The Cell

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The Cell

• Cell Theory/HistoryStructuresTransport
  Differentiation Levels of Organization

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Robert Hooke

• English physicist
• 1665
• Saw a slice of cork tree tissue
• Tiny chambers
• Termed them cells
• (looked like monks cells in monastery)

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Robert Hooke

• Published his book Micrographia
• Contained drawings of cork cells
• Used early microscope

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Anton Van Leeuwenhoek

• Dutch businessman
• 1674
• Perfected microscope
• (about 300x)
• Saw living things in pond water
• Animalcules
• Observed bacteria (on wood teeth) and protozoa

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Matthias Schleiden

• German botanist
• 1838
• Concludes that all plants are made up of cells

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Theodor Schwann

• German zoologist
• 1839
• Concluded that all animals are made up of cells

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Rudolph Virchow

• German physician/pathologist
• 1855
• Worked with eggs from various organisms
• Proposes that all cells come from existing cells

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Cell Theory

• All living things are composed of cells.
• Cells are the basic units of structure and
  function in living things.
• New cells are produced from existing cells.

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Janet Plowe

• 1931
• Demonstrates that the cell membrane is a physical
  structure, not an interface between two liquids.

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Lynn Margulis

• 1970
• Proposes a theory that certain organelles were
  once free-living cells themselves

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Singer - Nicholson

• 1972
• Fluid Mosaic Model
• Membranes are phospholipid bilayers with globular
  proteins embedded in them
• Membrane is always moving
• Made up of smaller pieces (mosaic)

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Prokaryote cells

• Very simple (bacteria)

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Eukarote cells

• Larger, complex

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Cell Structures
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Barriers

• Cell Wall
• Plants prok. (not animals)
• Structural (plant support) protective role
• Cellulose
• Freely permeable

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Cell walls of onion skin
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Barriers

• Cell Membrane (plasma membrane)
• In ALL cells
• Support/protection
• Regulates movement in/out of
• Water
• Nutrients
• Waste products

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Cell Membrane...
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Barriers

• Nuclear Envelope (nuclear membrane)
• Surrounds nucleus
• Thousands of pores
• Material move in/out, incl. RNA

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Nuclear envelope
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Fluids

• Cytoplasm (cytosol)
• Bet. cell mem. and nuclear env., site of most
  chemical activity
• Nucleoplasm
• Semi-fluid medium of nucleus
• Protoplasm
• Term used for all substances inside cell

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The Control Center

• The Nucleus

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The Nucleus

• Controls most cell processes
• Contains Chromatin
• DNA bound to proteins
• During cell division, condenses to Chromosomes
• Has a Nucleolus
• Small, dense region
• Assembly of Ribosomes
• Nuclear Envelope (or membrane)

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Little Organsassist the cell in conducting
reproductive, respiratory, and structural needs

• Organelles of the cytoplasm

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Cytoskeleton

• Protein filaments
• Maintains cell shape
• Involved in cell movement

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Cytoskeleton
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Ribosomes

• Small,made of RNA
• Assembly of proteins
• Free in cytoplasm or att. to ER

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Endoplasmic Reticulum

• Called ER
• Two types
• Rough ER
• Ribosomes stud surface
• Aids in synthesis and modif. of proteins
• Found wrapped around nucleus
• Smooth ER
• No ribosomes
• Special tasks with certain enzymes
• (such as making lipids)

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Mitochondrion

• Uses energy from food
• Makes high-energy compounds (ATP) needed for Rx
  elsewhere.
• The POWERHOUSE of the cell

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Golgi Apparatus

• Receives proteins from rough ER
• Enzymes attach carbs and lipids to the proteins
• Can store proteins until needed
• Proteins then sent to final destination
• PACKAGING and SHIPPING

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Golgi Apparatus
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Vacuoles

• Saclike structure
• Stores water, salts, proteins, carbs
• Can be large in plant cells
• Helps in plant support by keeping turgor pressure
  high

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Vacuoles
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Vacuoles
Korotnovella, an amoeba. Inside this cell we can
see a nucleus near the center with a rather
angular dark nucleolus, various food vacuoles,
and a clear round contractile vacuole at about 10
o'clock.
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Lysosomes

• Filled with enzymes
• Breaks down
• lipids, carbs, and proteins from food
• old organelles
• debris and harmful invaders

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Video
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Plastid 1 Chloroplasts

• In plants, not animals or fungi
• Uses sunlight to make energy rich food mol. thru
  photosynthesis

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Chloroplasts
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Chloroplast
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Plastid 2 Leucoplast

• Sometimes called amyloplast stores starch
  (amylose starch)

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Plastid 3 Chromoplast

• Stores pigments in plants

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Centrioles

• Cylindrical group of microtubules
• In animal cells, used in cell division
• As basal bodies, form cilia and flagella

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The Cell Membrane

• Is composed of a phospholipid bilayer
• A barrier reg. what passes in/out
• Supports and protects
• Selectively permeable only certain things pass
  through.
• About 5 nanometers thick (1 nm 1 Billionth of a
  meter)

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Cell membrane - Structure

• A phospholipid contains-
• one head negatively charged phosphate group that
  is hydrophilic (water-loving)
• two tails of fatty acid chains that are
  hydrophobic (water fearing)

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Cell membrane features

• The fluid mosaic model
• it is fluid in nature allowing cell mobility
• Scattered in the membrane are various proteins
  which perform various functions
• enzyme activity,
• cell attachment,
• communicating with other cells,
• Trans. of substances in and out

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Passive transport

• Diffusion net movement of sub. (liquid or gas)
  from an area of higher conc. to area of lower
  conc. Example perfume

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Passive transport

• Osmosis diffusion of water across a
  semi-permeable or selectively perm. membrane.
• Hypertonic Solution having a high conc. of
  solute.
• Hypotonic  Solution having a low conc. of
  solute.
• Isotonic  Both solutions have equal solute conc.
  
• This difference (?) of conc. of molecules across
  a space is called a Concentration Gradient

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Animal Plant
Lysis Equilibrium Plasmolysis
Turgid Flaccid Plasmolysis
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Passive transport

• Facilitated diffusion trans. of materials
  across membranes by transport proteins

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Active transport

• Active transport - Trans. of molecules against a
  concentration gradient (from regions of low conc.
  to regions of high conc.) with the aid of
  proteins in the cell mem. and energy from ATP

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Other types of active transport Endocytosis
import of materials into cell by infoldings of
the cell membrane. A. phagocytosis cell
eating extensions of the cell membrane
surround the food and make a vacuole.
Lysosomes then secrete enzymes into
vacuole to digest food. B. pinocytosis cell
drinking smaller infoldings allowing droplets
of liquid to enter cell.
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Endocytosis in general
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• Exocytosis reverse of endocytosis
• Dumping of excretions or wastes outside by
  discharging them from waste vacuoles.
• Also can result in secretion of substances (ex
  gland cells secreting hormones into the
  bloodstream)

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Cell Differentiation

• And hierarchy of organisms tissues

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Cell differentiation

• The process by which unspecialized cells develop
  into their mature forms and functions
• Embryonic Stem Cells
• Undifferentiated (unspecialized)
• Totipotent can develop into ANY type tissue
• Adult Stem Cells
• Pluripotent or multipotent can develop into
  certain types of tissues.

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Levels of organization

• Level one cells -basic unit of life examples
  are
• blood cells
• Red (RBC, or erythrocytes)
• White (leukocytes)
• nerve cells (neurons),
• bone cells (osteoblasts)

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Levels of organization

• Level two -tissues Made up of cells that are
  similar in structure and function and which work
  together to perform a specific activity
• -Humans have 4 basic tissues connective,
  epithelial, muscle, and nerve.
• Connective tissue
• include bones, ligaments, cartilage, blood,
  tendons
• Epithelial tissue-
• skin, the mucosa, and the serosa (lines body
  cavities and internal organs)
• Muscle tissue-
• skeletal muscle, smooth muscle, and cardiac
  muscle
• Nerve tissue-
• brain, spinal cord, and nerves

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Levels of organization

• LEVEL 3 Organs -Made up of tissues that work
  together to perform a specific activity
• heart, brain, skin, etc.
• LEVEL4 - Organ Systems -Groups of two or more
  organs that work together to perform a specific
  function for the organism.
• The Human body has 11 organ systems -
  circulatory, digestive, endocrine (hormonal),
  excretory (urinary), lymphatic (immune),
  integumentary (skin), muscular, nervous,
  reproductive, respiratory, and skeletal.

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Levels of organization

• LEVEL 5 - Organisms -Entire living things that
  can carry out all basic life processes.
• Meaning they can take in materials, release
  energy from food, release wastes, grow, respond
  to the environment, and reproduce.
• Usually made up of organ systems, but an organism
  may be made up of only one cell such as bacteria
  or protist.
• Examples - bacteria, amoeba, mushroom, sunflower,
  human

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Cell Regulation

• What makes a cell divide?
• Internal signal Enzymes produced by cell
• Ext. signal like growth factor produced
  elsewhere
• When cells packed close, NO division
• Not packed, division starts
• Checkpoints where stop/go signals reg. division

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Uncontrolled division

• Too many cells form a tumor
• Disrupts normal cell activity
• Takes nutrients
• If one area only benign
• If spreading malignant

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The staging of a carcinoma has to do with the
size of the tumor, and the degree to which it has
penetrated. When the tumor is small and has not
penetrated the mucosal layer, it is said to be
stage I cancer. Stage II tumors are into the
muscle wall, and stage III involves nearby lymph
nodes. The rare stage IV cancer has spread
(metastasized) to remote organs.
http//www.nytimes.com/imagepages/2007/08/01/healt
h/adam/19222Stagesofcancer.html
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