1. 1.2 Prokaryotic Cells
IB Biology

2. Essential Idea
Eukaryotes have a much more complex cell structure than prokaryotes

3. Prokaryotic Cells First organisms to evolve on Earth
3.5 billion years ago
cyanobacteria
Simplest cell structure
Eubacteria and Archaea

4. Origin of Life Miller-Urey Experiment
Stimulated pre-biotic life conditions in the lab for 1 week
Ammonia (NH3)
Methane (CH4)
Hydrogen (H2)
Water (H2O)
Spark of electricity (simulate lightning)

6. Origin of Life Experiment Results Organic compounds found
Amino acids which make up proteins of living things
Experiment not supported today other than to show that life can arise from a chemical origin
Recall: This is evidence supporting the cell theory “all cells come from preexisting cells”

7. DVD: Cosmos, Carl Sagan
1980s TV series narrated and produced by Carl Sagan
He was an astronomer, cosmologist, astrophysicist
Episode 2: Chapter 10
One Voice in the Cosmic Fugue
Time: min

8. Prokaryotes: Eubacteria vs. Archaea
No true nucleus
Heterotrophs or autotrophs
Most have cell wall with peptidoglycan
Live everywhere
Eg. Bacteria
cyanobacteria
No true nucleus
Heterotrophs
Cell wall with no peptidoglycan
Live in extreme environments
Salt (halophiles)
Heat (thermophiles)
Methane (methanogens)

9. Prokaryote Properties
Small size
Unicellular
One cell must carry out all the functions of life
Found everywhere
Can live in various extreme environments
Found in soil, water, volcanoes, intestines and skin

10. Metabolic Properties 1. Fermentation 2. Photosynthesis
Convert lactose (sugar) into lactic acid for yogurt production
2. Photosynthesis
Blue-green bacteria produce their own food
3. Nitrogen Fixation
Convert nitrogen from air into nitrogen compounds useful in soil

11. Prokaryotic Structures
No nucleus
No mitochondria
No membrane bound organelles

12. Escherichia coli Scanning Electron Microscope
Found in your gut
Escherichia coli
Scanning Electron Microscope
Transmission Electron Microscope

13. E. Coli Micrograph Cell wall Cell (plasma) membrane
CELL MEMBRANE
CYTOPLASM
Cell wall
Carbohydrate and protein
Protection
Maintains shape
Prevent bursting
Cell (plasma) membrane
Phospholipid bilayer
Partially permeable controls what enters and exits the cell

14. Cytoplasm Nucleiod Ribosomes (70s) Fluid, gel-like
CELL MEMBRANE
CYTOPLASM
Cytoplasm
Fluid, gel-like
Contains free floating molecules
Enzymes, ribosomes
Location of chemical
reactions of metabolism
Nucleiod
Small amount of circular
DNA with no protein
Controls cell activities
Ribosomes (70s)
Make proteins from RNA messages

15. Motion Flagella Pili Protein propeller Attached to cell wall
Use energy to move cell
Not very flexible
Pili
Protein filaments attached to cell wall
Pulled in or pushed out
Used to adhere or “stick” to other bacteria cells to exchange DNA
conjugation

16. Reproduction Binary Fission
Bacterium replicates its DNA and then divides the cytoplasm
One copy of DNA
on each side
Cytokinesis

18. Identify Prokaryotic Structures
ribosome
nucleiod
Cell membrane
Cell wall
cytoplasm

19. IB Objectives
Prokaryotes have a simple cell structure without compartmentalization.
Electron microscopes have a much higher resolution than light microscopes.
Application: Prokaryotes divide by binary fission.
Skill: Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.

20. Tasks
Bacteria worksheet