Introductory Biology

2.4 Energy and Chemical Reactions

Todays class about energy and chemical reactions was very interesting. The experiments and visual things, like the example of breaking things down shown by a piece of paper burning, helped me get a better understanding of the topic. It was interesting to see that by adding a little more energy to the to the paper (the heat), it allows the paper to break down and release energy, gas, and heat at the same time.

In class we talked about energy and chemical reactions. All organisms/living things need energy to stay alive. ‘Energy is the ability to move or change matter, and in living organisms involves chemical reactions.’ The food we consume becomes energy in the human body and keeps us alive. Metabolism absorb the energy and release energy from all chemical reactions that occur in the organism. They consume the energy from the food and produce more DNA, protein, lipids, etc. Activation energy keeps reactions from happening and is required to start any chemical reactions.

We also talked about enzymes, and how they help biochemical reactions occur by minimizing activation energy. Activation energy is the energy barrier required to make a reaction. Enzymes are protein molecules and speeds up chemical reactions by reducing activation energy, without heat.  They do things over and over again, and can build things up and break chemical bonds. The saliva in your mouth is an example of enzymes, and it helps break down food in your body. Enzymes are charged on the outside and lets itself dissolve in the water. They are very specific and sensitive to environmental factors, like the temperature and pH. When heat is added, enzymes no longer works because its shape is altered and could no longer fit with the substrates. This process can be seen when you have a fever and you do not feel like eating or doing anything because your metabolism slows down from the heat produced by the fever. But it is done on purpose to defeat the virus enzymes even though it puts the enzymes at risk.

In an enzyme action, the enzyme can be reused over and over again. First, a substrate attaches to an enzymes active site. (‘Substrates are substances that enzymes act upon.) The enzymes and substrates attract if they have the corresponding shape and charge. There are specific enzymes for specific substrates and the substrate is thought as like a key to the lock, enzyme.  Then, the enzyme reduces the activation energy of the reaction. After this reaction, the enzymes do not change and can be reused. During the process, water can be added to break down the substrate, also known as hydrolysis.


One thought on “2.4 Energy and Chemical Reactions

  1. Yurika,

    Great post! You’ve done another super job of covering all the key ideas in a well organized thorough entry.

    Mr. F.

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