Chapter 7 Cells

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Chapter 7Cells
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7.1 Life is Cellular

• Robert Hooke 1665 saw plant cell walls in cork.
• Anton van Leeuwenhoek 1667 sees microorganisms
• Matthias Schleiden 1838 all plants are made of
  cells
• Theodor Schwann 1839 all animals are made of
  cells
• Rudolph Virchow 1855
• Where a cell exists, there must have been
  a
• preexisting cell.

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Cell Theory

• 1. All living things are made of cells
• 2. Cells are the basic unit of structure and
  function.
• 3. New cells are made from existing cells

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2 Groups of Cells

• 1. Prokaryotic
• Generally smaller (.1-10 microns)
• No nucleus. DNA is a circular
• chromosome called a plasmid
• No membrane-bound organelles
• All bacteria are prokaryotes
• Found everywhere even extreme
• environments

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• 2. Eukaryotic
• Larger, more complex (10 100microns)
• Have a nucleus.
• highly specialized
• Have organelles little organs
• Ex plant, animal, fungus, protists

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• Prokaryote cell vs. Eukaryote Cell

No true nucleus Has DNA, however
True nucleus and other organelles
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7.2 Basic Cell Structure
Eukaryotes

• Eukaryotic cells have 2 general regions
• 1. cell membrane thin flexible barrier around
  cell.
• 2. cytoplasm
  inside the cell
• membrane,
  outside
• the nucleus,
• contains
  organelles.

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• A. Nucleus
• Controls cell activities
• Contains DNA hereditary material
• 2 forms of DNA in nucleus
• chromatin granular
• - DNA bound around proteins.
• - spread out through nucleus
• - seen in a non- dividing cell
• chromosomes
• - condensed threads
• of DNA
• - found in dividing cells

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chromatin

• nucleolus
• inside nucleus
• helps make ribosomes
• Nuclear envelope
• composed of 2
• membranes with pores
• for RNA to get out to the cytoplasm

Nuclear pores
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• B. Endoplasmic Reticulum
• large internal membrane system
• lipid components of the cell membrane are
  assembled along with proteins that will be used
  or exported from the cell.

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• Rough ER
• Ribosome studded
• where proteins are made
• and modified for export
• Smooth ER
• no ribosomes.
• contains enzymes
• for many reactions including
• synthesizing membrane lipids

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• C. Ribosomes
• made of RNA
• Assemble proteins following the coded
• instructions from DNA.
• Found either on the rough ER
• or free in the cytoplasm.

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• D. Golgi Apparatus
• membranes that contain
• enzymes to modify, sort,
• and package proteins
• Proteins are used in the cell or
• shipped out for
• use elsewhere in the
• organism.

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• E. Lysosomes
• small sacs of digestive enzymes that digest
  lipids, carbs, proteins.
• lysosomes break
• down old cell parts

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• F. Vacuole
• Large membrane bound sac. stores water,
  carbohydrates, salts
• In many plant cells there is a single, large
  central
• vacuole filled with liquid.
• The pressure of the
• vacuole allows plants to
• support heavy structures
• such as leaves and flowers.
• This pressure is called
• turgor pressure
• Animal cells have smaller vacuoles

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• Vacuoles are also found in some unicellular
  organisms.
• The paramecium has a contractile vacuole that
  pumps excess water out of its cell. The use of
  the vacuole helps the paramecium maintain
  homeostasis.

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Vacuole
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• G. Mitochondria
• Mitochondria convert
• the energy in food into forms that are more
• convenient for cells to use.
• Glucose from food
• is converted into ATP.
• .

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• H. Cytoskeleton
• Network of protein filaments that help the cell
  maintain its shape.
• Involved in movement of organelles inside the
  cell
• The cytoskeleton is made up of
• microfilaments
• microtubules

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• Microfilaments
• are threads made up of the protein actin
• flexible framework that supports the cell
• help some cells move cytoplasm- Amoeba
• Allows movement of organelles in cell
• Microtubules
• hollow structures made of the protein tubulin
• maintain cell shape
• are important in cell division spindle fibers
• build projections from the cell surfacecilia and
  flagella that help some cells to swim rapidly.

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Cytoskeleton
Cell membrane
Endoplasmic reticulum
Microtubule
Microfilament
Ribosomes
Mitochondrion
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• I. Centrioles
• In animal cells, structures known as centrioles
  are formed from tubulin.
• Centrioles are located near the nucleus and help
  to organize cell division.

centrioles
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• J. Cell Wall
• plants, algae, fungi, bacteria all have C.W.
• tough membrane made of cellulose It supports and
  protects the cells.
• K. Chloroplast
• located in plants , some algae, protists,
  bacteria.
• oval organelle with membranes that contain the
  pigment chlorophyll that plants use to make
  carbohydrates from the sun
• 
  

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Organisms that have chloroplasts
Your Basic plant
chloroplast
Euglena protist
Cyanobacteria .a bacteria
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Plant Cell!!
Notice the cell wall
and chloroplast
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Animal Cell
cytoplasm
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(No Transcript)
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• Cell animation

Egg sperm,
Macrophage eating bacteria
E. coli
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7.3 Cell Boundaries

• All cells are surrounded by a thin, flexible
  barrier
• known as the cell membrane.
• A. Cell Membrane
• controls what goes in / out of the cell
  selectively permeable
• protects and supports the cell
• Helps with communication with other cells

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• Materials needed for life
• water
• oxygen
• correct balance of ions (Na, Mg,
• Ca, H, Cl-, K)
• CO2 for autotrophs
• hormones
• building material for food and proteins
• The cell membrane acts as a gateway for these
  important materials.

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• Components of cell membranes
• 2 thin layers of phospholipid molecules.
• non-polar fatty acid chains form the inner part
  of the membrane
• polar heads form the outermost and innermost
  (facing cytoplasm), parts of the membrane.
• membrane is fluid flexible not rigid
• it is selectively permeable
• Structure called fluid mosaic model

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phospholipid bilayer
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• Proteins
• embedded in lipids like ice in a punch bowl.
• Form channels for things to pass through

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Membrane Structure

• cool animation of cm
• Fluid Mosaic Structure
• Membrane - web

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• B. Transport of Materials in/out of cells
• Molecules naturally move from areas of high
  concentration to areas of low concentration. Does
  not require energy.
• The concentration of a solution is the mass of
  solute in a given volume of solution, or mass /
  volume.
• A concentration gradient means theres a
  difference in the concentration of solute in 2
  areas or on either side of a membrane.

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• During the process of diffusion, particles in a
  solution tend to move from an area of greater
  concentration to an area where they are less
  concentrated.
• Does not require energy passive transport

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• When equilibrium is reached, solute particles
  continue to diffuse across the membrane in both
  directions.

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• Osmosis?
• The movement of water across a selectively
• permeable membrane until equilibrium is
  reached.

Sugar is the solute in this solution
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Sugar is the solute in this solution the
membrane is only permeable to water.
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• Osmosis ?
• 3 Types of solutions that affect how water moves
  
• isotonic solution concentration of solute
  concentration of water cell size stays constant
• hypertonic solution concentration of solute is
  
• greater than water causes a cell to shrink
  (hyper more solute)
• hypotonic solution concentration of solute is
  less than water causes a cell to swell
  (hypo less solute)

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• osmosis demo
• Simulation - web
• simulation 2 - web
• simulation 3 - web

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Osmotic Pressure

• Osmosis exerts a pressure known as osmotic
  pressure on the cell membrane.
• Cells in large organisms are not in danger of
  bursting because they are bathed in fluids, such
  as blood, that are isotonic.
• Other cells are surrounded by tough cell walls
  that prevent the cells from expanding even under
  tremendous osmotic pressure.

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The effects of osmosis on plant cells red
blood cells
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• Facilitated Diffusion diffusion with a helper
• Some molecules cant cross through the lipid
  membrane, but still move from high to low
  concentration through protein channels
• helper a carrier protein
• no energy required, still passive transport

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Facilitated Diffusion

• facilitated diffusion web

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• Active Transport
• Moves materials across membranes against the
  concentration gradient
• requires energy
• Uses pumps proteins that pump molecules
  against
• the gradient. Ex. Na K

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• Active Transport - pump web
• Active Transport 2

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• Endocytosis?
• Cell engulfs a large amount of material by
  forming pockets within the cell membrane.
• results in large vacuoles in the cytoplasm
• phagocytosis large solid particles
• pinocytosis large amounts of liquid
• phagocytosis web
• endocytosis Prent hall

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• Exocytosis?
• Release of large amounts of material through the
  cell membrane.

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• Movement of materials in plants?
• Xylem moves water up
• Hollow tube-shaped cells that carry water
• minerals up from the roots to the leaves for
• use in photosynthesis.

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• Phloem moves food down
• food moves down from leaves after
  photosynthesis- to stems and roots for storage.

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7.4 Cellular Diversity

• A. Unicellular Organisms?
• organisms that perform all cell functions and
  are
• one single cell.
• 1. prokaryotes bacteria.good
  survival
• adaptations. Most abundant on
  earth.
• 2. eukaryotes some protists and
  fungus
• euglena,
  amoeba, yeast
• amoeboid movement

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• B. Colony ?
• a group of unicellular organisms living together
• biofilm mixed bacterial colonies coordinating
  efforts to survive
• - surround themselves w/ a slime
  layer
• example dental plaque

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• volvox a colonial algae in which individuals
• take on special roles
• some propose it is a multicellular organism

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• C. Multicellular Organisms?
• Organisms composed of many cells
• Cell specialization cells are specialized to
  perform different functions in organisms.
• Increases efficiency.

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Cell Differentiation
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• Hydra a small freshwater animal showing
  considerable cell specialization.
• - stinging cells - muscle cells
• - gland cells - reproductive cells
• - epidermal cells - sensory cells
• - flagellated cells - nerve cells

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• D. Levels of organization?
• Cells within organisms are classified into
  levels
• 1. Cells (muscle cell)
• 2. Tissues group of similar cells with a
  function
• (muscle)
• 3. Organs several tissues working
  together
• (stomach)
• 4. Organ systems organs that work
  together to
• complete a task. (Digestive)

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• Human systems
• Reproductive
• Integumentary
• Endocrine
• Lymphatic
• Skeletal
• Muscular

Digestive Cardiovascular Nervous Urinary Respi
ratory Immune