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 !