Which of the following can be considered extra-genomic DNA in eukaryotic cells?

The cell is the most basic functional unit of life. Everything that we consider to be living is made up of cells, and while there are different kinds of cells, they all have some essential features that link them all together under the category of "life." One of the most important parts of a cell is the membrane that surrounds it, seperating it from the rest of the environment.

While organisms from the three main domains live in incredibly different environments, they all possess similar cell membranes. This phospholipid bilayer protects the cell, giving it a way to allow certain things in while keeping other things out. Though organisms from different domains have different kinds of fatty linkages in their membranes, they all serve this essential purpose.

Membranes contain all kinds of essential proteins and signal molecules that allow the inside of the cell to respond to the outside of the cell. In a multicellular eukaryote, this ability can be used to allow cells to communicate. In a bacterial colony, an extracellular signal could be used to signal other bacteria. Signals cascade through a series of molecular pathways that go from the outside of the cell all the way to the nucleus and back out again, giving the cell control on a genetic level. This allows cellular responses to be quick and effective, and it also allows the cell to control how long it stays in that state.

What characteristic of a cell could a scientist use to determine what domain to which an unknown cell belonged?

Which of the following leukocytes is not a participant in the innate immune response?

All of the following are examples of asexual reproduction, except __________.

Which of the following types of microscopy is best for the visualization of living organisms?

The following processes occur both in eukaryotes and prokaryotes except for which answer choice?

What should a scientist look for if he is trying to determine whether a certain organism is a bacteria rather than a virus?