Chapter 9 Notes. Cellular Respiration. 9-1 Chemical Pathways. All living organisms need food to survive. Food provides living things with the chemical building blocks they need to grow and reproduce. 9-1 Chemical Pathways. 1 gram of glucose releases 3811 calories of heat energy
All living organisms need food to survive.
Food provides living things with the chemical building blocks they need to grow and reproduce.
1 gram of glucose releases 3811 calories of heat energy
Calorie (c): the amount of energy needed to raise the temperature of 1 gram of water 1 Celsius degree
The calories on food labels (C) are kilocalories or 1000 calories
Cells gradually release energy from glucose and other food compounds.
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen.
- 3 parts: glycolysis, the Krebs cycle, and the electron transport chain
Electrons carried in NADH and FADH2
Electron Transport Chain
Equation for Cellular Respiration
6O2 + C6H12O6 6CO2 + 6 H2O + Energy
Alcohol or lactic acid
Fermentation (without oxygen)
The first set of chemical reactions in cellular respiration is glycolysis.
Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound
Net results of glycolysis
- 2 molecules of ATP are gained
- 2 molecules of NADH are gained
- 2 molecules of pyruvic acid (3C) are formed from 1 glucose molecule
When oxygen is present in the cell, glycolysis is followed by the Krebs cycle.
If there is no oxygen present, glycolysis is followed by fermentation.
Fermentation releases energy from food molecules in the absence of oxygen
Because fermentation does not require oxygen it is said to be anaerobic.
The two main types of fermentation are alcoholic fermentation and lactic acid fermentation
Alcoholic fermentation is used mainly by plants and yeasts
- alcohol is the product
Lactic acid fermentation occurs in muscle cells when the body cannot supply enough oxygen to the tissues
- lactic acid is the product
The raw materials required for cellular respiration are
Glycolysis occurs in the
The net gain of ATP molecules after glycolysis is
Fermentation releases energy from food molecules in the absence of
The first step in fermentation is always
Oxygen is used for the final steps of cellular respiration. Because the pathway requires oxygen, it is said to be aerobic.
In the presence of O2, pyruvic acid passes on to the second stage of cellular respiration, the Krebs cycle
During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions
Net result of the Krebs cycle
- 2 molecules of pyruvic acid enter
- 8 molecules of NADH are gained
- 2 molecules of FADH2 are gained
- 2 molecules of ATP are gained
Citric Acid Production
From glycolysis and the Krebs cycle high energy electron carriers, NADH and FADH2, are produced. The electrons are then passed to the electron transport chain.
The electron transport chain uses high energy electrons to convert ADP to ATP.
ETC Movie pt 1
ETC Movie pt 2
Each NADH make 3 ATP while each FADH2 makes 2 ATP
1 glucose molecule can then make 38 total ATP ( 4 ATP, 10 NADH 30 ATP, 2 FADH2 4 ATP)
Cellular Respiration Animation
The Krebs cycle breaks pyruvic acid down into
In eukaryotes, the electron transport chain is located in the
To generate energy over long periods, the body must use
Which statement correctly describes photosynthesis and cellular respiration?