Transcript Bio 20 7.4 - Stirling School

Anaerobic Cellular
Respiration
 Anaerobic = without oxygen
Anaerobic Cellular
Respiration
 During Glycolysis, energy is obtained without
oxygen.
 This type of energy production is called
Fermentation.
 Fermentation occurs without oxygen.
Fermentation
 Bacteria species engage in a host of specific
fermentation processes.
 Eukaryotic organisms engage in 2 types of
fermentation.
 Eukaryotes: have a nucleus
 This section will focus on these 2 types of
fermentation.
Eukaryotic Fermentation
 Both methods of fermentation have 2 steps.
 Step 1: Glycolysis
 Step 2: fermentation (accomplished by recycling the
products of glycolysis).
Alcohol Fermentation
 Common in yeast.
 Acetaldehyde is produced when carbon dioxide was
removed from pyruvate by the enzyme pyruvate
decarboxylase.
 NADH passes Hydrogen Atoms to acetaldehyde.
 This generates carbon dioxide, ethanol, and NAD+.
 The NADH was a product of glycolysis.
Alcohol Fermentation
 The alcohol ethanol is produced as a result.
 (alcohol found in alcoholic drinks.)
 The process recycles NAD+, therefore, glycolysis can
continue.
 2 ATP produced in glycolysis satisfy energy needs.
 Ethanol and Carbon dioxide are released as wastes.
Alcohol Fermentation
Applications of Alcohol
Fermentation
 Fermentation is commonly used by humans.
 Breads, pastries, wine, beer, liquor, and soy sauce
are all produced by fermentation.
Bread
 Yeast is added which will undergo fermentation.
 The bread will rise due to the release of Carbon
dioxide.
 Alcohol is also produced
 Can you get drunk by eating bread?
 Alcohol is produced, but it evaporates upon baking.
 Don’t try to eat dough to get drunk!! It will make you
sick not drunk.
Wine
 Yeast ferments sugar of fruit juice (Grape juice).
 Mixture bubbles due to carbon dioxide.
 At 12% alcohol concentration yeast cells die.
Homemade Root beer
 Is Homemade Root beer Alcoholic?
 Fermentation generates alcohol as a waste
products, So the answer is Yes.
 Homemade Root Beer is about 0.5% alcohol.
 A Beer is about 6% alcohol.
 You won’t be able to drink the necessary volume of
liquid to get drunk.
Homemade Root beer
Lactic Acid Fermentation
 During strenuous exercise, the muscles energy
demands are greater than aerobic respiration can
supply.
 Additional ATP is supplied by lactic acid fermentation
 See Figure 5 page 224.
Lactic Acid Fermentation
 NADH made in glycolysis transfers H atoms to
pyruvate to make lactic acid and NAD+
 Formation of NAD+ allows glycolysis to continue.
 Accumulation of lactic acid leads to muscle stiffness/
soreness, and fatigue.
 Lactic acid is transported to the liver and converted
to pyruvate when vigorous exercise ceases.
Lactic Acid Fermentation
 Pyruvates then go through aerobic respiration
 Extra oxygen in necessary to process lactic acid.
(oxygen debt)
 Panting accompanying hard exercise is the bodies
way to pay off the oxygen debt.
Exercise Physiology
 The branch of biology that studies the bodies
biological responses to exercise.
 Most common problem encountered by athletes?
 Shortage of energy.
Aerobic Fitness
 A measure of the capacity of the heart, lungs, and
bloodstream to provide oxygen to the cells of the
body during exercise.
 Aerobic fitness is one of the major factors to
consider when assessing an individuals overall
fitness level.
Other Factors
 Muscle Strength
 Muscular Endurance
 Flexibility
 Body composition
VO2 Max
 Maximum volume of oxygen that the cells can
remove from the bloodstream in 1 min/kg of body
mass at maximum exertion.
 mL/kg/min
Assessing VO2 max
 Treadmill test
 Person forced to go faster and faster while expired
air is collected and measured by a computer.
 Lasts about 10 to 15 minutes.
VO2 Max
 High VO2 max = better aerobic fitness.
 Figure 8 page 225.
2 Components to VO2 Max
 Exercise and Genetics.
 When an individual increases there levels of exercise,
their VO2 max will generally increase as well.
 Genetic composition plays a part as well.
 This is why some people are elite marathon runners
and some are not.
 VO2 max also decreases with age.
Lactic Acid Threshold
 Value of exercise intensity at which lactic acid
production increases
 Leads to sore muscles, increased pain, and fatigue.
 Exercising below lactic acid threshold = longer
duration of exercise
 PACE YOURSELF!!!!
Lactic Acid Threshold
 Untrained person has a lactic acid threshold at about
60% of VO2 max
 Trained person has a lactic acid threshold at about
80% of VO2 max.
Environmental Factors and
Cellular Respiration
 Environmental Factors can have an influence on
cellular respiration.
 Two examples are Supplements and Toxins
Supplements
 Buffers: counteract the acidic nature of lactic acid
and will allow an athlete to have enhanced
performance for a short period of time.
 Creatine: contains a phosphate that is donated to
ADP to allow for the creation of more ATP.
 Net effect: more energy available for the muscles to
use.
 Long term side effects not well understood at this
point.
Toxins
 Some environmental substances will influence
cellular respiration either indirectly or directly.
Indirect Influence
 Carbon monoxide binds at the oxygen receptor sites
of the bodies hemoglobin.
 Oxygen is not available to drive the ETC.
 Cell Death follows.
Direct Influence
 Cyanide and hydrogen sulfide act directly on a
specific rxn within the respiration pathway.
Summary