Download Bio 20 5.3 Rs Notes

Bio 20
5.3
CELLULAR RESPIRATION pg. 182
Watch http://www.youtube.com/watch?v=-Gb2EzF_XqA , an awesome clip!
Formula for Cellular Respiration:
C6H12O6 + 6O2  6CO2 + 6H2O + energy (ATP)
Cellular Respiration releases the energy stored by photosynthesis in glucose by oxidizing
glucose to CO2 and making ATP for cell work. In cellular respiration we will see our old
friends – oxidation and reduction to produce high energy reduced compounds, electron
transport chains (systems), chemiosmosis, and ATP synthase, and a cycle.
OXIDATION = lose electrons and hydrogen ions
REDUCTION = gain electrons and hydrogen ions – produces high reducing power
“LEO says GER”
Remember where oxidation and reduction occurs in photosynthesis?
H2O is oxidized to O2 + H+ + 2e- in the thylakoid lumen. O2 becomes a product and is released
to the atmosphere, the H+ ions are used to help generate the H+ gradient for chemiosmosis and
for reduction reactions, and the 2e- (electrons) are used to replace the electrons lost from PS II to
the electron transport chain.
CO2 is reduced to synthesize glucose in the light independent reactions (Calvin Cycle).
NADP+ is reduced when e- from the electron transport chain after PS I joins with H+ ions and
makes NADPH which is transferred to the Calvin Cycle where it is oxidized to provide energy for
glucose synthesis.
 Watch http://www.youtube.com/watch?v=eOFrsQOZFX8 formation of NADH
Cellular Respiration
• Occurs in the cytoplasm and mitochondria in plants and animals
• Releases chemical energy stored in the chemical bonds of high energy organic molecules
(derived from sugars made by plants in photosynthesis) and transfers this energy to ATP and
heat.
• The ATP is then used to do work in the cell.
• In cells that are very active (muscle and liver cells) there may be up to 1000 mitochondria/cell.
• There are two types of cellular respiration: aerobic (most efficient) and anaerobic.
 Draw a diagram of a mitochondrion and label outer membrane, inner membrane, matrix
and cristae (see pg. 165). Come back to this diagram and label where the 4 main stages of
cellular respiration occur (1) glycolysis 2) Kreb cycle prep 3) Kreb (citric acid) cycle 4)
electron transport system (chain) as you learn this information.
4 MAIN STAGES OF AEROBIC CELLULAR RESPIRATION (BLM 5.3.2)
STEP 1: GLYCOLYSIS
GLUCOSE (C6)  2 PYRUVATE (C3)MOLECULES
• Main function is to split glucose into
pyruvate
• Occurs in the cytoplasm
• needs 2 ATP to get started
• anaerobic pathway
• produces small amount of the 2 high
energy compounds: ATP and NADH
 Draw the flow chart for Glycolysis pg. 186
 Learning Check:
1) Where does glycolysis occur in the cell?
2) Does it require oxygen?
3) Name three products that result from glycolysis.
STEP 2: KREBS CYCLE PREPARATION: PYRUVATE (C3) ACETYL CoA (C2) + CO2
• Occurs in the
mitochondrial matrix
• produces acetyl CoA,
NADH and CO2
• coenzyme A (CoA) is
needed for this
reaction
 Watch where the carbons go!
pyruvate (3C)  ______________
(__C) + _____________ (___ C)
__________________
STEP 3: KREBS CYCLE:
ACETYL CoA  electrons + H+ + CO2
• occurs in the
mitochondrial matrix
• major function is to transform
energy of glucose into the high
energy reduced compounds
NADH and FADH2.
• also produces a small amount
of ATP (two) and 4 CO2
molecules (so now all the C in
the pyruvate molecules from
glycolysis have gone to CO2)
• electrons and H+ (from NADH
and FADH2) are now
transported to an electron
transport system
diagram from bbc.co.uk
 Learning Check:
1. Where does the reactions of the Krebs cycle occur in the mitochondria?
2. What compound that is derived from glucose actually enters the Krebs cycle?
3. What is the starting and ending compound in the Krebs Cycle (Hint: in the Calvin cycle it
was RuBP)?
4. The carbon atoms that are derived from glucose are fully oxidized in the Krebs cycle. In
what compound do all the carbon atoms eventually end up? _____________ What becomes
reduced in the Krebs cycle? _______________ , ________________.
STEP 4: ELECTRON TRANSPORT SYSTEM (+ chemiosmosis): electrons + O2 32 ATP + H2O
http://www.youtube.com/watch?v=lrEzholnAwE
• occurs in inner membrane (cristae) of mitochondria
• electrons are passed through an ET system producing a large amount of ATP by
chemiosmosis. During this process NADH and FADH2 are oxidized, yielding the H+ ions that
are pumped into the mitochondrial intermembrane space producing a concentration
gradient, and when released through ATP synthase, produce ATP.
• O2 is the final acceptor of electrons and combines with H+ to form H2O
• the majority of ATP produced in cellular respiration is generated by chemiosmosis using
energy generated by the electron transport system.
• ET system: high energy electrons are passed through a chain of electron-carrying
molecules (proteins including cytochromes) attached to the inner membrane (cristae) of
mitochondria.
• The energy from electrons moving along the electron transport chain is trapped in small,
controlled amounts, and used to actively transport H+ across the membrane from the matrix
to the intermembrane space (the space between the inner and outer membranes of the
mitochondria) forming a high concentration gradient of H+ ions.
• Using chemiosmosis, the H+ ions diffuse back to the matrix across the membrane through
channels created by ATP synthase, and a large amount of ATP is made from ADP.
• O2 is CRUCIAL. It is final acceptor of electrons from the electron transport system, and
combines with H+ to form H2O. If oxygen was not present to be the final electron acceptor, the
electron transport system would back up and stop running. This is why this process is called
AEROBIC RESPIRATION.
**The ATP, NADH, FADH, and CO2 TALLY!**
******* From 1 glucose molecule we get 36 ATP. *******
 Learning Check!
1. From 1 glucose molecule we get 36 ATP, ________ NADH, ________FADH2 and _______ CO2
2. Where, in the mitochondria, are the electron carriers located?
3. What is the source of the high energy electrons for ETS in the mitochondria (what was
oxidized?)
4. What is the function of oxygen in cellular respiration?
The Importance of Cellular Respiration
Organisms can get energy from all of the major food sources through cellular respiration.
How do organisms get energy when O2 is not present? By glycolysis and fermentation!
http://www.youtube.com/watch?v=cDC29iBxb3w a quick review of Rs and discussion of
fermentation
There are 2 types of fermentation: ethanol fermentation and lactate fermentation.
In some anaerobic organisms, glycolysis is their only source of energy. In these organisms, the
pyruvate is broken down into carbon dioxide and alcohol (ethanol) or lactic acid (lactate).
Lactate fermentation also occurs in muscle during intense activity when oxygen cannot get to
muscle fast enough (oxygen debt). The muscle has to function anaerobically and glycolysis is the
only source of energy. Lactic acid builds up, causing cramps and muscle fatigue. When O2 is
present again, the lactate is converted back to pyruvate and then the pyruvate goes through the
usual aerobic cellular respiration. This can take a few days which is one reason muscles are sore
after intense activity.
• Ethanol fermentation produces alcoholic beverages, and CO2. Depending on the variety of
yeast used and whether CO2 is allowed to escape during the process, fermentation can make
wine, champagne, beer, and cause rising in bread.
• Fermentation of manure makes methane (biogas) to heat homes, cook food and power
generators. Fermentation of corn and wheat is used to make ethanol – an additive to gas that
is renewable, increases the octane rating, prevents engine “ping” and decreases the release of CO
in the exhaust.
 To review 5.3:
1. Review Section 5.3 Summary pg. 193 – 194
2. Study Chapter 5 Summary pg. 195
3. Watch Mr. Anderson, Bozeman University Cellular Respiration
https://www.youtube.com/watch?annotation_id=annotation_661161&feature=iv&src_vid=cDC2
9iBxb3w&v=Gh2P5CmCC0M
4. Take 5.3 Review test online