ALL of bacteria: Eubacteria, Archaebacteria, labelling

1

capsule

2

cell wall

3

plasma membrane

4

cytoplasm

5

ribosomes

6

plasmid

7

pili

9

flagellum

8

nucleoid

general characteristics of bacteria

• single celled

• single chromosome

• prokaryotes: no nucleus, much smaller

• organelles are NOT surrounded by membrane

archaea

• oldest group of organisms (evolution)

• found in extreme environments

• classified by the type of environment they inhabit

• methanogens: methane producing, poisoned by oxygen

• halophiles: live in high saline, salt loving

• thermacidophiles: live in extreme temperatures and pH, heat and acid loving

Eubacteria

• unicellular prokaryotes

• most bacteria are eubacteria

• have a cell wall made of peptidoglycan

how are bacteria classified?

• cell shape

• gram stain

• nutrition

• respiration

classification of bacteria: cell shape

• spirilla: spirals

• bacilli: rounded rectangles

• cocci/coccus: circles

• may also be asymmetrical

classification of bacteria: gram stain

• the reaction between bacteria and a crystal violet iodine dye

• gram-positive: cell appear purple

• gram-negative: cell appears light pink → pathogens

classification of bacteria: nutrition

• heterotroph: use organic molecules from their environment to produce their energy (cannot make own food)

• autoroph: produces their own organic molecules molecules from their environment (can make own food)

classification of bacteria: respiration

• aerobes: use oxygen to produce energy from their food

• anaearobes: produce energy from food in the absence of oxygen

pathogens

any organism that causes disease: viruses, bacteria, fungi, parasites

reproduction of bacteria

• binary fission (asexual)

• conjugation (sexual)

binary fission

• asexual reproduction for bacteria

• exact copy; no diversity

• cell elongates, then forms a septum (pinching part), forms distinct walls, then seperates

conjugation

• sexual reproduction in bacteria

• genetically different

• two cells form a tube, part of the DNA moves over, results in two genetics diverse cells

how can bacteria be helpful?

• most bacteria are helpful

• natural recycling through nitrogen cycle, converts nitrogen gas intro useable nitrogen for plants and provides oxygen

• health and medicine: foods (yogurt, cheese, pickles), help digestion, release vitamins

• clean-up (bioremediation): clean up oil spills and gasoline leaks

pathogenic bacteria release

endotoxins or exotoxins

endotoxins

• pathogenic bacteria

• release gram-negative bacteria split

• cause fever, vomiting, diarrhea

• i.e. salmonella

exotoxins

• pathogenic bacteria

• mostly gram positive

• released around bacteria

• toxic and fatal