Anaerobic Respirationand Respiratory

Quotient

Alternative Energy Sources• Triglycerides (fats) are

hydrolyzed into glycerol and then G3P (step 6 in glycolysis)

• Triglycerides (fats) are broken into 2-C units and bind with CoA Acetyl-CoA

• Fats are great source of energy but take longer to breakdown

• More H atoms = more energy– Energy density

• Proteins are broken into AA (lose their amino group) and then change into pyruvate or an intermediate step in the citric acid cycle

Aerobic and Anaerobic Reactions• Organism can be:

– Strict anaerobes can’t survive in oxygen

– Strict aerobes can’t survive without oxygen

– Facultative aerobes can survive with or without oxygen

• What parts of cellular respiration are aerobic/anaerobic?– Aerobic Krebs cycle/Oxidative

Phosphorylation– Anaerobic Glycolysis

• Anaerobic Organism can still do glycolysis, but what is left at the end?– pyruvate

• Breaking down pyruvate after glycolysis creates different kinds of fermentation

Fermentation• Alcoholic pyruvate is converted into ethanal

and then ethanol (alcohol and fuel)– CH3CHO +2H+ C2H5OH

• Also releases CO2; used to make bread/cakes raise

• Lactic Acid pyruvate is converted into lactate by lactate dehydrogenase

• Energy supply in muscles when oxygen runs low

• Why is it dangerous to us?– Builds up in cells and lowers pH (acidic)– Causes muscle crams and soreness after

working out – Must be removed from the cells and broken

down in the liver; 20% changed to CO2 and H2O

– Oxygen debt O2 needed to remove lactate

How Efficient Are Our Energy Sources?• Respiratory Quotient value based on

the ratio of CO2 made to O2 used during respiration– Value also terms if anaerobic or

aerobic respiration is occurring• RQ = #mol CO2 / # mol of O2 • Glucose 6/6 = 1.0• Olive Oil 36/51= 0.7• Protein 0.9• Fermentation:– Alcohol <2– Lactate No value (no CO2 made)

• RQ > 1; anaerobic respiration

2 C18H34O2 + 51 O2 36 CO2 + 34 H2O + Energy

C6H12O6 2 C2H5OH + 2 CO2 + Energy

C6H12O6 2 C3H6O3 +Energy

Measuring RQ• Respirometer sensitive device to

measure O2 consumption by an organism

• What variables must we account for?– Temperature – Pressure– Activity level– CO2 produced

• CO2 is removed from the air by an absorbent chemical; KOH (aq)

• Drop in O2 volume displayed with manometer fluid

• How can we measure CO2 production?

Measuring RQ• Remove CO2 absorbing chemical to

measure CO2

• RQ = 1; the manometer wont move• What is the energy source?– Carbohydrates

• What does it mean if we see an increase in volume?– More CO2 produced– Moving into anaerobic respiration

(RQ>1)• What does it mean if we see a drop in

volume?– Less CO2 produced– Moving to lipid/protein use (RQ<1)

Practice Problems1) A compound is burned inside a 1000ml bell jar and the air was

analyzed before and after. After the reaction the data showed the amount of O2 dropped 2.7% while the amount of CO2 measured 4ml. What type of organic fuel is this compound?

2) What would be the average RQ for an organism that divides it diet evenly between carbohydrates and fats?

• Air is 21% O2

•21% in 1000ml of air 210ml•2.7% of 210ml 5.67ml• 4 ml/ 5.6 ml = 0.71 fatty acid

• RQ of carbohydrates= 1.0 ; RQ of lipids 0.7• (1.0 x 0.5) + (0.7 x 0.5) = 0.85

Homework• Respiration review

sheet• Questions 15.8 and

15.9 in textbook• Read pages 211-

215• Quizlet vocab• Study for quiz on

Ch. 16 next week