Life Structure and Classification

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Life Structure and Classification

• What are living things like?
• Any living thing is an organism
• Organisms
• are organized
• grow and develop
• respond
• maintain homeostasis
• use energy
• reproduce

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Organized

• All living organisms are composed of cells
• Cells are smallest unit of life that carries on
  the function of life
• Cells take in materials and use them in complex
  ways
• Have orderly structure and instruction for
  transfer of heriditary material

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Living Things grow and Develope

• Single cell organisms increase cell size
• Multi-celled organisms grow by increasing number
  of cells
• Changes that take place during lifetime is known
  as development
• Figure 2 shows examples of development
• Life span is the length of time an organism is
  expected to live

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Living things Respond

• Living things interact with their surroundings
• Anything that causes change in an organism is a
  stimulus and the reaction to that is a response
• Organisms must respond to stimuli to carry on
  daily activity and to survive

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Maintain Homeostasis

• Inside cells they must respond to stimuli within
  (water or food levels within)
• Cells internally make adjustments
• This regulation of an organisms internal life
  maintaining conditions that is in response to
  its environment is called homeostasis

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Living things use energy

• All energy for cells originates from the sun
• Plants use sun directly to produce energy
  (photosynthesis) where H2O CO2 produces C6H12O6
  (carbohydrates) and O2
• Animals and some other organisms take in
  carbohydrates and oxygen to produce its energy
• Some bacteria deep in dark ocean floors use
  stored energy in chemical compounds to make food

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Living things must reproduce

• In order for an organism to continue to its own
  kind it must be able to reproduce itself

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What do living things need to survive

• Place to live
• Needs water
• Water transport minerals within and between cells
• Water is released by organisms and homeostasis is
  maintained
• Needs food source
• Animals need to take in food, where plants
  produce their own food
• Organisms die and are decomposed by
• other organisms that are reused again

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How are living things classifiedsection 2

• Carolus Linnaeus
• Developed a system of organizing organisms by
  similar structure in system called Binomial
  Nomenclature.
• Used Scientific Names rather than common names
• Modern classification use structure, hereditary
  information and early stages of development

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Binomial Nomenclature

• Two word naming system (latin names)
• First word is the genus name (contain similar
  species)
• Second word is the species name
• Can describe a feature, place or honor an
  individual
• Ambystoma tigrinum (salamander named because of
  tiger stripes)
• Organisms of same species can reproduce amongst
  themselves

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Scientific NamesWhy they are important

• Help avoid confusion with common names
• Organisms with similar evolutionary histories are
  group together
• Gives descriptive information about species
  (tiger salamander)
• It is organized efficiently

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Classification Order

• Organisms are classified in following order
• Kingdom
• Phylum (Division in plants)
• Class
• Order
• Family
• Genus
• species

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Modern Classification

• Today scientist use phylogeny to classify
  organisms
• Uses fossils, evolutionary history and changes
  over time to classify
• Smallest group is a species
• Broadest group is Kingdom
• Figure 6 in book classifies a brottle nosed
  dolphin

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Tools for Identifying Organisms

• Field guides and dichotomous keys aide to
  identify organisms
• Dichotomous key (use 2 characteristics that you
  choose between that leads to identification of
  organisms)
• The key will lead to genus-species final name of
  organism

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Cell Structuresection 3

• Viewing cell structure
• First developed by using two magnifying glasses
  together to see larger view of cells
• Leeuwenhoek (Dutch) saw inside cells (1600s)
  called them beasties

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Development of Cell Theory

• Hooke in 1665 sliced a piece of cork and saw
  empty space he called cells
• 1830 Scheiden used a microscope to study plant
  parts and called them cells
• Schwann observed animal cells
• Both men combined their ideas and were convinced
  all living things are made of cells
• Mid 1800s Virchow proposed that cells divide
  and every cell comes from a cell that already
  existed

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Cell Theorytable 2 (page 221)

• All Cells are made up of one or more cells
• Cells are the basic unit of organization in
  organism
• All Cells come from pre-existing cells

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Cell organization

• Scientists divide cells that have a membrane
  bound structure and those that dont
• Cells without a membrane are called prokaryote
  cells
• Cells with a membrane around the cell are called
  eukaryote cells
• Each cell performs specific functions but all
  cells must take in nutrients, store, produce and
  breakdown substances, take in and use energy
• Structure of cells perform certain functions

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Cell Wall

• Tough rigid outer coverings that protect cells
  and give them shape
• Found in all plants, algae, fungi and most
  bacteria
• Plants cell wall contain mostly cellulose
  (carbohydrate) and allows water and nutrients in
  and out
• Pectin (found in plant cell walls) is glue-like
  structure that has thick structure (jams and
  jellies)
• Lignin (makes cell walls rigid) found mostly in
  plant cells that aide in supporting plants

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Cell Membrane

• All cells contain a cell membrane
• It is the outermost covering of cells unless they
  have a cell wall
• Regulates interactions between cells and
  environment
• Allows nutrients to move in and wastes to leave
  cell

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Cytoplasm

• Gell-like substance inside cell membrane is
  called cytoplasm
• Life processes take place here
• Prokaryote cells cytoplasm contains the
  hereditary material
• All organelles are located here
• Cytoskeleton found in cytoplasm is made of
  proteins that help cell change shape, enable some
  cells to move

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Manufacture of Proteins in Cells

• Every cell activity involves proteins
• Proteins are part of cell membrane and are part
  of all chemical reactions in cell
• Ribosomes produce protein in cells
• Found in cytoplasm
• Get their instruction from hereditary material
  that tells them how, when and in what order to
  make specific proteins

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Membrane-bound Organelles

• Organelles are structure in cytoplasm that carry
  out life functions in cells
• Found in cytoplasm of eukaryotic cells
• Nucleus is largest organelle
• Ribosomes are not membrane bound but are
  considered an organelle

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Organelles that produce Energy

• Chloroplasts (organelle found in plants)
• Contain chylorophyll (green pigments) that
  captures sunlight to make sugars called glucose
• Captured light energy is stored in glucose as
  chemical energy where plants utilizes glucose to
  carry out life functions in cells

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Organelles that produce Energy

• Organelle that releases energy is Mitochondria
• Food (glucose and carbohydrates) is broken down
  into CO2 and H2O and releases energy
• Sometimes called the powerhouse organelle
  because it provides the energy for cells
• All plants and animal cells have these

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Organelles that process, transport and store
materials

• Endoplasmic reticulum (ER) takes up considerable
  amount of space that process and move materials
  around cell like a conveyor belt
• Rough ER contains ribosomes where protein is made
  and moved in cell
• Smooth ER process lipids and oils that store
  energy

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Organelles that process, transport and store
materials

• After proteins is made they are transferred to
  Golgi bodies where they are packaged and moved to
  areas of cells in vesicles
• Materials are also moved to outer membrane for
  release outside of cell
• Vacuoles also are organelles that store water,
  waste products, food and other cell materials

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Organelles that Recycle

• Lysosomes are structures that break down food
  molecules, cell waste, worn-out cell parts and
  viruses
• Chemicals released from lysosomes break down food
  and dead cells
• These chemicals are contained in lysosomes and
  when a cell dies, the chemicals are released and
  break down the dead cell

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Many Celled Organisms

• Many celled organisms rely of other cells to
  perform all life functions
• Tissue is a group of similar cells that work
  together to do one job
• Tissues are organized into organs.
• Organs are a group of tissues that work together
  to perform a function (heart..nerve, blood and
  cardic muscle tissue)
• Group of organs working together perform a
  certain function is an organ system
• Organ systems work together to make up many
  celled organisms (heart, arteries, veins, and
  capillaries)

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Virusessection 4

• Viruses causes many diseases
• Viruses are non-living strands of hereditary
  material surrounded by a protein coat
• Do not have nucleus, other organelles or a cell
  membrane
• Viruses rely on host cells to live inside (living
  cells)
• Have two kinds of viruses Active and Latent

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Active Viruses

• Occurs when virus enters host cell and
  immediately begins to make new viruses
• Destroys the host cells when it makes new viruses
• Virus uses host cell to duplicate its hereditary
  material and later releases duplicated virus and
  kills host cell when they are released
• Figure 17 page 232

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Latent Viruses

• Some viruses enter host cell and remain inactive
  for a period of time
• Does not immediately cause the host cell to
  duplicate new virus
• At a later time it may begin to duplicate and
  release new viruses that kill the host cell
• AIDS, cold sores are examples

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How do viruses affect organisms

• Viruses attach specific cells that match host
  cells
• Many times viruses only attach to certain host
  cells (potato leafroll)
• Some viruses can affect numerous organisms
  (rabies)
• Viruses are moved by wind and inhaled where they
  attach
• Figure 18 page 233

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Treating/Preventing Viral Diseases

• Treatment difficult because antibiotics do not
  kill viruses
• Prevention is best method of avoiding viral
  infections (eliminate mosquito to fight yellow
  fever)

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Natural Immunity

• Human bodies fight viral infections by making
  interferons
• Interferons are proteins that make a protective
  covering for cells that are infected (produced by
  healthy cells to protect affected cells)

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Vaccines

• Vaccines are weakened viruses that cant enter
  host cells and duplicate, but cells begin to make
  interferons that protect all cells from infection
• Measles, mumps, small pox, chicken pox, polio,
  and rabies
• Found vaccine by taking weakened cow pox cells
  and entering them into healthy people to prevent
  small pox (1786) Jenner

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Virus Research

• AIDS is a disease that is caused by human
  immuno-deficiency virus (HIV)
• AIDS (acquired immune deficiency syndrome)
• The HIV virus weakens the immune system and body
  cant fight infections like pneumonia, TB
• People usually die from weakened system rather
  than disease