Download chapter 9 cellular respiration

9.1 Cellular Respiration
Feel the Burn
• Do you like to bike, run, or swim? These are
good ways to exercise. When you exercise,
your body uses O2 to get energy from glucose, a
6-carbon sugar.
• 1. How does your body feel at the start of exercise, such as a
long, slow run? How do you feel 1 min. into the run? 10 min.
into the run?
• 2. What do you think is happening in your cells to cause the
changes in how you feel?
• 3. Think about running as fast as you can for a 100 meter run.
Could you keep this pace for a long distance? Explain.
A. Chemical Energy and Food
• 1 gram of glucose releases 3811 calories.
• A calorie-amount of heat energy required
to raise the temperature of 1 gram of water
1 degree Celcius.
• A Calorie-Kilocalorie=1000 calories
– (food labels)
B. Overview of Cellular Respiration
• Glycolysis, the Krebs cycle, and the
electron transport chain make up a
process called CELLULAR RESPIRATION
• Cellular Respiration is a process that
releases energy by breaking down food
molecules in the presence of oxygen.
Equation for Cellular Respiration
• C6H12O6 + 6O2 → 6CO2 + 6H2O +
energy
• Remind you of anything???
Cellular Respiration
• Requires oxygen (aerobic)
• Breaks down food to release energy
• C6H12O6 + 6O2 → 6CO2 + 6H2O +
energy
• So what is the food that is being broken
down???
Where C.R. takes place
• Cellular Respiration takes place in the
mitochondria.
– 1st reaction takes place in the inner
membrane
– 2nd reaction in the inner-inner “coils”
membrane
Makes 34 ATPs
FIRST STEP
• The first step of cellular respiration is
glycolysis.
• Glycolysis-produces 2 molecules of
pyruvic acid, 2 molecules of ATP, and 2
molecules of NADH.
C. Glycolysis
•
•
•
•
Breaks down glucose
Does NOT require oxygen (anaerobic)
Takes place in the cytoplasm
6-carbon sugar is split into a 3 carbon
PGAL molecule. (2 ATP’s are used here)
• 4 molecules of ADP are built up to ATP
• -2 ATP(start)+4 ATP(made)=2 ATP net
total
D. Fermentation
• An anaerobic process (doesn’t require
oxygen)
Alcoholic Fermentation
• Pyruvic Acid is broken down to produce 2
carbon alcohol and CO2
• Bakers and brewers
• Dough to rise (air spaces in bread)
• CO2 released by fermentation=bubbles in
beers or wine
• When alcohol reaches 12%, yeast cells
die.
Alcolholic Fermentation
Lactic Acid Fermentation
• Pyruvic Acid accumulates as a result of
glycolysis converted to lactic acid
• Lactic acid produced in muscles during
rapid exercise when body cannot supply
enough O2 to the tissue to produce all
ATP required
• Burning, painful a few sec. after exercise
• Large muscles cannot get enough oxygen
Lactic Acid Fermentation
•
•
•
•
What to do to help???
Stretch
Drink lots of water
Don’t forget to breath!
Glycolysis pathways
• At the end of glycolysis about 90% of the
chemical NRG in glucose was not used.
• Cells get that energy by using OXYGEN.
• If oxygen IS present…glycolysis will go
into cellular respiration.
9.2 The Krebs Cycle
and Electron Transport
• 1. Kreb Cycle -1st step in respiration (inner
membrane of mitochondria) breaks down carbs,
proteins, and lipids.
• 2. Electron Transport- H+ and O-2 form
H2O. ADP to ATP.
• 3. ATP Formation -different charges
release NRG in the form of ATP.
The TOTALS of ATP
• Glycolysis
• Respiration
»
2 ATP
34 ATP
36 ATP
Exercise and Energy
• Anaerobic (gycolysis) only last a short
period.
• Once runner is at 50 meter mark almost all
ATP is gone~90 sec.
• Fermentation builds up (lactic acid) need
to replenish body with breathing.
• What if race is longer than 90 sec.?
This is what happens…
• Cellular respiration will pick up the pace
and continue the supply of ATP.
• Muscles and other body parts store NRG
(last 15-20 min.) after that your body burns
stored molecules…FATS.
• Body uses NRG to release heat when we
exercise. Conserves heat in winter to stay
warm.
In Summary
• Glycolysis has two choices:
• If O2 is present glycolysis will go into
cellular respiration to supply body with
oxygen and ATP
• If O2 is NOT present then glycolysis will
go into the fermentation process.