Title: Unit 2 Learning Module
Course: SAT 170 Introductory Biotechnology > Section: SAT 170 Introductory Biotechnology

Unit 2 Learning Module

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Cells - The Basic Unit of Life
Cell Theory
- Cell theory is used to describe our current understanding of all cells. There are three components to cell theory:
  - Cells are the smallest unit of life.
  - All living things are composed of cells.
  - Cells arise from pre-existing cells.

In reference to our material from Unit 1, recall that a theory is a hypothesis that has been repeatedly verified through experimentation. There are two main types of cells: prokaryotes and eukaryotes. Cells are composed of internal structures known as organelles. Organisms may be unicellular (composed of a single cell), colonial (composed of many cells, each of which is capable of surviving on its own), or multicellular (composed of many cells).

Prokaryotes and Eukaryotes
- Although prokaryotes and eukaryotes are distinct, they do have several similarities including the following:
- Both cell types contain DNA, ribosomes, cytoplasm and a cell membrane.
- Both may contain cell walls and cytoskeletons .

Prokaryotes vs. Eukaryotes
- Some of the major differences between prokaryotes and eukaryotes include:
- Prokaryotes are small and simple because they lack a nucleus and other membrane bound organelles. Archaea and Bacteria are considered to be prokaryotes.
- Eukaryotes are large and complex because they have a nucleus, which stores their DNA, and many other membrane bound organelles. Animals, Plants, Protists and Fungi are all considered to be eukaryotes.

Cell Structure
- Although all cells vary extensively in form and function, there are basic cell structures that are important to most cells.

See Figure 1: This image depicts the major features of a typical eukaryotic cell.

Figure 1