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Title: Classification, Bacteria,


1
Classification, Bacteria, Viruses
  • Unit 9

2
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Early Systems of Classification
  • Biologists use a system of classification to
    organize information about living things.

3
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Aristotles System
  • Aristotle classified organisms as either animals
    or plants.

4
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Linnaeuss System
  • Linnaeuss system of classification was the first
    formal system of taxonomy.

Perching bird
Wading bird
Bird of prey
5
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Binomial Nomenclature
  • Linnaeuss method of naming organisms, called
    binomial nomenclature, gives each species a
    scientific name with two parts.
  • The first part is the genus name, and the second
    part is the species.
  • Ex. Ursus americanus

6
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
  • Biologists use scientific names for species
    because common names vary in different areas of
    the world.

Ursus americanus American black bear
7
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
  • When writing a scientific name, scientists use
    these rules
  • The first letter of the genus name always is
    capitalized, but the rest of the genus name and
    all letters of the species are lowercase.
  • If a scientific name is written in a printed book
    or magazine, it should be italicized.
  • When a scientific name is written by hand, both
    parts of the name should be underlined.
  • After the scientific name has been written
    completely, the genus name will be abbreviated to
    the first letter in later appearances
  • (e.g., C. cardinalis).

8
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Taxonomic Categories
  • The taxonomic categories are part of a hierarchal
    system.

9
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Species and Genus
  • A named group of organisms is called a taxa.
  • A genus is a group of species that are closely
    related and share a common ancestor.

10
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Family
  • A family is the next higher taxon, consisting of
    similar, related genera.

11
Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Higher Taxa
  • An order contains related families.
  • A class contains related orders.
  • A phylum contains related classes.
  • The taxon of related phyla or divisions is a
    kingdom.
  • The domain is the broadest of all the taxa and
    contains one or more kingdoms.

12
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13
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Typological Species Concept
  • Aristotle and Linnaeus thought of each species as
    a distinctly different group of organisms based
    on physical similarities.

14
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Biological Species Concept
  • The biological species concept? a species as a
    group of organisms that is able to interbreed and
    produce fertile offspring in a natural setting.

15
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Phylogenic Species Concept
  • Phylogeny is the evolutionary history of a
    species.
  • The phylogenic species concept shows evidence of
    a pattern of ancestry and descent.

16
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Morphological Characters
  • Shared morphological characters suggest that
    species are related closely and evolved from a
    recent common ancestor.
  • Analogous characters ? the same function but
    different underlying construction.
  • Homologous characters ? different functions, but
    show an anatomical similarity inherited from a
    common ancestor.

17
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Biochemical Characters
  • Scientists use biochemical characters, such as
    amino acids and nucleotides, to help them
    determine evolutionary relationships among
    species.
  • DNA and RNA analyses are powerful tools for
    reconstructing phylogenies.

18
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Phylogenetic Reconstruction
  • Cladistics reconstructs phylogenies based on
    shared characters.
  • Scientists consider two main types of characters
    when doing cladistic analysis.
  • An ancestral character is found within the entire
    line of descent of a group of organisms.
  • Derived characters are present members of one
    group of the line but not in the common ancestor.

19
Organizing Lifes Diversity
Chapter 17
17.2 Modern Classification
Cladograms
  • The greater the number of derived characters
    shared by groups, the more recently the groups
    share a common ancestor.

20
Section 18-2
Traditional Classification Versus Cladogram
Appendages
Conical Shells
Crustaceans
Gastropod
Crab
Barnacle
Limpet
Crab
Barnacle
Limpet
Molted exoskeleton
Segmentation
Tiny free-swimming larva
CLASSIFICATION BASED ON VISIBLE SIMILARITIES
CLADOGRAM
21
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Grouping Species
  • The three domains are Bacteria, Archaea, and
    Eukarya.
  • The six kingdoms are Bacteria, Archaea,
    Protists, Fungi, Plantae, and Animalia.

22
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Domain Bacteria
  • Eubacteria are prokaryotes whose cell walls
    contain peptidoglycan.

23
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Domain Archaea
  • Archaea are thought to be more ancient than
    bacteria and yet more closely related to our
    eukaryote ancestors.
  • They are called extremophiles because they can
    live in extreme environments.

24
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Domain Eukarya
  • All eukaryotes are classified in Domain Eukarya.
  • Domain Eukarya contains Kingdom Protista, Kingdom
    Fungi, Kingdom Plantae, and Kingdom Animalia.

25
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Protista
  • Protists are classified into three different
    groupsplantlike, animal-like, and funguslike.

26
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Fungi
27
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Plantae
  • Members of Kingdom Plantae form the base of all
    terrestrial habitats.
  • All plants are multicellular and have cell walls
    composed of cellulose.

28
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Animalia
  • All animals are heterotrophic, multicellular
    eukaryotes.
  • Animal organs often are organized into complex
    organ systems.
  • They live in the water, on land, and in the air.

29
Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
30
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Diversity of Prokaryotes
  • Bacteria are microscopic organisms that are
    prokaryotes.
  • Prokaryotes are divided into two domainsthe
    Domain Bacteria (eubacteria) and the Domain
    Archaea (archaebacteria).

31
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Photosynthetic eubacteria
Archaebacteria
Eubacteria
3000x
9560x
magnification unavailable
32
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Eubacteria
  • Very strong cell walls
  • Contain peptidoglycan
  • Some have a second cell wall

33
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Archaebacteria
  • Thermoacidophiles (thur muh uh SIH duh filz) live
    in hot, acidic environments.
  • Halophiles (HA luh filz) live in very salty
    environments.
  • Methanogens (meh THAHN oh jenz) cannot live in
    the presence of oxygen.

34
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Differences Between Eubacteria and Archaebacteria
  • The cell walls of the eubacteria contain
    peptidoglycan, but the cell walls of
    archaebacteria do not.
  • The two groups of organisms have different lipids
    in their plasma membranes.
  • Different ribosomal proteins and RNA

35
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Prokaryote Structure
  • Prokaryotes are microscopic, unicellular
    organisms.
  • They have some characteristics of all cells, such
    as DNA and ribosomes.
  • Lack a nuclear membrane and other membrane-bound
    organelles

36
Bacteria and Viruses
Chapter 18
18.1 Bacteria
  • Chromosomes
  • Capsule
  • Pili
  • Size

37
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Identifying Prokaryotes
  • Shape
  • Spherical Cocci
  • Rod-shaped Bacilli
  • Spiral-shaped Spirochetes

Spirochetes
Bacilli
Cocci
5460x
2000x
400x
38
  • Identified by shape, cell wall, method of
    movement,
  • and how they obtain food
  • Shapes
  • Bacilli rod
  • Cocci round
  • Spirilla spiral
  • Prefixes strep long chains, staph clumps,
    diplo pairs

39
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Cell Walls
  • Eubacterial cells have peptidoglycan.
  • Dyes added to the bacteria identify those with
    and those without an outer layer of lipid.

Purple gram positivecell wall contains
peptidoglycan
40
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Movement
  • Prokaryotic flagella are made of filaments.
  • Flagella help prokaryotes to move toward
    materials that they need to survive.

41
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Reproduction of Prokaryotes
  • Binary Fission
  • Division of a cell into two genetically identical
    cells
  • Conjugation
  • Two prokaryotes attach to each other and exchange
    genetic information.

42
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Photoautotrophs
  • Carry out photosynthesis in a similar manner as
    plants

Chemoautotrophs
  • Break down and release inorganic compounds that
    contain nitrogen or sulfur

Aerobes and Anaerobes
  • Obligate aerobes are bacteria that require oxygen
    to grow.
  • Anaerobic bacteria do not use oxygen for growth
    or metabolism.

43
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44
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Survival of Bacteria
  • Endospores
  • Resistant to harsh environments and might be able
    to survive extreme heat, extreme cold,
    dehydration, and large amounts of ultraviolet
    radiation

45
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Mutations
  • Bacteria reproduce quickly and their population
    grows rapidly.
  • Mutations lead to new forms of genes, new gene
    combinations, new characteristics, and genetic
    diversity.

46
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Ecology of Bacteria
  • Nutrient cycling and nitrogen fixation
  • Bacteria are decomposers, returning vital
    nutrients to the environment.
  • Nitrogen-fixing bacteria live in a symbiotic
    relationship in the root nodules of plants such
    as soybeans, clover, and alfalfa.

47
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Normal Flora
  • Most of the bacteria that live in or on you are
    harmless and are called normal flora.

21,674x
E. coli
48
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Foods and Medicines
  • Some foods are made with the aid of bacteria.
  • cheese
  • yogurt
  • buttermilk
  • pickles
  • vitamins

49
Bacteria and Viruses
Chapter 18
18.1 Bacteria
Disease-causing Bacteria
  • A small percentage of bacteria cause disease.
  • Bacteria multiply quickly at the site of
    infection.
  • Bacteria secrete a toxin.

50
Bacteria and Viruses
Chapter 18
18.2 Viruses and Prions
Viruses
  • A nonliving strand of genetic material within a
    protein coat
  • No organelles to take in nutrients or use energy
  • Cannot make proteins
  • Cannot move
  • Cannot replicate on their own

51
Bacteria and Viruses
Chapter 18
18.2 Viruses and Prions
Viral Infection
  • In order to replicate, a virus must enter a host
    cell.
  • The virus attaches to the host cell using
    specific receptors on the plasma membrane.
  • Many viruses cannot be transmitted between
    different species.

52
Bacteria and Viruses
Chapter 18
18.2 Viruses and Prions
Lytic Cycle
  • The host cell makes many copies of the viral RNA
    or DNA.

Lysogenic Cycle
  • Viral DNA inserts, or integrates into a
    chromosome in a host cell.
  • Infected cell will have the viral genes
    permanently.

53
Bacteria and Viruses
Chapter 18
18.2 Viruses and Prions
54
Bacteria and Viruses
Chapter 18
18.2 Viruses and Prions
Retroviruses
  • Viruses that have RNA instead of DNA for their
    genetic material
  • Retroviruses have a protein capsid.
  • Lipid envelope is obtained from the plasma
    membrane of a host cell

55
Protists
Chapter 19
19.1 Introduction to Protists
Protists
  • All protists are eukaryotes.
  • Some reproduce asexually by mitosis while others
    exchange genetic material during meiosis.

56
Protists
Chapter 19
19.1 Introduction to Protists
Classifying Protists
  • Some scientists classify protists by their
    methods of obtaining nutrition.
  • Animal-like protists
  • Plantlike protists
  • Funguslike protists

57
Fungi
Chapter 20
20.1 Introduction to Fungi
Major Features of Fungi
  • Cell wall composed of chitin
  • Hyphae form a netlike mass called a mycelium.
  • Hyphae provide a larger surface area for nutrient
    absorption.

58
Fungi
Chapter 20
20.1 Introduction to Fungi
Spore Production
  • The asexual and sexual life cycle of most fungi
    includes spore production.
  • A spore develops into a new organism without the
    fusion of gametes.
  • Spores produce new hyphae that form a mycelium.

59
Introduction to Plants
Chapter 21
21.1 Plant Evolution and Adaptations
Stomata
  • Enable the exchange of gases on a plant
  • Openings in the outer cell layer of leaves and
    some stems

60
Introduction to Plants
Chapter 21
21.1 Plant Evolution and Adaptations
Vascular Tissues
  • Vascular tissue enables faster movement of
    substances than by osmosis and diffusion, and
    over greater distances.
  • Vascular tissue provides support and structure,
    so vascular plants can grow larger than
    nonvascular plants.

61
Introduction to Plants
Chapter 21
21.1 Plant Evolution and Adaptations
Seeds
  • A plant structure that contains an embryo,
    contains nutrients for the embryo, and is covered
    with a protective coat

62
Plant Structure and Function
Chapter 22
22.1 Plant Cells and Tissues
Vascular Tissue
  • Xylem
  • Transports substances away from the roots

63
Plant Structure and Function
Chapter 22
22.1 Plant Cells and Tissues
Phloem
  • Transports dissolved sugars and other organic
    compounds throughout the plant.

64
Reproduction in Plants
Chapter 23
Flower Organs
23.2 Flowers
65
Introduction to Animals
Chapter 24
24.1 Animal Characteristics
Support
  • Invertebrates
  • Exoskeletons
  • Hard or tough outer coverings that provide a
    framework of support

66
Introduction to Animals
Chapter 24
24.1 Animal Characteristics
Support
  • Vertebrates
  • Endoskeletons
  • Provide support for the body
  • Provide an internal brace for muscles to pull
    against

67
Introduction to Animals
Chapter 24
24.2 Animal Body Plans
Symmetry
  • Similarity or balance among body structures of
    organisms
  • Asymmetry
  • Radial symmetry
  • Bilateral symmetry

68
Kingdom Protista
  • Ch. 20-1 and 2

69
What is a protist?
  • Eukaryotes that dont fit in the other kingdoms
  • Very diverse kingdom 200,000 species
  • Most are unicellular
  • Protist the very first first eukaryotes on
    earth
  • 3 main groups based on how they obtain food

70
Animal-like protists
  • Heterotrophs
  • protozoans first animals
  • 4 phyla (groups) based on mode of movement

71
Zooflagellates
  • Swim with use of flagella
  • Flagella long whip-like projection used to
    propel an organism
  • Live in lakes and streams
  • Absorb food through cell membrane
  • Reproduce asexually through binary fission
  • i.e. euglena

72
Sarcodines
  • Move and feed through use of pseudopods
  • Pseudopod temporary projection of the cytoplasm
  • i.e. Amoebas
  • When feeding, they surround food and bring into
    cell in the form of a food vacuole

73
Ciliates
  • Use cilia for feeding and movement
  • Cilia hair-like projections that flow back and
    forth like ores
  • i.e. Paramecium
  • Contain macro (working copy) and micronucleus
    (reserve copy of genetic info)
  • Food is swept into the gullet where it is forced
    into food vacuoles

74
Sporozoans
  • Dont move on their own and are parasites

Malaria sporozoite
75
Zooflagellates and disease
  • Malaria effects 300-500 million people
  • Caused by the sporozoan Plasmodium
  • Carried by the female Anopheles mosquito
  • Infection cycle mosquito bites human, saliva
    and plasmodium sporozites enter blood, plasmodium
    infects liver and red blood cells, red blood
    cells burst dumping toxins into bloodstream

76
  • African sleeping sickness
  • Caused by zooflagellate Trypanosoma
  • Spread by the bite of the Tsetse fly
  • Effects the nervous system causing loss of
    consciousness and coma
  • Amebic dysentery
  • Caused by Entamoeba in contaminated water

77
Kingdom Fungi
  • Ch. 21

78
What are fungi?
  • Eukaryotic heterotrophs that have cell walls made
    of chitin
  • Chitin complex carbohydrate
  • Digest food outside their bodies and absorb the
    nutrients
  • Some absorb from decaying matter others are
    parasites and absorb from a host

79
Fungi structure and function
  • All but yeasts are multi-cellular
  • Hyphae tiny filaments in the fungi made of 1
    cell
  • Mycelium- many hyphae tangled together in a mass
    underground
  • Fruiting body reproductive structure above
    ground
  • Often clusters of fruiting bodies belong to same
    mycelium

Fruiting body
hyphae
mycellium
80
Fungi reproduction
  • Asexually and sexually
  • Asexual
  • parts of hyphae break off and grow on their own
  • Spores released from sporangiophores into the
    air and will settle and grow on their own
  • Fungi spread by spores, spores grown when
    environmental conditions are right
  • Sexual two hyphae ( and -) meet and form a
    gamete

81
Figure 21-5 The Life Cycle of Rhizopus
Section 21-2
FERTILIZATION
MEIOSIS
Sexual Reproduction
Asexual Reproduction
Diploid Haploid
82
How are fungi classified?
  • According to structure and method of reproduction
  • 4 groups
  • Common Molds - Grow on meat, cheese, and breads
  • Sac Fungi larges phylum, yeasts
  • Club Fungi club shaped cap to mushroom, some
    edible but many are poisonous
  • Imperfect fungi fungi that dont fit in any
    other phylum (penicillium)

83
Kingdom Plantae Chapter 22
84
What are plants?
  • Multi-cellular eukaryotes
  • Cell walls made of cellulose.
  • Develop from multi-cellular embryos
  • Carry out photosynthesis using green pigments
    chlorophyll a b

85
Survival Requirements
  • Sunlight
  • water/minerals
  • gas exchange
  • movement of water and nutrients

86
Bryophytes
  • Need water for reproduction
  • No vascular tissuewater by osmosis
  • Can move few centimeters above the ground
  • Small in size
  • i.e. mosses, liverworts, and hornworts.
  • adapted to environments with wet habitats and
    nutrient-poor soils.
  • No true roots
  • have rhizoidslong, thin cells
  • anchor them in the ground
  • absorb water minerals from the surrounding soil.

87
Seedless Vascular Plants
  • Plants containing vascular tissues
  • Specialized to conduct water and nutrients
    through the body of the plant.
  • True roots, leaves, and stems
  • i.e. club mosses, horsetails, and ferns.
  • Developed phloem xylem

88
Movement in plants
  • Xylem
  • Tissue that carries water upward from the roots
    to every part of the plant.
  • Tracheids are the key cells in xylem
  • Hollow cells with thick cell walls that resist
    pressure
  • Phloem
  • Transports solutions of nutrients and carbs
    produced by photosynthesis

89
Seed Plants
  • Two groups
  • Gymnosperms
  • Angiosperms
  • Gymnosperms
  • seeds on surface of cones
  • Angiosperms
  • i.e. flowering plants
  • seed within a layer of tissue that protects it.
  • Reproduce without water!

90
AngiospermsFlowering Plants
  • Reproductive organs Flowers!
  • Contain ovaries that surround/protect seeds
  • Monocots one seed leaf, or cotyledon
  • i.e. corn, wheat, lilies, orchids, and palms
  • Dicots two seed leaves, or cotyledons
  • i.e. roses, clover, tomatoes, oaks, and daisies

91
Parts of Plants
  • Roots, stems, and leaves
  • Roots tap roots fibrous roots absorb water,
    nutrients, minerals anchor plants
  • Stems support plant body, transport nutrients,
    contains vascular system (made of xylem and
    phloem)
  • Leaves Site of photosynthesis Absorbs light

Tap Root
92
Plant Responses
  • Phototropism Plant movement towards light
  • Gravitropism / geotropismroots grow downward
    shoots upward
  • Thigmotropismresponse to touch / vines wrap
    around climb

93
Kingdom Animalia
  • Survey of organisms
  • Chs. 26-32

94
What is an Animal?
  • An animal is a multicellular, eukaryotic
    heterotroph whose cells lack cell walls

95
How are they classified?
  • Invertebrates
  • Animals that have no backbone, or vertebral
    column.
  • 95 of animals
  • i.e. insects, worms, jellyfish, sea stars
  • Vertebrates
  • Animals that have a backbone
  • 5 of animals
  • i.e. fish, amphibians, reptiles, birds, mammals

96
Essential Functions
Circulatory system or diffusion
  • Feeding
  • Respiration
  • Oxygen in
  • Carbon Dioxide out
  • Circulation
  • Circulatory system
  • Diffusion
  • Excretion
  • Bi-product of metabolism
  • Response
  • Nervous system
  • Movement
  • Skeleton Muscles
  • Reproduction
  • Sexual or Asexual

97
Phylum Chordata
  • What are chordates?
  • Animal that has for some stage of its life
  • Dorsal (back), hollow nerve cord
  • Pharyngeal slits
  • Post-anal tail
  • A notochord
  • Most are vertebrates, but not all!
  • i.e. tunicates, lancelets, sponges

98
Mammalia
  • What are they?
  • Animals that have hair, ability to nourish young
    (milk), breath air, four-chambered hearts,
    endotherms.
  • Endotherm animal that generates body heat
    internally
  • Feeding herbivores, carnivores, omnivores,
    filter feeders.

99
Maintaining Homeostasis
  • Endothermy
  • Organism that maintains an internal temperature
    by generating its own body heat from within
  • Example?
  • Ectothermy
  • Organism that relies on interactions with the
    environment to help control body temperature
  • Example?

100
Unit 7 Ch. 19.1-2
  • Bacteria

101
Prokaryotes
  • Single cell
  • No true nucleus
  • few organelles
  • Archaebacteria extreme environments
  • Eubacteria

102
Eubacteria
  • Wide variety of bacteria with different
    lifestyles
  • Cell wall for protection from injury also
    determines the shape of bacteria
  • E. Coli lives in mammal intestines

103
Section 19-1
The Structure of a Eubacterium
Go to Section
104
Archaebacteria
  • Cell walls made from different materials than
    eubacteria
  • Cell membrane lipids different from eubacteria
  • DNA sequences are more like eukaryotes than
    eubacteria
  • Live in extreme environments like great salt
    lake, hot springs, oxygen deprived mud

105
Identifying prokaryotes
  • Identified by shape, cell wall, method of
    movement, and how they obtain food
  • Shapes
  • Bacilli rod
  • Cocci round
  • Spirilla spiral
  • Prefixes strep long chains, staph clumps,
    diplo pairs

106
Cell walls
  • Chemical make-up determined by a gram stain
    (purple or red)
  • Peptidoglycan purple, gram positive
  • Outer layer of lipid and carbohydrates pink,
    gram negative

107
Movement
  • Flagella whip-like structure
  • Snake type movement
  • Move in a slime they secrete
  • Do not move at all

108
Obtaining energy
  • Autotrophs some carry out photosynthesis and
    others carry out chemosynthesis
  • Heterotrophs eat food (food spoilage)
  • Photoheterotrophs get energy using both methods
    above

109
Releasing energy
  • Obligate aerobes carry out cellular respiration
    with oxygen
  • Obligate anaerobes cannot live in presence of
    oxygen
  • Clostridium botulinum - botulism
  • Facultative anaerobes can live with or without
    oxygen

110
Growth and Reproduction
  • Binary fission DNA replicated and splits in
    half asexual
  • Conjugation genetic info exchange between cells

111
Unit 9
  • Bacteria in Nature

112
Bacterias importance
  • Vital to living world
  • Photosynthetic producers putting oxygen into air
  • Decomposers of dead matter to allow recycling of
    nutrients

113
Decomposers
  • Break down of dead matter
  • Helps to recycle nutrients in the ecosystem
  • Play an important role in sewage treatment
  • Produces purified water, nitrogen, carbon dioxide
    gases, and byproducts to be used as fertilizers

114
Nitrogen fixers
  • Plants depend on nitrogen to make amino acids and
    proteins ?animals get nitrogen from plant
    proteins
  • Nitrogen from atmosphere must be converted to
    ammonia NH3 before plants can use it
  • This is done by nitrogen-fixing bacteria
  • Symbiotic relationship between plants and
    bacteria -

Rhizobium
115
Bacteria and disease
  • Pathogens disease causing agents (small
    percentage of bacteria)
  • Treated with antibiotics block the growth and
    reproduction of bacteria
  • Cause disease in two ways
  • Break down tissue for food
  • Tuberculosis
  • Release toxins that harm the body
  • Food poisoning
  • Strep throat scarlet fever streptococcus

Lung infection
116
Human use for bacteria
  • Manufacturing food cheese, buttermilk, yogurt,
    sour cream
  • Digesting oil spills
  • Water treatment
  • Medicines
  • warfare

Anthrax
117
Controlling bacteria
  • Sterilization destroy bacteria by subjecting
    them to great heat or chemical action
  • Disinfectants chemical solution that kills
    bacteria
  • Refrigeration bacteria grows more slowly in
    cold temps. food
  • Boiling at high temps to kill bacteria
  • Salt, vinegar, sugar

118
virus
  • Living or not?

119
Virus (latin for poison)
  • Requires host cell to reproduce--intracellular
    parasite
  • Dont move, respire, or grow no independent
    metabolism
  • smaller than tiniest bacteria
  • possess either DNA or RNA
  • may be inactive indefinitey
  • mutates rapidly
  • Named for disease caused, organ infected , or
    region detected in

120
structure
  • Contain a nucleic acid and protein
  • HEAD region
  • Capsid--protein coat with nucleic acid core
  • TAIL region
  • to attach to bacteria/cells

121
Viral recognition and attachment
  • Virus must recognize specific receptor site on
    host cell
  • Part of virus matches site on host, lands and
    locks in
  • Attachment is specific- virus can only enter and
    reproduce in a few types of cells
  • I. E. - tobacco mosaic virus cannot infect human
    cells even though we are exposed to it daily

122
Figure 19-9 Virus Structures
Section 19-2
Tobacco Mosaic Virus
T4 Bacteriophage
Influenza Virus
123
Reproduction
  • Must take place inside a host cell
  • Infection--chance contact
  • Lytic Infection
  • Viral DNA takes over host nucleus, produces new
    viruses
  • Lysis of host cell bursts and dies new
    viruses are released

124
Alternate reproduction
  • Lysogenic cycle (infection) virus attacks cell
    but doesnt kill immediately
  • Viral DNA mixes with host DNA prophage
  • Doesnt always reproduce right away, cell may
    function normally
  • Viral DNA activates and viral reproduction begins

125
Figure 19-10 Lytic and Lysogenic Infections
126
Figure 19-11 Viruses and Cells
Section 19-2
127
Pathogenic viruses
  • Ebola zaire--
  • AIDS
  • rhinoviruses
  • influenza
  • measles, mumps, chicken pox
  • polio
  • rabies
  • smallpox

128
Vaccines
  • cow pox--Edward Jenner
  • 1796
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