Classification, Bacteria,

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Classification, Bacteria, Viruses

• Unit 9

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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.

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Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Aristotles System

• Aristotle classified organisms as either animals
  or plants.

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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
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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

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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
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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).

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Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Taxonomic Categories

• The taxonomic categories are part of a hierarchal
  system.

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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.

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Organizing Lifes Diversity
Chapter 17
17.1 The History of Classification
Family

• A family is the next higher taxon, consisting of
  similar, related genera.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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
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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.

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Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Domain Bacteria

• Eubacteria are prokaryotes whose cell walls
  contain peptidoglycan.

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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.

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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.

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Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Protista

• Protists are classified into three different
  groupsplantlike, animal-like, and funguslike.

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Organizing Lifes Diversity
Chapter 17
17.3 Domains and Kingdoms
Kingdom Fungi
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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.

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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.

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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).

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Bacteria and Viruses
Chapter 18
18.1 Bacteria
Photosynthetic eubacteria
Archaebacteria
Eubacteria
3000x
9560x
magnification unavailable
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Bacteria and Viruses
Chapter 18
18.1 Bacteria
Eubacteria

• Very strong cell walls

• Contain peptidoglycan

• Some have a second cell wall

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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.

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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

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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

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Bacteria and Viruses
Chapter 18
18.1 Bacteria

• Chromosomes

• Capsule

• Pili

• Size

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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
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• 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

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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
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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.

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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.

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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.

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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

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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.

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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.

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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
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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

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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.

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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

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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.

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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.

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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

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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.

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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

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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.

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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.

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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

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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.

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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

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Plant Structure and Function
Chapter 22
22.1 Plant Cells and Tissues
Vascular Tissue

• Xylem

• Transports substances away from the roots

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Plant Structure and Function
Chapter 22
22.1 Plant Cells and Tissues
Phloem

• Transports dissolved sugars and other organic
  compounds throughout the plant.

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Reproduction in Plants
Chapter 23
Flower Organs
23.2 Flowers
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Introduction to Animals
Chapter 24
24.1 Animal Characteristics
Support

• Invertebrates

• Exoskeletons

• Hard or tough outer coverings that provide a
  framework of support

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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

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Introduction to Animals
Chapter 24
24.2 Animal Body Plans
Symmetry

• Similarity or balance among body structures of
  organisms

• Asymmetry

• Radial symmetry

• Bilateral symmetry

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Kingdom Protista

• Ch. 20-1 and 2

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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

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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

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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

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Sporozoans

• Dont move on their own and are parasites

Malaria sporozoite
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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

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• 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

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Kingdom Fungi

• Ch. 21

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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
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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

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Figure 21-5 The Life Cycle of Rhizopus
Section 21-2
FERTILIZATION
MEIOSIS
Sexual Reproduction
Asexual Reproduction
Diploid Haploid
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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)

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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

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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.

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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

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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

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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

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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
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Plant Responses

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

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Kingdom Animalia

• Survey of organisms
• Chs. 26-32

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What is an Animal?

• An animal is a multicellular, eukaryotic
  heterotroph whose cells lack cell walls

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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

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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

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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

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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.

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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
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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

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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

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Figure 19-10 Lytic and Lysogenic Infections
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Figure 19-11 Viruses and Cells
Section 19-2
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Pathogenic viruses

• Ebola zaire--
• AIDS
• rhinoviruses
• influenza
• measles, mumps, chicken pox
• polio
• rabies
• smallpox

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Vaccines

• cow pox--Edward Jenner
• 1796