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Chapter 19 Prokaryotes

Notes on Bacteria 

Prokaryotic – organism that is one-celled and contains no nucleus or other membrane  bound organelles.

Their sizes range between  1-5 micrometers.

Previously, Kingdom Monera contained all bacteria. It is now divided into two kingdoms:

Kingdom Eubacteria  VS  Kingdom Archaebacteria

Cell walls contain a carbohydrate                        Cell walls do not contain

called peptidoglycan                                             peptidoglycan

Cell membrane lipids differ                              Cell membrane lipids differ

DNA unlike  eukaryote  DNA                    DNA  similar to  eukaryote DNA

The three major types of archaebacteria are

  1. Methanogens -(methane-producers) are responsible for the production of  methane, or Swamp  gas. They are also found in the intestines of animals.

 

  1. Thermophiles – are heat tolerant and live in hot Springs and  Black  smokers  (where hot gases are released into the bottom of the ocean).
  2. Halophiles – are slat tolerant and  live in saturated brine and salted areas.

The five major types of eubacteria are:

1. Nitrogen Fixing -fixing bacteria. These bacteria convert nitrogen gas into a form of nitrogen that can be used by plants. They are essential to the ecosystem and its food webs.

Sketch and Label Figure 3-14.

2. Blue green-bacteria most are colonial and some have a symbiotic relationship with fungi to form lichens (primary succession)

Also photosynthetic: green-sulfur bacteria and purple bacteria, and Prochlorophyta (which live in a relationship with marine animals)

3. Gram postive – bacteria can be affected by penicillin while Gram negative bacteria can not.

4. Spiral  bacteria

5. Intra cellular   parasites

Identifying Prokaryotes

Shapes              Sketch                                    Example

  1. Bacillus                 rod                                                                      anthrax
  2. Coccus                sphere                                                                 strept throat
  3. Spirillum            corkscrew                                                            cholera

Cell Walls

With PEPTIDOGLYCAN are called GRAM positive

Peptidoglycan and outer layer of lipid and carbohydrate =  GRAM negative

Movement can be by: Flagella, glide if slime, spiral, no movement

Obtaining Energy

Autotrophs can produce their own food given an outside energy source.

Examples:

PHOTOAUTOTROPHS- use sunlight to produce their own food, by the process of photosynthesis. They  must obtain organic compounds from their environment for this process.

Equation for Photosynthesis: __________________________________________

EX cyanobacteria

CHEMOAUTOTROPHs- use energy from chemical reactions in their environment to produce their own food

EX black smokers

Heterotrophs must obtain food from their environment. They do this by either

Ingestion  (example Animals )   or  Absorption    (example Fungus )

Releasing Energy

All living things require energy. They must break down food to obtain it. This is done in different manners depending on the organism and the presence of oxygen.

Aerobic Cellular Respiration requires oxygen (releases  more energy, ATP)

Anaerobic Cellular Respiration (also called fermentation)  does not require oxygen and releases less energy.

Facultative Anaerobes switch between cellular respiration and fermentation depending on the presence of oxygen in their environment.

Growth and Reproduction

Binary Fission is a form of asexual reproduction. One cell divides into 2 smaller cells.  (20 minutes)

Sketch:

Conjugation is a form of  “sexual reproduction” where one bacteria donates DNA to a second bacterial cell. This type of reproduction leads to increased variability in bacterial cells and possible antibiotic resistance.

Sketch:

Under unfavorable conditions, spores (vegetative reproductive structures) can form. These structures are resistant to harsh conditions, such as heat, cold, and drought and can survive for years.  Given good conditions, they grow.

Endospores are composed of a thick internal wall that encloses DNA and some cytoplasm.

Bacterial Reproduction

(Bacterial Growth Curve)

a. Lag phase- bacteria adjust to their environment

b. Exponential growth phase- bacterial increase rapidly in number (binary fission)

c. Stationary phase- bacteria reproduce at the same rate as cells die

d. Death phase- bacteria die as their environment is contaminated and food is used up.