bacteria 1
TRANSCRIPT
Bacteria
Quick Quiz True or False 1. 600 different kinds of bacteria live on your skin. True 2. Saliva contains 30 different kinds of bacteria. False; 6 3. Most bacteria multiply using the process of binary
fission. True 4. You can see, taste, and smell bacteria. False; cannot see with naked eye 5. Leaving foods at room temperature will slow
bacterial growth. False; Place in cold environments 6. There are more microbes on your body than there
are humans on the entire planet. True.
True / False con’t 7. Bacteria help our bodies with digestion and
produce True: E. coli makes vitamin K and B12 8. Bacteria are used to make chocolate. True; it helps digest the hard outer covering of
the bean 9. Only 50% of all bacteria are helpful. False; 99% 10. The four shapes of bacteria are circular,
square, rod, and spiral. False; No square
Prokaryotes vs. Eukaryotes
Prokaryotes No true Nucleus No membrane
bound organelles Small Simple Evolved 3.5 bya
Eukaryotes Membrane bound
nucleus Membrane bound
organelles Larger Complex Evolved 1.5 bya
Bacteria Can be found almost everywhere on
Earth. Earliest known fossils 3.5 bya Oldest group of organisms All bacteria are prokaryotes 2 main groups (kingdoms)
EubacteriaArchaebacteria
EUBACTERIA / TRUE BACTERIA
Most common today Cause disease & decay Cell wall protects and determines
shape. Contains peptidoglycan (carbohydrate)
Example: E. coli= live in intestines of humans
Archaebacteria “ancient bacteria”
Live in extreme environments Direct ancestors of eukaryotes Examples:
Methanogens= oxygen free environments thick mud and digestive tracks.
Halophites= Salty environments Utah’s Great Salt Lake
Prokaryotes are Identified By their…
1. Shape2. Chemical Nature3. The way they move4. The way they obtain
energy.
Shapes of Bacteria
Spherical (round / cocci)Streptococcus aureus
Spiral (sprilla) Trepnema pallidum (syphilis)
Rod-Shaped (bacillus) Escherichia coli
Shapes of Bacteria
Structure of Bacteria
Cell Walls of Bacteria Gram staining helps distinguish between the 2 different types of
bacteria. Gram +
Thicker peptidoglycan walls Keeps dark stain Appears purple
Gram – Thinner cell wall Appears pink
Gram Staining- Use to diagnose & treat disease
Gram +HarmlessImportant in
food and dairy industries
Turns purple Ex)
Streptococcus pneumonia
Gram –Harmful Unaffected by
many antibiotics. Can’t penetrate cell wall
Turns pink Ex) E. coli
Movement
1) Flagella- whip like structures
2) Lash, snake, or spiral
3) Glide along slime
Flagella Position
Obtaining Energy
Heterotrophs- Get energy by consuming organic
molecules made by other organisms. Autotrophs-
Make their own food from inorganic molecules.
Autotrophs Photoautotrophs
Use sunlight to convert carbon dioxide & water to carbon compounds and oxygen.Ex: Cyanobacteria
ChemoautrotrophsUse energy from chemical reactions
to make organic carbon moleculesLive in darkness; ocean bottoms.
Releasing Energy Obligate aerobes- require oxygen
TB Mycobacteruim tuberculosis Obligate anaerobes- NO oxygen
Clostridium botulinum (canned food)
Facultative anaerobes- do not require oxygen but are not killed by it. E. coli (large intestines and canned
food)
Growth & Reproduction
Some bacteria can divide in ~20 min
3 ways bacteria divide 1) binary fission 2) Conjugation 3) Spore formation
Bacteria Reproduction
Binary fissionAsexual – clonesSplitting in ½ 1st growth2nd DNA is copied3rd splits into 2
cells
Conjugation
Sexual reproduction Hollow bridge forms between 2
bacteria cellsExchange of DNAResult: increase in genetic
variation
Spore Formation
Formed in unfavorable conditions
Can keep for months or years Produces a thick internal wall
that encloses the DNA & cytoplasm
Dangerous
Limiting Factors in Bacteria Reproduction (Growth)
Nutrients temp (freeze/
pasteurization) Moisture pH Time Sanitizing
Importance of Bacteria
1. Producers 2. Decomposers 3. Human uses
1) Producers / Nitrogen Fixers
Plants & animals depend on bacteria for nitrogen
Need N2 to make amino acids.
N2 makes up ~ 80% of Earth’s atm
Plants take N2 convert it to NH3
(ammonia) this process is known as nitrogen fixation is done by bacteria.
2) Decomposers
Bacteria recycle nutrients Trees die -> Bacteria break
down -> Nutrients are returned to the soil -> Process repeats
3) Human Uses
Food- cheese, yogurt Beverages- wine, milk Industry- digest petroleum, clean
up oil spills Medical uses- synthesize drugs E. coli- makes vitamins the body
cannot make Etc.