The term cellular respiration refers to the biochemical pathway by which cells release energy from the chemical bonds of food molecules and provide that energy for the essential processes of life. All living cells must carry out cellular respiration. It can be in the presence of oxygen or . carry out cellular respiration within the cytoplasm or on the inner surfaces of the cells. More emphasis here will be placed on where the are the site of most of the reactions. The energy currency of these cells is , and one way to view the outcome of cellular respiration is as a production process for ATP.
By definition, .
The process of photosynthesis uses raw materials like carbon dioxide, water, and solar energy to produce oxygen and carbohydrates.
After making sure your brochure is perfect, it is time to print it out and share it with your classmates. Choose another team to share your brochure with. Each team will be responsible for sharing their brochure with at least one other team. Make sure your classmates understand the processes of photosynthesis and cellular respiration. Remember it is your job to make sure they understand!
Following photosynthesis, the glucose constructed within plant cells can then be used as a source of energy and materials for cellular activities such as growth, reproduction and the synthesis of more complex materials such as starch, proteins, and fats. The existence of all naturally-occurring molecules (any molecule containing carbon, , and oxygen), and therefore, all sources of energy, can be traced back to the process of photosynthesis. This concept will become very important as we study the flow of energy through ecosystems and the use of energy by humans later in the course.
Energy is defined as the ability to do work. The cells of all organisms, and therefore, all organisms, require a continuous supply of energy for the performance of their daily, vital activities. Carbohydrates, especially glucose, generally provide this energy through the process of respiration. Simply stated, respiration is the release of energy from energy-storing compounds. It is represented by the chemical equation:
Glycolysis itself yields two ATP molecules, so it is the first step of anaerobic respiration. , the product of glycolysis, can be used in to produce ethanol and + or for the production of lactate and NAD+. The production of NAD+ is crucial because glycolysis requires it and would cease when its supply was exhausted, resulting in cell death. A general sketch of the anaerobic steps is shown below. It follows Karp's organization.
Aerobic respiration, or in the presence of oxygen, uses the end product of (pyruvate) in the to produce much more energy currency in the form of than can be obtained from any . Aerobic respiration is characteristic of when they have sufficient oxygen and most of it takes place in the .
Anaerobic respiration (both glycolysis and fermentation) takes place in the fluid portion of the cytoplasm whereas the bulk of the energy yield of aerobic respiration takes place in the . Anaerobic respiration leaves a lot of energy in the ethanol or lactate molecules that the cell cannot use and must excrete.
You should be careful to notice that the process of cellular respiration is essentially the reverse of photosynthesis. The catabolic breakdown (burning) of glucose requires the presence of oxygen and yields energy and . This process is generally the same when any organic molecule is respired (or burned) whether it is glucose in a living animal or plant cell, wood in a fire, or gasoline in a car. The breakdown of any energy storing chemical releases carbon dioxide as a byproduct, which may then be used by plants in the photosynthetic process.
Their cells comprise additional organelles specific for photosynthesis as well as rigidity.
Given below is a simple procedure to construct a plant cell model from some easily available items which can be used to represent the different organelles.
Higher plants, phytoplankton, algae, as well as some bacteria carry out the process of photosynthesis.
Steps of Photosynthesis
Photosynthesis occurs in two main stages, the first stage being towards light reaction and the second stage being the Calvin Benson Cycle.
You and your teammate will use Microsoft Word to create the brochure about photosynthesis and cellular respiration. You can use the following resources to help you create the perfect brochure!
During photosynthesis, a plant is able to convert solar energy into a chemical form. It does this by capturing light coming from the sun and, through a series of reactions, using its energy to help build a sugar molecule called glucose. Glucose is made of six carbon atoms, six oxygen atoms, and twelve hydrogen atoms. When the plant makes the glucose molecule, it gets the carbon and oxygen atoms it needs from carbon dioxide, which it takes from the air. Carbon dioxide doesn't have any hydrogen in it, though, so the plant must use another source for hydrogen. The source that it uses is water. There is a lot of water on the earth, and every water molecule is composed of two hydrogen atoms and one oxygen atom. In order to take the hydrogen it needs to build glucose molecules, the plant uses the energy from the sun to break the water molecule apart, taking electrons and hydrogen from it and releasing the oxygen into the air. The electrons it takes are put into an electron transport system, where they are used to produce energy molecules called ATP that are used to build the glucose molecule-- all made possible by the sun's energy. Thus, during photosynthesis a plant consumes water, carbon dioxide, and light energy, and produces glucose and oxygen.
The sugar glucose is important because it is necessary for cellular respiration. During cellular respiration, the chemical energy in the glucose molecule is converted into a form that the plant can use for growth and reproduction. In the first step of respiration, called glycolysis, the glucose molecule is broken down into two smaller molecules called pyruvate, and a little energy is released in the form of ATP. This step in respiration does not require any oxygen and is therefore called anaerobic respiration. In the second step of respiration, the pyruvate molecules are rearranged and combined and rearranged again in a cycle. While the molecules are being rearranged in this cycle, carbon dioxide is produced, and electrons are pulled off and passed into an electron transport system which, just as in photosynthesis, generates a lot of ATP for the plant to use for growth and reproduction. This last step requires oxygen, and therefore is called aerobic respiration. Thus, the final result of cellular respiration is that the plant consumes glucose and oxygen and produces carbon dioxide, water, and ATP energy molecules.
At first, this doesn't seem to make any sense! If the plant can use the energy from the sun to make ATP, why does it go through all the trouble of then using up the ATP to make glucose, just so it can get ATP again? There are two reasons why the plant does this. First, in addition to ATP, the plant needs materials to grow. Glucose is an important building block that is necessary to produce all of the proteins, DNA, cells, tissues, etc. that are important to life, growth, and reproduction. Second, one problem with the sun is that it goes away every night, and during winter it isn't very bright. The plant needs energy all of the time. So, by producing glucose, the plant can store this molecule and then use it to produce energy during the night and over winter when there isn't enough sun to provide good photosynthesis.
It is very interesting how photosynthesis and cellular respiration help each other. During photosynthesis, the plant needs carbon dioxide and water-- both of which are released into the air during respiration. And during respiration, the plant needs oxygen and glucose, which are both produced through photosynthesis! So in a way, the products of photosynthesis support respiration, and the products of respiration support photosynthesis, forming a cycle.
While plants can complete this cycle by themselves, animals cannot, since animals aren't capable of photosynthesis! This means that animals have to survive solely through respiration. Also, since we animals can't produce glucose by ourselves, we have to get it from somewhere else-- from eating plants. We produce carbon dioxide that the plants need, and they produce the oxygen that we need, and then we eat them to get the glucose that we need. It seems that we need the plants a lot more than they need us!