia, by Brews Oshare
Wikipedia, by cybertory
