THE CELL
Dec 27, 2015
THE CELL
• WHAT IS A CELL?– ROBERT HOOKE IN MID-
1960’S OBSERVED CORK WITH A COMPOUND MICROSCOPE
– COINED THE TERM “CELL” TO DESCRIBE WHAT HE OBSERVED
THE CELL
• WHAT IS A CELL?– ANTON VAN
LEEUWENHOEK DEVELOPED NEW MICROSCOPES AND OBSERVED POND WATER
– OBSERVED THINGS NEVER SEEN BEFORE!!
– DIDN’T DRAW ANY CONCLUSIONS, THOUGH…JUST SHARED OBSERVATIONS
THE CELL
• THE CELL THEORY STATES THAT– ALL LIVING THINGS ARE MADE UP OF CELLS– CELLS ARE THE BASIC UNIT OF STRUCTURE AND
FUNCTION IN LIVING THINGS– ALL CELLS ARISE FROM PRE-EXISTING CELLS
THE CELL
• HOW COME WE NEED MICROMETERS?– CELLS CAN’T BE VERY LARGE…
WHY NOT??– IT IS DUE TO
THE SURFACE AREA TO VOLUMERATIO
THE CELL
• CELLS MUST BE ABLE TO OBTAIN NECESSARY NUTRIENTS AND REMOVE WASTES ACROSS THEIR CELL MEMBRANE AT A RATE THAT SUSTAINS THEIR NEEDS
THE CELL
• STRUCTURES THAT MAKE UP THE CELL ARE CALLED??– ORGANELLES
• ORGANELLES– CELL WALL– CELL MEMBRANE– NUCLEUS– ENDOPLASMIC
RETICULUM– RIBOSOMES– LYSOSOMES– MITOCHONDRIA– CHLOROPLASTS– ETC…
THE CELL
• CELL WALL– MOST BACTERIA,
VARIOUS OTHER MICROORGANISMS, AND ALL PLANT CELLS
– PROVIDES STRUCTURE AND PROTECTION
– WHAT IS IT MADE OF?• CELLULOSE
THE CELL
• CELL MEMBRANE (A.K.A. PLASMA MEMBRANE)– COMPOSED OF CARBS, PROTEINS, AND LIPIDS– PHOSPHOLIPID BILAYER– FUNCTION?• BARRIER BETWEEN
INTERNAL AND EXTERNALENVIRONMENTS
THE CELL
• CELL MEMBRANE (A.K.A. PLASMA MEMBRANE)– SELECTIVELY
PERMEABLE• SOME SUBSTANCES
CAN PASSTHROUGH, WHILE OTHERSUBSTANCESCAN NOT
THE CELL
• NUCLEUS– MEMBRANE-BOUND
STRUCTURE THAT SERVESAS CONTROLCENTER FORMETABOLISM AND CELLULAR REPRODUCTION
– *LARGEST ORGANELLE*– CONTAINS DNA (BLUEPRINTS)
THE CELL
• NUCLEUS– NUCLEAR ENVELOPE• MEMBRANE THAT
SURROUNDS NUCLEUS
– NUCLEOLUS• PLURAL = NUCLEOLI• COMPOSED OF DNA/RNA/PROTEIN• SITE OF RIBOSOMAL PRODUCTION
THE CELL
• CYTOPLASM– WATERY MATERIAL IN THE
CELL BETWEEN THE CELL MEMBRANE ANDNUCLEUS
– CONTAINS DISSOLVED SUBSTANCES THAT ARE A PART OF METABOLIC REACTIONS
– LOCATION OF A VARIETY OF CELLULAR ORGANELLES
THE CELL
• ENDOPLASMIC RETICULUM (E.R.)– ROUGH E.R. VS SMOOTH
E.R.– SYSTEM OF FLUID-FILLED
CANALS– INVOLVED IN INTRA-
CELLULAR TRANSPORT, AND SURFACE AREA FOR METABOLIC REACTIONS WITHIN THE CELL
THE CELL
• GOLGI BODY (A.K.A. GOLGI APPARATUS)– MODIFY,
PACKAGE, AND TRANSPORTPROTEINS MADEBY THE CELLTO THEIR FINAL DESTINATION
THE CELL
• LYSOSOMES– BREAKDOWN BODY– CONTAIN HYDROLYTIC
ENZYMES• ENZYMES THAT
CATALYZE HYDROLYSIS
– LYSOSOMES CAN DIGEST THE ORGANISMIF NOT CONTAINED!! (EX. TAY-SACHS)
– LYSOSOMAL DISEASE
THE CELL• MITOCHONDRIA
– INVOLVED IN CELLULAR RESPIRATION• ATP PRODUCTION (ATP
IS A HIGH ENERGY MOLECULE)
– EVERY EUKARYOTIC CELL HAS THIS ORGANELLE!!
– WE WILL SPEND A WHOLE CHAPTER ON CELLULAR RESPIRATION
THE CELL
• CYTOSKELETON– SUPPORTS CELL,
PROVIDES MOVEMENT
– COMPOSED OFMICROTUBULES ANDMICROFILAMENTS
THE CELL
• VACUOLES– STORAGE SACKS– DIFFERENT TYPES• FOOD VACUOLE• CENTRAL VACUOLE• CONTRACTILE
VACUOLE
THE CELL• CHLOROPLASTS
– INVOLVED IN PHOTOSYNTHESIS– CONTAIN CHLOROPHYLL (SUBSTANCE THAT MAKES THEM GREEN)– ONE OF THE
GROUP OF ORGANELLES CALLEDPLASTIDS• LEUCOPLASTS• CHROMOPLASTS• CHLOROPLASTS
– PLASTIDS• GROUP OF ORGANELLES
ONLY FOUND INPHOTOSYNTHETIC EUKARYOTES
THE CELL
• REMEMBER, WHAT IS THE DIFFERENCE BETWEEN PROKARYOTIC AND EUKARYOTIC CELLS?
• WHAT ORGANELLES AREN’T IN PROKARYOTES THAT ARE IN EUKARYOTES?
• HOW DID THOSE ORGANELLES GET THERE?
THE CELL
• ENDOSYMBIOTIC THEORY– IT IS BELIEVED
THAT PROKARYOTESFUSED TOGETHERAND FORMEDTHE FIRSTEUKARYOTICCELLS
THE CELL
• MAINTAINING A CONSTANT CELL ENVIRONMENT– THE INTERNAL ENVIRONMENT OF THE CELL MUST
BE KEPT CONSTANT AT ALL TIMES– HOMEOSTASIS• WHAT HAPPENS IF HOMEOSTASIS IS INTERUPTED?
– THE INTERNAL ENVIRONMENT IS CONTROLLED BY HOMEOSTASIS, BUT WHAT ABOUT THE EXTERNAL ENVIRONMENT?• IT IS CONSTANTLY CHANGING!!!
THE CELL
• THE SELECTIVELY PERMEABLE CELL MEMBRANE PROTECTS THE INTERNAL ENVIRONMENT FROM THE CRAZY CHANGES OF THE EXTERNAL ENVIRONMENT
THE CELL
• HOW DO SUBSTANCES THAT CAN GET THROUGH THE MEMBRANE DO IT?
• DIFFUSION– THE
MOVEMENT OF PARTICLESFROM HIGH CONCENTRATIONTO LOWCONCENTRATION
THE CELL
• KEY CONCEPTS WITH DIFFUSION:– EQUILIBRIUM– CONCENTRATION GRADIENT
• DIFFUSION IS VITAL TOWARDS THE MOVEMENT OF PARTICLES/MOLECULES IN AND OUT OF CELLS
THE CELL
• THE CELL MEMBRANE CREATES A BARRIER BETWEEN THE INTERNAL AND EXTERNAL ENVIRONMENT, LEADING TO THE FORMATION OF A CONCETRATION GRADIENT WHICH ALLOWS DIFFUSION TO OCCUR
THE CELL• SPECIALIZED
PROTEINS IN THE CELL MEMBRANE MAKE DIFFUSION HAPPEN FASTER THAN IT WOULD NATURALLY– FACILITATED
DIFFUSION• DIFFUSION THAT
OCCURS WITH ASSISTANCE (IN THIS CASE, PROTEINS IN THE MEMBRANE)
THE CELL
• WHO REMEMBERS WHAT THE MOST AWESOME, COOL, RADICAL, GNARLIEST INORGANIC COMPOUND IS??
–H2O• BECAUSE WATER IS SO SUPER COOL, IT
HAS ITS OWN TYPE OF DIFFUSION
THE CELL
• OSMOSIS– THE DIFFUSION OF WATER ACROSS A SELECTIVELY
PERMEABLE MEMBRANE– WHAT CAN YOU FILL IN FOR THE WORD
DIFFUSION??– WHY IS WATER
SO DIFFERENT?• BECAUSE STUFF
CAN BE DISSOLVED IN THEWATER
THE CELL
• EFFECTS OF OSMOSIS ON CELLS– ISOTONIC• NO EFFECT
– HYPOTONIC• SWELLING /
TURGID
– HYPERTONIC• SHRIVELED /
PLASMOLYSIS
THE CELL
• DIFFUSION, FACILITATED DIFFUSION, AND OSMOSIS ALL HAVE SOMETHING IN COMMON– HIGH TO LOW MOVEMENT…
REQUIRING NO INPUT OF ENERGY– MOVEMENT ACROSS A MEMBRANE WITHOUT
ENERGY INPUT IS CALLED
–PASSIVE TRANSPORT
THE CELL
• PASSIVE TRANSPORT VS ACTIVE TRANSPORT– IF PASSIVE TRANSPORT DOESN’T REQUIRE
ENERGY…WHAT DO YOU THINK IS TRUE ABOUT ACTIVE TRANSPORT?
– WHY DOES ACTIVE TRANSPORT REQUIRE ENERGY?
THE CELL
• ACTIVE TRANSPORT– THE MOVEMENT OF MATERIALS FROM LOW
CONCENTRATION TO HIGH CONCENTRATION THROUGH THE EXPENDITURE OF CELLULAR ENERGY (ATP)
– TWO PROCESSES• MOLECULE BY MOLECULE• FORMATION OF VESICLES (VACUOLES)
– ENDOCYTOSIS & EXOCYTOSIS