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A fatty acid molecule will yield more energy than a single glucose molecule both if oxidised by the body to produce ATP, or when burnt in oxygen to give heat.
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In general this first answer looks right, and in most cases it can be applied very well.
However the amount of energy basically depends on the molecule's structure and bonding properties of C-O, C=O, C-H and O-H bonds plus the number of those bonds, which have to be 'broken down' by O2 to form CO2 and H2O.
Also the (mean) molecular weight should be accounted for when comparing energy per 100 GRAM, as is usually done in food science.
It is mainly proportional to the amount of oxygen needed to 'burn' or oxidise 100 gram of fatty acid or glucose biologically.
Some table values:
Glucose (monosaccharide) 1563 kJ / 100 g
Saccharose (disaccharide) 1650 kJ / 100 g
Starch, (polysaccharide)... 1748 kJ / 100 g
Acetic acid , C2H4O2 about 1.6 MJ / 100 g
Butyric acid, C4H8O2 about 1.9 MJ / 100 g
Stearic acid, C18H36O2 about 4.0 MJ / 100 g
Fat, in general, mean value: 3.7-3.8 MJ / 100 g
Fats and ethanol have the greatest amount of food energy per mass: 38 and 30 kJ/g respectively.
Proteins and most carbohydrates have about 17 kJ/g. Carbohydrates that are not easily absorbed, such as fiber or lactose in lactose-intolerant individuals, contribute less food energy.
Polyols (including sugar alcohols) and organic acids have less than 16 kcal/g.
The Energy Content of Foods
The food we eat can be divided up into several classes; fats or lipids, sugars and starch, proteins and alcohols. These can give us energy, usually measured in calories per gram. It may be surprising for some of you, but these
different foods contain varying amounts of energy. While fats yield 9 kilocalories / gram, sugars and starch give us a little less than half of this, that is, 4 kilocalories / gram. Proteins also give about 4 kilocalories / gram. Alcohol yields 7,5 kilocalories / gram. That means that a glass of wine gives us as much energy as double as much cola! Beer and wine are major contributors to the current global obesity epidemic.
What is the basis for these differences? Remember, the energy content of the food we eat is directly related to "electron-hopping" from hydrogen-carbon complexes to oxygen atoms. Food with many carbon-oxygen links can be said to be partially burned or oxidized before we eat it. It contains fewer high-energy electrons and, therefore, less energy.
Now, just look at the figure. You will quickly see that fats contain mostly carbon-hydrogen bonds and little oxygen. Fats or lipids are almost fully reduced and excellent donors of high-energy electrons. The sugar (glucose) at the bottom of the figure contains many oxygen atoms and is partially oxidized before being eaten. That means that it has fewer electrons to donate to oxygen during metabolism and, therefore, gives us less energy than fats. Alcohol (ethanol) lies between these in oxidation state and "energy content". It contains fewer hydrogen atoms and high-energy electrons per molecule than fats, but more than sugars.
What else can I help you with?
Why do human cells rely far more on glucose and fat for energy than on protein?
More energy is available to us aerobically (fat can only be metabolized aerobically), the high energy needs of endurance MORE
During photosynthesis is energy stored in the form of fat?
No, during photosynthesis, energy from sunlight is converted into chemical energy in the form of glucose, not fat. Plants then use this glucose as a source of energy for growth and metabolism. Fat is typically stored in plants as a reserve energy source.
What are the four sources of energy for muscle cells?
fat, calories, sugar, and energy or glucose
How do animals store glucose?
Animals primarily store glucose in the form of glycogen in their liver and muscles. Glycogen serves as a readily accessible energy reserve that can be broken down into glucose when needed. Excess glucose can also be converted into fat for long-term energy storage.
Does starch break down fat?
Starch is a carbohydrate and does not directly break down fat. However, when you consume starch, your body converts it into glucose for energy. If you consume more starch (calories) than your body needs, the excess glucose can be stored as fat.
Why will cell choose to use glucose over fat when fat yields more energy?
cell use glucose instead of fat because glucose is easy to burn into energy but it takes a lot of workout ot burn fat..
How does the energy stored in glucose compare to the energy stored in fat?
The energy stored in fat is significantly higher than that in glucose. While glucose provides about 4 calories per gram, fat offers approximately 9 calories per gram. This makes fat a more efficient energy storage molecule, allowing the body to store more energy in a smaller volume. Consequently, while glucose is readily available for quick energy use, fat serves as a long-term energy reserve.
Does unit of fat take more oxygen to be converted to energy than glucose?
yes
Why do human cells rely far more on glucose and fat for energy than on protein?
More energy is available to us aerobically (fat can only be metabolized aerobically), the high energy needs of endurance MORE
What is a property of conditioned muscles?
they rely less on fat breakdown and more on glucose oxidation for energy
Does glucose build muscles?
no, because glucose is a form of sugar, and sugar is energy, and energy is pretty much fat.
During photosynthesis is energy stored in the form of fat?
No, during photosynthesis, energy from sunlight is converted into chemical energy in the form of glucose, not fat. Plants then use this glucose as a source of energy for growth and metabolism. Fat is typically stored in plants as a reserve energy source.
What does glucose produce for the body?
Your body uses glucose to produce energy. In fact, glucose serves as your body's primary source of energy because it can be broken down more efficiently than either fat or protein. Read more: What Does Glucose Produce? | eHow.com http://www.ehow.com/facts_5868649_glucose-produce_.html#ixzz2LNJTobrZ
What are the four sources of energy for muscle cells?
fat, calories, sugar, and energy or glucose
Which Energy system uses glucose fat and protein fuel?
The aerobic energy system uses glucose, fat, and protein as fuel sources. Glucose and fat are the primary sources of energy, while protein can be used as a last resort if the other sources are depleted. This system requires oxygen to efficiently produce energy through the process of cellular respiration.
What is the preferred energy fuel for the brain is fat?
The preferred energy fuel for the brain is glucose. While the brain can also use ketones produced from fat during periods of low glucose availability, glucose is the most efficient and preferred source of energy for normal brain function.
What energy does the body store from eating food?
The body uses glucose as energy. Excess glucose is stored as fat (in animals) and as starch (in plants).
