Pratica di Shadowing: Mitosis: Splitting Up is Complicated - Crash Course Biology #12 - Impara a parlare inglese con i video

Scegli una modalità di pratica

Ogni modalità apre una sala di pratica a schermo intero.

146 frasi

Se le frasi sono troppo corte o troppo lunghe, clicca su Edit per modificarle.

Now check this out.

Ha, cool huh?

I bet you wish you could do this.

Have a clone, clean up around the apartment for you, go to class, maybe take your mom out to dinner on her birthday.

Well, you can't do that, and actually there are some really good reasons why you can't do that.

We're gonna talk about those in the next episode.

But you know what can clone themselves?

Your cells.

Like almost every single one of them, and in fact, they're doing it right now.

For any creature bigger than a single -celled organism, all of life stems from cells' ability to reproduce themselves

because that's what allows organisms to develop and grow and heal and keep from dying for as long as possible.

This particular kind of cell division is called mitosis and it's responsible for a whole lot of your body's key functions.

If you get it cut, your body needs to make new cells.

Mitosis.

Have too much to drink?

Damage your liver?

You gotta replace those cells.

Mitosis.

Tumor growing in your spine?

Unfortunately, again, mitosis.

While you go from a seven pound baby to a 70 pound child, it's not your cells that are increasing in mass,

you're just getting more of them over and over and over again.

That's mitosis.

This process is so central to your life that it will take place in your body, over your lifetime, about 10 quadrillion times.

That's 10 ,000 billion times.

Like all split ups, it's not easy.

It's gonna maybe be a little bit messy.

There's a lot of drama and it can take a surprisingly long amount of time

But trust me after we're done with it.

We'll all be better off

So you are made of trillions of cells just like giraffes

and redwood trees and remember that inside each cell there's a nucleus

that stores your DNA which contains all of the instructions on how to build you.

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.

One in each pair is from your mom, and the other one is from your dad.

Cells with all 46 chromosomes are called diploid cells because they have two sets each, and that's what we're focusing on today.

You also have haploid cells that have half as many chromosomes as 23.

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.

But for now, the main thing to remember about mitosis is

that it allows one cell with 46 chromosomes to split into two cells that are genetically identical,

each with 46 chromosomes, all in order to keep the party of life going.

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,

so you don't need to duplicate the whole cell.

All you need to do is duplicate the DNA, get it wrapped up, and then if you have two separate pockets of DNA,

that's all you need to have two new cells.

Mitosis takes place in a series of discrete stages called prophase, metaphase, anaphase, and telophase.

And you could just say that over and over again and let it sink into your head.

And part of what's, you know, really amazing about this whole process is that while we know what these stages are,

we don't always know the underlying mechanisms that make all of them happen.

And this is part of science.

Science isn't like all the stuff we know, it's how we're trying to figure all this stuff out.

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.

And this is one of them.

Alright, let's get our clone on.

So most of their lives, cells hang out in this limbo period called interphase, which means they're in between episodes of mitosis.

Mostly growing and working and doing all the stuff that makes them useful to us.

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.

That mess of DNA is called chromatin.

But as the mitosis process begins to gear up, lots of things start happening in the cell to get ready for the big division.

One of the more important things that happens is

that this little set of protein cylinders next to the nucleus called the centrosome duplicates itself.

We're gonna have to move a lot of stuff around in the nucleus, and that's gonna be regulated by these centrosomes.

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.

To brush up on how DNA replicates itself like this, check out this episode and then come on back.

Now the cell enters the first phase, or the prophase, when that mess of chromatin condenses

and coils up on itself to produce thick strands of DNA wrapped around proteins.

Those, my friends, are your chromosomes.

Instead of dust bunnies, the DNA is starting to look a little bit more like dreadlocks.

And the duplicates that have been made don't just float around freely.

They stay attached to the original, and together they look like little X's.

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.

Where they meet in the middle is called the centromere.

Just so you know, these X's are also called chromosomes, sometimes double chromosomes or double -stranded chromosomes,

and when the chromatids separate.. they're considered individual chromosomes too.

Now while the chromosomes are forming, the nuclear envelope gets out of the way by like, completely disintegrating.

And the centrosomes then peel away from the nucleus, start heading to the opposite ends of the cell.

As they go, they leave behind a wide trail of protein ropes called microtubules, running from one centrosome to the other.

You might recall from our anatomy of the animal cell, that microtubules help provide a kind of structure to the cell.

This is exactly what they're doing here.

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.

During the metaphase, the chromosomes attach to those ropey microtubules right in the middle at their centromeres.

The chromosomes then begin to be moved around, and this seems to be being done by molecules called motor proteins.

And while we don't know too much about how these motors work, we do know, for instance,

that there are two of them on each side of the centromere.

These are called centromere -associated protein E.

So these motor proteins attached to the microtubule ropes basically serve to spool up the tubule slack.

At the same time, another protein called dynion is pulling up the slack from other ends of the ropes near the cell membranes.

After being pulled in this direction and that, the chromosomes line up right down the middle of the cell.

And that brings us to the latest installment of Biolography.

So how do chromosomes line up like that?

We know that there are motor proteins involved, but like, how?

What are they doing?

Well, remember when I said earlier that there were a lot of things that we don't totally understand about mitosis?

It's sort of weird that we don't, because we can literally watch mitosis happening under microscopes.

But chromosome alignment is a good example of a small detail that has only very recently been figured out.

And it was a revelation like 130 years in the making.

Mitosis was first observed by a German biologist by the name of Walter Fleming, who in 1878 was studying the tissue of salamander,

gills, and fins when he saw cells' nuclei split in two and migrate away from each other to form two new cells.

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.

Scarica l'app

Tutto ciò che serve per parlare fluentemente

Pronuncia con IAVoto per ogni frase

Pratica IPAPadroneggia ogni suono

VocabolarioCostruisci il tuo lessico

Gioco di vocabolarioImpara giocando

Scansiona QR

Download on theApp Store Get it onGoogle Play

Stesso Canale

The Bicameral Congress: Crash Course Government and Politics #2

Daily ConversationHigh School StudentsUniversity Students

Crash Course US History Preview

Daily ConversationUniversity Students

What's all the Yellen About? Monetary Policy and the Federal Reserve: Crash Course Economics #10

Daily ConversationUniversity Students

Defense Against the Dark Arts of Influence: Crash Course Business Soft Skills #2

Business EnglishUniversity StudentsWorking Adults

FOR YOU

Video consigliato

82 frasi

Mitosis vs. Meiosis: Side by Side Comparison

Daily ConversationUniversity Students

77 frasi

Why sex, food, and shelter aren’t enough for Homo Sapiens | Agustín Fuentes

Daily ConversationUniversity Students

14 frasi

Queen Ant Clones Another Species

Daily ConversationUniversity Students

100 frasi

Epithelial Tissue

Daily ConversationUniversity Students

685 frasi

Editing Your DNA, with Nobel Prize Winner Dr. Jennifer Doudna

Daily ConversationUniversity Students

799 frasi

Cell Biology | Cell Structure & Function

Daily ConversationUniversity Students

32 frasi

RE2 Unit 9B

Daily ConversationUniversity Students

170 frasi

Glycolysis

Daily ConversationUniversity Students

50 frasi

We Fell For The Oldest Lie On The Internet

Daily ConversationUniversity StudentsWorking Adults

298 frasi

GENERAL CHEMISTRY explained in 19 Minutes

Daily ConversationUniversity Students

153 frasi

The Neuroscience of Love and Attachment: Oxytocin, Vasopressin, and Dopamine's Role in Bonding

Daily ConversationUniversity StudentsWorking Adults

Vocabolario e note di pronuncia per questa lezione

Questa lezione di conversazione si basa sul video “Mitosis: Splitting Up is Complicated - Crash Course Biology”. Le parole che ritornano più spesso: cell, chromosome, mitosis, Dna, protein. Questo video contiene 146 frasi e 2110 parole da ripetere con lo shadowing. Il parlato dura 10:38. Chi parla va veloce, circa 199 parole al minuto: aspettati suoni legati e ridotti. Il 83% delle parole rientra nelle 3.000 più comuni dell’inglese; conviene studiare le altre prima di iniziare.

Vocaboli chiave di questo video

15 parole del video che vale la pena imparare, con pronuncia e significato:

Parola	Pronuncia	Significato
nucleus sostantivo	/ˈnuː.kli.əs/	nucleo
clone sostantivo	/kloʊn/	clone
rope sostantivo	/ɹoʊp/	corda, cavo
identical aggettivo	/ɪˈdɛntɪkl̩/	identico
duplicate verbo	/ˈd(j)uː.plɪˌkeɪt/	duplicare
genetic aggettivo	/d͡ʒəˈnɛt.ɪk/	genetico
twin sostantivo	/twɪn/	gemello, gemella
messy aggettivo	/ˈmɛsi/	disordinato
membrane sostantivo	/ˈmɛm.bɹeɪn/	membrana
attach verbo	/əˈtæt͡ʃ/	legare, appiccare
strand sostantivo	/ˈstɹænd/	filo
replicate verbo	/ˈɹɛplɪkeɪt/	replicare
discovery sostantivo	/dɪˈskʌv.ɹi/	scoperta, scoprimento
dust sostantivo	/dʌst/	polvere
scientist sostantivo	/ˈsaɪəntəst/	scienziato, scienziata

I phrasal verb che sentirai

Parola	Pronuncia	Significato
figure out verbo		scoprire, rendersi conto
line up verbo	/laɪnˈʌp/	allineare
check out verbo		investigare
clean up verbo		ripulire
go through verbo		attraversare
wrap up verbo		imballare, impacchettare

Frasi da ripetere

Frasi brevi e complete del video che puoi riutilizzare nella conversazione di tutti i giorni:

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 grammatica di questo video

Le strutture che chi parla usa di più, con le parole esatte del video:

Struttura	Nel video
Forma passiva be + participio passato — conta ciò che accade, non chi lo fa	is called · are made · is organized
Present perfect have/has + participio passato — un’azione passata che conta ancora adesso	we've mentioned · have been made · we've gone
Frasi relative who / which + frase — un’informazione in più su una persona o una cosa	interphase, which means · genetics, which was · people who are

Pronuncia a cui fare attenzione

Chi parla usa 35 contrazioni e forme ridotte, come they're, don't, we're. Pronunciale nella forma breve, così come le senti.

I suoni “th”: thick /θɪk/, thread /ˈθɹɛd/
I suoni “sh” e “zh”: instruction /ɪnˈstɹʌkʃən/, contribution /ˌkɑntɹɪˈbjuʃən/, tissue /ˈtɪʃ.(j)u/, brush /bɹʌʃ/, shout /ʃaʊt/
Parole lunghe — attenzione all’accento: organism /ˈɔɹ.ɡəˌnɪz.əm/, contribution /ˌkɑntɹɪˈbjuʃən/, mechanism /ˈmɛk.ə.nɪ.zəm/, surprisingly /səˈpɹaɪzɪŋli/, revelation /ˌɹɛv.əˈleɪ.ʃən/

I suoni difficili per chi parla italiano:

/h/ — va soffiata, non è muta: heal /ˈhiːl/, haploid /ˈhæplɔɪd/
Consonante finale — senza aggiungere una vocale dopo: nucleus /ˈnuː.kli.əs/, rope /ɹoʊp/, duplicate /ˈd(j)uː.plɪˌkeɪt/, genetic /d͡ʒəˈnɛt.ɪk/, attach /əˈtæt͡ʃ/
/æ/ — più aperta della “e”: attach /əˈtæt͡ʃ/, strand /ˈstɹænd/, wrap /ɹæp/, slack /slæk/, rank /ˈɹæŋk/

Come esercitarsi con questo video

Ascolta tutto il video una volta senza parlare e annota le parole che non conosci.
Inizia a velocità 0,75×, fai shadowing frase per frase e torna alla velocità normale quando diventa facile.
Registrati e confronta con l’originale, facendo attenzione a parole come nucleus, clone, rope.

Cos'è la tecnica dello Shadowing?

Shadowing è una tecnica di apprendimento delle lingue supportata da studi scientifici, originariamente sviluppata per la formazione dei traduttori professionisti e resa popolare dal poliglotta Dr. Alexander Arguelles. Il metodo è semplice ma potente: ascolti un audio in inglese di madrelingua e lo ripeti immediatamente ad alta voce — come un'ombra che segue il parlante con un ritardo di solo 1–2 secondi. A differenza dell'ascolto passivo o degli esercizi di grammatica, lo shadowing costringe il tuo cervello e i muscoli della bocca a elaborare e riprodurre simultaneamente i modelli di discorso reale. La ricerca dimostra che migliora significativamente la precisione della pronuncia, l'intonazione, il ritmo, il discorso connesso, la comprensione dell'ascolto e la fluidità del parlato — rendendolo uno dei metodi più efficaci per la preparazione alla prova di speaking dell'IELTS e per la comunicazione reale in inglese.

Tecnica dello shadowing: leggi la guida completa passo dopo passo →

Pratica di Shadowing: Mitosis: Splitting Up is Complicated - Crash Course Biology #12 - Impara a parlare inglese con i video

Scegli una modalità di pratica

Scarica l'app

The Bicameral Congress: Crash Course Government and Politics #2

Crash Course US History Preview

What's all the Yellen About? Monetary Policy and the Federal Reserve: Crash Course Economics #10

How Water Shapes the Land: Crash Course Geology #9

How Often do Asteroids Hit the Earth?: Crash Course Geology #20

Crash Course Sex Ed Preview

Derivatives: Crash Course Physics #2

Indus Valley Civilization: Crash Course World History #2

Ancient Egypt: Crash Course World History #4

What is Engineering?: Crash Course Engineering #1

The Persians & Greeks: Crash Course World History #5

The Secret to Business Writing: Crash Course Business - Soft Skills #3

Supervised Learning: Crash Course AI #2

Why Are US Politics Today So Divisive?: Crash Course US Government #1

The Periodic Table: Crash Course Chemistry #4

Where Do Diamonds Come From?: Crash Course Geology #8

Tissues, Part 1: Crash Course Anatomy & Physiology #2

Where Did Democracy Come From, and Does It Still Work?

The Nucleus: Crash Course Chemistry #1

Defense Against the Dark Arts of Influence: Crash Course Business Soft Skills #2

Mitosis vs. Meiosis: Side by Side Comparison

Why sex, food, and shelter aren’t enough for Homo Sapiens | Agustín Fuentes

Queen Ant Clones Another Species

Epithelial Tissue

Editing Your DNA, with Nobel Prize Winner Dr. Jennifer Doudna

Cell Biology | Cell Structure & Function

RE2 Unit 9B

Glycolysis

We Fell For The Oldest Lie On The Internet

GENERAL CHEMISTRY explained in 19 Minutes

The Neuroscience of Love and Attachment: Oxytocin, Vasopressin, and Dopamine's Role in Bonding

Vocabolario e note di pronuncia per questa lezione

Vocaboli chiave di questo video

I phrasal verb che sentirai

Frasi da ripetere

La grammatica di questo video

Pronuncia a cui fare attenzione

Come esercitarsi con questo video

Cos'è la tecnica dello Shadowing?