Classification of Life

Transcription

1 Classification of Life Aristotle 2 divisions: Plant and Animal Linnaeus ( ) New division Vermes New category Chaos (where microbes were placed)

2 Classification of Life Ernst Haeckel (1866) 3 Kingdom System Plantae, Animalia, and Protista Robert Whittaker (1969) 5 Kingdom System Plantae, Animalia, Protista, Fungi, Monera

3 Classification of Life Carl Woese (1970s) 3 Domain System Bacteria Archaea Eukarya prokaryotic

4 commonalities of the 3 domains conduct glycolysis replicate DNA semiconservatively use same genetic code DNA encodes polypeptides polypeptides produced by transcription and translation have phospholipid bi-layer plasma membranes and ribosomes

5 2 prokaryotic Domains: Bacteria and Archaea Kingdom: Monera

6 are they alive?

7 the monerans: 1000x smaller than most human cells the most abundant kingdom - ubiquitous

8 Archaea Prokaryotes Extremophiles: Thermophils acidophiles methanogens Psychrophils halophils enzymes from these organisms used in many industrial applications.

9 Bacteria Prokaryotes Very diverse NOT all bad! # of good far outweigh bad!

10 key characteristics for these domains: (differ from eukaryotes) Lack a membrane-bound nucleus DNA is double-stranded; circular

11 lack membrane-bound organelles Contain a full compliment of genetic and protein synthesizing systems: DNA, RNA, enzymes, ribosomes and ATP generation

12 Lack cytoskeleton Without a cytoskeleton cannot replicate by mitosis divide by fission

13

14 variety of metabolic life styles alcohol anaerobic pathways No O 2 aerobic pathways O 2 ATP lactic acid

15 the aerobes obligate aerobes: must have O 2 to live (cellular respiration) Mycobacterium tuberculosis aerotolerant anaerobes: not killed by O 2 - but not used for respiration Lactobacillus acidophilus

16 the anaerobes obligate anaerobes: must live in the absense of O 2 (exposure to oxygen = death!) Clostridium botulism facultative anaerobes: can alter their metabolism and live with/without O 2 Escherichia coli

17 alternatives to oxygen nitrogen fixers: metabolize N 2 some plants have developed a symbiotic relationship with bacteria which infect their roots and, in return for sugars from the plant, fix nitrogen which can be used by the plant for growth

18 sulfur metabolism Cell counts and DNA analyses confirm that cold-loving bacteria are living in the artic glacial ice. Astrophysicists and planetary scientists associated with NASA feel this unique example of life in an extreme ecosystem (bacteria living within or beneath a glacier and performing mineral transformation) may be a perfect analogue to what life may look like on another planet.

19 Variety of nutritional systems:

20 produce their own food photoautotrophs (true photosynthesis) Use as source of E and CO 2 as source of C chemoautotrophs get E from chem. sources such as ammonia, hydrogen, sulfur, etc., and C from CO 2

21 get their food from other sources chemoheterotrophs organic molecules are sources for E and C photoheterotrophs Light is source for E, organic compounds for C most prokaryotes

22 prokaryotes are identified by: shape cell wall the way they move how they obtain energy DNA

23 classified based on: metabolism - energy and food their source of Energy whether or not they use oxygen for respiration (or fermentation) or

24 shape bacilli - rod shaped coccus - spherical spirilla - spiral/corkscrew

25 Bacterial morphologies (1)

26 movement sessile flagella slime secretions

27 cell wall the cell wall (capsule) is composed of petidoglycans Some bacteria have thick and some have thin cell walls

28 Differences in cell wall component indicator of differences in pathogenicity Target of antibiotics interferes with synthesis of peptidoglycans

29 distinguished based on Gram staining Gram staining combination of 2 stains: primary stain violet alcohol rinse (rinses away thin walls) red counterstain

30 Gram+ bacteria rod shaped anthrax bacteria in spinal fluid thick cell walls

31 Gram bacteria Salmonella typhi thin cell wall

32 growth and reproduction Could divide as quickly as every 20 minutes if a single bacteria divided unchecked every 20 min., in 48 hrs. the colony would reach a mass 4000X the mass of earth!!!

33 growth is contained by: of

34 reproduction is asexual Binary fission

35 reproduction can include exchange of genetic material conjugation

36 transformation

37 reproductive preservation spore formation When growth conditions are unfavorable Spores can lay dormant for years

38 BACTERIA in the environment Serve as primary decomposers Bacteria start the process of decaying organic matter. They are the first to break down plant tissue and also the most numerous and effective composters. The most efficient decomposing bacteria thrive in temperatures between 110 and 160 degrees F. Thus, the hotter the pile, the faster the decomposing. (A 3' by 3' by 3' pile (1 cubic yard) is considered minimum size for hot, fast composting.)

39 most are beneficial Streptococcus lactis and other lactic acid bacteria are used to make cheese. They ripen the cheese and provide characteristic flavor. Streptococcus thermophilus is one of the major yogurtforming bacteria. The other is Lactobacillus bulgaricus

40 beneficial Used widely in the food industry (i.e., cheese making) Used in sewage treatment to break down wastes

41 Feed on petroleum clean up oil spills and extract metals from mining waste Produce antibiotics such as streptomycin

42 Feed on petroleum clean up oil spills and extract metals from mining waste Produce antibiotics such as streptomycin

43 some are pathogenic (disease causing) Campylobacter jejuni is one of the major causes of diarrhea in humans Salmonella infection of meat is one of the major causes of food poisoning Listeria monocytogenes are psychrotropic food pathogens which can grow even in refrigerated foods

44 pathogenic Helicobacter pylori stomach ulcers Streptococcus pyogenes - flesh eating bacteria

45 Success as a pathogen depends on: invasiveness toxigenicity ability to multiply ability to produce chemical toxins harmful to the host Gram-positive cocci - Staphylococcus aureus (Figure 1) and Staphylococcus epidermidis (Figure 2) together cause about half the ocular infections that occur in humans

46 two types of bacterial toxins endotoxins exotoxins Released by lysis of Gram neg. bacteria. Causes fever, vomiting and diarrhea; rarely fatal Proteins released by living bacteria. Highly toxic; often fatal; usually no fever E. coli 0157:H7 Bordetella pertussis

47 Causal agent of Diphtheria Corynebacteria diphtheriae are Grampositive, aerobic, nonmotile, rod-shaped bacteria diphtheria as "an upper respiratory tract illness characterized by sore throat, lowgrade fever, and an adherent membrane of the tonsil(s), pharynx, and/or nose". The diphtheria bacilli invade surface epithelial cells. At this site they produce the toxin that is absorbed and disseminated through lymph channels and blood to the susceptible tissues of the body. Degenerative changes in these tissues, which include heart, muscle, peripheral nerves, adrenals, kidneys, liver and spleen, result in the systemic pathology of the disease. About one person in 10 who gets diphtheria dies of it. Diphtheria is more severe for those under 5 and over 40 years of age.

48 Causal agent of Anthrax Bacillus anthracis is a Gram positive rod that produces spores and is nonmotile. There are three major anthrax syndromes: cutaneous (most common); inhalation (most lethal); and gastrointestinal anthrax. The essential virulence factors of anthrax are encoded on two plasmids: one codes for an antiphagocytic capsule, and the other plasmid carries the toxin genes. Disease is caused by the actions of three exotoxin subunits: Edema factor (EF) edema. Lethal factor (LF) mitogen-activated protein (MAP) kinases leading to their inactivation causing death through an unknown mechanism. Anthrax Vaccine Adsorbed (AVA), containing a crude preparation of protective antigen, is the only licensed human anthrax vaccine in the US.

49 biofilms Gel-like polysaccharide trapping other bacteria which protects the invading bacteria. Difficult to clear. Film may be impermeable to antibiotics.

50

51 Cystic fibrosis Pseudomonas aeruginosa Alveoli biofilm with unactivated neutrophils

52 NO Archeae are known to be pathogenic

53 normal human microbiota Most of the microbes living on you do not cause disease, but some are opportunistic. Pathogenesis is a matter of balance E. Coli in intestines digest food and make Vitamin K and B 12

54 eyes mouth nose and throat skin urinary and genital systems large intestine

55 Skin the first line of defense acidic secretions little moisture* radiation exposure barrier preventing entrance Hand washing keeps numbers down. repopulated quickly from hair follicle and sweat gland colonies Propionibacteria acnes anaerobic *except armpits and between legs

56 mouth and intestines More than 300 species found in the mouth Dental caries (cavity) one of the most common infectious diseases in humans today glucose - dextran fructose lactic acid 1,000,000/ml of saliva Enormous populations 40% of feces is bacteria Mostly anaerobic & facultative anaerobes Some synthesize vitamins

57

58

59

60

61

62 Archaebacteria differs from bacteria: 1. Cell Membrane Form lipid monolayer instead of lipid bilayer (in methanogens and thermophilic archaebacteria) 2. Cell Wall Archaebacteria has no muramic acid and D-amino acids. Has pseudopeptidoglycan 3. Extremophiles Most of them are thermophilic or methanogens.