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First Life on Earth

Single Celled OrganismsArchaebacteria and Eubacteria,

• Key Questions:1. How and where did bacteria evolve?2. When did these Kingdoms evolve?3. Can bacteria be helpful, harmful, neither?4. How small are bacteria? 5. What do they look like?6. Why are bacteria small?7. What are characteristics of Kingdom

Archaebacteria?8. What are characteristics of Kingdom Eubacteria?9. How do bacteria get energy?10. How do bacteria reproduce?11. How do bacteria get rid of waste?

1. How and where did bacteria evolve?

Deep Sea Vents…where life originated

• http://www.teachersdomain.org/resource/tdc02.sci.ess.earthsys.deepseavents/

Stanley Miller’s experiment

• Bill Nye- Greatest Discoveries video

2. When did these Kingdoms evolve?

• Despite this bombardment, very primitive life had already formed by 3.5 billion years ago.

3. Can bacteria be helpful, harmful, neither?

• Bacteria in the cafeteria activity• Microslide viewers• packet

4. How small are bacteria?

• Go to http://www.cellsalive.com/howbig.htm

5. What do they look like?

They are rod shaped,

Round

And coiled

6. Why are bacteria small?

• Class experiment with cell models to answer this question

• Use potatoes and iodine

7. What are the Characteristics of Kingdom Archaebacteria?

• Single celled (Unicellular)• Prokaryotes (no nucleus)• Asexual (reproduce through binaryfission)• Anaerobic (do not require oxygen) • Heterotrophic (consume other organisms)• Autotrophic (can make own food)

Types of Archaebacteria • The archaebacteria generally grow in extreme environments. • methanogens, anaerobic bacteria found in swamps, sewage, and other areas of decomposing

matter. Many such species live in the intestines of animals. They help breakdown food in the intestines and also provide essential nutrients. In return, the bacteria get a source of energy. This is an example of a mutualistic symbiotic relationship, which is when two organisms work together to survive.

• halobacteria, phototrophs (producing their energy from light), a group of rods that live in high-salt environments. These bacteria have the ability to obtain energy from light by a mechanism different from the usual process of photosynthesis. such as the Great Salt Lake (Utah) and the Dead Sea (Middle East).

• extreme thermophiles. These bacteria live at extremely high temperatures, such as in hot springs, and are associated with extreme acid environments. Many depend on sulfur in their metabolism, and many produce sulfuric acid as an end-product.

CliffsNotes.com. Archaebacteria. 28 Sep 2008 <http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/topicArticleId-8524,articleId-8445.html>.

(J. W. Schopf, http://www.astrobiology.ucla.edu/)

• Where might Archaebacteria exist today? What types of places on Earth would be similar to the harsh conditions of 4 billion years ago?

• Watch Life Before Oxygen and Deep Sea Vents

Hot springs at Yellowstone National Park

Symbiotic with animals in digestive tract

8. What are the characteristics of Eubacteria?

• Single celled (Unicellular)• Prokaryotes (no nucleus)• Asexual (reproduce through binaryfission)• Anaerobic (do not require oxygen) • Heterotrophic (consume other organisms)• Autotrophic (can make own food)

Life Before Oxygen

• http://www.teachersdomain.org/resource/tdc02.sci.life.cell.stetteroxygen/

Eubacteria •

Eubacteria, the second group of Monerans, make up their own Kingdom.They live in a wide variety of habitats and obtain their energy needs in a variety of ways. The main phylum are orgainzed by how they obtain energy. 1. Heterotrophs: This type of bacteria is found just about everywhere. These bacteria need organic molecules as an energy source but are not adapted for trapping the food that contains these molecules. Thus, some live as parasites, absorbing nutrients from living organisms. Others live as saprobes, organisms that feed on dead organisms or organic wastes. Saprobes help recycle the nutrients from decomposing organisms back into the environment, so those nutrients can be used for new or existing life. 2. Autotrophs: These bacteria are photosynthetic autotrophs. An autotroph is an organism that can make its own food. This is done through photosynthesis, a process that uses the suns energy to make sugar molecules. Most Cyanobacteria are blue-green in color, which is why they are often called blue-green bacteria. They are common in ponds, lakes,streams and moist areas of land. They are composed of chains of bacteria cells, an exception to the rule that Monerans are unicellular. These chains and the existence of chlorophyll (photosynthetic pigment) help provide evidence for bacteria being the ancestors of plants. 3. Chemotrophs: The third phylum is the chemosynthetic autotrophs. These bacteria obtain their energy from chemosynthetic breakdown of inorganic (nonliving matter - no carbon) substances such as sulfur and nitorgen compounds. Some of these bacteria are important in converting nitrogen in the atmosphere to forms that can be used by plants.

Examples of Eubacteria• At a site in NW Australia (left), a bed of 3.5 billion year old stromatolite fossils has been

discovered (below left). (W. Aust. Petroleum, http://www.dme.wa.gov.au/ancientfossils/)

Stromatolites are an organization of primitive cyanobacteria (lower left) into large-scale structures that might have been analogous to coral reefs or "pond scum"(Worldwide Museum

Nat. Hist., http://www.wmnh.com/wmel0000.htm, U. Cal. Mus. Paleontology, http://www.ucmp.berkeley.edu/bacteria/cyanofr.html

Fossil stromatolites can be identified through a characteristic layering that results from the growth patterns of their constituent bacteria.(Worldwide Museum Nat. Hist.,

http://www.wmnh.com/wmel0000.htm B. G. Sutton http://www.lakeneosho.org/More7.html)

Artist's concept (painting by Peter Sawyer, copyright Smithsonian Institution) of early stromatolites on a beach 3.5 billion years ago, from

http://www.wf.carleton.ca/Museum/camex/1darchean.html

There are a few surviving living beds of these most primitive life forms still in Australia and a few other places.(from J. Vicens http://www-ecpm.u-strasbg.fr/Actu/A-curious/a-c-stromato.html) (more have been found in a number of other

places, too)

Filaments of photosynthetic cyanobacteria

Helicobacter pylori electron micrograph, showing multiple flagella on the cell

surface

9. How do bacteria get energy?

• Some bacteria can make their own food and are called Autotrophs or autotrophic. Some use chemicals and convert the chemicals such as sulfur into food.

• Some bacteria need to consume other organisms for energy and are called Heterotrophs or heterotrophic.

10. How do bacteria reproduce?

• Bacteria are asexual reproducers meaning they do not need a mate to produce offspring.

• Bacteria make copies of themselves by copying all their organelles and DNA and splitting in two. This is called binary fission.

Structure and contents of a typical bacterial cell