Understanding Energy: Forms and Laws in the Working Cell

1. Chapter 5 The Working Cell

2. All about Energy...

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

4. 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

5. 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

6. A short quiz… choose potential or kinetic

7. 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)

8. 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)

9. 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 __________

10. 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

11. 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.

12. 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

13. 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

14. 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

15. 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

16. 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?

17. 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)

18. 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

19. 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

20. All about membranes

21. 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)

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

23. 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

24. Types of transport • Passive: no ATP necessary • 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

25. 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)

26. 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

27. 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!