Практика Shadowing: Glycolysis - Изучайте разговорный английский по видео

Выберите режим практики

Каждый режим открывает полноэкранную комнату практики.

170 предложений

Если предложения слишком короткие или длинные, нажмите Edit, чтобы их изменить.

Welcome back to the high -yield biochemistry series.

This is brought to you by Dirty Medicine.

In today's video, we're going to continue our discussion about the biochemical pathways and talk about glycolysis.

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.

It shows up on exams all of the time.

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.

And when I say that, I'm referring to things like what is the function or the role of glycolysis?

What are we taking as a reactant and turning into a product?

And what are the regulatory mechanisms in terms of feedback?

So what makes this go forward?

What inhibits this?

And what is the rate limiting enzyme?

Just like all of the biochemistry videos that I've created, you need to know the rate -limiting enzyme and the regulatory mechanisms.

So we're talking about things like inhibitors, etc. So let's start with a quick overview of glycolysis.

Glycolysis is an irreversible biochemical reaction that occurs in the cytoplasm.

The net equation for glycolysis is that you start with glucose, and the goal is to take that glucose and turn it into pyruvate,

where it can downstream take multiple pathways through that pyruvate pathway

and preferentially usually this goes into the citric acid cycle

but here's the net equation you've you start with glucose

and you add two phosphates two adps and two nads

and what you get out of

that is two 2 pyruvates plus 2 ATPs plus 2 NADH plus 2 hydrogens plus 2 waters.

But if you wanted to just think very simply about what glycolysis is doing,

it's taking glucose and breaking that glucose down into storable products that the body can use in other biochemical pathways.

So now that we've understood the overview of glycolysis, let's just get into the meat and potatoes here.

We're going to talk about the pathway.

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.

So you start with glucose, right?

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.

And that carbohydrate is composed usually of glucose.

And if it's not of glucose, then the other types of sugars will get turned into glucose so

that glycolysis can utilize

it the first step is glucose will get turned into glucose

6 -phosphate glucose 6 -phosphate will get turned into fructose

6 -phosphate fructose 6 -phosphate will get turned into fructose 1 -6 -bisphosphate

and now you've got like multiple steps

that are going to happen there's going to be four

or five more reactions in this pathway and you'll end up with phosphoenolpyruvate which will get turned into pyruvate.

And going from glucose down to pyruvate is the entire glycolysis pathway.

So when you get to pyruvate you're basically finished with glycolysis.

Now let's talk about the important enzymes that you need to know.

So the first step that converts glucose to glucose 6 -phosphate, there's actually two different enzymes

that can be used depending on the circumstances of the glucose concentration and where in the body we're talking about.

So those two enzymes are glucokinase and hexokinase.

So to be perfectly clear, either glucokinase or hexokinase can convert glucose to glucose 6 -phosphate.

And what you'll need to know for test day that's really high yield is to understand under

which circumstances both of these enzymes might be used.

So for glucokinase, this enzyme has a low affinity and a high

Km, Just remember the reciprocal relationship between affinity and Km.

The higher the Km, the lower the enzyme has an affinity for its substrate.

So glucokinase has a low affinity for glucose.

It typically doesn't want to go and grab glucose.

And the reason for this is because glucokinase acts as a glucose sensor.

It's present in the liver and the pancreatic beta cells, and it's only used when glucose is at high concentrations.

So basically what you should think of glucokinase as is an emergency enzyme that is acting as a glucose sensor.

And it's really not grabbing glucose because instead of grabbing glucose and breaking it down through glycolysis,

what it's doing is it's sensing glucose and it's going, okay, let's test how much glucose is over here.

uh that's okay we're not going to jump in yet um hexokinase you go first

so hexokinase on the other hand that is a high affinity enzyme

which means it has a low km and

because it has high affinity for its substrate hexokinase is the one that's constantly going to be latching onto glucose

and converting it to glucose 6 -phosphate and sending it down the glycolysis pathway

and the reason for that is because hexokinase is the enzyme that's used to operate the basal glucose metabolism.

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.

It's trying to make sure that your glucose level is adequate throughout the body in all of the tissues.

But if hexokinase becomes overwhelmed because suddenly there's a massive influx of glucose, that is when hexokinase turns to glucokinase and says,

glucose, I know you usually have a low affinity, but I really need some help now because the glucose concentration is high.

So if you think about it, that's the reason that glucokinase is only found in the liver and the pancreatic beta cells,

because it does a very specific regulatory job where it's only acting when the blood glucose levels are super, super high.

When that concentration reaches some critical point, that's when glucokinase in the liver and the pancreatic beta cells jumps in to save hexokinase.

So the takeaway from this slide is that both glucokinase

and hexokinase are enzymes that catalyze that conversion from glucose to glucose 6 -phosphate.

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.

But understand the differences between those two enzymes that I've put in the gray boxes.

They are extremely high yield and probably will show up on your test.

So here's where we are.

We've talked about the enzymes in the first step.

The enzyme that converts fructose 6 -phosphate to fructose 1 ,6 -bisphosphate is the rate -limiting enzyme of glycolysis,

and that's phosphofructokinase 1.

Sometimes you'll hear this referred to as PFK1.

So PFK1, or phosphofructokinase 1, is the rate -limiting enzyme, and it converts fructose 6 -phosphate to fructose 1 ,6 -bisphosphate.

Now, I told you at the start of this video

that the very important thing to keep in mind for USMLE and Comlex is the regulatory mechanisms.

And what I mean when I say regulatory mechanisms are what inhibits this pathway and what promotes this pathway.

And we're going to talk about that for the first time right here.

And because phosphofructokinase 1 is the rate -limiting enzyme,

it's really high yield to understand what inhibits phosphofructokinase 1 and what promotes phosphofructokinase 1.

And that's what you see here.

So ATP and citrate will inhibit the rate -limiting enzyme PFK1,

but AMP will promote the rate -limiting enzyme of PFK1.

And this should be somewhat intuitive to you.

So think about what glycolysis is doing.

The role of glycolysis is to take glucose, convert it to pyruvate and ATP,

and then let that pyruvate enter one of many different pathways, but usually the citric acid cycle where you'll then create citrate.

So if you think about that,

the question becomes, what would this pathway want to do if it already had ATP and therefore didn't need to make it,

or if it already had citrate and therefore didn't need to make pyruvate, which would then go to citrate.

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.

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

Скачать приложение

Всё для свободной речи

ИИ-оценка произношенияОценка каждой фразы

Практика IPAОсвойте каждый звук

СловарьСоберите свой словарный запас

Игра со словамиУчитесь играя

Сканировать QR

Download on theApp Store Get it onGoogle Play

Тот же канал

FOR YOU

Лексика и советы по произношению к этому уроку

Чаще всего повторяются слова: glucose, glycolysis, enzyme, pathway, fructose. В этом видео 170 предложений и 2233 слов для шедоуинга. Речь длится 14:16. Говорящий говорит в естественном темпе, около 156 слов в минуту, близком к повседневной речи. Только 76% слов входят в 3000 самых частых слов английского языка, поэтому лексика сложная.

Ключевая лексика этого видео

15 слов из видео, которые стоит выучить, с произношением и значением:

Слово	Произношение	Значение
glucose существительное	/ˈɡluː.kəʊz/	глюко́за
enzyme существительное	/ˈɛn.zaɪm/	ферме́нт, энзи́м
mechanism существительное	/ˈmɛk.ə.nɪ.zəm/	механи́зм
convert глагол	/kənˈvɝt/	превраща́ть, преврати́ть
affinity существительное	/əˈfɪnɪti/	бли́зость, сродство́
slide существительное	/ˈslaɪ̯d/	го́рка
yield глагол	/jiːld/	дава́ть, приводи́ть к
insulin существительное	/ˈɪnsəlɪn/	инсули́н
occur глагол	/əˈkɜː/	происходи́ть, произойти́
concentration существительное	/ˌkɑn.sənˈtɹeɪ.ʃən/	концентра́ция
beta существительное	/ˈbeɪtə/	бе́та
acid существительное	/ˈæsɪd/	кислота́, кисля́тина
refer глагол	/ɹɪˈfɜː/	ссыла́ться, сосла́ться
tissue существительное	/ˈtɪʃ.(j)u/	ткань
conversion существительное	/kənˈvɝʒən/	превраще́ние, обраще́ние

Фразовые глаголы, которые вы услышите

Слово	Значение
break down глагол	ломаться, сломаться

Фразы, которые стоит повторять

Короткие законченные фразы из видео, которые пригодятся в повседневном разговоре:

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.

Грамматика в этом видео

Конструкции, которые говорящий использует чаще всего, с точными словами из видео:

Конструкция	В видео
Пассивный залог be + причастие прошедшего времени — важно, что происходит, а не кто это делает	is brought · is composed · is only found
Present Perfect have/has + причастие прошедшего времени — прошлое действие, важное сейчас	I've created · we've understood · I've put
Придаточные определительные who / which + предложение — уточнение о человеке или предмете	phosphoenolpyruvate which will · AMP, which is · pyruvate, which can

Произношение, на которое стоит обратить внимание

Говорящий использует 41 сокращённых и редуцированных форм, например don't, you're, we're. Произносите их коротко, так, как слышите.

Звуки «sh» и «zh»: concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, tissue /ˈtɪʃ.(j)u/, conversion /kənˈvɝʒən/, equation /ɪˈkweɪ.ʒən/, donation /doʊˈneɪʃən/
Длинные слова — следите за ударением: regulatory /ˈɹɛɡ.jʊ.lə.t(ɔː.)ɹi/, mechanism /ˈmɛk.ə.nɪ.zəm/, affinity /əˈfɪnɪti/, concentration /ˌkɑn.sənˈtɹeɪ.ʃən/, metabolism /məˈtæb.əˌlɪz.əm/

Звуки, трудные для русскоязычных:

/w/ — губы округлены, это не /v/: pathway /ˈpæθˌweɪ/, equation /ɪˈkweɪ.ʒən/, adequate /ˈæd.ə.kwɪt/, likewise /ˈlaɪkˌwaɪz/, whoa /woʊ/
/h/ — лёгкий выдох, а не русское «х»: hydrogen /ˈhaɪdɹəd͡ʒ(ə)n/, inhibit /ɪnˈhɪbɪt/, carbohydrate /kɑɹboʊˈhaɪdɹeɪt/, inhibitor /ɪnˈhɪbɪtɚ/
Звонкие согласные в конце слова — не оглушайте их: glucose /ˈɡluː.kəʊz/, slide /ˈslaɪ̯d/, yield /jiːld/, acid /ˈæsɪd/, encourage /ɪnˈkʌɹ.ɪd͡ʒ/

Как заниматься с этим видео

Прослушайте всё видео один раз молча и выпишите незнакомые слова.
Начните со скорости 0,75×, повторяйте предложение за предложением и вернитесь к обычной скорости, когда станет легко.
Запишите себя и сравните с оригиналом, обращая внимание на такие слова, как glucose, enzyme, mechanism.

Что такое техника Shadowing?

Shadowing — это научно обоснованная техника изучения языка, изначально разработанная для подготовки профессиональных переводчиков и популяризированная полиглотом доктором Александром Аргуэльесом. Метод прост, но эффективен: вы слушаете аудио на английском от носителей языка и немедленно повторяете вслух — как тень, следующая за говорящим с задержкой в 1–2 секунды. В отличие от пассивного прослушивания или грамматических упражнений, Shadowing заставляет мозг и мышцы рта одновременно обрабатывать и воспроизводить реальные речевые паттерны. Исследования показывают, что это значительно улучшает точность произношения, интонацию, ритм, связную речь, понимание на слух и беглость речи — что делает его одним из самых эффективных методов для подготовки к IELTS Speaking и реального общения на английском.

Техника шедоуинга: читать полное пошаговое руководство →

Практика Shadowing: Glycolysis - Изучайте разговорный английский по видео

Выберите режим практики

Скачать приложение

Тот же канал

Retinal Artery Occlusion vs. Retinal Vein Occlusion

Pyruvate Pathways & Metabolism

Embryology of the Nervous System

Lymphoma

Рекомендуемое видео

Cell Biology | Cell Structure & Function

Introduction to HPLC - Lecture 1: HPLC Basics

Go’s Big Mistake

Creatine: is there truth behind the hype?

Lecture 12: Retina, Part 2: Retinal vascular occlusions

Faces of Chemistry: Organic solar cells (BASF) - Video 2 (14+)

Homeostasis - How Your Body Keeps its Balance - Physiology Series

Pharmaceutical Industry Overview | Pharma and Biotech: Distinctions | Understanding Pharmaceuticals

Diodes Explained - The basics how diodes work working principle pn junction

Antimycobacterials | Anti-TB Drugs

Petroleum - 06 - Drilling Fluid Laboratory