Chapter 5:The Microbial World

Part One:

A Comparison of Prokaryotes

The Classification of Organisms

Domain Bacteria Domain Archaea Domain Eukarya

Kingdom Protista

Kingdom Animalia

Kingdom Plantae

Kingdom Fungi

EukaryotesProkaryotes

Assignment

1.Create a Venn Diagram to compare and contrast PROKARYOTIC and EUKARYOTIC cells

2.Create a table to identify the characteristics of the six kingdoms

Cell Types

Kingdom Characteristics and Examples

Archaebacteria

Eubacteria

Protista

Fungi

Plantae

Animalia

Characteristics of Prokaryotes

Small (0.001 to 0.75 mm) Structurally simple Enclosed in a protective cell wall Cell membrane lies inside cell wall Lack a nucleus and membrane-bound organelles Have a single circular molecule of DNA Contain small ribosomes for protein manufacture Two kingdoms of prokaryotes –

Archaea Bacteria

Domain: BacteriaDistribution, Shape, & Size

Abundant in all parts of the ocean. Many shapes – spheres, rods,

spirals, and rings Often found in chain-like colonies

or filaments in the marine environment.

Decay bacteria break down waste products and dead organic matter and release nutrients

Bacteria chain from www.vendian.org/.../ bacteria_chain2.jpg

Bacteria

Recently discovered bacteria, SAR11, may be most abundant life form on earth

Role in the ecosystem still unknown

http://www.bios.edu/research/sar11.html

Domain: BacteriaStructural Characteristics

Rigid cell wall containing peptidoglycan

Some have a slimy capsule of glycoprotein and polysaccharides that protects the cell

w3.dwm.ks.edu.tw/bio/ activelearner/23/ch23c3.html

Domain: BacteriaStructural Characteristics

Short pili cover the surface of the bacteria and function in attachment to specific host cell surfaces.

A modified sex pilus can transfer DNA plasmids from one bacteria to another.

w3.dwm.ks.edu.tw/bio/ activelearner/23/ch23c3.html

Domain: BacteriaMotility

Bacteria possess flagella for movement. These occur singly, in bundles, or covering the surface of the cell.

All prokaryotes lack cilia.

w3.dwm.ks.edu.tw/bio/ activelearner/23/ch23c3.html

Importance of Cyanobacteria

Photosynthetic bacteria – also known as “blue-green algae.”

Believed to be the first photosynthetic organisms on Earth.

Played an important role in the accumulation of oxygen (O2) in the atmosphere.

Cyanobacteria – Diversity

www.anselm.edu/.../ genbios/surveybi04.html

Ecological Role of Cyanobacteria

Contain three photosynthetic pigments: Chlorophyll a - green Phycocyanin – blue Phycoerythrin – red

Pigment – molecule that captures absorbs certain colors of light but reflects others

Phycoerythrins from planktonic cyanobacteria are responsible for harmful algal blooms or red tides.

© Copyright 2005 by NIWA

www.niwa.co.nz/ncabb/ abb/2003-03/blooms

Ecological Role of Cyanobacteria

Massive calcareous mounds called stromatolites were formed by cyanobacteria and date back 3 billion years.

These “living fossils” still occur in warm, hypersaline waters of the world.

Modern Stromatolites, Shark Bay, Australia. Photo courtesy Marjory Martin, Deakin Univ, Australia

www.calm.wa.gov.au/.../ hamelin_pool_mnr.html

Ecological Role of Cyanobacteria

Some capable of nitrogen fixation, a process by which nitrogen gas (N2) dissolved

in seawater is converted into ammonia (NH3)

NH3 can be used directly in bacterial metabolism and converted to nitrates.

Eukaryotes cannot fix nitrogen. Some terrestrial bacteria can also fix nitrogen.

Naturally, nitrogen is a limiting nutrient in marine ecosystems.

http://www.ibmc.up.pt/webpagesgrupos/cam/cyanobacteria.htm

Ecological Role of Cyanobacteria

One species, Anabaena, actually generates specialized cells called heterocysts for nitrogen fixation.

http://www.ibmc.up.pt/webpagesgrupos/cam/cyanobacteria.htm

Domain: ArchaeaSize & Shape

Sometimes called archaebacteria Among the most primitive and oldest

forms of life. Cells are small and spherical, spiral,

or rod-shaped. More closely related to eukaryotes

than to bacteria.

Domain: ArchaeaDistribution

Many species inhabit extreme environments and are thus called “extremophiles.” Halophiles – live in

extremely salty conditions Methanogens – produce

methane and live in anaerobic environments such as the human gut

Thermoacidophiles – grow in hot, acidic environments

Boiling volcanic pools – © Dr. Malcolm White

Domain: ArchaeaDistribution

“Extreme” marine environments where archaebacteria are found include: Deep-sea hydrothermal vents Coastal salt pans Deep water

Prokaryote Metabolism Autotrophs – “self feeders”

make their own “food” (organic compounds). Photoautotrophs

use sunlight contain photosynthetic pigments

Chemoautotrophs use energy from inorganic chemicals to create organic

matter

Heterotrophs obtain energy/organic matter by consuming other organisms

Light-mediated ATP synthesis sunlight energy directly converted into ATP

Overview: Photosynthesis

Kunkel, Dennis. "Education Website." Dennis Kunkel Microscopy Inc. 2007. 11 Nov 2008 <http://www.denniskunkel.com/>.

CO2 + H2OGlucose + O2

(organic matter)

Sunlight Pigments Metabolized to create ATP in cellular respiration.

Cyanobacteria

Overview: Chemosynthesis

Sloth, N.. "Purple sulfur bacteria." Biopix. 2003. 11 Nov 2008 <http://www.biopix.com/Photo.asp?PhotoId=28071&Photo=Purple-sulfur-bacteria>.

CO2 + H2SGlucose + S (or SO4

2-)

(organic matter)

Sunlight Pigments

Metabolized to create ATP in cellular respiration.

Purple-sulfur bacteria

Light-mediated ATP synthesisPhotoautotrophy without chlorophyll

Sunlight energy captured and stored in ATP directly.

Domain Bacteria contain pigment proteorhodopsin

Domain Archaea common in halophilic bacteria live in salterns, saline pools Contain reddish-purple pigment

bacteriorhodopsin

IMAGE: Piquepaille, Roland. "ZDNet." [Weblog Life in extreme environments] 30 Dec 2007. CBS Interactive, Inc. 11 Nov 2008 <http://blogs.zdnet.com/emergingtech/?p=788>.

San Francisco Bay salt ponds

Resources

http://curriculum.calstatela.edu/courses/builders/lessons/less/les4/archaea.html

w3.dwm.ks.edu.tw/bio/ activelearner/23/ch23c3.html

Villee, C.A. et. al. (1989) Biology, 2nd Edition, Saunders Publishing Company, Philadelphia, PA.

Castro, P. & M. E. Huber (2005) Marine Biology, 5th Edition, McGraw-Hill Higher Education, Boston, MA.