2.1 Prokaryotic cells

ProkaryotesPro = before

Karyon = nucleus

There are two basic kinds of cells. One kind—a prokaryotic cell— lacks a nucleus and most other organelles.

Bacteria and archaea are prokaryotic cells.

Prokaryotic organisms appear earliest in Earth's fossil record.

2.2.1 Draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote.

The diagram should show the cell wall, plasma membrane, cytoplasm, pili, flagella, ribosomes and nucleoid (region containing naked DNA).

2.2.2 Annotate the diagram from 2.2.1 with the functions of each named structure.

Draw: Represent by means of pencil lines.

Label: Add labels to a diagram.

Annotate: Add brief notes to a diagram or graph.

E. coli as an example of a prokaryote These cell parts are not bound by a

membrane, so they are not called organelles

E. coli as an example of a prokaryote

Cell wall: forms a protective layer that prevents damage from outside and also bursting if internal pressure is high.

Plasma membrane: controls entry and exit, pumping some in by active transport.

E. coli as an example of a prokaryote

Cytoplasm: contains enzymes that catalyze the chemical reactions of metabolism and contains DNA in a region called the nucleoid.

Pili: hair-like structures projecting from the cell wall that can be ratcheted in and out. When connected to another bacterial cell they can be used to pull cells together.

E. coli as an example of a prokaryote

Flagella: solid protein structures with corkscrew shape, projecting from cell wall, which rotates and causes locomotion (movement). Sing.: Flagellum

Ribosome: small granular structures that synthesis protein by translating messenger RNA. Some proteins stay inside the cell and others are secreted.

E. coli as an example of a prokaryote

Nucleoid: region of the cytoplasm that contains naked DNA, which is the genetic information of the cell.

Capsule: protects the bacteria against phagocytes and

Identify the parts in this electron micrograph

Prokaryotic cells divide by binary fision

Diversity of prokaryotesTwo domains:

Archaea: are prokaryotes, many of which live in some of the most extreme environments on Earth, extremophiles, meaning "lovers of the extreme."

Bacteria: Bacteria come in three basic shapes: spherical, rod-shaped, and spiral-shaped. Nearly all bacteria have a cell wall outside their plasma membrane. The two types can be distinguished by a testing method called Gram staining.

HomeworkRead 16.1 and 16.2 in the book.