RuBisCO Protein: Definition, Function & Structure Video

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  • 0:00 Definition of RuBisCO
  • 1:05 Structure of RuBisCO
  • 2:26 Function of RuBisCO
  • 3:20 Lesson Summary
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Lesson Transcript
Instructor: Julie Zundel

Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

Without photosynthesis, life as we know it would not exist. This lesson will examine RuBisCO, an enzyme that is involved in photosynthesis, looking at how it works and why it is considered one of the most important enzymes on the planet.

Definition of RuBisCO

What is the most abundant protein and the most important molecule on Earth? You've probably never heard of ribulose-1,5-bisphosphate carboxylase/oxygenase, or if you did, you probably immediately tuned out because the name sounds terrifying. Fortunately it has a nickname, RuBisCO, and it is a type of protein, called an enzyme, that is involved in the Calvin cycle. Wow, that was a lot of vocabulary! So, let's take a closer look at that definition.

An enzyme is a type of protein that makes reactions occur faster. For example, there is an enzyme in our body that helps transfer carbon dioxide from our cells to our blood. This reaction occurs 107 times faster with the enzyme than without.

The Calvin Cycle is a part of photosynthesis where plants take water, carbon dioxide, and light and turn them into sugar and oxygen. The Calvin Cycle starts with carbon dioxide and ends with sugar.

Structure of RuBisCO

As mentioned previously, RuBisCO is an important part of photosynthesis. In plants, it is found in the chloroplasts, where photosynthesis takes place. It can also be found in some photosynthesizing bacteria, archaea, and protists. Since every plant (and some bacteria, archaea, and protists) utilize RuBisCO, it is the most plentiful protein on earth with approximately 88,000,000,000 pounds being made every second!

In order to understand its function, we'll need to take a closer look at its structure. RuBisCO can come in four different forms. For simplicity, we will focus on RuBisCO I, but it is important to note there are different types. Here is a brief breakdown of different forms with examples:

  • Form I, the most common type, found in plants, algae, and some bacteria
  • Form II, found in different types of bacteria
  • Form III, found in some archaea
  • Form IV, RuBisCO-like and found in some bacteria and archaea

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