1. Chapter 18

2.  Domain Archaea  Only one kingdom: Archaebacteria ▪ Cells contain cell walls ▪ Live in extreme environments (hot, acidic, salty, no O 2 ) ▪ Thermoacidophiles (example: Staphylothermus marinus in hot sea vents; pictured below) ▪ Halophiles (example: Dead Sea bacteria) ▪ Methanogens (example: sewage treatment bacteria)

3.  Domain Eubacteria  Only one kingdom: Eubacteria ▪ Very strong cell walls containing peptidoglycan (a polymer) ▪ Cannot survive in extreme environments ▪ Can be photosynthetic (autotrophs) ▪ Examples: ▪ Anabaena (autotrophs) ▪ Mycobacterium tuberculosis (heterotroph) Anabaena Mycobacterium tuberculosis

4. No nucleus, just a chromosome Unicellular organisms. They have some characteristics of all cells, such as DNA and ribosomes. Lack a nuclear membrane and other membrane- bound organelles

5. Chromosomes: large, circular and found in a nucleoid Capsule: secreted layer of polysaccharides outside of the cell wall that prevents the cell from drying out and helps it attach to surfaces Pili: tiny, hairlike protein structures that help attach to surfaces; can transfer genetic info across them Size: VERY small; much smaller than eukaryotic cells

6.  Three criteria:  Shape  Cell Wall  Movement

7.  Three common bacteria shapes:  Spherical = Cocci  Rod-shaped = Bacilli  Spiral-shaped = Spirochetes Cocci BacilliSpirochetes

8.  Gram staining: a dye is added to a sample of bacteria; peptidoglycan is indicated with purple color  Two Categories:  Gram positive: Turns purple during Gram staining; indicates high level of peptidoglycan in the cell wall  Gram negative: Turns light pink during Gram staining; indicates a low level of peptidoglycan in the cell wall

9.  Three common modes of movement:  Stationary: no movement  Flagella: filament that moves like a tail to propel the bacteria through an environment  Gliding: secrete a slime layer to glide across

10.  Prokaryotes reproduce by:  Binary Fission ▪ Division of the cell into two genetically identical cells ▪ Occurs quickly (can be every 20 minutes) ▪ 1 bacterium can become 1 billion in 10 hours  Conjugation ▪ Two prokaryotes attach to each other and exchange genetic information using pili ▪ New gene combinations result in increased diversity

11.  All living things require energy to carry out cellular respiration.  Two categories of obtaining energy:  Heterotrophs: cannot make their own food; must take in food from surroundings ▪ Saprobes: decompose organic molecules in dead organisms or organic waste  Autotrophs: make their own food ▪ Photoautotrophs: carry out photosynthesis; require light ▪ Chemoautotrophs: break down inorganic compounds; do not require light

12.  How can bacteria survive when their surroundings become unfavorable?  Two methods of survival: ▪ Endospores: production of a “dormant” cell ▪ Mutations: new combinations of genes and rapid reproduction

13. 1.Spore coat surrounds chromosome and small cytoplasm. 2.Endospore protected if bacteria cell dies. 3.Endospore grow. (germinates) 4.New bacterial cell outgrowth.

14.  Bacteria is significant in recycling nutrients to the environment.  Decomposer – Breaks down dead organisms to return organic compounds to the environment.  Nitrogen-fixing – Converts N 2 gas in the atmosphere to NH 3 (ammonia); allows nitrogen to be taken into the food chain via plants; N is key in amino acids therefore proteins.

15.  Most of the bacteria that live in or on you are harmless and are called normal flora. E. coli 21,674x

16.  Some food are made with the aid of bacteria:  Cheese  Yogurt  Buttermilk  Pickles  Vitamins  Chocolate

17.  Disease-causing bacteria are called pathogens.  Antibiotics are used to treat bacterial infections.  Body Story - Salmonella