Bacteria Chapter 24

Classification Structure Physiology Molecular composition Reactions too stain rRNA sequences

Archaebacteria aka: ancient bacteria Unusual lipids in cell membrane- no petoglycan Introns in DNA Cell walls lack peptidoglycan Genes closely related to early eukaryotes Extreme environments

Archaebacteria

Methanogens –Convert H 2 and CO 2 into methane gas –Live in anaerobic environment –Found in intestinal tracts of humans and other animals Extreme halophiles –Salt lovers –Use salt to generate ATP –Found in Dead Sea

Archaebacteria Thermoacidophiles –Live in acidic environments pH <2 –Live in high temperatures up to 230 –Live near volcanic vents and cracks in the ocean floor

Gram staining pg 471 Gram-positive - appear purple under a microscope –Thicker peptoglycan –Causes different resistance to antibiotics –Produce different toxins Gram-negative - do not retain stain appearing pink under a microscope

Gram Staining

Eubacteria aka: new bacteria Three basic shapes –cocci –bacilli –Spirilla Strepto= Chains Staphlo= Grape like clusters 12 different phyla according to evolutionary relationships

Cocci

Bacilli

Spirilla

Eubacteria Cyanobacteria –Autotrophic Makes its own food Photosynthetic –“Blue-green algae” –Often cling in colonies –Thrive on nitrates and phosphates in a body of water Population bloom or eutrophication

Cynobacteria aka: blue green algae

Eubacteria Spirochetes –Gram-negative –Spiral shaped –Heterotrophic Cannot make its own food Example- Treponema pallidium (Syphilis)

Spirochetes

Eubacteria Gram-Positive Bacteria –Not all are gram-positive –Cause tooth decay –Turn milk into yogurt –Causes strep throat

Eubacteria Proteobacteria- largest most diverse group –Enteric bacteria inhabit animal intestines (E. Coli) –Chemoautotrophic Gram-negative bacteria Oxidizes chemicals –Nitrogen-fixing bacteria Convert nitrogen into ammonia

E. Coli

Nitrogen-fixing Bacteria pg

Structure Cell Wall –Eubacteria - peptidoglycan Cell Membrane –Acts like mitochondria in cells –Contains enzymes that speed up cellular respiration Cytoplasm –Contains DNA, ribosomes, & organic compounds

Structure Capsules –Outer covering that protects the cell and assist in attaching the cell to other surfaces Pili- used for adhesion –Hairlike protein structures that transfer genetic material from one bacterium to another Endospores –Dormant structure protecting against harsh conditions –When conditions are right, bacteria emerge.

Yogurt

Nutrition and Growth Saprophytes - feed on dead and decaying material Photoautotrophic – uses the sun to make its own food (blue-green algae) Obligate anaerobe - cannot live in presence of oxygen (Tetnus) Facultative anaerobe - Can live with or without oxygen (E.coli)

Nutrition and Growth Obligate aerobes - Cannot live without oxygen (Turberculosis) Thermophilic - Grow between

Bacteria and Disease Pathology - Studying diseases Toxins = poisons Exotoxins = Toxins made of proteins (Gram-Positive Bacteria) Endotoxins = Toxins made of lipids and carbohydrates (Gram-Negative Bacteria) –Not released till bacteria die –Cause fever, aches, weakness

Antibiotics Combat bacteria by interfering with various cellular functions Resistance –Mutated bacteria that is resistant to antibiotics can continue to grow and reproduce Example- Penicillin attacks bacteria cell walls

Body’s Defense

Useful Bacteria Insecticides Clean up environmental disasters Produce and process food Turn sewage into simpler organic compounds

Bacteria Replication

Binary fission Divides a prokaryotic cell into 2 off spring cells

Binary fission cont. DNA is copied

Binary fission cont. Cell begins to divide

Binary fission cont. Two identical haploid cells (original # of chromosomes)

Binary Fission

More terms to know Population bloom Capsule Saprophytes Pathogen Conjugation –2 bacteria connect and transfer genetic material to each other.