feel the burn do you like to run, bike, or swim? these all are good ways to exercise. when you...
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Chemical Energy & Food FoodFood – source of: Energy Raw materials caloriecalorie amount of energy needed to raise 1g of water by 1 C Calorie” –“Calorie” 1 kcal, or 1000 calories Cells breakdown food slowly & gradually –Cells can’t use food energy directly convert to ATP – If all at once, too explosive and most energy lost as heat –Slowly releases energy of food to make ATPTRANSCRIPT
Feel the Burn
Do you like to run, bike, or swim? These all are good ways to exercise. When you exercise, your body uses oxygen to get energy from glucose, a six-carbon sugar.
1. How does your body feel at the start of exercise, such as a long, slow run? How do you feel 1 minute into the run; 10 minutes 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 100 meters. Could you keep up this pace for a much longer distance? Explain your answer.
Chapter 9-1Chapter 9-1Chemical Pathways
Chemical Energy & Food• FoodFood – source of:
Energy Raw materials
• caloriecalorie amount of energy needed to raise 1g of water by 1C– “Calorie”Calorie” 1 kcal, or 1000 calories
• Cells breakdown food slowly & gradually– Cells can’t use food energy directly convert to ATP– If all at once, too explosive and most energy lost as heat– Slowly releases energy of food to make ATP
Cellular RespirationThe process that releases energy by
breaking down glucose and other food molecules in the presence of oxygen
6O6O22 + C + C66HH1212OO66 6CO 6CO22 + 6H + 6H22O + EnergyO + Energy
• Three main steps:Glycolysis, Krebs cycle, Electron Transport
Chain
oxygen glucose carbon dioxide
water
FlowchartSection 9-2
Glucose(C6H1206)
+Oxygen
(02)
Glycolysis KrebsCycle
ElectronTransport
Chain
Carbon Dioxide
(CO2)+
Water(H2O)
Cellular Respiration
Glucose
Glycolysis Krebs cycle
Electrontransport
Fermentation (without oxygen)
Alcohol or lactic acid
Chemical PathwaysSection 9-1
GlucoseGlycolysis
Cytoplasm
Pyruvic acid
Electrons carried in NADH
Krebs Cycle
Electrons carried in NADH and
FADH2
Electron Transport Chain
Mitochondrion
Mitochondrion
Cellular Respiration: 3 Stages 1. Glycolysis ( in cytoplasm)
2. Krebs Cycle ( in mitochondrial matrix)
3. Electron Transport Chain ( in mitochondrial cristae)
Net vs. Gross• Gross amount of product made
– Ex: Made $20.00 babysitting
• Net amount of product made minus amount of product used– Ex: Made $15.00 babysitting
• $5.00 for gas to get to babysitting job• $20.00 babysitting made• $20.00 - $5.00 = $15.00 net
GlycolysisProcess in which one molecule of glucose
is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound.– 6 carbon molecule (glucose) to two 3-carbon
molecules (pyruvic acid)
Takes place in the cytoplasm
• Does not require oxygen
Glycolysis• 2 ATP molecules must be added to get the reaction
startedCan be considered activation energy
• 4 ATP molecules are produced (4 – 2 = net gain of 2 ATP)
• 2 NADH molecules are also created– NADHNADH
• Electron carrier = NAD+ (nicotinamide adenine dinucleotide)• NAD+ + H+ + 2 high energy electrons NADH• Takes electrons to other parts of respiration
• Glycolysis nets 2 ATP, 2 NADH, and 2 pyruvic acids
Glycolysis
Glucose
To the electron transport chain
2 Pyruvic acid
http://www.youtube.com/watch?v=O5eMW4b29rg
Glycolysis: Advantages vs. Disadvantages
Advantages Occurs quickly
– Can produce 1000s of ATP in a few milliseconds
Does not require oxygen – Can occur w/o oxygen
Disadvantages Net gain of only 2 ATP
NAD+ become filled with electrons quickly– Can’t make more ATP
Anaerobic Respiration = Fermentation
Occurs after glycolysis only if no oxygen is available
• NADH from glycolysis used, turned back into NAD+– Goes back to glycolysis– Keeps glycolysis going– Generate as many ATP as possible
Important because it recycles the NAD+ molecules so that the cell can continue to make energy
an = “without” aerobic = “air”
Alcoholic Fermentation In the absence of oxygen, pyruvic acid is
broken down to produce alcohol and carbon dioxide – Carried out by yeasts and a few other micoorganisms
• pyruvic acid + NADH → alcohol + CO2 + NAD+
Used to make alcoholic beverages and to cause bread dough to rise
Lactic Acid Fermentation In many cells, the pyruvic acid that accumulates
due to glycolysis is converted to lactic acid.
• pyruvic acid + NADH → lactic acid + NAD+
Occurs in muscles during heavy exercise– Lactic acid buildup in muscles causes painful, burning
sensation = why muscles feel sore
Prokaryotes also produce lactic acid– Used to make cheese, yogurt, buttermilk, sour cream,
pickles, sauerkraut, and kimchi.
Glucose Pyruvic acidLactic acid
Lactic Acid Fermentation
Respiration Videos
• Aerobic Respiration
• Glycolysis
Review Questions• 1. What is cellular respiration? What is the equation for it?
• 2. What are the 3 stages of cellular respiration in order?
• 3. What is glycolysis and where does it take place in a cell? What are the products of glycolysis?
• 4. What are the advantages and disadvantages of glycolysis?
• 5. What is anaerobic respiration and what is its purpose?
• 6. Compare and contrast alcoholic fermentation with lactic acid fermentation.