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 OF
GLUCOSE, 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 !