Research on microbial growth has resulted in a large number of different equations to describe growth kinetics, the most famous of which is that of Monod. In the present work, the case of single substrate limitation in the absence of substrate inhibition is studied. Metabolism can then be regarded as a simple network consisting of a single reaction for anabolism and another for catabolism. These reactions are interconnected by cofactors of rather constant concentration. Growth is described as a combination of substrate uptake kinetics and growth kinetics. The notion that enzymatic activities of anabolism and catabolism depend on growth rate leads to a number of substrate uptake models, which fall into a few families. Each of them can be described by a general and flexible three-parameter equation. Well-known equations like that of Monod and Blackman turn out to be special cases. It could be concluded that the presented equations show more or less the same behavior in a scaled uptake rate versus substrate concentration plot, although the (powered) Monod equation might in general be preferred because its overall shape seems to resemble experimental observations most.