1 / 27

The Working Cell

The Working Cell. Chapter 5. What is energy? Energy is defined as the capacity to perform work. Biology and Society: Stonewashing Without the Stones. Levi Strauss began selling jeans in the 1870s - cotton denim fabric was used because of its toughness

wendi
Download Presentation

The Working Cell

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Working Cell Chapter 5

  2. What is energy? Energy is defined as the capacity to perform work

  3. Biology and Society:Stonewashing Without the Stones • Levi Strauss began selling jeans in the 1870s - cotton denim fabric was used because of its toughness • Today people also wear jeans as a fashion choice • Stonewashing jeans with pumice stone - damage fabric and equipment - requires wasteful mining of stones • Recently the enzyme cellulase has achieved better results – catalyst that speeds up chemical reactions - breaks down the polysaccharide cellulose, the main component of cotton and other natural fibers

  4. Figure 3.13

  5. ‘Biostoning’ • Washing denim in cellulase breaks down some of the cellulose fibers in the fabric • Softens the denim and releases the indigo dye • Cellulase is removed by rinsing Fig 5.1

  6. Some Basic Energy Concepts • Energy makes the world go round - both at the cellular level and the larger world • We have defined energy as the capacity to perform work • Work is performed whenever an object is moved against an opposing force - work moves things in ways they would not move if left alone • Example: Disorganized room versus organized room

  7. Conservation of Energy • Kinetic energy is the energy of motion • Potential energy is stored energy • Conservation of Matter – matter cannot be created or destroyed but can only be converted from one form to another • Conservation of Energy - energy cannot be created or destroy but can only be converted from one form to another

  8. Energy conversions during a dive • Chemical energy from food is being converted to kinetic energy • Kinetic energy of muscle movement is stored in potential energy – because of elevation the diver has more potential energy Fig 5.2

  9. Heat • Energy can be changed from one form to another • If energy cannot be destroyed, where has it gone once the diver hits the water? • Converted to heat - kinetic energy contained in the random motion of atoms and molecule - friction between the falling body and its surroundings generated heat in the air and then in the water • All energy conversions generate heat - makes energy less useful because it is the energy in its most chaotic form, aimless molecular movement

  10. Entropy • Scientists use the term entropy as a measure of disorder, or randomness - all energy conversions increase the entropy of the universe • Example: Energy conversions during the climb up and dive off the platform increased entropy because all of the diver’s potential energy was lost as heat

  11. Chemical Energy • Is a form of potential energy - found in food, gasoline, and other fuels which arises from the arrangement of atoms - carbohydrates, fats, and gasoline have structures that make them rich in chemical energy • Living cells and car engines use the same basic process to make chemical energy do work • How can molecules derived from food provide energy for our working cells? - process of breaking down organic fuel into smaller waste molecules with less chemical energy - releases energy that can be used to perform work

  12. Oxygen mixes with gasoline in an chemical reaction that breaks down the fuel molecules and pushes the pistons that will eventually move thewheels • ~25% of energy extracted from the fuel is converted to the kinetic energy of the car’s movement Fig 5.3a

  13. Cells also use oxygen to harvest chemical energy • Just as in the car engine, the ‘exhaust’ is mostly carbon dioxide and water Fig 5.3b

  14. Cellular Respiration • Is the energy-releasing chemical breakdown of fuel molecules - and also storage of that energy in a form the cell can use to perform work • Provides energy for the cell to do work - you convert ~40% of food energy to useful work - the other 60% releases generates body heat - humans use this heat to maintain an almost constant body temperature of 37 °C - liberation of heat explains why you feel hot after exercise

  15. Food Calories • Calories are units of energy - a calorie is the amount of energy required to raise the temperature of one gram of water by one degree Celsius • The kilocalories is the unit used to measure the energy in food - 1,000 calories • Energy of calories in food is burned off by many activities

  16. Figure 5.4a

  17. Figure 5.4b

  18. Checkpoint • How can an object at rest have energy? 2. Describe the energy transformations that occur when you climb to the top of a stairway. 3. Which form of energy is the most randomized and the most difficult to put to useful work?

  19. Answers • Potential energy = location or arrangement of its atoms 2. Convert chemical energy of food to the kinetic energy of your upward climb; at the top some of the energy has been stored as potential energy because of your higher elevation 3. Heat energy

  20. ATP and Cellular Work • Carbohydrates, fats, and other fuel molecules from food indirectly provide our cells energy • Chemical energy released by the breakdown of organic molecules during cellular respiration is used to generate ATP molecules in the ______ - ATP stores energy obtained from food releasing it as needed

  21. The Structure of ATP • Adenosine Triphosphate (ATP) - consists of adenosine, an organic molecule + a tail of three phosphate groups (P) - the tail is the ‘business’ end, the part that provides energy - each P group has a negative charge that repel each other - crowding of negative charges contributes to the potential energy of ATP • ATP is broken down to ADP, accompanied by the release of energy

  22. ATP Power P = phosphate group (a phosphorus bonded to oxygen atoms) Triphosphate tail is unstable, partly because of repulsion between the P groups which have a negative charge The P at the end tends to break away and bond to other molecules; this transfer, catalyzed by enzymes, provides energy for cellular work- ADP leftover Figure 5.5

  23. Phosphate Transfer • ATP energizes other molecules in cells by transferring phosphate groups - this energy can be used to drive cellular work • 3 main kinds of cellular work: Mechanical – muscle contraction Transport – brain cells pump ions across membranes Chemical – making macromolecules from monomers

  24. Figure 5.6

  25. The ATP Cycle • Cellular work spends ATP • ATP is recycled from ADP and phosphate through cellular respiration • ATP functions in what is called energy coupling, or the ATP cycle

  26. The ATP Cycle Figure 5.7

More Related