1. CHAPTER 7 THE WORKING CELL: ENERGY FROM FOOD

2. Concept 7.1 Sunlight Powers Life

4. Obtaining Food
Autotrophs- organisms that make their own food (self-feeder)
Photosynthesis- (from the Greek photo-meaning light and synthesis meaning to make something).
Producers- produce organic molecules that serve as food for an ecosystem.

5. Heterotrophs- organisms that cannot make their own food depend on the energy from producers
(also called consumers)

6. Cellular Respiration
Cellular respiration is a chemical process that utilizes oxygen to convert chemical energy stored in organic molecules into another form called ATP (adenosine triphosphate)
                                                                                                                                                                        

7. 7.2 Food stores chemical energy
Kinetic Energy- the energy of motion
Potential Energy- energy that is stored due to an object's position or arrangement.
Thermal Energy- total amount of energy associated with the random movement of atoms and molecules in a sample of matter

8. Chemical Energy
Chemical energy- potential to perform work due to the arrangement of atoms within molecules

9.                                                                                                                                                                                                                                                                                               
Within your cells, organic molecules such as glucose also react with oxygen in the process of cellular respiration. And similar to an automobile engine, working cells produce carbon dioxide and water as their "exhaust."

10. Calories
the amount of energy required to raise the temperature of 1 gram (g) of water by 1 degree Celsius (°C).

11. Concept 7.3 ATP provides energy for cellular work
Adenosine-contains adenine and a five carbon sugar called ribose. Triphosphate- three phosphate groups that are the source of energy used for most cellular work

12. ATP and Cellular Work
                                                                                                                                                                            

13. The ATP Cycle ATP is recyclable
                                                                                                                                                       
ATP is recyclable
Work consumes ATP and it is turned into ADP and then a phosphate group is added to regenerate the ATP

14. Concept 7.4 Electrons “fall” from food to oxygen during cellular respiration
Cellular respiration is an aerobic process, it requires oxygen
Gas exchange occurs (oxygen in, and carbon dioxide out)

15.                                                                                                                                                                                                                                           
Overall Equation
Glucose is a common fuel for cellular respiration, the double arrow represents many steps required not just one.

16. “Falling Electrons”
During cellular respiration, the carbon and hydrogen atoms change partners and bond with oxygen atoms instead.
The carbon-hydrogen bonds are replaced by carbon-oxygen and hydrogen-oxygen bonds.
As the electrons of these bonds "fall" toward oxygen, energy is released.

17. Electron Transport Chains
Sequence of electron carrier molecules that transfer electrons and release energy during cellular respiration
Like a staircase, as electrons fall down a small amount of energy is released.

18. 7.5 Cellular respiration converts energy in food to energy in ATP
Mitochondria- “powerhouse of cell”
Structure of folded membranes inside are the key to cellular respiration.

19. Metabolic pathway:
metabolism: all of a cell's chemical processes.

20. The three stages of cellular respiration
Stage 1- Glycolysis “splitting of sugar”

21. Stage 1: Glycolysis Occurs in cytoplasm
Glucose is converted into pyruvic acid
(2-3 carbon molecules)
(NAD+) accepts 2 electrons and one hydrogen ion it is converted into (NADH)
2 ATP invested, 4 ATP are produced
Net gain of 2 ATP

22. Stage 2: The Krebs Cycle
                                                                                                                                                                                                                                                                                              

23. Stage 2: The Krebs Cycle
Occurs in the fluid matrix of the mitochondria
Pyruvic acid is broken down into Acetyl Co-A, releasing carbon dioxide and more energy.
Each of the two Acetyl Co-A (2 carbon molecules) goes through the Krebs cycle, generating 2 CO2 , 1 ATP, and 1 FADH2 , and 3 NADH
Total after 2 cycles: 4 CO2 , 2 ATP,
2 FADH2 , and 6 NADH

24. Stage 3: Electron Transport Chain and ATP Synthase Action
                                                                                                                                                                                                                                                                                              

25. Stage 3: The E.T.C. Occurs in the inner membranes of the mitochondria
There are two parts
a) an e.t.c, b) ATP synthase which generates ATP
NADH transfers electrons, water is split, and hydrogen ions are transferred across the membrane to create a
H+ ion concentration gradient

26. Adding up the ATP One Glucose molecule yields….
Stage 1: Glycolysis = 2 ATP
Stage 2: Krebs Cycle = 2 ATP
Stage 3: E.T.C. ~ 34 ATP
MAXIMUM OF ABOUT 38 ATP PRODUCED

27. Concept 7.6 Some cells can harvest energy without oxygen
Fermentation in human muscle cells occurs when oxygen is not readily available.
                                                                                                                                                                                                                                                                                              

28. Lactic Acid Fermentation
Makes ATP entirely from glycolysis
2 ATP are generated
Even though there are only two ATP, by burning enough glucose, fermentation can regenerate enough ATP molecules for short bursts of activity such as a short sprint.
Lactic acid is a waste product causing fatigue and soreness in muscles

29. Your body consumes oxygen as it converts the lactic acid back to pyruvic acid.
You restore your oxygen supply by breathing heavily for several minutes after you stop exercising.

30. Fermentation in Microorganisms
Anaerobic- no oxygen environment
These organisms ferment sugar and other foods creating alcohol as a waste product instead of lactic acid
This process also releases CO2.

31. Examples of fermentation
Yeast makes bread rise
Fungi and bacteria produce lactic acid and humans use these to transform milk into cheese and yogurt (sharpness and sour flavor), soy beans make soy sauce, cabbage into sauerkraut, potatoes into vodka…