Pratique du Shadowing: Mitosis: Splitting Up is Complicated - Crash Course Biology #12 - Apprendre l'anglais à l'oral avec la vidéo
Choisissez un mode d'entraînement
Chaque mode ouvre une salle d'entraînement en plein écran.
146 phrases
Si les phrases sont trop courtes ou trop longues, cliquez sur Edit pour les ajuster.
1
Now check this out.
2
Ha, cool huh?
3
I bet you wish you could do this.
4
Have a clone, clean up around the apartment for you, go to class, maybe take your mom out to dinner on her birthday.
5
Well, you can't do that, and actually there are some really good reasons why you can't do that.
6
We're gonna talk about those in the next episode.
7
But you know what can clone themselves?
8
Your cells.
9
Like almost every single one of them, and in fact, they're doing it right now.
10
For any creature bigger than a single -celled organism, all of life stems from cells' ability to reproduce themselves
11
because that's what allows organisms to develop and grow and heal and keep from dying for as long as possible.
12
This particular kind of cell division is called mitosis and it's responsible for a whole lot of your body's key functions.
13
If you get it cut, your body needs to make new cells.
14
Mitosis.
15
Have too much to drink?
16
Damage your liver?
17
You gotta replace those cells.
18
Mitosis.
19
Tumor growing in your spine?
20
Unfortunately, again, mitosis.
21
While you go from a seven pound baby to a 70 pound child, it's not your cells that are increasing in mass,
22
you're just getting more of them over and over and over again.
23
That's mitosis.
24
This process is so central to your life that it will take place in your body, over your lifetime, about 10 quadrillion times.
25
That's 10 ,000 billion times.
26
Like all split ups, it's not easy.
27
It's gonna maybe be a little bit messy.
28
There's a lot of drama and it can take a surprisingly long amount of time
29
But trust me after we're done with it.
30
We'll all be better off
31
So you are made of trillions of cells just like giraffes
32
and redwood trees and remember that inside each cell there's a nucleus
33
that stores your DNA which contains all of the instructions on how to build you.
34
That DNA is organized into chromosomes, and as we've mentioned before, in your body cells, or somatic cells, you have 46 chromosomes grouped into 23 pairs.
35
One in each pair is from your mom, and the other one is from your dad.
36
Cells with all 46 chromosomes are called diploid cells because they have two sets each, and that's what we're focusing on today.
37
You also have haploid cells that have half as many chromosomes as 23.
38
And those are your sex cells, they're produced in an equally fantastic process called meiosis, which we'll be talking about in the next episode.
39
But for now, the main thing to remember about mitosis is
40
that it allows one cell with 46 chromosomes to split into two cells that are genetically identical,
41
each with 46 chromosomes, all in order to keep the party of life going.
42
Now the nucleus in your cell controls everything that goes on in the cell, it has all the instructions necessary for making the cell survive,
43
so you don't need to duplicate the whole cell.
44
All you need to do is duplicate the DNA, get it wrapped up, and then if you have two separate pockets of DNA,
45
that's all you need to have two new cells.
46
Mitosis takes place in a series of discrete stages called prophase, metaphase, anaphase, and telophase.
47
And you could just say that over and over again and let it sink into your head.
48
And part of what's, you know, really amazing about this whole process is that while we know what these stages are,
49
we don't always know the underlying mechanisms that make all of them happen.
50
And this is part of science.
51
Science isn't like all the stuff we know, it's how we're trying to figure all this stuff out.
52
Consider it job security, if you ever want to be a biologist, there is a lot of stuff that future biologists have to still figure out.
53
And this is one of them.
54
Alright, let's get our clone on.
55
So most of their lives, cells hang out in this limbo period called interphase, which means they're in between episodes of mitosis.
56
Mostly growing and working and doing all the stuff that makes them useful to us.
57
During interphase, the long strings of DNA are loosely coiled and messy, like that dust bunny of dog fur and laundry lint under your bed.
58
That mess of DNA is called chromatin.
59
But as the mitosis process begins to gear up, lots of things start happening in the cell to get ready for the big division.
60
One of the more important things that happens is
61
that this little set of protein cylinders next to the nucleus called the centrosome duplicates itself.
62
We're gonna have to move a lot of stuff around in the nucleus, and that's gonna be regulated by these centrosomes.
63
The other thing that happens is that all of the DNA begins to replicate itself too, giving the cell two copies of every strand of DNA.
64
To brush up on how DNA replicates itself like this, check out this episode and then come on back.
65
Now the cell enters the first phase, or the prophase, when that mess of chromatin condenses
66
and coils up on itself to produce thick strands of DNA wrapped around proteins.
67
Those, my friends, are your chromosomes.
68
Instead of dust bunnies, the DNA is starting to look a little bit more like dreadlocks.
69
And the duplicates that have been made don't just float around freely.
70
They stay attached to the original, and together they look like little X's.
71
These are called the chromatids, and one copy is the left legging arm of the X, and the other copy is the right legging arm.
72
Where they meet in the middle is called the centromere.
73
Just so you know, these X's are also called chromosomes, sometimes double chromosomes or double -stranded chromosomes,
74
and when the chromatids separate.. they're considered individual chromosomes too.
75
Now while the chromosomes are forming, the nuclear envelope gets out of the way by like, completely disintegrating.
76
And the centrosomes then peel away from the nucleus, start heading to the opposite ends of the cell.
77
As they go, they leave behind a wide trail of protein ropes called microtubules, running from one centrosome to the other.
78
You might recall from our anatomy of the animal cell, that microtubules help provide a kind of structure to the cell.
79
This is exactly what they're doing here.
80
Now we reach the metaphase, which literally means after phase, and it's the longest phase of mitosis that can take up to 20 minutes.
81
During the metaphase, the chromosomes attach to those ropey microtubules right in the middle at their centromeres.
82
The chromosomes then begin to be moved around, and this seems to be being done by molecules called motor proteins.
83
And while we don't know too much about how these motors work, we do know, for instance,
84
that there are two of them on each side of the centromere.
85
These are called centromere -associated protein E.
86
So these motor proteins attached to the microtubule ropes basically serve to spool up the tubule slack.
87
At the same time, another protein called dynion is pulling up the slack from other ends of the ropes near the cell membranes.
88
After being pulled in this direction and that, the chromosomes line up right down the middle of the cell.
89
And that brings us to the latest installment of Biolography.
90
So how do chromosomes line up like that?
91
We know that there are motor proteins involved, but like, how?
92
What are they doing?
93
Well, remember when I said earlier that there were a lot of things that we don't totally understand about mitosis?
94
It's sort of weird that we don't, because we can literally watch mitosis happening under microscopes.
95
But chromosome alignment is a good example of a small detail that has only very recently been figured out.
96
And it was a revelation like 130 years in the making.
97
Mitosis was first observed by a German biologist by the name of Walter Fleming, who in 1878 was studying the tissue of salamander,
98
gills, and fins when he saw cells' nuclei split in two and migrate away from each other to form two new cells.
99
He called this process mitosis, after the Greek word for thread because of the messy jumble of chromatin,
100
a term he also coined that he saw in the nuclei.
101
But Fleming didn't pick up on the implications of this discovery for genetics, which was still a young discipline.
102
And over the next century, generations of scientists started piecing together the mitosis puzzle by determining the role of microtubules, say, or identifying motor proteins.
103
Now the most recent contribution to this research was made by a postdoctoral student named Tomomi Kiyomitsu at MIT.
104
He watched the same process that Fleming watched
105
and figured out how at least one of the motor proteins helped snap the chromosomes into line.
106
He was studying a motor protein called dynion, which sits on the inside of the membrane.
107
Think of the microtubules as tug -of -war ropes, with the chromosomes as the flag in the middle.
108
What Kiyomitsu discovered was that the Dainian plays tug -of -war with itself.
109
Dainian grabs onto one end of the microtubules and pulls the tubules and chromosomes toward one end of the cell.
110
When the ends of the microtubules come too close to the cell membrane,
111
they release a chemical signal that punts the Dainian to the other side of the cell.
112
There, it grabs onto the other end of the microtubules and starts pulling until until smack, it gets punted back again.
113
All of this ensures that the chromosomes will line up exactly in the middle, so that they will be split evenly.
114
That discovery was published in February of 2012, a couple of weeks before I sat down in this chair,
115
and 134 years after mitosis was first observed.
116
If you want to join the ranks of scientists who are answering the many questions left about mitosis
117
and lots of other things about our lives, maybe someday I'll do a biolography about you.
118
Now so far we've gone through the interphase, where the centrosomes in DNA replicate themselves and get ready for the split.
119
The prophase, where the chromosomes form and the centrosomes start to spread apart.
120
And the metaphase, where the chromosomes align in the middle of the cell.
121
And now it's time to separate the chromosomes from their copies.
122
This time, motor proteins start pulling so hard on the ropes
123
that the X -shaped chromosomes split back into their individual single chromosomes.
124
Once they're detached from each other, they're dragged toward either end of the cell.
125
Since the prefix ana means back, that may help you remember the name of this phase called anaphase.
126
After this, it's just a matter of using all that genetic material to rebuild,
127
so that the copied genetic material has all of the accoutrements of home.
128
In the last phase, telophase, each of the new cell structures are reconstructed.
129
First, the nuclear membrane reforms, the nucleoli form within them, and the chromosomes relax back into chromatin.
130
Then a little crease forms between the two new cells, which marks the beginning of the final split.
131
That division between the two new cells is called cleavage, and all that's left is to make a clean break.
132
This is done by cytokinesis, literally cell movement, by which the two new nuclei move apart from each other, and the cells separate.
133
We now have two new cells, each with a full set of 46 chromosomes.
134
These clones are called the daughter cells of the original cell,
135
and like identical twins, they are genetic copies of each other and also of their parents.
136
But of course, that's obviously not the case for you, even if you are an identical twin.
137
Shout out identical twins!
138
See me in the comments.
139
While you kind of are a clone of your sibling, you are not a clone of your parents.
140
Instead, half of your DNA in each of your cells is from your mom and half is from your dad.
141
To understand why that is, we have to understand how eggs and sperm are formed, and that is meiosis.
142
And that's what we're going to be talking about next week on Crash Course.
143
Until then, you can just watch this video over and over again,
144
or you can just watch the bits that you want to rewatch using our table of contents,
145
which is also available in the description for people who are using iPhones and can't click annotations.
146
If you have any questions, you can reach us on Facebook or on Twitter, or of course, in the comments below.
Télécharger l'application
Tout pour parler couramment
Prononciation IAChaque phrase notée
Phonétique (IPA)Maîtrisez chaque son
VocabulaireEnrichissez votre lexique
Jeu de vocabulaireApprenez en jouant
Même chaîne
C11
Meet Your Master - Getting to Know Your Brain: Crash Course Psychology #4
Daily ConversationUniversity Students
B21
The Bicameral Congress: Crash Course Government and Politics #2
Daily ConversationHigh School StudentsUniversity Students
B21
Crash Course US History Preview
Daily ConversationUniversity Students
C1What's all the Yellen About? Monetary Policy and the Federal Reserve: Crash Course Economics #10
Daily ConversationUniversity Students
C12
How Water Shapes the Land: Crash Course Geology #9
Daily ConversationUniversity Students
B210
Crash Course Sex Ed Preview
Daily ConversationUniversity StudentsWorking Adults
C12
Derivatives: Crash Course Physics #2
Daily ConversationUniversity Students
C13
Introduction to Astronomy: Crash Course Astronomy #1
Daily ConversationUniversity Students
C13
Indus Valley Civilization: Crash Course World History #2
Daily ConversationUniversity Students
B22
Ancient Egypt: Crash Course World History #4
Daily ConversationHigh School StudentsUniversity Students
C12
What is Engineering?: Crash Course Engineering #1
Business EnglishUniversity StudentsWorking Adults
B22
The Persians & Greeks: Crash Course World History #5
Cambridge Exam PrepHigh School StudentsUniversity Students
C13
The Secret to Business Writing: Crash Course Business - Soft Skills #3
Business EnglishUniversity StudentsWorking Adults
C12
Supervised Learning: Crash Course AI #2
Business EnglishUniversity StudentsWorking Adults
C1Why Are US Politics Today So Divisive?: Crash Course US Government #1
Daily ConversationUniversity Students
B22
Where Do Diamonds Come From?: Crash Course Geology #8
IELTS PrepTOEFL PrepCambridge Exam Prep
C11
Tissues, Part 1: Crash Course Anatomy & Physiology #2
Cambridge Exam PrepUniversity StudentsWorking Adults
C11
Psychological Research: Crash Course Psychology #2
Daily ConversationUniversity Students
C13
Where Did Democracy Come From, and Does It Still Work?
IELTS PrepTOEFL PrepUniversity Students
C12
The Nucleus: Crash Course Chemistry #1
IELTS PrepTOEFL PrepUniversity Students
FOR YOU
Vidéo recommandée
C182 phrases
Mitosis vs. Meiosis: Side by Side Comparison
Daily ConversationUniversity Students
C134
23 phrases
Happy Brain Chemicals: dopamine, serotonin, oxytocin, endorphin
Daily ConversationUniversity StudentsWorking Adults
C12
100 phrases
Epithelial Tissue
Daily ConversationUniversity Students
C12
799 phrases
Cell Biology | Cell Structure & Function
Daily ConversationUniversity Students
C12
64 phrases
We can cure almost all human diseases. Here’s how. | Albert-László Barabási
Daily ConversationUniversity Students
C12
32 phrases
RE2 Unit 9B
Daily ConversationUniversity Students
C11
99 phrases
PCR (Polymerase Chain Reaction)
Daily ConversationUniversity Students
C11
142 phrases
The Civil War, Part I: Crash Course US History #20
Daily ConversationHigh School StudentsUniversity Students
C121
14 phrases
Queen Ant Clones Another Species
Daily ConversationUniversity Students
C14
77 phrases
Why sex, food, and shelter aren’t enough for Homo Sapiens | Agustín Fuentes
Daily ConversationUniversity Students
C1170 phrases
Glycolysis
Daily ConversationUniversity Students
Vocabulaire et conseils d’expression pour cette leçon
Cette leçon d’expression orale s’appuie sur la vidéo « Mitosis: Splitting Up is Complicated - Crash Course Biology ». Les mots qui reviennent le plus souvent : cell, chromosome, mitosis, Dna, protein. Cette vidéo contient 146 phrases et 2110 mots à répéter en shadowing. La partie parlée dure 10:38. Le locuteur parle vite, environ 199 mots par minute : attendez-vous à des liaisons et à des sons réduits. 83 % des mots font partie des 3 000 mots les plus courants en anglais ; le reste mérite d’être vu avant de commencer.
Vocabulaire clé de cette vidéo
15 mots de la vidéo à retenir, avec leur prononciation et leur sens :
| Mot | Prononciation | Sens |
|---|---|---|
| nucleus nom | /ˈnuː.kli.əs/ | noyau |
| clone nom | /kloʊn/ | clone |
| rope nom | /ɹoʊp/ | corde |
| identical adjectif | /ɪˈdɛntɪkl̩/ | identique |
| duplicate verbe | /ˈd(j)uː.plɪˌkeɪt/ | copier, dupliquer |
| genetic adjectif | /d͡ʒəˈnɛt.ɪk/ | génétique |
| twin nom | /twɪn/ | jumeau, jumelle |
| messy adjectif | /ˈmɛsi/ | désordonné, désorganisé |
| membrane nom | /ˈmɛm.bɹeɪn/ | membrane |
| attach verbe | /əˈtæt͡ʃ/ | attacher |
| strand nom | /ˈstɹænd/ | brin, toron |
| replicate verbe | /ˈɹɛplɪkeɪt/ | répliquer |
| discovery nom | /dɪˈskʌv.ɹi/ | découverte |
| dust nom | /dʌst/ | poussière |
| scientist nom | /ˈsaɪəntəst/ | scientifique, savant |
Les verbes à particule que vous entendrez
| Mot | Prononciation | Sens |
|---|---|---|
| figure out verbe | cerner | |
| check out verbe | mater, regarder | |
| clean up verbe | nettoyer | |
| go through verbe | traverser | |
| leave behind verbe | abandonner | |
| pull up verbe | /ˌpʊl ˈʌp/ | soulever |
| wrap up verbe | emballer |
Des phrases à répéter
Des phrases courtes et complètes de la vidéo, à réutiliser dans la conversation de tous les jours :
- We're gonna talk about those in the next episode.
- Tumor growing in your spine?
- Alright, let's get our clone on.
- We know that there are motor proteins involved, but like, how?
La grammaire de cette vidéo
Les structures que le locuteur utilise le plus, avec les mots exacts de la vidéo :
| Structure | Dans la vidéo |
|---|---|
| Voix passive be + participe passé — l’accent est mis sur ce qui arrive, pas sur qui le fait | is called · are made · is organized |
| Present perfect have/has + participe passé — une action passée qui compte encore maintenant | we've mentioned · have been made · we've gone |
| Propositions relatives who / which + proposition — une précision sur une personne ou une chose | interphase, which means · genetics, which was · people who are |
Prononciation à surveiller
Le locuteur utilise 35 contractions et formes réduites, comme they're, don't, we're. Prononcez-les sous leur forme courte, telles que vous les entendez.
- Les sons « th »: thick /θɪk/, thread /ˈθɹɛd/
- Les sons « sh » et « zh »: instruction /ɪnˈstɹʌkʃən/, contribution /ˌkɑntɹɪˈbjuʃən/, tissue /ˈtɪʃ.(j)u/, brush /bɹʌʃ/, shout /ʃaʊt/
- Mots longs — placez bien l’accent: organism /ˈɔɹ.ɡəˌnɪz.əm/, contribution /ˌkɑntɹɪˈbjuʃən/, mechanism /ˈmɛk.ə.nɪ.zəm/, surprisingly /səˈpɹaɪzɪŋli/, revelation /ˌɹɛv.əˈleɪ.ʃən/
Les sons difficiles pour les francophones :
- /h/ — il se souffle, il n’est pas muet: heal /ˈhiːl/, haploid /ˈhæplɔɪd/
- /tʃ/ et /dʒ/ — à ne pas adoucir en « ch » et « j »: genetic /d͡ʒəˈnɛt.ɪk/, attach /əˈtæt͡ʃ/, genetics /dʒəˈnɛt.ɪks/, genetically /d͡ʒəˈneɾɪkli/, biologist /baɪˈɒləd͡ʒɪst/
- /r/ anglais — langue recourbée, sans frotter la gorge: rope /ɹoʊp/, membrane /ˈmɛm.bɹeɪn/, strand /ˈstɹænd/, replicate /ˈɹɛplɪkeɪt/, discovery /dɪˈskʌv.ɹi/
Comment s’entraîner avec cette vidéo
- Écoutez la vidéo en entier une fois sans parler et notez les mots que vous ne connaissez pas.
- Commencez à la vitesse 0,75×, répétez phrase par phrase, puis revenez à la vitesse normale quand cela devient facile.
- Enregistrez-vous et comparez avec l’original, en faisant attention à des mots comme nucleus, clone, rope.
Qu'est-ce que la technique du Shadowing ?
Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.