Glycolysis & Respiration -Or- How to release the energy stored in the glucose.
The Main Goal ? = To make as much ATP as possible!
Glucose (C 6 H 12 O 6 ) Recall that this molecule stored the energy of the sun in chemical form during photosynthesis. Now we have to release this energy so that it can be used efficiently. A fire releases this same energy but inefficiently (all at once) and much of the energy escapes as heat!
Glycolysis -lysis: to break down. Glyco- refers to the glucose.(remember Hydrolysis) Glycolysis breaks down glucose and gets it ready for the next step.
Glycolysis Glucose 2 PGAL 2 Pyruvic Acids (6-Carbon) (3-Carbon) (3-Carbon) Draw Figure 4.10 on page 113 in text. Draw Figure 4.10 on page 113 in text. In the process of breaking glucose down from a six- carbon sugar to (2) three-carbon acids some energy is captured by the cell in the form of 6 ATP molecules. Remember, ATP is like the batteries for the cell. NET ATP GAIN= 2 ATP
Respiration Takes place in the mitochondria. pyruvic acidTakes the pyruvic acid from glycolysis and gets more energy out of it. acetic acid.First changes Pyruvic acid (a 3-carbon compound) and drops off a carbon dioxide molecule leaving the 2-carbon molecule called acetic acid. (Where have you heard of that before?) Vinegar!
Respiration—Kreb’s Cycle In the Krebs Cycle acetic acid (yuk!) is first changed into citric acid. (Where have you heard of that before?) From here it goes through a number of steps which release CO 2 and high energy compounds like NADH (no P), and FADH 2. Kreb’s produces the CO2 that you exhale. Citrus fruit (much better!)
Respiration This is the beginning of Pyruvic Acid -C 3 Acetic Acid -C 2 CO 2 Citric Acid -C 6 C4C4 From glycolysis
Citric Acid -C 6 CO 2 C5C5 C4C4 C4C4 Changes its structure C4C4 C4C4 C4C4 Acetic Acid -C 2 Changes its structure
Citric Acid -C 6 C5C5 CO 2 C4C4 C4C4 C4C4 C4C4 C4C4 Acetic Acid -C 2 NAD + NADH NAD + GDP GTP FAD + FADH 2 NAD + NADH
As a result –2 CO 2 are given off –3 NADH are made –1 FADH 2 is made –1GTP is made These are high energy molecules that will go to make ATP molecules NET ATP GAIN = 2 ATP
Respiration The final electron acceptor is oxygen. When glycolysis and respiration are finished the result is that 36 ATP molecules have been produced.
Total Breakdown of Glucose Glucose Glycolysis Pyruvic Acid Kreb’s Cycle ETC 2 ATP 32 ATP !!! TOTAL = 36 ATP FOR EVERY GLUCOSE. 36 ATP FOR EVERY GLUCOSE. Only when O 2 is present
Respiration The overall reaction for respiration is:The overall reaction for respiration is: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O The overall reaction for photosynthesis wasThe overall reaction for photosynthesis was: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2
Comparisons Photosynthesis has two reactions called the light and dark reactions. The dark (light independent) reaction of photosynthesis was called the Calvin Cycle because it had no clear cut end product. Energy production is broken down into two reactions - glycolysis and respiration. Respiration can also be called the Krebs (or citric acid) Cycle because there is no clear cut end product.