Bacteria
(Pages 470-477)
All bacteria are prokaryotes (lacking a nucleus). Originally all bacteria were lumped together into
one kingdom, Monera. Currently, bacteria are classified into two kingdoms:
1. Kingdom Archaebacteria
 archae means “ancient”, primitive/earliest bacteria.
 Lack peptidoglycan and have very different membrane lipids than the eubacteria.
 DNA is also more like eukaryotes than eubacteria.
 often called “extremophiles” as many live in harsh conditions such as sulfur vents and
geysers.
2. Kingdom Eubacteria
 Have a carbohydrate called peptidoglycan that gives structure to their cell wall.
 Many different phyla as eubacteria can be heterotrophs (consumers, decomposers,
parasites) or autotrophs (photo or chemosynthetic).
Movement
 Most bacteria are unable to move
 Those that can move:
o have a flagellum- which is a tail-like structure
o glide/spiral forward
Shapes
 Bacteria are named for the way they look. It consists of two parts: their arrangement and
their shape.
Arrangement
Shape
Strepto = chain
Cocci = round
Diplo = paired
Bacilli = rod
Staphylo = cluster
Spirilla = spiral
___Streptococcus____
____Bacilli___________
_____Spirilla___________
Cell Wall
Eubacteria are further classified by their cell wall. A
method called Gram staining, which consists of a
violet and a red dye, is used to tell them apart.
1. Gram-positive: absorbs the violet dye and appears
purple under a microscope.
2. Gram-negative: has an extra layer of lipids and
carbohydrates, so absorbs the red dye and
appears pink under a microscope.
Mode of Nutrition
Bacteria are either heterotrophs or autotrophs.
Growth/ Reproduction:
1. Binary fission- the bacteria copies its
DNA and separates into two identical
daughter cells. This process is asexual
and very similar to mitosis.
2. Conjugation- the bacteria forms
a bridge with another bacteria and they
transfer genetic material to one another.
This helps create genetic diversity among
bacteria.
3. Endospores- when conditions are
unfavorable, bacteria can thicken their cell wall to form a
tough protective coating that allows them to remain
dormant until conditions are favorable again (boiling,
freezing or dry conditions).
Importance of Bacteria
1. Decomposers- break down nutrients in dead matter
2. Nitrogen fixers- Change nitrogen gas to ammonia or other
nitrogen compounds. (into a form plants can use)
3. Human uses:
 Industry (examples= clean up oil spills, food/yogurt)
 Genetics (example= use plasmids in genetic engineering)
 Medicine (example= insulin)
4. Bacteria can be harmful
 pathogenic bacteria cause diseases such as strep throat, cavities, ulcers, food poisoning
and Lyme disease. They can attack any of the 6 kingdoms.