Cell cycle phases | Cells | MCAT | Khan Academy
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- Опубликовано: 30 сен 2024
- Learn about the different "seasons" of a cell's life and how it grows with time. By Raja Narayan. Visit us (www.khanacademy...) for health and medicine content or (www.khanacademy...) 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?
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
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
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!!!
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'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 😭
you already know I have a test in pre-ap bio in 5 minutes so im cramming super quick
How did your test go?
Perfect introductory explanation! I'm continuing zoology after a two years of break. Thank you Khan academy
The way you explained this was pure love!
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?
Perfect explanation ......better than a 3 hours lecture !!
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.
I can finally ACE my FINALS! Thank you so much!
Laila Almaliki بالتوفيق
That synthesis phase was wrong...i guess because your chromosome number remains constant whereas your dna duplicates🤷
Hi I am surian you mast proffesor
wait, 2meters tall? a person? I'm only 150cm tall....
wow, great video!!!
So clear and straightforward! Congrats!
Correction: the number of chromosomes does not double in S phase, that's just fundamentally wrong. In the S phase the DNA replicates itself and each chromosome splits into 2 sister chromatids but the no. of chromosomes remains the same.
If chromosomes replicates itself, how the number of chromosomes do not get doubled? 🤔
@@asiandiana6257 When a chromosome is said to be "replicated" that doesn't mean it doubled in number, it means that the chromatid has been doubled. Look, a chromosome can either have 1 chromatid or 2 chromatids, during cell replication, chromatids double so that they form for us a chromosome consisting of 2 chromatids.
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
Average person’s height is a little less than 2 meters? I think you meant like 30 cm less
This sounds so simple yet my textbook and my teacher makes it seem so complicated
What grade are u in?
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 😎
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?
All of these are in IB Biology, while others study this in universities.. :(
This is probably the most basic and core topics in Med University exams.
Zetsuke4 there's no way this stuff is ib for you. This is easy as shit.
Rahul Bargujar we review it for like 15 minutes and it's a very little part of all the thingfs we have to know you idiot.
ha i'm the idiot
Zetsuke4 I study this in high school.. I'm a senior
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?
Khan academy is so wordy.
awesome man, have a look at my channel, let me know what you think, i've just started
5 feet is not 'about 2 metres' hahahaha. It's just over 1.5m ... 0:04
1.5 m rounds up to 2
@@n1ghtmar331 there's a big difference between 1.5m and 2m! you can't just 'round it up' in this case.
i didn't get the part of synthesis like from 23 pairs to 46 pairs? it's always 23 pairs i thought with the number of chromatids and not chromosomes duplicated. i also found in many french biology material that once a cell enters G1 it doesn't get back to G0 instead it's stuck in G1 in case of neurons for example. i wonder if that's true. other than this couple of remarks , i love this platform and i'm grateful that it exists. i study in french but i find it easy to understand you. merciiiii infiniment
Heyy...isn't the S phase wrong🤔..meaning to say ..the chromosome number Remains The Same and the DNA replicates???
I wanted to ask why you wrote 46 pairs of chromosomes in the S phase when the number of chromosomes in the S phase remains the same just the amount of DNA gets doubled. I am confused.
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.
thank you so much for this simple explanation, I understood this a lot better than the 2hour lecture my professor gave
At 3:51 second its wrong from 23 pairs to 46 pairs after dna replication ok
Even after dna replication its still 23 pairs but each chromosome or to be precise chromatin in every pairs has copy of dna.
How it can be 46 pairs chromosomes in S phase ?? Only amount of Dna doubles not chromosomes ..number
The average person is little less than 2 meters tall?? No, 1.65 cm is average. A little less than 2 m is a tall person. Just throwing this there before I continue the video
Thank you. Gid bless this institution.
neurons do divide! Remember that.
Hi, I am preparing for medical school. Anyone wanna be friends so we can group study?
When someone said you can't explain 2 hours shit in just five minutes, this dear teacher said- you bet?
best explanation video for non science background people despite the fact its a really difficult concept
Thank u sooo sooo much Sir This literally helped so much :)
Thank you so much for this video I needed this ❤️❤️
Cell phases is
1. Interphase
2. Growth cell
3. DNA
4. Meiosis
5. Mitosis
6. ?
2 METERS IS THE AVERAGE HEIGHT OF A HUMAN??? LeBron James height is 2 meters.
thank you sooo sound and understandable!
Neurons do divide, if you don't drink alcohol and if you don't eat carbohydrates. Read Dr David Perlmutter's Grain Brain
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
I don't know why all the comments are full of mistake of 2m why dont you clear your concept rather than talking about mistake made by him😞😡😡
Ugh the teacher torched me and put this on the quiz i didn't study for this nor I had the materials wow..............
You should keep it up (:
How about Cytokinesis? The cytoplasm division? Isn't it included in the cell cycle?
simply uh-mazing!!! fricking easy to understand :)
You probably should have said "diameter" instead of "size" at 43 seconds
Most confusing diagram ive ever seen...
You have skipped cytokinesis😔
An avarage persen is not "littleless than 2m tall"
oh my god this is so much easier to understand 😭
Medicine students do not have much time to listen unnecessary discussion please get quickly to the topic in your next videos.
A 2-meter female is pretty hard to find.
Wait why In my book that making protein in (s period )not (g period )?! Now I’m confused
I don't get how he converted to get 1/1,000,000
when ur lowkey learning this as a freshman in bio honors lol
why not high key?
Idk bout you guys I'm learning this in 6th grade, (middle school)
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.
is it bad that i giggled when he said "ur mom"
Why can the cell in G0 back to G2?
And what is the different inside the cell that in G0 and G1?
👍 👌 video but i have one question if the neurons stop dividing when they mature why are there older patients with brain tumors?
I had paid a lot to my institute teacher to know what I can learn for absolutely free
during mitosis, what is interphase doing?
Avarage person 2 m
Me: don’t cry, don’t cry donttt
Tell me a better lecturer than this narrator.🙌🏽 Thanks bro.
A two meter "average" human is very tall !!! 6'8'' .......
ap bio final tomorrow and im ready to fail ha
Who else is here due to COVID canceling their classes?
can you not write like that please
im from egypt and i thank you for your explain is very good
you sound like sal khan a little bit.
What phase of chromatin can I see 30 nm fiber in the cell cycle?
well done khan I understood it from you more than our professor
Very short and simple... Thanks... Have a test on it tomorrow 😌
What about cytokinesis?
That's the last step
How is inter and G1 both phases a place were cells spend most of the time?
interphase is the place were cells spend most of the time compared to M phase ...and G1 is the place were cells spend most of the time compared to S and G2 phases of interphase .
Holy shit 5ft =2 metres XD my brain
it's called the mitotic phase, mitosis is just the nucleus
5ft isnt 2m and an average person isnt 2m height.
Doesnt M-Phase consist of mitosis and cytokinesis? not just mitosis?
did he say 5 feet is 2 m bro i WISH
Khan academy sucks so bad
Great
2 metres is 6 and a half foot ... not "just over 5ft"
Thx
Too much talk get to the point
i love how i can understand this 5 min more than a 1 hour lesson
Sal said a little LESS than 2m and not exactly 2m.
Excellent breakdown.
*tinder logic* is a little over 5 feet or about 2 meters tall
The mitotic phase and mitosis are not the same, my friend.