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The food we eat comes from living things. Food is organic, which means it has high energy bonds and can burn. When your body uses food for energy it breaks the high energy bonds in the food, releasing the energy. We also eat food in order to grow. The food we eat contains the molecules that are needed to make more cells.
When you buy food at the store it comes with a nutrition label. This label tells you what kind of molecules are found in the food and how much energy is stored in the bonds of the molecules. Calories - measure energy Molecules that contain energy are CARBOHYDRATES, PROTEINS, and FATS. Fats include saturated and unsaturated fat as well as cholesterol. Carbohydrates include sugar, fiber, and starch. Non-energy molecules are vitamins, minerals, and water. |
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Images from: http://carbontime.bscs.org
How do cells use food for energy: Cellular Respiration
What do we get from air?
With every breath, your lungs fill up with air, but you don’t breathe out all of the oxygen you took in. What happens to the oxygen that you breathe in? Lungs have tiny spaces where the air goes, and each space is surrounded by tiny blood vessels. Some of the oxygen you breathe in goes into these blood vessels. The blood then takes oxygen to cells all over your body.
What do we get from food?
You’ve already learned that we get organic matter from the foods we eat. These are carbohydrates, proteins, and fats. This organic matter is digested and broken down to monomers and taken to cells by the blood. Sometimes cells rebuild the monomers back into polymers in order to grow. But most monomers are used by cells in a different way: they are “reacted” with oxygen in the cells. What happens when organic matter is reacted with oxygen? Do you have any ideas?
How do we get energy from food?
Every cell in your body needs energy, but how does it get energy? At first the energy is stored in food molecules as chemical energy. The food molecules have carbon-carbon and carbon- hydrogen bonds. The cell can change this chemical energy into other forms of energy, such as kinetic energy, more chemical energy, or heat. The cell does this by reacting food molecules with oxygen and changing the organic food matter into waste products it doesn’t need: carbon dioxide and water. How can it get rid of the waste products? Give them back to the blood! And the blood takes these waste products back to the lungs so you can breathe them out and get rid of them.
With every breath, your lungs fill up with air, but you don’t breathe out all of the oxygen you took in. What happens to the oxygen that you breathe in? Lungs have tiny spaces where the air goes, and each space is surrounded by tiny blood vessels. Some of the oxygen you breathe in goes into these blood vessels. The blood then takes oxygen to cells all over your body.
What do we get from food?
You’ve already learned that we get organic matter from the foods we eat. These are carbohydrates, proteins, and fats. This organic matter is digested and broken down to monomers and taken to cells by the blood. Sometimes cells rebuild the monomers back into polymers in order to grow. But most monomers are used by cells in a different way: they are “reacted” with oxygen in the cells. What happens when organic matter is reacted with oxygen? Do you have any ideas?
How do we get energy from food?
Every cell in your body needs energy, but how does it get energy? At first the energy is stored in food molecules as chemical energy. The food molecules have carbon-carbon and carbon- hydrogen bonds. The cell can change this chemical energy into other forms of energy, such as kinetic energy, more chemical energy, or heat. The cell does this by reacting food molecules with oxygen and changing the organic food matter into waste products it doesn’t need: carbon dioxide and water. How can it get rid of the waste products? Give them back to the blood! And the blood takes these waste products back to the lungs so you can breathe them out and get rid of them.
Images from: http://carbontime.bscs.org
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Evidence of Cellular Respiration
We Breathe Out CO2 and H2O: As cells work, they give off carbon dioxide and water that they do not need. Carbon dioxide and water are inorganic molecules that do not have chemical energy. These molecules leave the cells and go back into the blood vessels. Eventually the H2O and CO2 leave our bodies. Carbon dioxide leaves when we breathe out. Water leaves when we breathe and sweat and urinate. What ways could you measure the H2O and CO2 animals give off when they breathe?
We Give Off Heat: Just like when you burn a piece of wood, burning food in your body also changes chemical energy to heat. Animal cells do this during cellular respiration. In fact, the heat you get from the food you eat is the same amount of heat that would be given off if you burned the food in a pan on the stove! A scientist name Max Rubner proved this to be true over 100 years ago. He found that burning dog food released the same amount of energy as was released if the dog ate and metabolized the food! The heat created when our cells do cellular respiration helps our body maintain its 98.6° temperature in warm and cold weather.
Our “Energy Level” Changes With Food: If animals do not get enough food and chemical energy they get tired. But when animals eat, they feel “energized.” That’s why athletes eat certain foods before a big race. Our bodies react the food with oxygen, changing the chemical energy in food into motion energy we use to move around and be active.
We Give Off Heat: Just like when you burn a piece of wood, burning food in your body also changes chemical energy to heat. Animal cells do this during cellular respiration. In fact, the heat you get from the food you eat is the same amount of heat that would be given off if you burned the food in a pan on the stove! A scientist name Max Rubner proved this to be true over 100 years ago. He found that burning dog food released the same amount of energy as was released if the dog ate and metabolized the food! The heat created when our cells do cellular respiration helps our body maintain its 98.6° temperature in warm and cold weather.
Our “Energy Level” Changes With Food: If animals do not get enough food and chemical energy they get tired. But when animals eat, they feel “energized.” That’s why athletes eat certain foods before a big race. Our bodies react the food with oxygen, changing the chemical energy in food into motion energy we use to move around and be active.
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Energy in ATP - Honors
ATP, or adenosine triphosphate, is often called the "energy currency" of the cell. Imagine it as a rechargeable battery that powers various processes in living organisms.
Structure: ATP is made up of three parts:
- Adenine: a nitrogenous base
- Ribose: a sugar molecule
- Three phosphate groups
Structure: ATP is made up of three parts:
- Adenine: a nitrogenous base
- Ribose: a sugar molecule
- Three phosphate groups
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The energy is stored in the bonds between the phosphate groups. When one of these bonds is broken (usually the bond between the second and third phosphate), ATP is converted into ADP (adenosine diphosphate) and energy is released. This energy is then used for various cellular activities, like muscle contraction, nerve impulse transmission, and chemical reactions.
Cells can regenerate ATP from ADP and inorganic phosphate, making ATP a continuously used and reused energy source. ATP is essential for all life. Without it, cells wouldn’t be able to perform necessary functions, which means organisms wouldn’t survive. The energy needed to produce ATP from ADP comes from the high energy bonds in biomolecules when they are broken down during cellular respiration. |
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Text and images from Carbon Time.