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Bacteria
1. BACTERIA
The Oldest Living Structures on
the Earth!
http://
www.ted.com/talks/lang/en/bonnie_bassler
2. Kingdom Archaebacteria
Most inhabit extreme environments on the
earth. There are THREE main groupings.
– Methanogens
Are anaerobic and live in swamps, marshes, the
guts of animals, and sewage treatment ponds
– Extreme Halophiles
Live in high salt areas such as the Dead Sea and
the Great Salt Lake
– Extreme Thermophiles
Live in hot springs with temperatures of 60oC to
80oC
Cell walls do not contain peptidoglycan
3. Kingdom Eubacteria
Prokaryotic
Includes the spirochetes, gram-positive
bacteria and cyanobacteria
Live just about anywhere
Have a cell wall that contains
peptidoglycan (carbohydrate)
6. Bacterial Shapes
Bacillus bacteria are rod
shaped
Cocci bacteria are round
Spirillum are spiral shaped
7.
8. Groupings of Bacteria
Individual
Diplo – in pairs
Strepto – in chains
Staphlo – clustered like grapes
9. Identification
Gram Stain
– The gram stain differentiates bacteria on the
basis of structure and composition of the
layers of the cell wall.
– After staining:
Gram positive bacteria appear purple
Gram negative bacteria appear pink.
– Cell walls have a simpler structure than gram
negative cell walls
11. General Structure
Nearly all prokaryotes
have cell walls
Bacteria have one
major chromosome
and rings of DNA
called plasmids
Ribosomes are
present to help in
protein formation
12. General Structure
Ribosome
Peptidoglycan
Cell Cell
wall membrane Many disease
causing bacteria
have a thick
outer slime
capsule for
protection
Many bacteria
have small hair-
Flagellum DNA Pili like pili to attach
to other cells
13. Bacteria Cell Structure
Single cell
Nucleoid (plasmid)
– Area where single DNA strand is found
Flagella
– For movement
Capsule (Peptidoglycan)
– Coating on outside of cell wall
14. Bacteria Cell Structure
Cell Wall
– Tough, rigid structure for support, shape and
protection
– Main function – prevent osmotic rupture
– Water always moving in cell, so if cell wall OK,
cell is OK
– Bacteria growing in Penicillin grow holes in
their cell walls, rupture, and die
Cell membrane
Ribosomes for making proteins
16. Bacterial Reproduction
Prokaryotes
– Reproduce asexually by binary fission (cell
splits apart)
– Continually making new DNA in good
conditions
– In bad conditions, form endospore
Internal resting cell that surrounds the DNA, some
cytoplasm, and thick outer coat
May live in for long time
17. Bacterial Reproduction
Genetic Information Exchanged 3 Ways
– Transformation
Genes taken up from the surrounding environment
– Conjugation
Genes are transferred from cell to cell (sexually—
through a tube)
– Transduction
Genes are transferred between prokaryotes by
viruses
18. Bacterial Population Growth
Click on the icon above. Upon viewing the
dividing bacteria, take note of the FOUR
stages of the population growth curve
19. Aerobic vs. Anaerobic
Aerobic Anaerobic
– Obligate aerobes – Obligate anaerobes
Must have oxygen Must live where there is
present to live no oxygen
Get energy from
fermentation
– Faculative anaerobes
Live where there is
oxygen
Live where there is no
oxygen
20. Bacterial Nutrition
Autotrophs Heterotrophs
– Make own food – Decomposers
– Smelly food caused by Feed on dead plants
bacteria that are and animals
Usually do not cause
making food from
disease
substances that have
Ex: Nitrogen Cycle
sulfur or iron
– Parasites
Live on or in living
organisms
Can cause disease
21. Economic Importance of Bacteria
Nitrogen Fixation
– All organisms need nitrogen to make proteins
– Bacteria convert nitrogen to a form organisms
can use
Recycling of Nutrients
– Necessary to breakdown the organic matter in
dead organisms and wastes, returning
nutrients to the soil
22. Economic Importance of Bacteria
Food
– Breakdown chemicals for their food by
fermentation
– Release other molecules we use because of
distinct flavors and aromas (cheese, yogurt,
sauerkraut)
Medicines
– Produce antibiotics which kill other bacteria
23. Economic Importance of Bacteria
Disease
– Only a few
– About half of all human diseases are caused
by bacteria
24. Food Bourne Bacteria
Can Harm You
Botulism
Salmonella
Staphylococcus
E. Coli