Real-World Applications of Cell Function

Bio 10: Intro to BiologyInstructor: Paul Nagami

Laney CollegeSeptember 25, 2013

Agenda• Administrative Stuff• Exercise and Respiration• Aerobic and Anaerobic Exercise• Respiration vs. Fermentation (Review)• Fast and Slow Twitch Muscle

• Free Radicals and Antioxidants• The Need to Exercise Consistently

• Seven Deaths in Chicago (adapted from a case study by Michaela Gadzik)

• Wrap-Up

Aerobic vs. Anaerobic Exercise

Take a guess: On your index card, write down what you think the difference between aerobic and anaerobic exercise is.

Oxygen Use and ExerciseAerobic exercise:• Sustained exercise• Trains endurance (cardiovascular system)• Relies mostly on respiration using oxygen.Anaerobic exercise:• Short, intense exertion• Trains muscle strength• Relies on respiration and lactic acid fermentation.

Sept. 20, 2013

O2

O2O2

AerobicAnaerobic

Fermentation

If O2 runs low, muscles do fermentation to get rid of extra NADH and pyruvic

acid.

Citric Acid Cycle

The Electron Transport Chain: A Molecular “Waterwheel”

Lactic Acid Fermentation: A Source of “Muscle Burn”

Fermentation turns pyruvic acid into lactic acid and recycles NADH.

Make a Prediction

Which of these two activities would have a faster, stronger effect on the pH of muscle tissue? Why do you think so?

Muscle Fatigue and Fermentation

Fast Twitch vs. Slow Twitch Muscle Fibers

Skeletal muscle fibers can be fast twitch or slow twitch fibers.

Slow twitch fibers use a lot of oxygen.• Lots of blood vessels for sustained contraction!Fast twitch fibers are specialized for quick, strenuous action.• Fewer blood vessels

On your index card:Which of these muscle

fiber types would do aerobic respiration?

Which type would you expect to find in leg

muscles that support standing up?

Dark and White Meat = Different Muscle Fibers!

White meat = fast twitch, anaerobicChicken breast = muscles that don’t need as much oxygen

Dark meat = slow twitch, aerobic

Chicken legs/thighs = muscles that need lots of oxygen

Oxidative Damage and Free Radicals

AntioxidantsInhibit reduction and oxidation reactions.May reduce formation of free radicals and reduce damage.But regular exercise also produces antioxidants!Why might doing heavy aerobic exercise only once a week be unhealthy?

Deaths in the Chicago AreaCase 1 (September 29th, 1982):The night before, a twelve-year-old girl had a

stuffy nose and sore throat. Her parents gave her an extra-strength Tylenol and sent her to bed. The next morning, she was found collapsed on the floor of the bathroom.Case 2 (September 29th,

1982):A twenty-seven-year-old postal worker was found unconscious on the floor of his kitchen. He died within two hours.

Cases 3 and 4 (September 29th, 1982):Two relatives of the second victim died while preparing for

his funeral at his house. Before the patients collapsed, they felt dizzy and confused, suffering from headache and shortness of breath. They died within two hours.

More deaths in the Chicago area followed rapidly.

What Do We Know? What Do We Need to Know?

Autopsy Results

Some Possible Data from Cells

MoleculeAverage level in

patients’ cells

Normal levels

Glucose 99 uM 100 uM

Pyruvate 27 uM 25 uM

NAD+ 10 uM 75 uM

NADH 400 uM 50 uM

What was affected? Was it glycolysis, the citric acid cycle, or the electron transport chain?

Conclusions