Copyright

The Evolution of Protists: Importance & Evolutionary History

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: The Evolution of Plants and Fungi: Characteristics & Evolutionary History

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:05 Characteristics of Protists
  • 0:51 Types of Protists
  • 1:56 Endosymbiosis in Protists
  • 2:54 Examples and…
  • 4:18 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Login or Sign up

Timeline
Autoplay
Autoplay

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Danielle Weber

Danielle teaches high school science and has an master's degree in science education.

Some organisms are very familiar. However, there are some that play vital roles in our lives that we don't even think about. We will look at a group of one of these unfamiliar kingdoms - protists.

Characteristics of Protists

The cellular structure of protists
Protist Cell Structure

You know the basics of what plants, animals, and fungi are, but what about those eukaryotic organisms that don't quite fit within these groups? Within our system of classification, these organisms fall into the Protista kingdom. Protists are eukaryotic, mostly unicellular, and mostly aquatic. 'Eukaryotic' means that they have cells with a nucleus and membrane-bound organelles and are similar to the cells that make up our bodies. Because they are eukaryotic, protists fall within the domain Eukarya. Most protists are unicellular, meaning they are only made of one cell. However, some protists are multicellular and are made of more than one cell. Most are aquatic, meaning that they live in the water.

Types of Protists

Protists are broken up into three main groups based on how similar they are to other eukaryotic kingdoms. The three groups are animal-like, plant-like, and fungus-like protists.

Animal-like protists are heterotrophs and get their nutrients by ingesting food, which is how animals, who are also heterotrophs, get their nutrients and energy. Animal-like protists are also called 'protozoa,' which means 'first animals.'

Plant-like protists are autotrophs and get their nutrients by performing photosynthesis, which is a process that uses sunlight to make sugars and oxygen and is also performed by plants to make nutrients and energy. Plant-like protists are also called 'protophyta,' which means 'first plants.'

The third group, the fungus-like protists, are also heterotrophs and get their nutrients by absorbing food. Now, this may seem a bit unusual, but this is how fungi get their nutrients and energy. Rather than eating food and then digesting it like animals and protozoa, fungus and fungus-like protists externally digest food and then absorb the nutrients.

Endosymbiosis in Protists

You may remember that endosymbiosis is basically the idea that one cell engulfs another cell. The endosymbiosis theory used this idea to explain the evolution of eukaryotic cells - and specifically, the presence of chloroplasts and mitochondria in cells.

Within the Protista kingdom, there is evidence to help support this theory. Remember that the endosymbiosis theory proposed that the mitochondria was engulfed first. Later, a cell that was capable of photosynthesis, most likely cyanobacteria, was then engulfed and became the chloroplast. Red and green algae, while you may think of them as plants, are actually protists. These simple plant-like protists have DNA that is very similar to the genetic material of cyanobacteria. This similarity helps show the evolutionary connection between cyanobacteria and algae - the more simple cyanobacteria is an evolutionary ancestor of both red and green algae.

Examples and Importance of Protists

Unicellular diatoms are used in nanotechnology
Diatom Image

To unlock this lesson you must be a Study.com Member.
Create your account

Register for a free trial

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Free 5-day trial

Earning College Credit

Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!
Create An Account
Support