Tutor profile: Maggie W.

What do all animals have in common with each other?

The kingdom Animalia is approximately 600 million years old, are eukaryotes with multiple cells, are heterotrophic (can not manufacture own food internally), generally are able to move, and have at least rudimentary circulation and neural networks.

Give one definition of a protein, and tie this into the central dogma of biology.

There are several definitions of proteins, depending on the perspective of the scientist. One definition is that a protein is: a macromolecule comprised of many amino acids strung together in a particular sequence and taking on a particular shape. This ties into the central dogma of biology (DNA-RNA-amino acid-protein), in that the transcription of DNA eventually leads to a specific amino acid sequence, that given the "correct" conditions of temperature and pH, will generate the same protein shape each time.

Give the name for a channel that specifically allows potassium ions to flux due to a change in the membrane potential. In which direction would the potassium flux?

This would be a voltage-gated potassium channel, and the potassium would efflux or flow out of the cell. Explanation: The voltage-gated potassium channel is a transmembrane protein channel that responds to a change in membrane potential (due to positively charged sodium ions lining up on the inside of the membrane, thus temporarily reversing the voltage). When the voltage changes in this manner, the channel will open after a slight delay, and since potassium ions are held at greater concentration inside the cell (primarily because of the presence of the sodium-potassium pump), potassium would flow down its concentration gradient, from inside the cell where it is more highly concentrated, to the outside of the cell where it is less concentrated.