CHAPTER 7: A VIEW OF THE CELL
THE DISCOVERY OF CELLS!!
▸1.THE FIRST MICROSCOPIST:▸ ANTHON VAN LEEUWENHOEK
–A. MID 1600'S–B. HIS MICROSCOPE HAD ONE LENS–C. IT USED NATURAL LIGHT–D. HE WAS THE FIRST TO OBSERVE
LIVING THING S IN WATER!
2. ROBERT HOOKE - NAMED CELLS
▪A. HE LIVED AT THE SAME TIME AS VAN LEEVWENHOEK!
▪B. HIS MICROSCOPE WAS COMPOUND, WITH 2 OR MORE LENSES.
▪C. HE OBSERVED CORK - THE DEAD CELLS OF OAK BARK.
▪D. THE SHAPE OF THE CORK PARTS REMINDED HIM OF THE SMALL ROOMS THAT MONKS LIVED IN AT THE MONASTERY.
▪E. HOOKE NAMED THE SHAPES “CELLS”
3. MATTHIAS SCHLEIDEN
▪A.OBSERVED MANY PLANTS MICROSCOPICALLY
▪B. CONCLUDED “ALL PLANTS” ARE MADE OF CELLS
▪4. THEODORE SCHWANN▪A. OBSERVED MANY ANIMALS
MICROSCOPICALLY▪B. CONCLUDED “ALL ANIMALS”
ARE MADE OF CELLS
5. ROBERT BROWN
▪A. DISCOVERED THE CELL NUCLEUS ▪B. THE NUCLEUS WAS DISCOVERED
IN 1856
6. RUDOLPH VIRCHOW ▪A. DECIDED THAT THE NUCLEUS WAS
RESPONSIBLE FOR CELL DIVISION▪B. CONCLUDED “ALL CELLS COME
FROM OTHER LIVING CELLS”
THE CELL THEORY
▪1. ALL ORGANISMS ARE MADE OF ONE OR MORE CELLS!
▪2. THE CELL IS THE BASIC UNIT OF ORGANIZATION
▪3. ALL CELLS COME FROM PRE-EXISTING CELLS
TYPES OF MICROSCOPES
A. COMPOUND LIGHT MICROSCOPES
▪1. USED TO VIEW SINGLE CELLS OR SLICED & STAINED PARTS OF CELLS
▪2. MAGNIFIES ABOUT 1500 TIMES▪3. TWO OR MORE GLASS LENSES
ARE USED TO MAGNIFY OBJECTS
B. PHASE CONTRAST MICROSCOPE
▪1. BEST TO SEE INSIDE LIVING CELLS▪2. 3-D EFFECT GIVES DEPTH TO
OBJECTS▪3. 1500 MAGNIFICATIONS POSSIBLE
SCANNING ELECTRON MICROSCOPE
▪1. SHOWS A 3-D IMAGE OF THE SURFACE OF OBJECTS (LIKE CELLS)
▪2. MAGNIFIES FROM 60,000 TO 500,000 TIMES!
▪3. USES A BEAM OF ELECTRONS TO SWEEP OVER THE SURFACE OF CELLS!
TRANSMISSION ELECTRON MICROSCOPE
▪1. A BEAM OF ELECTRONS MUST PASS THROUGH SPECIMENS
▪2. THIS PROVIDES A 2-D IMAGE ONLY
▪3. IT IS USED TO STUDY SLICED & STAINED CELL PARTS & OBJECTS
▪4. 500,000 MAGNIFICATIONS ARE POSSIBLE!
SCANNING TUNNELING MICROSCOPE
▪1. CREATES A 3-D IMAGE BY USING A STREAM OF ELECTRONS TO MAP THE CONTOUR OF THE ATOMS ON AN OBJECT’S SURFACE.
▪2. DYES CAN ALSO BE ADDED TO SOME PARTS OF THE OBJECT. THIS NEW TECHNIQUE ENHANCES OUR ABILITY TO EXAMINE THESE SUPER SMALL IMAGES.
TWO BASIC CELL TYPES
▪PROKARYOTES:–1. LACK INTERNAL MEMBRANE BOUND STRUCTURES–2. NO NUCLEAR MEMBRANE–3. EXAMPLES: BACTERIA & CYANO (BLUE-GREEN) BACTERIA
EUKARYOTE:
▪1. CONTAIN INTERNAL MEMBRANE BOUND STRUCTURES, SUCH AS A NUCLEUS & MITOCHONDRIA!
▪2. ANIMAL CELLS, PLANT CELLS, PROTIST CELLS, & FUNGI CELLS ARE ALL EUKARYOTIC!
THE PLASMA MEMBRANE:BOUNDARY BETWEEN THE CELL
& ITS ENVIRONMENT!
▪1. IT CONTROLS ENTRY OFGLUCOSE, AMINO ACIDS, LIPIDS, ETC.
▪2. IT KEEPS OUT HARMFUL STUFF! ▪3. IT REMOVES EXCESS IONS, ETC.!▪4. IT IS SELECTIVELY PERMEABLE!
PLASMA MEMBRANE STRUCTURE
A PHOSPHOLIPID BILAYER
▪TWO LAYERS OF PHOSPHOLIPID MAKE A SANDWICH WITH THE FATTY ACID TAILS FORMING THE INTERIOR OF THE MEMBRANE.
▪ PHOSPHOLIPID HEAD▪ FATTY ACID TAIL▼▪ FATTY ACID TAIL ▲▪ PHOSPHOLIPID HEAD
▪WITH THE PHOSPHOLIPID ON THE OUTSIDE & THE FATTY ACID ON THE INSIDE THE BARRIER IS WATER SOLUBLE ON THE OUTSIDE & WATER INSOLUBLE IN THE MIDDLE!
▪WATER SOLUBLE MOLECULES WILL NOT EASILY MOVE THROUGH THE PLASMA MEMBRANE BECAUSE THEY ARE STOPPED BY THE WATER INSOLUBLE MIDDLE LAYER!
THE FLUID MOSAIC MODEL▪1. THE MEMBRANE IS FLEXIBLE!▪2. PHOSPHOLIPID MOVE WITHIN THE
MEMBRANE LIKE WATER MOVES IN THE CURRENTS OF A LAKE!
▪3. PROTEINS IN THE MEMBRANE MOVE AMONG THE PHOSPHOLIPID LIKE BOATS WITH THE DECKS ABOVE WATER & THE HULL BELOW WATER!
▪4. THE PROTEINS CREATE A“MOSAIC” OR PATTERN ON THE MEMBRANE’S SURFACE
▪CHOLESTEROL:▸1. IS FOUND IN THE PLASMA
MEMBRANE▸2. IS CRITICAL IN THE STABILITY
OF THE PLASMA MEMBRANE▸3. PREVENTS FATTY ACID CHAINS
IN THE MEMBRANE FROM STICKING TOGETHER
PROTEINS ▪1.SPAN THE ENTIRE MEMBRANE
CREATING SELECTIVE PERMEABILITY▪2.THESE PROTEINS ARE TRANSPORT
PROTEINS THAT ALLOW NEEDED MATERIALS OR WASTES TO MOVE THROUGH THE PLASMA MEMBRANE!
▪3.OTHER PROTEINS & CARBOHYDRATES STICK OUT FROM THE SURFACE & HELP CELLS IDENTIFY EACH OTHER
▪4.THIS IS IMPORTANT IN PROTECTING YOUR CELLS FROM INFECTION!
EUKARYOTIC CELL STRUCTURE
( CELL PARTS FOR YOU TO LEARN ! )
▪1. CELL WALL▪2. PLASMA MEMBRANE/ CELL
MEMBRANE▪3. NUCLEUS▪4. NUCLEOLUS▪5. CHROMATIN▪6. DNA▪7. CHROMOSOMES
( CELL ORGANELLE’S CONTINUED )
▪8. RIBOSOMES▪9. CYTOPLASM▪10. ENDOPLASMIC RETICULUM▪11. GOLGI APPARATUS▪12. VACUOLE▪13. LYSOSOME▪14. PLASTIDS▸ A. CHLOROPLAST▸ B. CHROMOPLAST▸ C. LEUCOPLAST
( CELL ORGANELLES CONTINUED )
▪15. MITOCHONDRIA▪16. CYTOSKELETON▸A.MICROTUBULES▸B.MICROFILAMENTS
▪EACH ORGANELLE HAS IMPORTANT FUNCTIONS TO TAKE CARE OF IN THE CELL. THEY ENABLE EACH CELL TO CARRY OUT ALL OF THE FUNCTIONS OF LIFE !
COMPARING PLANT & ANIMAL CELLS
▪PLANT CELLS HAVE:▪A CELL WALL▪CHLOROPLASTS
&▪USUALLY ONLY ONE VERY LARGE WATER VACUOLE !
▪ANIMAL CELLS:
▪THE CENTRIOLE IS THE ONLY ORGANELLE UNIQUE TO ANIMAL CELLS
▪ANIMAL CELLS TYPICALLY HAVE MANY SMALL VACUOLES
▪ALL OTHER ORGANELLES ARE FOUND IN BOTH PLANTS & ANIMALS !
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