Chapter 5 The Working Cell

All about Energy...

Understanding Energy Energy: what gives the ability to do work _________ Heat Chemical

Kinetic Energy: The energy of motion Actually using up stores of energy in order to move matter Riding a bike, falling, running Heat and light are also forms of kinetic energy because they are _______ __________ ___________ _________… they are signs that energy is being used… byproducts

Potential Energy: what could happen No motion… just the POTENTIAL for motion ______________: When PE is due to the arrangement of molecules and their potential to allow work to get done Most important type in living system Only useful when transformed

A short quiz… choose potential or kinetic

Thermodynamics… the study of energy Energy can change forms… from chemical (the food you eat) to _________ (motion) From light (sun) to _________ (sugar) in plant photosynthesis From chemical (wood) to heat (burning) From electrical to light (light bulb) From wind to _______________ (electric wind mills)

All of energy behaves according to two laws… First law of thermodynamics: The total amount of energy in the universe is ___________ (energy cannot be created or destroyed) Second Law of Thermodynamics: Energy conversions _____________ of the universe (Entropy)

Neither created or destroyed All energy must be transferred… for every bit of energy put in there has to be that much coming out Excess is usually associated with __________

More on Entropy It is __________ (doesn’t require energy) to lose order It takes _______ to gain order Therefore the progression of time leads to disorder

Endergonic vs. Exergonic A reaction that takes in energy is ________ (the products are at a higher energy level– not spontaneous) A reaction that releases energy is ___________ (the products are at a lower energy level-- spontaneous) The form of energy can vary– heat (endo or exothermic) light, or even movement.

When Cells use energy its called ATP Adenosine triphosphate: Molecule that stores energy in a high energy phosphate bond… ________, 5 carbon sugar and 3 phosphates Once it transfers the energy of the bond it is ______ (adenosine diphosphate) That is the exergonic part… then is uses the energy to run an endergonic part ADP = greater disorder

Coupling When an exergonic and endergonic reaction are paired to create a product When this is done with ATP it is called _______________ High energy phosphate is transferred to another molecule, then broken off to provide ______ for the next reaction

Enzymes help us use less energy Activation Energy is the amount of energy to get started Enzymes lower ____________ _________ Like getting a push on the swings, it doesn’t take much energy to keep it going once you start but starting can be hard. Otherwise getting started would take to long… you would starve before you could use the food energy

How enzymes work They have an ACTIVE SITE that allows a particular SUBSTRATE to bind It _________ the reaction between or within substrates Then it lets go of the new product… because the change makes it _________ ______ in the active site

Enzymes are not always active To time a particular activity there are times when enzymes are active, or inactive Cofactors (_________) and coenzymes (________) speed up enzymatic activity Vitamins, minerals, pH, temperature all can effect activity Act on _________ ______ or on area around the enzyme Cofactor or coenzyme?

How to inhibit an enzyme Can either establish an ___________ inhibitor (competes for the active site) Or a ____________ inhibitor (binds to allosteric site and alters the active site so the original substrate cannot bind)

Some other things inhibit enzymes Pesticides, antibiotics, and other chemicals sometimes inhibit enzymatic processes CO is a competitive inhibitor for O2 binding to hemoglobin We use this idea to fight disease… we have competitive inhibitors for bacteria proteins (penicillin) We are looking for more… maybe the key to AIDS cure

Negative feedback This is when the ________ of the enzyme acts a an ________, either competitive or noncompetitive This stops the enzyme from making too much product

All about membranes

A review of basic membrane information Made primarily of phospholipid bilayer (hydrophilic heads, hydrophobic tails) ________________: some things (lipids/fat soluble and really small) can get through some cannot (water soluble/ larger)

Fluid Mosaic model of the membrane Containing phospholipids, carbohydrates and proteins all in ________ and constantly rearranging

The proteins transport other molecules Integral proteins can be Enzymes, catalyzing reactions on the membrane Signal ____________, a messenger that tells the inside what the outside of the cell said ___________, let certain molecules, that would otherwise be trapped, through the membrane

Types of transport Passive: no ATP necessary Active: requires ATP Diffusion: movement of ________ along their concentration gradient Osmosis: movement of _______ along its concentration gradient Facilitated diffusion: movement along a concentration gradient helped by a ________ _______ Active: requires ATP Moves against concentration gradient… usually through protein Endocytosis/ exocytosis: brining in or out of large molecule… to big to fit through a protein

Water balance Osmosis remember is the movement of water along its concentration gradient The problem comes when the water moves too quickly and shrinks, or explodes the cell Isotonic a solution that is the same concentration as the cell itself (regular) Hypotonic is when _____ concentration of water is _______ the cell so the water rushes in (swollen) Hypertonic is when the _____ concentration of water is ________ the cell so water tends to rush out (shriveled)

Endocytosis/ exocytosis When a molecule is too big to fit though a membrane protein it has to be engulfed into the cell or spewed out of it ____________: bringing into the cell Phagocytosis: cell eating Pinocytosis: cell drinking Exocytosis: taking ______ of the cell

Don’t forget– most of this took energy Every bit of ATP we use needs to recycled into ADP… Recycling because of the first law of thermodynamics That takes work (reversing entropy) ATP is made in the membrane of mitochondria… that will be discussed more next chapter!