THE WORKING CELL

THE WORKING CELL

• WHAT IS WORK?– ANYTHING THAT REQUIRES ENERGY

• WHAT IS ENERGY?– THE ABILITY TO DO WORK

• HUH??• WORK IS REALLY DEFINED AS???

THE WORKING CELL

• ENERGY– TWO TYPES• KINETIC VS POTENTIAL• CHEMICAL ENERGY?

– THE POTENTIALENERGY OFMOLECULES

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• UNDERSTANDING ENERGY HELPS US UNDERSTAND WORK– ENERGY IS GOVERNED BY THE LAWS OF

THERMODYNAMICS• THE STUDY OF ENERGY TRANSFORMATIONS THAT

OCCUR IN COLLECTIONS OF MATTER

THE WORKING CELL

• THE FIRST LAW OF THERMODYNAMICS– THE ENERGY IN THE UNIVERSE IS CONSTANT;

ENERGY CAN NEITHER BE CREATED OR DESTROYED, ONLY CHANGE FORMS

• THE SECOND LAW OF THERMODYNAMICS– ALL REACTIONS INCREASE ENTROPY!!

THE WORKING CELL

• CHEMICAL REACTIONS EITHER STORE OR RELEASE ENERGY– TWO TYPES• EXERGONIC• ENDERGONIC

• CELLULARMETABOLISM??

THE WORKING CELL

• ATP SHUTTLES ENERGY WITHIN THE CELL– WHAT IS ATP??• 3 PHOSPHATES + RIBOSE + ADENINE (N.B.)

THE WORKING CELL

• HYDROLYZING ATP RELEASES ENERGY

THE WORKING CELL

• PHOSPHORYLATION– HELPS RECYCLE ATP!!!

THE WORKING CELL

• ENZYMES HELP CELL’S TO DO WORK– ALL REACTIONS REQUIRE SOME AMOUNT OF

ENERGY TO GET STARTED• EVEN A BOULDER AT THE TOP OF A MOUNTAIN WON’T

JUST ROLL DOWN THE HILL WITHOUT AN INITIAL PUSH!!!!!

– ENZYMES WORK BY LOWERING THE AMOUNT OF ENERGY NECESSARY TO START A REACTION• ACTIVATION ENERGY!!

THE WORKING CELL

• WHAT ARE ENZYMES?– CHEMICAL CATALYSTS!!– ENZYME VS SUBSTRATE VS ACTIVE SITE??– INDUCED FIT VS LOCK AND KEY MODELS??– ENZYME NAMES??

THE WORKING CELL

• WHAT CLASS OF ORGANIC COMPOUND ARE ENZYMES??– WHAT CONTROLS THEIR FUNCTION?– WHAT CAN ALTER THEIR SHAPE?• DENATURATION??• PH• TEMPERATURE• SALT CONCENTRATION• CO-FACTORS

– COENZYMES (VITAMINS)

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• ENZYME FUNCTION CAN BE BLOCKED BY INHIBITORS– INHIBITOR DEFINITION??– TWO TYPES• COMPETITIVE• NON-COMPETITIVE

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• WHY WOULD YOUR CELL WANT TO INHIBIT ENZYME ACTION?– NEGATIVE FEEDBACK IS

A TYPE OF INHIBITION– WE USE INHIBITORS TO

CREATE PESTICIDES ANDANTIBIOTICS

THE WORKING CELL

• MEMBRANES ORGANIZE THE CHEMICAL ACTIVITIES OF CELLS– CELL MEMBRANE• DEFINITION?

– SELECTIVE PERMEABILITY• DEFINITION?

THE WORKING CELL

THE WORKING CELL

• MEMBRANE PHOSPHOLIPIDS FORM A BILAYER– WHY ARE PHOSPHOLIPIDS GREAT AS BARRIERS?– HOW DO SUBSTANCES GET THROUGH THE

BARRIER?• NON-POLAR SUBSTANCES• POLAR SUBSTANCES

THE WORKING CELL

• MEMBRANES ARE A MOSAIC OF FUNCTION

THE WORKING CELL

• FLUID MOSAIC MODEL– MOST COMMON DESCRIPTION OF THE

STRUCTURE OF THE CELL MEMBRANE– WHY FLUID?• BENT TAILS OF PHOSPHOLIPIDS

– WHY MOSAIC?

THE WORKING CELL

THE WORKING CELL

• PROTEINS ARE WHAT MAKE THE MEMBRANE A MOSAIC OF FUNCTION– ATTACH MEMBRANE TO CYTOSKELETON– ID’S CELL– FORMS JUNCTIONS BETWEEN CELLS– CHEMICAL RECEPTORS• SIGNAL TRANSDUCTION

– HELP MOVE SUBSTANCES ACROSS THE MEMBRANE

THE WORKING CELL

• HOW DO SUBSTANCES PASS THROUGH THE MEMBRANE?– PASSIVE TRANSPORT• DIFFUSION ACROSS A MEMBRANE

– WHAT IS DIFFUSION??

THE WORKING CELL

• DOES NOT REQUIREENERGY!!!

• REQUIRES ACONCENTRATIONGRADIENT

THE WORKING CELL

• WATER IS SPECIAL, SO IT GETS ITS OWN NAME!!– OSMOSIS• THE PASSIVE TRANSPORT (DIFFUSION) OF WATER

THE WORKING CELL

THE WORKING CELL

• PAYING ATTENTION TO THE SURROUNDING ENVIRONMENT IS ESSENTIAL FOR CELL SURVIVAL!!!– HYPERTONIC– HYPOTONIC– ISOTONIC

THE WORKING CELL

• WHAT HAPPENS TO CELLS PLACED IN THESE DIFFERENT ENVIRONMENTS?

THE WORKING CELL

CELLS INHYPERTONIC

HYPOTONIC

ISOTONIC

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• FACILITATED DIFFUSION– A SPECIFIC TYPE OF PASSIVE TRANSPORT

THE WORKING CELL

• FACILITATED DIFFUSION– DEFINITION??

THE WORKING CELL

• WHAT ABOUT WHEN THE SUBSTANCE DESIRED BY THE CELL IS IN GREATER CONCENTRATION INSIDE THE CELL??– ACTIVE TRANSPORT

THE WORKING CELL

• ACTIVE TRANSPORT– WHY ACTIVE??– DEFINITION??– WHERE DOES THE ENERGY TO DO THIS COME

FROM?– SODIUM-POTASSIUM PUMP (MOST IMPORTANT

EXAMPLE IN THE HUMAN BODY)

THE WORKING CELL

• WHAT ABOUT LARGE MOLECULES?– ENDOCYTOSIS VS EXOCYTOSIS– DEFINTIONS??

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• ENDOCYTOSIS– THREE TYPES• PHAGOCYTOSIS• PINOCYTOSIS• RECEPTER-MEDIATEDENDOCYTOSIS

• EXOCYTOSIS

THE WORKING CELL

• “WAIT…MR. KRAUZ, WHERE DOES THE ENERGY COME FROM FOR THE CELL TO DO ALL THIS WORK??”

• STAY SAFE, AND COME BACK TO CLASS, AND YOU JUST MAY GET TO FIND OUT!!!