Cell cycle phases | Cells | MCAT | Khan Academy
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- เผยแพร่เมื่อ 24 พ.ค. 2015
- Learn about the different "seasons" of a cell's life and how it grows with time. By Raja Narayan. Visit us (www.khanacademy.org/science/he...) for health and medicine content or (www.khanacademy.org/test-prep/...) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video.
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Who else understood this a lot better than their 3 hour lecture?
Emily Laramore 🙋🏼♂️
Literally me
lol you got a 3 hour lecture? Lucky you, I get a 50min one.
Lol, right? Idk what is going on with teachers. Always gotta make stuff like this hard to understand when Khan can break it down so simply.
Littaraly in 7th grade
My lecturer went over this for a whole hour and I didn’t get it, you spent 5 minutes and it was perfect! Thanks
Rhi Amy and who says the internet is bad?
Preach!
@@legohead23432 🙏
Well you probably understood this so satisfactorily because your mind was already primed by the lecturer.. You just needed a fine polishing..
SORTING OUT THE PARTS: PROPHASE
As the first active phase of mitosis, prophase is when structures in the cell’s nucleus begin to disappear, including the nuclear membrane (or envelope), nucleoplasm, and nucleoli. The two centrosomes, duplicated in the synthesis process during interphase and each containing two centrioles, push apart to opposite ends of the nucleus, forming poles.
The centrioles produce protein filaments that form mitotic spindles between the poles as well as asters (or astral rays) that radiate from the poles into the cytoplasm.
At the same time, the chromatin threads (or chromonemata) shorten and coil, forming visible chromosomes. The chromosomes divide into chromatids that remain attached at an area called the centromere, which produces microtubules called kinetochore fibers. These interact with the mitotic spindles to assure that each daughter cell ultimately has a full set of chromosomes. The chromatids start to migrate toward the equatorial plane, an imaginary line between the poles.
DIVIDING AT THE EQUATOR: METAPHASE
After the chromosomes are lined up and attached along the cell’s newly formed equator, metaphase officially debuts. The nucleus itself is gone. The chromatids line up exactly along the centerline of the cell (or the equatorial plane), attaching to the mitotic spindles by the centromeres. The centromere also is attached by microtubules (spindles) to opposite poles in the cell.
PACKING UP TO MOVE OUT: ANAPHASE
In anaphase, the centromeres split, separating the duplicate chromatids and forming two chromosomes. The spindles attached to the divided centromeres shorten, pulling the chromosomes toward the opposite poles. The cell begins to elongate. In late anaphase, as the chromosomes approach the poles, a slight furrow develops in the cytoplasm, showing where cytokinesis will eventually take place.
PINCHING OFF: TELOPHASE
Telophase occurs as the chromosomes reach the poles and the cell nears the end of division. The spindles and asters of early mitosis disappear, and each newly forming cell begins to synthesize its own structure. New nuclear membranes enclose the separated chromosomes. The coiled chromosomes unwind, becoming chromonemata once again. There’s a more pronounced pinching, or furrowing, of the cytoplasm into two separate bodies, but there continues to be only one cell.
SPLITTING UP: CYTOKINESIS
Cytokinesis means it’s time for the big breakup. The furrow, formed by a contractile ring that will divide the newly formed sister nuclei, migrates inward until it cleaves the single, altered cell into two new cells. Each new cell is smaller and contains less cytoplasm than the mother cell, but the daughter cells are genetically identical to each other and to the original mother cell, and will grow to normal size during interphase.
thank you so much
Omg thank you sooo much 😭😭
This explain so much than my teachers presentation
LOOK OUT HARVARD I'M COMING FOR
+James Soria for... the end of your sentence?
*you*
You wanna go to Harvard but you can’t finish a sentence. 😂
James Soria wow god luck
How was the entrance exam?
you already know I have a test in pre-ap bio in 5 minutes so im cramming super quick
The way you explained this was pure love!
I'm trying SOOOO hard to understand everything in Campbell's Biology book but after the first few sections of a chapter I just can't focus anymore, it all just goes WA WA WA WA WAAAAAH, WA WA WAAA WA....this helps tremendously thank you Khan academy!!!
Bro just chill out campbel is too much for High school 😭
Perfect introductory explanation! I'm continuing zoology after a two years of break. Thank you Khan academy
wow, great video!!!
So clear and straightforward! Congrats!
5 feet and 2m have a huge difference
Irwin Crook thanks Irwin
It's about 1.6m so I guess he rounded up.
I was too distracted by "the average person being 2 m tall" to listen to any of it. A young person that tall have basketball coaches approaching them left and right
@@agentsus9681 rounded up?
Thats not how that works. Its like rounding up from 5.5 to 6 feet.
We are not 2 meters tall in avarage lmao
Love the comparison to seasons and the pictures. Thank you
I admired ur way of explanation..have a blessed life sir
This video made things clearer thank you!
very very well explained... thanks so much
Thanks for the lecture. It helped a lot👍🏾
Thank u sooo sooo much Sir This literally helped so much :)
Perfect explanation ......better than a 3 hours lecture !!
Very helpful! Thanks
excellent explanation thank you!
Great work, mister!
thank you sooo sound and understandable!
Excellent breakdown.
Thank you. Gid bless this institution.
Thank you so much for this video I needed this ❤️❤️
Thanks a lot !
thank you khan academy for this information. ,
simple illustration. Good job
Very short and simple... Thanks... Have a test on it tomorrow 😌
I like this guy's voice, he sounds dedicated and very clear lecture
I enjoyed your video on interphase. I look forward to watching your videos on mitosis.
This is great
Thanx a lot brothr!
Good explanation for an AP Bio student
THANK YOU!!!! This video helped me a lot on my TEST (
So helpful
thank you for the good video!
Perfect ❤
simply uh-mazing!!! fricking easy to understand :)
I don't think an average person is 2m tall .... or maybe I'm too short :(
Darragi Arfawi Assala I thought 2m is like 6"2 -not an average height
you're off by almost 6 inches
no its not
Let’s be short together 😔✊
the Republic of short people
amazing.
Thanks!
well done khan I understood it from you more than our professor
You should keep it up (:
Nice video!!!!
thank you khan academy
best explanation video for non science background people despite the fact its a really difficult concept
awesome
U r a legend😘
😀thanks
So underrated deserves more views subs and likes 😦
Thanks so much !!!!!!
Nice 🙂
Why does he lowkey sound like the actual Khan? the repeating of a word while struggling to find a new color lol ..we found the IMPOSTER!!!
i love how i can understand this 5 min more than a 1 hour lesson
im from egypt and i thank you for your explain is very good
Great
Humans aren't about 2M. 2M is about 6.5 feet.
+cramegg hahahah same thought here
Lol I was thinking the same thing...
cramegg is true , nothing can be done if you are a dwarf
I was going to write the same... Average can be 1,60-70 for women and 1,80 for men. Juan Martín Del Potro is 2 metres tall. That's not normal!
I bet you're asian
I love your hand writing, literally the biggest reason why I stayed to watch the video and subscribed lol
NICE
I am here for two reasons, really. I need to prep for a cell division and inheritance test. Additionally, I need more science for my Fiction stories.
Super
I can finally ACE my FINALS! Thank you so much!
Laila Almaliki بالتوفيق
thx sir
Thx
Ugh the teacher torched me and put this on the quiz i didn't study for this nor I had the materials wow..............
love the video and explination..how long is the process...does this happen in seconds..minutes..hours..days...weeks ect. ? @khanacademymedicine
thank you!
This sounds so simple yet my textbook and my teacher makes it seem so complicated
What grade are u in?
Thanks for this I have a test fore this in 10/23/2019
how did it go?
most cells go through the Go phase. Some cells stay there permanently and others continue to the S phase but it's part of the cycle for all cells.
during mitosis, what is interphase doing?
Hi I am surian you mast proffesor
👍 👌 video but i have one question if the neurons stop dividing when they mature why are there older patients with brain tumors?
How do you know when a cell dose to the GNot Phase?
Tell me a better lecturer than this narrator.🙌🏽 Thanks bro.
🙏🙏✨
❤️❤️😍
Thank you :) I think there is a small mistake, the cell has 46 chromosomes in the nucleus, they come in 23 pairs and not 46 pairs !
imene ben but he said after replication
Exactly. Human cells have 46 chromosomes both before and after replication. The only thing that changes is that they become sister chromatids after they are replicated.
You guys ammuse me with your knowledge but it is actually 2 pairs of 23 chrmosomes which becomes 46. An average adult has a total of 23 chromosomes whereas an embryo is started with 46 chromosomes
@@michigan1085 still 23 PAIRS. Each pair just has 4 chromatids (2 chromatids per chromosome in each pair that are joined at a centromere so they look like 2 "x" side by side)
Daam right
During the S phase, It's the number of chromatids that double not chromosomes.
Its chromosomes actually. But its the same thing. Like 2 chromatids make a chromosome right?
How about Cytokinesis? The cytoplasm division? Isn't it included in the cell cycle?
Sir. As FROM THIS DEFINITION ;THE INTERPHASE IS THE INTERVAL BETWEEN TWO SUCCESSIVE DIVISIONS .🤔🤔🤔🤔🤔 Sir what are the names of these two successive divisions please let me know I am very confused
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👏
Does the S phase only happen to sex cells (gametes) or all cells experience it? The video explains "many" cells go in that direction but I thought it's only about sex cells. (Thanks superb clear explanation video!)
It occurs prior to mitosis and mitosis occurs in all cells
neurons do divide! Remember that.
Why can the cell in G0 back to G2?
And what is the different inside the cell that in G0 and G1?
You didn't mention the most important thing about cells division which is it how many times the one cell will dividing during the human life. and how long stay as a one cell particulary before dividing 😎
Khan academy is so wordy.
👍
Can anyone point me towards some independent cancer research publications? I've only found official publications from institutes of higher learning but I've never seen anyone actually independently work on this subject enough to correctly explain the science behind their research.
since a cell's diameter measures 100 micrometers and a micrometer is 10^-6 of a meter... at 1:40 shouldn't it be 1/10 000 of the human size?
how does the cell know that it needs to go into the next phase? why does the cycle not move backwards? how does the cell know?
there are different checkpoint during cell cycle where all the necessary stuff required for cell division check , if cell full all needs then it send to next step of cell division .
also there are different type of protein , enzymes and other things which act as regulator during cell division . you should search for cell cycle regulation at google
does that help?
I had paid a lot to my institute teacher to know what I can learn for absolutely free
Doesnt M-Phase consist of mitosis and cytokinesis? not just mitosis?
Harvard bouta not know what hit them 👊🏼
Dude, 5 feet = 2 meters hahaha
For reference, 2 meters are about 6 ft 6 or 6 ft 7.
I got a heart attack when you said the average person is 2 meters tall :D
even I got an attack when he said avg person is 2 meters coz I'm not even 1 meter and I thought... what the hell I'm not even a human or what?😂
@@nivedithapraisy6032 1 meter is 3'4" or 100 centimeters... There's no way you're shorter than that.
G is not for growth but for Gap
'round and around and around.....the cell cycle
Where does cytokinesis take place
What phase of chromatin can I see 30 nm fiber in the cell cycle?