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.