Prometaphase: Definition & Concept

Prometaphase: Definition & Concept
Coming up next: What is MPF?

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

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:02 What Is Prometaphase?
  • 1:20 Early Prometaphase
  • 3:22 Late Prometaphase
  • 4:24 Lesson Summary
Save Save Save

Want to watch this again later?

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

Log in or Sign up

Timeline
Autoplay
Autoplay
Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Artem Cheprasov
Have you ever heard of prometaphase? Some texts avoid this term, but this lesson goes over the six key events that occur during this specific phase of mitosis.

What Is Prometaphase?

Don't you hate it when one science textbook tells you one thing and another science textbook doesn't even mention that one thing at all? Science is hard enough to understand, but it becomes even more confusing when scientists can't come to a consensus on what to call or label something. Such is the case with prometaphase, the phase of mitosis that begins when the nuclear envelope starts to break down.

Some textbooks identify prometaphase as a distinct phase of mitosis, the part of the cell cycle that involves the separation of chromosomes and other cellular constituents into two daughter cells. Other textbooks completely avoid mentioning prometaphase as a term. Instead, they include the concepts involved in prometaphase as a part of late prophase or late prophase and early metaphase. So just keep that tidbit in mind in case you are cross-referencing things.

In any case, this lesson focuses on prometaphase as a distinct phase of the cell cycle. Just know that as described herein, prometaphase of mitosis follows open mitosis, which applies to plants and animals. Closed mitosis, which applies to the likes of yeast and slime molds, is not discussed.

Early Prometaphase

The difference between the two lies, in part, with the nuclear envelope. In closed mitosis, chromosome separation occurs in an intact nuclear envelope. In open mitosis, the chromosomes separate after the nuclear envelope disintegrates. That latter sentence should remind you of our definition for prometaphase, as it is a phase of mitosis that begins when the nuclear envelope disassembles into vesicles and begins to sort of look like the smooth endoplasmic reticulum as it does so. If it hasn't already, prior to prometaphase, the nucleolis completely disappears at this point as well. Thus, the first part of early prometaphase involves the disassembly of the nuclear envelope.

The nuclear envelope now looks like a really old t-shirt full of holes and tears. While not pretty, it's pretty important. That's because the holes allow for the penetration of the nuclear envelope by microtubules, cylindrical structures made of a protein called tubule, which supports cellular structures and functions as tracks for the movement of intracellular components. These microtubules grow from the spindle poles towards the nuclear envelope and penetrate the envelope, so the second part of early prometaphase involves the growth of microtubules.

Once the microtubules make their way into the disintegrating nuclear envelope, they superglue themselves onto structures called kinetochores, button-like protein-based structures located on the surface of the centromere. The centromere is a structure that holds together the two sister chromatids of a replicated chromosome. Each sister chromatid has its own kinetochore located at opposite sides of the chromosome. Thus, the third part of early prometaphase involves the attachment of microtubules to kinetochores.

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

Register to view this lesson

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
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 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 risk-free for 30 days!
Create an account
Support