Pratica di Shadowing: Glycolysis - Impara a parlare inglese con i video
Scegli una modalità di pratica
Ogni modalità apre una sala di pratica a schermo intero.
170 frasi
Se le frasi sono troppo corte o troppo lunghe, clicca su Edit per modificarle.
1
Welcome back to the high -yield biochemistry series.
2
This is brought to you by Dirty Medicine.
3
In today's video, we're going to continue our discussion about the biochemical pathways and talk about glycolysis.
4
Glycolysis is typically the first biochemical pathway that you learn when you're learning about biochemistry, and it's because of that that it's extremely high -yield.
5
It shows up on exams all of the time.
6
Now, when you're learning about glycolysis, as you'll see me mention throughout this video, it's really important to remember the bigger picture.
7
And when I say that, I'm referring to things like what is the function or the role of glycolysis?
8
What are we taking as a reactant and turning into a product?
9
And what are the regulatory mechanisms in terms of feedback?
10
So what makes this go forward?
11
What inhibits this?
12
And what is the rate limiting enzyme?
13
Just like all of the biochemistry videos that I've created, you need to know the rate -limiting enzyme and the regulatory mechanisms.
14
So we're talking about things like inhibitors, etc. So let's start with a quick overview of glycolysis.
15
Glycolysis is an irreversible biochemical reaction that occurs in the cytoplasm.
16
The net equation for glycolysis is that you start with glucose, and the goal is to take that glucose and turn it into pyruvate,
17
where it can downstream take multiple pathways through that pyruvate pathway
18
and preferentially usually this goes into the citric acid cycle
19
but here's the net equation you've you start with glucose
20
and you add two phosphates two adps and two nads
21
and what you get out of
22
that is two 2 pyruvates plus 2 ATPs plus 2 NADH plus 2 hydrogens plus 2 waters.
23
But if you wanted to just think very simply about what glycolysis is doing,
24
it's taking glucose and breaking that glucose down into storable products that the body can use in other biochemical pathways.
25
So now that we've understood the overview of glycolysis, let's just get into the meat and potatoes here.
26
We're going to talk about the pathway.
27
You need to understand the pathway, and I'm going to pay very special attention to the regulatory mechanisms of this pathway and the rate -limiting enzyme.
28
So you start with glucose, right?
29
Any person takes a bite of a cheeseburger, eats a french fry, drinks a milkshake, and they've got a bunch of carbohydrate in their body.
30
And that carbohydrate is composed usually of glucose.
31
And if it's not of glucose, then the other types of sugars will get turned into glucose so
32
that glycolysis can utilize
33
it the first step is glucose will get turned into glucose
34
6 -phosphate glucose 6 -phosphate will get turned into fructose
35
6 -phosphate fructose 6 -phosphate will get turned into fructose 1 -6 -bisphosphate
36
and now you've got like multiple steps
37
that are going to happen there's going to be four
38
or five more reactions in this pathway and you'll end up with phosphoenolpyruvate which will get turned into pyruvate.
39
And going from glucose down to pyruvate is the entire glycolysis pathway.
40
So when you get to pyruvate you're basically finished with glycolysis.
41
Now let's talk about the important enzymes that you need to know.
42
So the first step that converts glucose to glucose 6 -phosphate, there's actually two different enzymes
43
that can be used depending on the circumstances of the glucose concentration and where in the body we're talking about.
44
So those two enzymes are glucokinase and hexokinase.
45
So to be perfectly clear, either glucokinase or hexokinase can convert glucose to glucose 6 -phosphate.
46
And what you'll need to know for test day that's really high yield is to understand under
47
which circumstances both of these enzymes might be used.
48
So for glucokinase, this enzyme has a low affinity and a high
49
Km, Just remember the reciprocal relationship between affinity and Km.
50
The higher the Km, the lower the enzyme has an affinity for its substrate.
51
So glucokinase has a low affinity for glucose.
52
It typically doesn't want to go and grab glucose.
53
And the reason for this is because glucokinase acts as a glucose sensor.
54
It's present in the liver and the pancreatic beta cells, and it's only used when glucose is at high concentrations.
55
So basically what you should think of glucokinase as is an emergency enzyme that is acting as a glucose sensor.
56
And it's really not grabbing glucose because instead of grabbing glucose and breaking it down through glycolysis,
57
what it's doing is it's sensing glucose and it's going, okay, let's test how much glucose is over here.
58
uh that's okay we're not going to jump in yet um hexokinase you go first
59
so hexokinase on the other hand that is a high affinity enzyme
60
which means it has a low km and
61
because it has high affinity for its substrate hexokinase is the one that's constantly going to be latching onto glucose
62
and converting it to glucose 6 -phosphate and sending it down the glycolysis pathway
63
and the reason for that is because hexokinase is the enzyme that's used to operate the basal glucose metabolism.
64
So constantly throughout your body in all of your tissues, you have this enzyme hexokinase that's just keeping a basal level of glucose metabolism present.
65
It's trying to make sure that your glucose level is adequate throughout the body in all of the tissues.
66
But if hexokinase becomes overwhelmed because suddenly there's a massive influx of glucose, that is when hexokinase turns to glucokinase and says,
67
glucose, I know you usually have a low affinity, but I really need some help now because the glucose concentration is high.
68
So if you think about it, that's the reason that glucokinase is only found in the liver and the pancreatic beta cells,
69
because it does a very specific regulatory job where it's only acting when the blood glucose levels are super, super high.
70
When that concentration reaches some critical point, that's when glucokinase in the liver and the pancreatic beta cells jumps in to save hexokinase.
71
So the takeaway from this slide is that both glucokinase
72
and hexokinase are enzymes that catalyze that conversion from glucose to glucose 6 -phosphate.
73
The only difference is that hexokinase is kind of there all of the time, making a basal level of glucose, and glucokinase jumps in in emergencies.
74
But understand the differences between those two enzymes that I've put in the gray boxes.
75
They are extremely high yield and probably will show up on your test.
76
So here's where we are.
77
We've talked about the enzymes in the first step.
78
The enzyme that converts fructose 6 -phosphate to fructose 1 ,6 -bisphosphate is the rate -limiting enzyme of glycolysis,
79
and that's phosphofructokinase 1.
80
Sometimes you'll hear this referred to as PFK1.
81
So PFK1, or phosphofructokinase 1, is the rate -limiting enzyme, and it converts fructose 6 -phosphate to fructose 1 ,6 -bisphosphate.
82
Now, I told you at the start of this video
83
that the very important thing to keep in mind for USMLE and Comlex is the regulatory mechanisms.
84
And what I mean when I say regulatory mechanisms are what inhibits this pathway and what promotes this pathway.
85
And we're going to talk about that for the first time right here.
86
And because phosphofructokinase 1 is the rate -limiting enzyme,
87
it's really high yield to understand what inhibits phosphofructokinase 1 and what promotes phosphofructokinase 1.
88
And that's what you see here.
89
So ATP and citrate will inhibit the rate -limiting enzyme PFK1,
90
but AMP will promote the rate -limiting enzyme of PFK1.
91
And this should be somewhat intuitive to you.
92
So think about what glycolysis is doing.
93
The role of glycolysis is to take glucose, convert it to pyruvate and ATP,
94
and then let that pyruvate enter one of many different pathways, but usually the citric acid cycle where you'll then create citrate.
95
So if you think about that,
96
the question becomes, what would this pathway want to do if it already had ATP and therefore didn't need to make it,
97
or if it already had citrate and therefore didn't need to make pyruvate, which would then go to citrate.
98
And that's why ATP and citrate inhibit PFK1, because if you have ATP and you already have citrate, then you don't need to do glycolysis.
99
So the presence of those products will inhibit the rate -limiting enzyme, and therefore glycolysis won't occur.
100
Now, likewise, think about AMP.
101
If you have AMP, which is monophosphate, only one, you don't have ATP.
102
And therefore, if you don't have ATP, you want to do glycolysis.
103
So in the presence of AMP, which is to say in a situation where you don't have ATP,
104
AMP will promote PFK1 and will therefore promote glycolysis.
105
So anytime you're not really sure about how the regulatory mechanisms are working, think about this intuitively.
106
Ask yourself on test say, well, would glycolysis happen if there was AMP?
107
Would glycolysis happen if there was citrate?
108
It should make sense to you if you understand what the big picture role of these pathways are.
109
So that's what promotes and inhibits PFK1.
110
Now I need to pause for a second and tell you about this little nuance of glycolysis.
111
So fructose 6 -phosphate can go to fructose 1 ,6 -bisphosphate as you see on this slide.
112
But additionally, there's sort of a side step that occurs, a pivot if you will.
113
Fructose 6 -phosphate can also become fructose 2 ,6 -bisphosphate.
114
And if fructose 6 -phosphate will become fructose 2 ,6 -bisphosphate,
115
the enzyme that catalyzes this conversion is phosphofructokinase 2, PFK2.
116
So very similarly named, of course, to the rate limiting enzyme that we just talked about, but instead of 1, it's 2.
117
So when this happens, you create fructose 2 ,6 -bisphosphate.
118
And interestingly, that fructose 2 ,6 -bisphosphate will promote PFK1.
119
So the goal when the body does this is to make glycolysis happen faster.
120
Now the question then becomes what is promoting or inhibiting phosphofructokinase 2 or PFK2?
121
And that's really simple.
122
So it's going to be inhibited by glucagon and it's going to be promoted by insulin.
123
So think about it.
124
If fructose 2 ,6 -bisphosphate makes glycolysis happen faster.
125
And in glycolysis, you're breaking down glucose.
126
It makes sense that insulin will promote PFK2 because in the presence of glucose,
127
the body's going to secrete insulin and the body's telling anything that any cell that has a glycolysis pathway occurring, it's like, yo, take that glucose,
128
break it down, please get this out of the system.
129
And that's insulin's role.
130
The opposite of that is glucagon.
131
Glucagon's putting the brakes on this pathway and saying, yo, chill, we need to reverse this and make energy available because blood glucose is low.
132
So think about it, guys.
133
Insulin will promote PFK2 because it will make fructose 2 ,6 -bisphosphate, which feeds back to PFK1 and makes this happen faster.
134
But in another situation, glucagon will inhibit PFK2 because PFK2 would normally make fructose 2 ,6 -bisphosphate,
135
which would feed back to PFK1 and make this process happen faster.
136
So again, understanding the big picture about what glycolysis is actually doing helps you understand the regulatory mechanisms
137
that you need to memorize for your test.
138
So the takeaway from this slide is that PFK2 inhibited by glucagon and promoted by insulin.
139
The last enzyme that we need to talk about is the enzyme that converts phosphoenolpyruvate to pyruvate, the last step of glycolysis.
140
That enzyme is pyruvate kinase.
141
And just like PFK1, this is going to be inhibited by ATP and citrate for the same exact reasons.
142
And those reasons are, again, glycolysis wants to create ATP.
143
Glycolysis wants to make pyruvate, which can then become citrate in the TCA cycle.
144
So therefore, if you already have ATP or you already have citrate, what's the point?
145
You don't need to do glycolysis.
146
So the presence of those products will inhibit the enzymes that usually make glycolysis work.
147
So guys, that's it for glycolysis.
148
And you're probably sitting there starting to have a panic attack thinking about, whoa, dirty.
149
What about all the other enzymes?
150
Don't worry about the other enzymes.
151
This is what you need to know for USMLE and Comlex.
152
You need to know the enzymes I put in these slides, the regulatory mechanisms that I put in these slides,
153
and understand the difference between glucokinase and hexokinase that we discussed at the beginning of this video.
154
All of the other intermediary steps, you don't need to know them.
155
You really don't.
156
They're not going to show up on your test unless you're taking a college level or intro to biochemistry course.
157
You really don't need to know them.
158
If you do want to know them for completeness sake, I would encourage you to go online, look at some diagrams, memorize some enzymes.
159
But this is what you need to know to answer 99 % of the questions that will show up on USMLE,
160
Comlex, your question banks, your practice tests, et cetera.
161
So again, and I cannot stress this enough because it's the biggest theme for all of biochemistry.
162
Know the rate limiting enzyme, know the regulatory mechanisms.
163
And if you get stuck on test day about what's inhibiting or what's promoting, ask yourself, what's the goal of this pathway?
164
And therefore, what do I think might happen?
165
That's it.
166
If you liked this video, drop me a like or a comment in the comment section.
167
Please remember to check my Patreon page.
168
You can click
169
that link in the description of any of my videos sign up to send a secure monthly donation
170
and support the channel love you good luck
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
Stesso Canale
FOR YOU
Video consigliato
C12
799 frasi
Cell Biology | Cell Structure & Function
Daily ConversationUniversity Students
C11
339 frasi
Introduction to HPLC - Lecture 1: HPLC Basics
Daily ConversationUniversity Students
C11
207 frasi
Go’s Big Mistake
Daily ConversationUniversity StudentsWorking Adults
C12
189 frasi
Creatine: is there truth behind the hype?
Daily ConversationUniversity StudentsWorking Adults
C11
287 frasi
Lecture 12: Retina, Part 2: Retinal vascular occlusions
Daily ConversationUniversity Students
C11
60 frasi
Faces of Chemistry: Organic solar cells (BASF) - Video 2 (14+)
Daily ConversationUniversity Students
C16
108 frasi
Homeostasis - How Your Body Keeps its Balance - Physiology Series
Daily ConversationUniversity Students
C11
48 frasi
Pharmaceutical Industry Overview | Pharma and Biotech: Distinctions | Understanding Pharmaceuticals
Daily ConversationUniversity StudentsWorking Adults
C11
7 frasi
Diodes Explained - The basics how diodes work working principle pn junction
Daily ConversationUniversity StudentsWorking Adults
C11
530 frasi
Antimycobacterials | Anti-TB Drugs
Daily ConversationUniversity Students
C1132 frasi
Petroleum - 06 - Drilling Fluid Laboratory
Daily ConversationUniversity Students
Vocabolario e note di pronuncia per questa lezione
Le parole che ritornano più spesso: glucose, glycolysis, enzyme, pathway, fructose. Questo video contiene 170 frasi e 2233 parole da ripetere con lo shadowing. Il parlato dura 14:16. Chi parla ha un ritmo naturale di circa 156 parole al minuto, vicino a una conversazione quotidiana. Solo il 76% delle parole rientra nelle 3.000 più comuni dell’inglese, quindi il lessico è impegnativo.
Vocaboli chiave di questo video
15 parole del video che vale la pena imparare, con pronuncia e significato:
| Parola | Pronuncia | Significato |
|---|---|---|
| glucose sostantivo | /ˈɡluː.kəʊz/ | glucosio |
| enzyme sostantivo | /ˈɛn.zaɪm/ | enzima |
| pathway sostantivo | /ˈpæθˌweɪ/ | via |
| mechanism sostantivo | /ˈmɛk.ə.nɪ.zəm/ | meccanismo |
| convert verbo | /kənˈvɝt/ | convertire |
| affinity sostantivo | /əˈfɪnɪti/ | affinità |
| slide sostantivo | /ˈslaɪ̯d/ | scivolo |
| yield verbo | /jiːld/ | restituire |
| insulin sostantivo | /ˈɪnsəlɪn/ | insulina |
| occur verbo | /əˈkɜː/ | verificarsi |
| concentration sostantivo | /ˌkɑn.sənˈtɹeɪ.ʃən/ | concentrazione |
| beta sostantivo | /ˈbeɪtə/ | beta |
| acid sostantivo | /ˈæsɪd/ | acido |
| refer verbo | /ɹɪˈfɜː/ | riferire |
| tissue sostantivo | /ˈtɪʃ.(j)u/ | tessuto |
Frasi da ripetere
Frasi brevi e complete del video che puoi riutilizzare nella conversazione di tutti i giorni:
- What are we taking as a reactant and turning into a product?
- We're going to talk about the pathway.
- We've talked about the enzymes in the first step.
- You don't need to do glycolysis.
- You really don't need to know them.
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 brought · is composed · is only found |
| Present perfect have/has + participio passato — un’azione passata che conta ancora adesso | I've created · we've understood · I've put |
| Frasi relative who / which + frase — un’informazione in più su una persona o una cosa | phosphoenolpyruvate which will · AMP, which is · pyruvate, which can |
Pronuncia a cui fare attenzione
Chi parla usa 41 contrazioni e forme ridotte, come don't, you're, we're. Pronunciale nella forma breve, così come le senti.
- I suoni “sh” e “zh”: concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, tissue /ˈtɪʃ.(j)u/, conversion /kənˈvɝʒən/, equation /ɪˈkweɪ.ʒən/, donation /doʊˈneɪʃən/
- Parole lunghe — attenzione all’accento: regulatory /ˈɹɛɡ.jʊ.lə.t(ɔː.)ɹi/, mechanism /ˈmɛk.ə.nɪ.zəm/, affinity /əˈfɪnɪti/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, metabolism /məˈtæb.əˌlɪz.əm/
I suoni difficili per chi parla italiano:
- /h/ — va soffiata, non è muta: hydrogen /ˈhaɪdɹəd͡ʒ(ə)n/, inhibit /ɪnˈhɪbɪt/, carbohydrate /kɑɹboʊˈhaɪdɹeɪt/, inhibitor /ɪnˈhɪbɪtɚ/
- Consonante finale — senza aggiungere una vocale dopo: glucose /ˈɡluː.kəʊz/, convert /kənˈvɝt/, slide /ˈslaɪ̯d/, yield /jiːld/, acid /ˈæsɪd/
- /æ/ — più aperta della “e”: pathway /ˈpæθˌweɪ/, acid /ˈæsɪd/, metabolism /məˈtæb.əˌlɪz.əm/, circumstance /ˈsɝ.kəmˌstæns/, feedback /ˈfiːdˌbæk/
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 glucose, enzyme, pathway.
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.