• All living things are made of cells, the smallest unit that can carry on all the processes of life

• In 1665, Robert Hooke observed the first cells from thin slices of cork. He gave them the name "cells" because they reminded him of small rooms or cells that monks lived in.

• In 1675, Anton van Leeuwenhoek was the first person to observe living cells. He looked at protozoans from pond water.

CELL THEORY

• About 150 years later scientists organized their observations into a cell theory:

• - All living things are composed of one or more cells.

• - Cells are the basic units of structure and function in an organism.

• - Cells come only from existing cells.

Prokaryotic Cells (Bacteria)

• The average size is about 1 micrometer. Bacteria have no nucleus and no membrane-bound organelles. An organelle is a cell component that performs specific functions for the cell.

Cell Membrane -

• separates the cell from its environment. • It regulates what moves into and out

of the cell.• The Fluid Mosaic Model: the cell

membrane is made up of 2 layers of phospholipids with proteins embedded throughout. These lipids and proteins constantly move laterally creating a fluid motion.

Cytoplasm

• the entire contents of the cell, except the DNA.

Ribosomes

• site where proteins are made.

Nucleoid

• tangled ball of DNA; tells cell what proteins to make.

• It is not called a nucleus because the DNA is not contained within a membrane.

Plasmids

• small rings of DNA (separate from the nucleoid).

Pili (pilus)

• appendages that allow the bacteria to adhere to other surfaces.

Flagella

• long extensions that aid in movement

Cell Wall

• outer rigid layer; maintains the shape of the cell and adds protection.