Topic 2.2 Prokaryotic
Cells
Assessment Statements:
2.2.1 Draw and label a diagram of the
ultrastructure of Escherichia coli (E. coli) as
an example of a prokaryote
2.2.2 Annotate the diagram from 2.2.1 with the
functions of each named structure.
2.2.3 Identify structures from 2.2.1 in electron
micrographs of E. coli
2.2.4 State that prokaryotic cells divide by
binary fission
Introduction to Prokaryotes
Prokaryotic Cell Structure
Annotate the diagram
Cell Membrane
Controls passage of materials into and out of
the cell
All cells have a cell membrane
Cytoplasm
Fluid portion of all cells
Location of cellular metabolism
Ribosomes
Float freely in the cytoplasm of all cells
Smaller in prokaryotes (70s)
The site of protein synthesis.
Nucleoid
The glob of DNA in all
prokaryotic cells
Still a double helix
Ends come together to form
a circle
Not wrapped around proteins
as in eukaryotic cells
(termed “naked DNA”).
Prokaryote vs. Eukaryote
Chromosome
Prokaryote
DNA double
helix
Eukaryote
Plasmid
A small circle of DNA found
in some prokaryotes that
exists and replicates
independently of the main
DNA in the nucleoid.
Often contain genetic
instructions for resistance
to antibiotics (antibiotics
are chemicals that kill
bacteria)
Some Prokaryotes have a cell wall
Gives shape, support
and protection to the
plasma membrane
and cytoplasm of the
cell.
Eubacteria wall made of
peptidoglycan*
(protein-sugar
molecules).
Flagellum (flagella)
Some bacteria have one or more
Used for motility.
Pili
Short fibers projecting from the cell wall found
on some bacteria.
They may help the bacteria cling to surfaces.
Capsule (or slime layer)
A special mucus-like protective coating found
on some disease-producing bacteria.
Prokaryotic cells do not have
membrane bound organelles
Reproduction in Prokaryotes
Binary Fission
Reproduction in Prokaryotes
Prokaryotes reproduce by binary
fission “division in half”
Type of asexual reproduction
The cell replicates its genetic
material
The cytoplasm divides by
cytokinesis
Two identical daughter cells are
produced (unless mutation
occurs)
Review
Something interesting to finish...