flow of energy
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Flow of Energy. Energy for Cells, Photosynthesis, and Respiration. Energy for Cells: Living organisms need energy to function. WHERE DO THEY GET IT?. Free Energy: energy available to do biological work Ex. Energy required for muscle contraction. - PowerPoint PPT PresentationTRANSCRIPT
Flow of Energy
Energy for Cells, Photosynthesis, and Respiration
Energy for Cells:
Living organisms need energy to function
WHERE DO THEY GET IT?
Free Energy: energy available to do biological work
Ex. Energy required for muscle contraction
Endergonic Reaction: chemical reaction requiring free energy
*Free energy comes from other chemical reactions:
Exergonic Reactions: “Energy releasing”
*Both reactions must be linked (b/c energy can’t just “wait around”)
*Most free energy comes from adenosine triphosphate-- ATP
ATP: A-P-P-P
*the bonds between P (phosphate groups) energy released
Ex. Hydrolysis: (ATP + H20); last P breaks off ADP
ATP + H20 ADP + Pi + energy
Mini Lab Demonstration:
*Can you detect energy released by a biological reaction?
1. Half fill a test tube with 3% hydrogen peroxide.
2. Use a thermometer– take initial temperature.
3. Add a small piece of fresh liver to the tube.
4. Observe what happens. After 1 min., retake temp.
What evidence of a reaction did you observe?
Was the reaction endergonic or exergonic?
Respiration with Oxygen:
*When ATP is used, energy is released.
HOW CAN ATP BE REPLENISHED???
*REJOIN ADP and PHOSPHATE to replenish supply of ATP
(But need energy to do so)
Cellular Respiration: some of energy released by breaking bonds of glucose converts ADP to ATP
*AEROBIC RESPIRATION: requires Oxygen
*Cellular respiration is usually aerobic
EXERGONIC
*First steps occur in cytoplasm; last steps are in mitochondria
C6H12O6 + 6O2 + 38 ADP + 38 Pi 6CO2 + 6H20 + 38 ATP
*Early steps of breaking down glucose require 2 ATP
Thus, a net product of 36 ATP are produced
*What’s this mean? 1 glucose molecule released little by little lots of ATP
ATP is the cell’s currency!!!!
Anaerobic Processes *absence of oxygen
*Some bacteria and muscle cells can switch between aerobic and anerobic processes
1. Lactic Acid Fermentation:
*enzymes break down glucose into 2 lactic acid molecules
C6H12O6 + 4 ADP + 4 Pi 2CH3CHOHCOOH + 4 ATP
Ex. Muscles build up lactic acid during excessive exercise
Alcoholic Fermentation: plants/ microorganisms
*enzymes break down glucose into 2 molecules of ethanol and 2 molecules of CO2
C6H12O6 + 4 ADP + 4 Pi 2C2H5OH + 2CO2 + 4 ATP
Ex. Yeast alcohol, gasoline additives, bubbles dough rises
*PRODUCERS absorb energy from
Creates chemical energy
LIGHT = WAVELENGTHSVISIBLE SPECTRUM= ROY G BIV
Some light is absorbed; some reflected
Ex. White reflects all
*Light energy chemical
energy due to pigments
Ex. Chlorophyll (a) appears green b/c reflects green light
Other pigments: CAROTENOIDS:
Yellow, orange, and red
*absorb other colors/ wavelengths and pass energy to chlorophyll (a)
THIS IS WHY
LEAVES CHANGE COLOR!!
!
PHOTOSYNTHESIS REACTION:6CO2 + 6H20 C6H12O6 + 6O2
* “” involves enzymes, chlorophyll, and light energy
*ENDERGONIC *ultimate source of energy comes from light
1. Place Elodea in two test tubes.
2. Fill test tubes w/ Bromothymol yellow and cover tubes with plastic.
3. Place one tube in direct light and the other in a dark place.
4. Compare in 24 hours.
5. If yellow color is gone, means CO2 is no longer present.
PHOTOSYNTHESIS: 2 PARTS:
1. LIGHT REACTIONS:
Chloroplasts: electrons absorb energy/ move to higher energy levels
3 MAIN EVENTS:
1. Light energy absorbed and converted to chemical energy in bonds of ATP
2. Water splits into H ions, O, and electrons
3. H ions from water attach to carrier coenzymes for later use
2. CALVIN CYCLE:
*Occurs in fluid of chloroplast
*Synthesizing sugars
REVIEW: WHAT ELEMENTS MUST BE PRESENT FOR SUGARS TO BE MADE?
Light reactions provide H ions and ATP + CO2
3 carbon sugars 6 carbon sugars more complex
*PLEASE REFER TO PAGE 160
**Photosynthesis is the opposite of respiration
**These processes are INTERDEPENDENT:
reactants of one are products of the other*Sugars are broken down in cellular respiration (ATP used)
ATP can’t be recycled– some given off as heat as well
Thus, a CONTINUOUS CYCLE is NECESSARY!!