There are two forms of active uptake/transport:

1. Active Carrier Transport

2. Endocytosis

1. Active Carrier Transport

Active carrier transport is similar to facilitated diffusion in that it utilizes a protein (carrier). However, energy is also used to move compounds against their concentration gradient. The following figure and video do a nice job of illustrating active carrier transport.

Figure 4.321 Sodium-potassium ATPase (aka sodium-potassium pump) an example of active carrier transport¹

2. Endocytosis

Endocytosis is the engulfing of particles, or fluids, to be taken up into the cell. If a particle is endocytosed, this process is referred to as phagocytosis. If a fluid is endocytosed, this process is referred to as pinocytosis as shown below.

Figure 4.322 Different types of endocytosis²

The following video does a really nice job of showing how endocytosis occurs.

References & Links

1. https://en.wikipedia.org/wiki/File:Scheme_sodium-potassium_pump-en.svg

2. http://commons.wikimedia.org/wiki/File:Endocytosis_types.svg

Videos

Active Transport – http://www.youtube.com/watch?v=STzOiRqzzL4

Endocytosis – http://www.youtube.com/watch?v=4gLtk8Yc1Zc