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The Cell. Cell Theory/History Structures Transport Differentiation Levels of Organization. Robert Hooke. English physicist 1665 Saw a slice of cork tree tissue Tiny chambers Termed them “cells” (looked like monks’ cells in monastery). Robert Hooke. Published his book Micrographia

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the cell

The Cell

Cell Theory/HistoryStructuresTransport Differentiation Levels of Organization

robert hooke
Robert Hooke
  • English physicist
  • 1665
  • Saw a slice of cork tree tissue
    • Tiny chambers
    • Termed them “cells”

(looked like monks’ cells in monastery)

robert hooke1
Robert Hooke
  • Published his book Micrographia
    • Contained drawings of cork cells
    • Used early microscope
anton van leeuwenhoek
Anton Van Leeuwenhoek
  • Dutch businessman
  • 1674
  • Perfected microscope

(about 300x)

  • Saw living things in pond water
    • “Animalcules”
    • Observed bacteria (on wood teeth) and protozoa
matthias schleiden
Matthias Schleiden
  • German botanist
  • 1838
  • Concludes that all plants are made up of cells
theodor schwann
Theodor Schwann
  • German zoologist
  • 1839
  • Concluded that all animals are made up of cells
rudolph virchow
Rudolph Virchow
  • German physician/pathologist
  • 1855
  • Worked with eggs from various organisms
  • Proposes that all cells come from existing cells
cell theory
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.
janet plowe
Janet Plowe
  • 1931
  • Demonstrates that the cell membrane is a physical structure, not an interface between two liquids.
lynn margulis
Lynn Margulis
  • 1970
  • Proposes a theory that certain organelles were once free-living cells themselves
singer nicholson
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)
prokaryote cells
Prokaryote cells
  • Very simple (bacteria)
eukarote cells
Eukarote cells
  • Larger, complex
  • Cell Wall
    • Plants & prok. (not animals)
    • Structural (plant support) & protective role
    • Cellulose
    • Freely permeable
  • Cell Membrane (plasma membrane)
    • In ALL cells
    • Support/protection
    • Regulates movement in/out of:
      • Water
      • Nutrients
      • Waste products
  • Nuclear Envelope (nuclear membrane)
    • Surrounds nucleus
    • Thousands of pores
      • Material move in/out, incl. RNA
  • 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
the nucleus1
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)
  • Protein filaments
  • Maintains cell shape
  • Involved in cell movement
  • Small,made of RNA
  • Assembly of proteins
  • Free in cytoplasm or att. to ER
endoplasmic reticulum
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)

  • Uses energy from food
  • Makes high-energy compounds (ATP) needed for Rx elsewhere.
  • The POWERHOUSE of the cell
golgi apparatus
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
  • Saclike structure
  • Stores water, salts, proteins, carbs
  • Can be large in plant cells
    • Helps in plant support by keeping turgor pressure high

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.

  • Filled with enzymes
  • Breaks down
    • lipids, carbs, and proteins from food
    • old organelles
    • debris and harmful invaders
plastid 1 chloroplasts
Plastid 1: Chloroplasts…
  • In plants, not animals or fungi
  • Uses sunlight to make energy rich food mol. thru photosynthesis
plastid 2 leucoplast
Plastid 2: Leucoplast
  • Sometimes called amyloplast; stores starch (amylose = starch)
plastid 3 chromoplast
Plastid 3: Chromoplast
  • Stores pigments in plants
  • Cylindrical; group of microtubules
  • In animal cells, used in cell division
  • As “basal bodies,” form cilia and flagella
the cell membrane
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)
cell membrane structure
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)
cell membrane features
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
passive transport
Passive transport
  • Diffusion: net movement of sub. (liquid or gas) from an area of higher conc. to area of lower conc. Example: perfume
passive transport1
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 (Δ) of conc. of molecules across a space is called a Concentration Gradient

Animal Plant

Lysis Equilibrium Plasmolysis

Turgid Flaccid Plasmolysis

passive transport2
Passive transport
  • Facilitated diffusion = trans. of materials across membranes by transport proteins
active transport
Active transport
  • Active transport - Trans. of molecules againstaconcentration gradient (from regions of low conc. to regions of high conc.) with the aid of proteins in the cell mem. and energy from ATP

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.


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)
cell differentiation

Cell Differentiation

And hierarchy of organisms’ tissues

cell differentiation1
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.
levels of organization
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)
levels of organization1
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
levels of organization2
Levels of organization
  • LEVEL3 – 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.
levels of organization3
Levels of organization
  • LEVEL5 - 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
cell regulation
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
uncontrolled division
Uncontrolled division
  • Too many cells form a tumor
    • Disrupts normal cell activity
    • Takes nutrients
    • If one area only: benign
    • If spreading: malignant

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.