1. Bacterial Cells
Their Structure

2. Structure of a Bacterial Cell
Cell Wall
Outside membrane- maintains cell structure
May have cell wall + capsule (second wall)
Protects the cell
Eubacteria-composed of peptidoglycan, a polymer of sugars and amino acids
Plasma Membrane
Controls what enters and exits, selectively permeable
phospholipid bilayer surrounding cell
contains proteins that play a role in transport of ions, nutrients, and wastes
Flagella (not found in all bacteria)
tail-like structure used for locomotion

3. Structure of a Bacterial Cell
Nucleoid
region DNA is found in prokaryotes
single double-stranded circular chromosome
Contains all genetic information
Plasmid (some bacteria)
small circular chromosome carrying special genes
may carry an antibiotic resistance gene
Can be exchanged through conjugation
Ribosomes
site of protein synthesis (translation)
Life Sciences-HHMI Outreach. Copyright 2008 President and Fellows of Harvard College.

4. Bacterial Structure Ribisomes Respiratory Enzymes Cytoplasm
Bacteria have ribosomes that make all proteins for the cell
Respiratory Enzymes
Use enzymes in the cytoplasm to undergo respiration
Cytoplasm
Fluid filling cell

5. Two Kingdoms of Bacteria
Kingdom Archaebacteria
- “Ancient”, most primitive
earliest known form of life -
Fluorescent micrograph of an archaeon
microbeworld.org
Kingdom Eubacteria
- includes bacteria and
cyanobacteria (blue-green)

6. Eubacteria

7. EUBACTERIA the “true” bacteria- more common

8. Cell Walls
eubacterial cells have two different cell wall structures. A technique called gram staining can distinguish between:
Gram-positive: cell wall containing mainly peptidoglycan- stains purple
Gram-negative: bacterial cell has a second, outer layer of lipids and carbs- stains pink

9. Kingdom Eubacteria Photosynthetic – 2 groups
1) cyanobacteria (aerobes)
Have chlorophyll a
and phycocyanin (blue)
Other colors, too
Most live in fresh water
Others live in salt water,
soil and lichens
Starr, 315
Nostoc
Schraer, 637

10. - colors range from pink to black - photosynthesize without water
More photosynthetics
2) green-sulfur and purple bacteria
- anaerobic
- colors range from pink to black
- photosynthesize without water
- make no oxygen
- live in pond and sea mud

11. Cyanobacteria
This is a group of bacteria that includes some that are single cells and some that are chains of cells. You may have seen them as "green slime" in your aquarium or in a pond.
Cyanobacteria can do "modern photosynthesis", which is the kind that makes oxygen from water. All plants do this kind of photosynthesis and inherited the ability from the cyanobacteria.

12. Cyanobacteria were the first organisms on Earth to do modern photosynthesis and they made the first oxygen in the Earth's atmosphere.

13. Biologic Importance of Bacteria
Essential to nutrient cycling
Decomposers – in soil, inside animals
Enterobacteria – live inside us,
break down waste, make vitamins
3) Process foods – cheese, yogurt etc..
4) Some MAKE antibiotics (streptomyacin)
5) Aid in human digestion- make vitamins

14. Many Bacteria live symbiotically in the guts of animals or elsewhere in their bodies.
For example, bacteria in your gut produce vitamin K which is essential to blood clot formation.

15. Bacterial uses cont. 6) Help with sewage treatment
Break down wastes
7) Can be utilized in genetic engineering, molecular research…
Insert foreign genes into new organism
Can be used to make specialized products like insulin
8) Indicate pollution levels
Provide visual clue to presence of pollution

16. 9) Nitrogen Fixation
Still other Bacteria live on the roots of certain plants, converting nitrogen into a usable form.

17. Some cause disease We call these “pathogens”
Anthrax, as seen by Koch
microbeworld.org
But most are
beneficial
Bacteria ferment cheese
Schraer, 641

18. Archae are extremophiles
Live in habitats like early earth
Too harsh for most organisms
1) methanogens – decomposers,
live in intestines, swamps & bogs
sewage treatment
2) Halophiles – “love salt”
Great Salt Lake, Dead Sea
3) Thermophiles – hot springs, geysers
4) Acidophiles – acidic environments
Starr,635

19. Kingdom Archaebacteria
Why a separate kingdom?
Archae differ chemically from other bacteria.
1) cell wall - different amino acids and sugars.
Eubacteria have peptidoglycan
Archaebacteria have varied polysaccharides
but not peptidoglycan.
2) membrane lipids
3) ribosomes
4) enzymes >
5) gene sequences And MORE
RNA polymerase

20. Archaebacteria Lack important carbohydrate found in cell walls
Have different lipids in their cell membrane
Different types of ribosomes
Very different gene sequences
Archaebacteria can live in extremely harsh environments
They do not require oxygen and can live in extremely salty environments as well as extremely hot environments.

21. Archaea, the “extremophiles” methanogens, thermophiles, halophiles

22. Nitrogen-fixing Chemosynthetic Eubacteria and Archaebacteria
make glucose using energy
from chemical compounds
**Mostly archae
Tube worms at ocean vent
Fed by chemoautotrophs
Starr, 745
Nitrogen-fixing
Fix nitrogen in special
cells called heterocysts
Legume roots – nodules contain
nitrogen-fixing bacteria
Starr, 314