Chap 9. Cell Respiration Why is cell respiration so necessary ? Living cells need a constant supply...
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Transcript of Chap 9. Cell Respiration Why is cell respiration so necessary ? Living cells need a constant supply...
Chap 9.Cell Respiration
Why is cell respiration
so necessary? Living cells need a constant
supply of energy
• Examples: heart cells beating,muscle cells contracting, cells being made and repaired, etc.
• Organisms take food & break it down
into glucose (mostly in the small intestine)• cell respiration – process of
breaking down glucose in the presence of O2 to release energy
- Done by eukaryotes!
Equation for Cell Resp.
6O2 + C6H12O6 → 6CO2 + 6H2O + energy
• The energy that isreleased is usedto make ATP
How Does It Happen?
• Glucose – simple sugar (C6H12O6) • Glucose is present in food• Food is broken down by our digestive
systems • The chemical bonds in food are broken & the
energy is released (Exergonic!)• 2 major types of organisms getting energy:
1. aerobic respiration. – with O2
2. anaerobic fermentation – without O2
Review of
ATP-ADP Cycle
Cell Respiration
• Step 1 – Glycolysis: Takes place in Cytoplasm• A. Process of 1 molecule of glucose broken in
half • B. Two 3-carbon compounds produced; each
called pyruvic acid• C. 4 ATP molecules are produced• D. 2 ATP molecules are used for the reaction
to occur• E. Net gain of ATP molecules = 2
Glycolysis – Cont.
• Each electron carrier (NAD+ or uncharged battery) accepts high- energy electrons from H & carries them to the next reaction
• NADH is now the charged battery
Review of Glycolysis
Glycolysis • Converts 1 glucose (C6) to 2 pyruvic acids (C3)• Produces :
2 pyruvic acids 2 NADH
2 ATP (net)• Occurs in
cytoplasm [anaerobic] –all organisms do glycolosis
Aerobic Respiration Needs Mitochondria!
• The Krebs Cycle and Electron Transport chain take place here!
Cell RespirationAEROBIC!
• Step 2 – Krebs Cycle (Citric Acid Cycle)• A. Pyruvic acid is broken down in a series of
reactions• B. Also called the citric acid cycle b/c citric
acid is the 1st compound produced
• C. CO2, 8NADH, 2FADH2 & 2 ATPs are produced
• Takes place in the mitochondria matrix• The matrix is inside the inner membrane• http://highered.mheducation.com/sites/0072507470/student_view0/
chapter25/animation__how_the_krebs_cycle_works__quiz_1_.html
Cell RespirationAEROBIC!
• Step 3 – Electron Transport Chain• Takes place in the mitochondria inner
membrane• Uses high-energy electrons carried from
NADH + FADH2 in the Krebs Cycle• The ETC produces 32 ATP molecules,
H2O, and un-charges electron carriers
Electron Transport Chain (ETC)
- Uses high-energy electrons from the Krebs cycle to convert ADP into ATP.
- Occurs along the inner membrane of the mitochondria.
- The electrons from NADH & FADH2 are passed along a series of proteins.
- This movement of electrons pumps H+ ions into the inner membrane space.
- The H+ ions will move from high to low concentration through the enzyme
ATP Synthase.
- This movement causes the enzyme to move like a turbine and bind ADP to P forming ATP.
http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120071/bio11.swf::Electron%20Transport%20System%20and%20ATP%20Synthesis
Why does it need oxygen?
Oxygen is the final electron acceptor!
Electron Transport Chain
Electron Transport Chain• Where are the electrons moving?__________________• Where are the H+ ions in a high concentration?_______• When the electrons are finished going through the chain,
what is the final electron acceptor?________, with H+ ions, it turns into ________.
• The enzyme that make ATP is _________________.
Totals of Aerobic Respiration- With aerobic respiration, a total of 36 ATPs are produced per glucose.
Comparing Photo & Cell Respiration
Photosynthesis Cell Respiration
Energy goes in and is stored
Energy comes out
Occurs in chloroplasts Occurs in mitochondria
Raw materials – CO2 & H2O
Raw materials – glucose & O2
Products – glucose & O2 Products – ATP, CO2 & H2O
Review of Glycolysis
Glycolysis • Converts 1 glucose (C6) to 2 pyruvic acids (C3)• Produces :
2 pyruvic acids 2 NADH
2 ATP (net)• Occurs in
cytoplasm [anaerobic]
Cell Respiration
When O2 is not present gylcolysis is followed by a different path
• A. Fermentation The release of energy from food in the absence of O2 – It allows the cells to continue glycolysis because it frees up NAD+
(NADH -> NAD+)
• B. Two types: • C. alcoholic fermentation• D. lactic acid fermentation
Types of Fermentation
1. Alcoholic Fermentation
• A. NADH is converted back to NAD+ and energy
• B. Occurs in yeast cells; used in baking bread (CO2 makes bread rise) & in making alcohol
• equation:
pyruvic acid + NADH → alcohol + CO2 + NAD+
Types of Fermentation
2. Lactic Acid Fermentation – • A.Occurs in muscle cells when they
run out of O2
• B.Causes pain & soreness
• equation: • pyruvic acid + NADH → lactic acid +NAD+
Also occurs in bacteria cells, we use it to make yogurt, sauerkraut, and kimchi
One more thing!
• The only way to get rid of your lactic acid after a hard workout is through a pathway that requires extra oxygen.
• That is why you breathe heavy after working out – to repay the oxygen debt.