Bacteria and Archaea Domains(3) and Kingdoms(6) Prokaryotes: Bactaria (Bacteria) and Archaea (Archaea) unicellular – autotrophs and heterotrophs – binary fission - Bacteria and Arcaea Eukarya Protists – eukaryotes – usually unicellular – autotrophs and heterotrophs – haploid life cycle - algae and protozoans Fungi – eukaryotes – mulitcellular or unicellular - saprotrophs (absorb food) – haploid life cycle – mushrooms Plants – eukaryotes –multicellular - photosynthetic autotrophs (make their own food) - alternation of generations – flowering plants, trees, ferns, moss Animals – eukaryotes – multicellular – heterotrophs – diploid life cycle – sponges, jelly fish, worms, dogs, humans Characteristics of Prokaryotes (Bacteria and Archaea) Prokaryotes – (pro = before) (karyote = nucleus) : before nucleus. Cells lack nucleus and membrane bound organelles Ex. Mitochondria, golgi apparatus, chloroplast DNA is a single chromosome found in the nucleoid and often accessory DNA is also present in a ring structure called a plasmid. Ribosomes are present and are responsible for protein synthesis Cells walls are present (except in some archaea) Motion using flagellum Pili (or fimbriae) aid in adhesion to surfaces

Reproduction No sexual reproduction – binary fission occurs. DNA attaches to the cell membrane and is replicated, then attached to cell membrane in a separate location. The cell grows until the DNA copies are physically separated along the membrane. The cell then grows inward and divides itself in half. Mutation is chief source of genetic variation. However: Exchange of genetic material: Prokaryotes do NOT undergo mitosis or meiosis, but do still exchange genetic material. This is accomplished in one of three ways.

1. Transformation: “free floating” DNA is taken up from fluid surrounding cell. 2. Transduction: DNA is “accidentally” transferred by bacteriaphages moving from one host

cell to another. 3. Conjugation: “mating” of two cells. The donor cell (“male”) has sex pili, attached itself to

receiving cell (“female”) and they form a cytoplasmic bridge (or conjugation pilus) DNA is transferred from “male” to “female” cell

Identifying Prokaryotes Cell Shape: Cocci = berries = round. Pair = diplococci Chain = streptococci Cluster = staphylococci Baccili = rod shaped Pair = diplobacilli Chain = streptobacilli Curved or Spiral Shapes: Vibrios – comma shape Spirilla – short, rigid helix Spirochetes – long, flexible helix

Prokaryotes: Archaea vs. Bacteria Bacteria Archaea Plasma membrane made of glycerol with fatty acids

Plasma Membrane made of glycerol and hydrocarbons

Cell wall made of peptidoglycan Cell wall lacks peptidoglycan Bacteria Specific IDs Cell walls composed of peptidoglycan = sugars cross linked with polypeptides Gram Stain Gram staining is used to help identify bacteria (but not archaea). The stain has purple and red/pink components. Bacteria with a thick layer of peptidoglycan absorb the purple component. These are Gram Positive Ex. Strepthroat and anthrax Bacteria that lack a thick layer of peptidoglycan will appear pink, as they do not absorb the purple stain, but the pink. These bacteria are Gram Negative Ex. Bubonic plague, cholera, cyanobacteria

Metabolism of Bacteria Obligate anaerobe – cannot survive in the presence of oxygen Obligate aerobe – cannot survive without oxygen Facultative Anaerobes - can grow with or without oxygen Autotrophs: Photoautotrophs: photosynthetic bacteria Some are obligate anaerobes. (live in marshes etc) CO2 + 2H2S � (CH2O)n + 2S Others are obligate aerobes – carry out photosynthesis in same way as plants

CO2 + H2O � (CH2O)n + O2

Example: Cyanobacteria – believed to have introduced free O2 to the atmosphere

Chemoautotrophs: use inorganic compounds to produce energy (such as nitrogen or sulfur)

Heterotrophs:

Chemoheterotrophs: are aerobic and use organic nutrients, are decomposers

(used to produce many products such as cheeses, sauerkraut, etc)

Antibiotics

Antibiotics are used to kill parasitic bacteria that cause illness

Bacteria cause illness in one of two ways- exotoxins are secretions from the bacteria and endotoxins are a component of the cell wall.

Antibiotics attack bacteria in ways that are only harmful to prokaryotes, so it does not endanger the cells that make up our body. Antibiotics inhibit protein synthesis or cell wall synthesis.

If a bacterial cell is resistant to antibiotics it’s genes could be shared with other bacteria. (Look back at prokaryote reproduction for information on how this can occur)

If too many bacteria become resistant what will happen to the human population?

Archae

Archae are prokaryotes. The majority of archaea are found in extreme environments and are classified based on the habitat they are found in.

Menthogens – anaerobes found in swamps, marshes and animal intestines – produce methane

Halophiles – require high salt concentrations. Have chloride pumps to handle salt concentrations. Are aerobic chemoheterotrophs. If O2 concentrations become to low, are able to conduct photosynthesis using bacteriorhodopsin instead of chlorophyll.

Thermoacidophiles – require hot acid environment – hot spring, geysers, thermal vents in the ocean. Are anaerobic chemoautotrophs and use H2 and S. Can live in temperatures up to 105°

Name:_____________________________ Date: ___________________ Grade___/10

1. What are the three domains recognized by modern science?

2. What kingdoms do we recognize for the purposes of this lab? Give an example of one organism from each kingdom.

3. What are the primary differences between prokaryotes and eukaryotes?

4. How do prokaryotic cells reproduce? What are the steps of this process?

5. Can prokaryotes exchange genetic material? Why or why not.

6. Why do you think it is important to be able to identify bacteria? What are two characteristics often used for identification?

7. What type of bacteria is believed to have first introduced O2 to the atmosphere? What process occurred within this bacterium that led to the release of O2?

8. Carefully read the information regarding the exchange of genetic material between prokaryotes and the information on antibiotics. Currently the frequency of bacteria being resistant to antibiotics is increasing. How is it possible that mutations that confer resistance are spreading and more and more bacteria are becoming resistant to treatment by antibiotics?

9. Considering your answer to number 8 – Why do doctors sometimes avoid prescribing an antibiotic without running tests to determine if an illness is due to a bacteria or virus? Since antibiotics do not harm eukaryotic cells, is there a risk associated with giving antibiotics to people who do not need them? Why or why not. (hint: consider basic ideas of evolution such as natural selection aka: survival of the fittest)

10. Study your diagram of the bacterial cell. Use the diagram below to help you quiz yourself. (Do NOT fill in the blanks, leave this blank to study with in the future.