Title: Classification, Bacteria,
1Classification, Bacteria, Viruses
2Organizing 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.
3Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Aristotles System
- Aristotle classified organisms as either animals
or plants.
4Organizing 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
5Organizing 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
6Organizing 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
7Organizing 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).
8Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Taxonomic Categories
- The taxonomic categories are part of a hierarchal
system.
9Organizing 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.
10Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Family
- A family is the next higher taxon, consisting of
similar, related genera.
11Organizing 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.
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13Organizing 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.
14Organizing 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.
15Organizing 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.
16Organizing 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.
17Organizing 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.
18Organizing 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.
19Organizing 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.
20Section 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
21Organizing 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.
22Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Domain Bacteria
- Eubacteria are prokaryotes whose cell walls
contain peptidoglycan.
23Organizing 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.
24Organizing 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.
25Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Protista
- Protists are classified into three different
groupsplantlike, animal-like, and funguslike.
26Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Fungi
27Organizing 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.
28Organizing 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.
29Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
30Bacteria 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).
31Bacteria and Viruses
Chapter 18
18.1 Bacteria
Photosynthetic eubacteria
Archaebacteria
Eubacteria
3000x
9560x
magnification unavailable
32Bacteria and Viruses
Chapter 18
18.1 Bacteria
Eubacteria
- Some have a second cell wall
33Bacteria 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.
34Bacteria 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
35Bacteria 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
36Bacteria and Viruses
Chapter 18
18.1 Bacteria
37Bacteria and Viruses
Chapter 18
18.1 Bacteria
Identifying Prokaryotes
- 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
39Bacteria 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
40Bacteria 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.
41Bacteria and Viruses
Chapter 18
18.1 Bacteria
Reproduction of Prokaryotes
- Division of a cell into two genetically identical
cells
- Two prokaryotes attach to each other and exchange
genetic information.
42Bacteria 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.
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44Bacteria and Viruses
Chapter 18
18.1 Bacteria
Survival of Bacteria
- Resistant to harsh environments and might be able
to survive extreme heat, extreme cold,
dehydration, and large amounts of ultraviolet
radiation
45Bacteria 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.
46Bacteria 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.
47Bacteria 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
48Bacteria and Viruses
Chapter 18
18.1 Bacteria
Foods and Medicines
- Some foods are made with the aid of bacteria.
49Bacteria 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.
50Bacteria 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 replicate on their own
51Bacteria 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.
52Bacteria 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.
53Bacteria and Viruses
Chapter 18
18.2 Viruses and Prions
54Bacteria 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
55Protists
Chapter 19
19.1 Introduction to Protists
Protists
- All protists are eukaryotes.
- Some reproduce asexually by mitosis while others
exchange genetic material during meiosis.
56Protists
Chapter 19
19.1 Introduction to Protists
Classifying Protists
- Some scientists classify protists by their
methods of obtaining nutrition.
57Fungi
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.
58Fungi
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.
59Introduction 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
60Introduction 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.
61Introduction 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
62Plant Structure and Function
Chapter 22
22.1 Plant Cells and Tissues
Vascular Tissue
- Transports substances away from the roots
63Plant Structure and Function
Chapter 22
22.1 Plant Cells and Tissues
Phloem
- Transports dissolved sugars and other organic
compounds throughout the plant.
64Reproduction in Plants
Chapter 23
Flower Organs
23.2 Flowers
65Introduction to Animals
Chapter 24
24.1 Animal Characteristics
Support
- Hard or tough outer coverings that provide a
framework of support
66Introduction to Animals
Chapter 24
24.1 Animal Characteristics
Support
- Provide support for the body
- Provide an internal brace for muscles to pull
against
67Introduction to Animals
Chapter 24
24.2 Animal Body Plans
Symmetry
- Similarity or balance among body structures of
organisms
68Kingdom Protista
69What 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
70Animal-like protists
- Heterotrophs
- protozoans first animals
- 4 phyla (groups) based on mode of movement
71Zooflagellates
- 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
72Sarcodines
- 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
73Ciliates
- 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
74Sporozoans
- Dont move on their own and are parasites
Malaria sporozoite
75Zooflagellates 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
77Kingdom Fungi
78What 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
79Fungi 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
80Fungi 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
81Figure 21-5 The Life Cycle of Rhizopus
Section 21-2
FERTILIZATION
MEIOSIS
Sexual Reproduction
Asexual Reproduction
Diploid Haploid
82How 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)
83Kingdom Plantae Chapter 22
84What are plants?
- Multi-cellular eukaryotes
- Cell walls made of cellulose.
- Develop from multi-cellular embryos
- Carry out photosynthesis using green pigments
chlorophyll a b
85Survival Requirements
- Sunlight
- water/minerals
- gas exchange
- movement of water and nutrients
86Bryophytes
- 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.
87Seedless 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
88Movement 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
89Seed 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!
90AngiospermsFlowering 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
91Parts 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
92Plant Responses
- Phototropism Plant movement towards light
- Gravitropism / geotropismroots grow downward
shoots upward - Thigmotropismresponse to touch / vines wrap
around climb
93Kingdom Animalia
- Survey of organisms
- Chs. 26-32
94What is an Animal?
- An animal is a multicellular, eukaryotic
heterotroph whose cells lack cell walls
95How 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
96Essential 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
97Phylum 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
98Mammalia
- 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.
99Maintaining 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?
100Unit 7 Ch. 19.1-2
101Prokaryotes
- Single cell
- No true nucleus
- few organelles
- Archaebacteria extreme environments
- Eubacteria
102Eubacteria
- 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
103Section 19-1
The Structure of a Eubacterium
Go to Section
104Archaebacteria
- 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
105Identifying 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
106Cell 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
107Movement
- Flagella whip-like structure
- Snake type movement
- Move in a slime they secrete
- Do not move at all
108Obtaining energy
- Autotrophs some carry out photosynthesis and
others carry out chemosynthesis - Heterotrophs eat food (food spoilage)
- Photoheterotrophs get energy using both methods
above
109Releasing 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
110Growth and Reproduction
- Binary fission DNA replicated and splits in
half asexual - Conjugation genetic info exchange between cells
111Unit 9
112Bacterias importance
- Vital to living world
- Photosynthetic producers putting oxygen into air
- Decomposers of dead matter to allow recycling of
nutrients
113Decomposers
- 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
114Nitrogen 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
115Bacteria 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
116Human use for bacteria
- Manufacturing food cheese, buttermilk, yogurt,
sour cream - Digesting oil spills
- Water treatment
- Medicines
- warfare
Anthrax
117Controlling 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
118virus
119Virus (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
120structure
- Contain a nucleic acid and protein
- HEAD region
- Capsid--protein coat with nucleic acid core
- TAIL region
- to attach to bacteria/cells
121Viral 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
122Figure 19-9 Virus Structures
Section 19-2
Tobacco Mosaic Virus
T4 Bacteriophage
Influenza Virus
123Reproduction
- 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
124Alternate 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
125Figure 19-10 Lytic and Lysogenic Infections
126Figure 19-11 Viruses and Cells
Section 19-2
127Pathogenic viruses
- Ebola zaire--
- AIDS
- rhinoviruses
- influenza
- measles, mumps, chicken pox
- polio
- rabies
- smallpox
128Vaccines
- cow pox--Edward Jenner
- 1796