Transcript Chap. 8 Cell Respiration

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 is
released is used
to 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 highenergy 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 Respiration
AEROBIC!
• 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/cha
pter25/animation__how_the_krebs_cycle_works__quiz_1_.html
Cell Respiration
AEROBIC!
• 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.
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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
Occurs in chloroplasts
Energy comes out
Raw materials – CO2 &
H2O
Raw materials –
glucose & O2
Products – glucose &
O2
Products – ATP, CO2 &
H2O
Occurs in
mitochondria
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.