Cellular Respiration (in detail)

Summary

This video delves into the process of cellular respiration, emphasizing the production of ATP, the cell's energy currency. It explains the breakdown of glucose through glycolysis, the Krebs cycle, and the electron transport chain. The video highlights how ATP is created, the role of NADH and FADH2, and the importance of enzymes in these processes. Additionally, it discusses the production of water as a byproduct of cellular respiration. The content is aimed at helping viewers understand how cells generate energy efficiently.

Takeaways

• 🔋 Cellular respiration is the process by which cells produce ATP, the energy currency of the cell.
• 💰 ATP (adenosine triphosphate) is often compared to money, as it is used by the cell to power various reactions.
• 🛠 Hydrolysis of ATP releases energy, which is crucial for driving cellular processes.
• 🌀 Glycolysis is the first stage of cellular respiration, occurring in the cytoplasm and breaking down glucose into pyruvate.
• 📍 Glycolysis involves an initial investment of 2 ATP molecules to ultimately produce a net gain of 2 ATP molecules.
• 🚀 The Krebs cycle, also known as the citric acid cycle, further breaks down pyruvate into ATP, NADH, and CO2 within the mitochondria.
• 🔄 The Krebs cycle is a repeating process that generates 2 ATP molecules per cycle but primarily produces NADH and FADH2 for the electron transport chain.
• 🌐 The electron transport chain, located in the inner mitochondrial membrane, uses NADH and FADH2 to create a proton gradient for ATP synthesis.
• 💧 The final step of the electron transport chain involves the combination of hydrogen ions and electrons with oxygen to form water.
• 🔌 ATP synthase harnesses the energy from the proton gradient to synthesize ATP from ADP and inorganic phosphate.
• 🔄 The process of cellular respiration is cyclical and continuous, with the Krebs cycle and electron transport chain repeating to produce more ATP.

Q & A

What is the primary reason cells perform cellular respiration?

Cells perform cellular respiration primarily to produce adenosine triphosphate (ATP), which is the energy molecule used by the cell for various processes.

How is ATP often described in relation to the cell's functions?

ATP is often described as the currency of a cell, similar to how money is used to purchase goods and services, because the cell spends ATP to perform various chemical reactions.

What happens during the hydrolysis of ATP?

During the hydrolysis of ATP, ATP reacts with water to yield adenosine diphosphate (ADP), a single phosphate, and energy, which powers cellular processes.

Where does the majority of ATP production occur in the cell?

The majority of ATP production occurs in the mitochondria, which is often referred to as the powerhouse of the cell.

What is glycolysis and where does it take place?

Glycolysis is the first step in cellular respiration where glucose is broken down to produce ATP. It takes place in the cytoplasm of a cell.

What is the net gain of ATP during glycolysis and why is it considered a net gain?

The net gain of ATP during glycolysis is two molecules. Although four ATP molecules are produced, two were used at the start of glycolysis, so the net gain is two ATP molecules.

What are the two possible pathways after glycolysis and what determines which pathway is followed?

The two possible pathways after glycolysis are the aerobic pathway, which requires oxygen and leads to the Krebs cycle and electron transport chain, and the anaerobic pathway, which occurs in the absence of oxygen and leads to fermentation.

What is the Krebs cycle and what is its main purpose in cellular respiration?

The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that further break down the products of glycolysis (pyruvates) into carbon dioxide and high-energy electron carriers (NADH and FADH2), which are used in the electron transport chain.

What is the role of NADH and FADH2 in the electron transport chain?

NADH and FADH2 are high-energy electron carriers that play a crucial role in the electron transport chain by providing electrons that drive a series of reactions, leading to the production of a large amount of ATP.

How is ATP synthesized in the electron transport chain?

ATP is synthesized in the electron transport chain through a process involving the transfer of electrons through protein complexes in the inner mitochondrial membrane, which pumps hydrogen ions to create a gradient. The flow of hydrogen ions back through ATP synthase powers the synthesis of ATP from ADP and inorganic phosphate.

What is the final product of the electron transport chain and how is it formed?

The final product of the electron transport chain is water. It is formed when oxygen from the air we breathe combines with hydrogen ions and electrons to produce water molecules.

Outlines

00:00

🔋 Cellular Respiration and ATP Production

This paragraph introduces the concept of cellular respiration with a focus on adenosine triphosphate (ATP), the energy currency of the cell. ATP is vital for cellular functions, and its production is the primary goal of cellular respiration. The paragraph explains the structure of ATP, highlighting its three phosphate groups and the energy stored within the bonds. It also describes the process of ATP hydrolysis, where ATP is broken down into ADP and a phosphate group, releasing energy that powers cellular processes. The script outlines the role of the mitochondria as the 'powerhouse' of the cell, where most ATP is produced through cellular respiration, starting with the breakdown of glucose.

05:03

🚀 Glycolysis: The First Step in Cellular Respiration

The second paragraph delves into the first stage of cellular respiration known as glycolysis, which occurs in the cytoplasm of the cell. Glycolysis involves the breakdown of one glucose molecule into two molecules of pyruvate, utilizing and producing ATP in the process. The paragraph explains how two ATP molecules are initially used to initiate glycolysis, but four ATP molecules are ultimately generated, resulting in a net gain of two ATP. It also discusses the role of NAD+ as a hydrogen carrier, which is converted to NADH during glycolysis, highlighting the importance of these molecules for subsequent stages of cellular respiration.

10:03

🌀 The Krebs Cycle: Continuing the Path to ATP

This paragraph focuses on the Krebs cycle, the next phase of cellular respiration that takes place in the mitochondria. The Krebs cycle involves the further breakdown of pyruvate into acetic acid, leading to the production of NADH and CO2 as waste. The paragraph describes the conversion of acetyl CoA into citric acid and the subsequent reactions that reduce citric acid back to its original form, releasing energy and creating NADH and FADH2 in the process. The Krebs cycle is emphasized for its role in generating high-energy electron carriers, rather than ATP, which are crucial for the electron transport chain.

15:04

⚡ The Electron Transport Chain: ATP Synthesis

The final paragraph discusses the electron transport chain, the last stage of cellular respiration, which is responsible for the majority of ATP production. The paragraph describes how NADH and FADH2 generated in previous stages transfer electrons to protein complexes in the inner mitochondrial membrane, creating a flow of hydrogen ions. This flow drives the enzyme ATP synthase, which synthesizes ATP from ADP and inorganic phosphate. The paragraph concludes with the formation of water as a byproduct, combining hydrogen ions and electrons with oxygen, completing the cellular respiration process and highlighting the efficiency of ATP production through this mechanism.

Keywords

💡Cellular Respiration

Cellular respiration is the process by which cells convert nutrients into energy in the form of ATP. It is central to the video's theme as it explains how cells perform this vital function to sustain life. The script discusses the different stages of cellular respiration, including glycolysis, the Krebs cycle, and the electron transport chain, all of which contribute to the production of ATP.

💡ATP (Adenosine Triphosphate)

ATP is often referred to as the 'energy currency' of the cell. It is the molecule that stores and provides energy for various cellular processes. In the script, ATP is highlighted as the end product of cellular respiration, with its production being the primary goal of the process. The hydrolysis of ATP to ADP and inorganic phosphate releases energy that powers the cell's activities.

💡Glycolysis

Glycolysis is the first stage of cellular respiration that occurs in the cytoplasm of the cell. It involves the breakdown of glucose into pyruvate, generating a small amount of ATP and NADH. The script describes glycolysis as a process that, although it consumes ATP initially, ultimately leads to a net gain of ATP, which is crucial for the cell's energy needs.

💡Krebs Cycle

The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria. It is part of the cellular respiration process and is responsible for the production of additional ATP, NADH, and FADH2, which are essential for the electron transport chain. The script explains how the Krebs cycle uses the pyruvate derived from glycolysis to generate these energy carriers.

💡Electron Transport Chain

The electron transport chain is the final stage of cellular respiration that takes place in the inner mitochondrial membrane. It uses the electrons carried by NADH and FADH2 to create a proton gradient across the membrane, which drives the synthesis of a large amount of ATP. The script emphasizes the importance of the electron transport chain in harnessing the energy from NADH and FADH2 to produce ATP.

💡Mitochondria

Mitochondria are known as the 'powerhouses' of the cell because they generate most of the cell's supply of ATP, through cellular respiration. The script mentions mitochondria as the location where the Krebs cycle and the electron transport chain occur, highlighting their role in the production of ATP.

💡NADH and FADH2

NADH and FADH2 are electron carriers that play a critical role in the electron transport chain. They are produced during glycolysis and the Krebs cycle, respectively. The script explains how these molecules transport electrons to the electron transport chain, where they contribute to the generation of ATP.

💡Pyruvate

Pyruvate is the end product of glycolysis and serves as the starting material for the Krebs cycle. The script describes how pyruvate is transported into the mitochondria, where it is further broken down to produce ATP, NADH, and carbon dioxide.

💡Acetyl CoA

Acetyl CoA is a central molecule in the Krebs cycle, formed by the combination of pyruvate and coenzyme A. The script details the conversion of pyruvate into Acetyl CoA, which then enters the Krebs cycle, leading to the production of ATP, NADH, and FADH2.

💡ATP Synthase

ATP synthase is an enzyme that catalyzes the synthesis of ATP from ADP and inorganic phosphate, using the energy derived from the proton gradient created by the electron transport chain. The script illustrates how ATP synthase operates during the electron transport chain to produce a significant amount of ATP.

💡Proton Gradient

The proton gradient is the concentration difference of protons across the inner mitochondrial membrane, which is established by the electron transport chain. The script explains that this gradient provides the energy needed for ATP synthase to produce ATP, highlighting the critical role of the proton gradient in the final stages of cellular respiration.

Highlights

Cellular respiration is the process by which cells create adenosine triphosphate (ATP), the energy molecule for cellular activities.

ATP is often compared to money, as it is 'spent' by the cell to perform various reactions.

The hydrolysis of ATP releases energy, which is crucial for powering cellular processes.

Glycolysis, the first stage of cellular respiration, takes place in the cytoplasm and involves the breakdown of glucose.

Two molecules of ATP are initially used in glycolysis, but the process ultimately yields a net gain of two ATP molecules.

The Krebs cycle, also known as the citric acid cycle, is the second stage of cellular respiration that occurs in the mitochondria.

Acetic acid is produced from pyruvate, generating NADH and carbon dioxide during the Krebs cycle.

Coenzyme A (CoA) is essential in the formation of acetyl CoA, a key intermediate in the Krebs cycle.

The Krebs cycle is a cycle of reactions that generates NADH and FADH2, which are critical for the electron transport chain.

The electron transport chain, located in the inner mitochondrial membrane, is the final stage of cellular respiration.

NADH and FADH2 donate electrons to the electron transport chain, which powers the production of ATP.

ATP synthase uses the energy from the diffusion of hydrogen ions to synthesize ATP from ADP and inorganic phosphate.

The electron transport chain culminates in the formation of water from oxygen, hydrogen ions, and electrons.

Cellular respiration is a continuous process, with the Krebs cycle repeating to generate more ATP.

The overall process of cellular respiration efficiently converts glucose into ATP, NADH, FADH2, carbon dioxide, and water.

The video provides a simplified yet comprehensive overview of cellular respiration, aiding in understanding the complex process.

Transcripts

okay so the topic of this video is

cellular respiration let's go ahead and

get started so right here this molecule

adenosine triphosphate this is why the

cell performs cellular respiration it's

trying to make this because ATP is the

energy molecule used by the cell you'll

often hear ATP as an analogy compared to

money or the currency of a cell because

you know we spend money on goods and

services and the cell will spend ATP to

perform you know these these reactions

and many others that I did not list but

here's the triphosphate part notice how

there are three phosphates and they're

in the bonds of these three phosphates

particularly between the second and

third phosphate is energy and in the

hydrolysis of ATP if you've forgotten

that hydro means water and lysis means

to break down so in the breakdown of ATP

ATP with water will yield adp a single

phosphate and energy and it's this

energy that will power the cell and so

in this very simplified diagram of an

ATP molecule here comes water and my

scissors represent the actions of an

enzyme and that third phosphate tends to

be broken off and in that energy is

released and it's this energy that will

often drive the cellular processes that

you see listed in the notes so how is

this molecule of ATP created well ATP

gets created through cellular

respiration cells need ATP to power

their chemical reactions and most ATP

gets produced by the powerhouse of the

cell the mitochondria the powerhouse

because it produces the ATP power now

ATP is created through this process of

cellular respiration which we're going

to go through in the rest of this video

and what happens is a molecule of

glucose that we get from our food is

gonna be broken down to make a whole

bunch of molecules of ATP

that's what half

during the the process of cellular

respiration glycolysis the Krebs cycle

the electron transport chain these are

all breaking down molecules of glucose

from our food to produce ATP so let's

move into glycolysis okay starting with

glycolysis the location takes place in

the cytoplasm of a cell and what happens

is that blue hexagon ring labeled

glucose glucose is going to be broken

down by molecules of ATP a molecule

called nad in various enzymes now for

simplicity I've only drawn the six

carbons of glucose in my diagram but

glucose you can see also has 12

hydrogen's and six oxygens so what

happens is two molecules of ATP plus and

plus enzymes are going to begin to break

down glucose then this might seem a

little counterproductive using ATP to

make ATP but keep in mind the goal is to

make a lot of ATP so if you have to

spend a little bit of ATP to make a lot

of ATP it's worth it

so a molecule of ATP plus the scissors

representing an enzyme will begin to

break down glucose into this

intermediate molecule here so next

another molecule of ATP and a different

enzyme will be broken down and the

energy from ATP will break that

intermediate down into two molecules

labeled P gal or phosphoglyceraldehyde

now P gal itself this is another

intermediate it will be broken down

further in a moment

so next enzymes which are in the

cytoplasm will add another phosphate

unto each of the P gals so here's an

enzyme the scissors adding a phosphate

to the P gal on the left and and the

phosphate being added to the P gal on

the right and by doing this this

converts the P gal into another

intermediate molecule

so next couple molecules called NADH are

going to be created and will enter the

mitochondria well they begin as

molecules call of nad and nad is in

abbreviation for nicotinamide adenine

dinucleotide and what happens of course

there's enzymes involved nad with the

help of an enzyme will strip off the

hydrogen to create NADH NADH can be

looked at as a hydrogen carrier carries

the hydrogen over to the mitochondria

the same thing happens with the other

nad an enzyme will help to strip off a

hydrogen and NADH will carry that

hydrogen over to the mitochondria these

are going to be very very important when

we get to the electron transport chain

so now that we're near the end of

glycolysis let's talk about how four

molecules of ATP are created

you see those four yellow circles with

the P those each represent a phosphate

group and what happens is here is four

molecules of ATP and ADP along with the

help of an enzyme will strip off one of

those phosphates to create a molecule of

ATP now this happens three more times an

ADP with the help of an enzyme will

strip off one of those phosphates to

make ATP adp strips off a phosphate to

make ATP and ADP again strips off a

phosphate with the help of enzymes to

make ATP and what we're left with what

was once glucose is now these two

molecules called pyruvates and the

pyruvates are gonna be very useful in

the Krebs cycle coming up we also have a

total amount of four ATP molecules

created although sometimes you'll hear

it referred to as a net gain of two

ATP's well what do we mean by that well

four ATP's are created but two ATP's

were used to start the process of

glycolysis so when you subtract the two

at the start from the four that were

created that's what we made net gain

well what happens next

what happens next depends upon the type

of cell and the conditions that the cell

is within there's two possible pathways

and both of them are going to involve

those pyruvates those pyruvates are

going to be broken down even further the

pathway that we're gonna follow in these

notes is the aerobic pathway with oxygen

leading to the Krebs cycle and the

electron transport chain

but if oxygen is lacking if a cell is in

an anaerobic environment those pyruvates

will be used in fermentation I have a

different video if you want to learn

about fermentation but this video is

gonna follow the aerobic pathway so here

we are back at our cell glycolysis has

just completed itself and we're about to

start the krebs cycle and so the two

molecules of pyruvate will migrate into

the mitochondria so let's go into the

mitochondria and take a closer look and

when we zoom into the mitochondria so

there's the two pyruvates notice how

they're in the mitochondrial matrix the

inner inner fluid layer of the

mitochondria and so what happens is

we're gonna follow the pyruvate on the

left now the same thing happens the

pyruvate on the right but for simplicity

we're gonna just follow the one on the

left the peruvians gonna be broken down

into acetic acid in the process of doing

this NADH is gonna be created so there's

a molecule of nad when pyruvate is being

broken down nad will come and strip off

a hydrogen to make NADH notice Haussmann

carbon dioxide was created as well

that's just waste what we're left with

is acetic acid acetic acid being a

intermediate molecule what happens next

is a really large molecule that I'm

being very simplistic in just drawing it

and labeling it Co a coenzyme a really

large molecule will bond to acetic acid

well how big is coenzyme a we'll look at

the formula of acetic acid when we bond

coenzyme a we form acetyl co a look at

how large that formula is

so acetyl co a is also an intermediate

molecule it's just the next step of the

krebs cycle what happens to the acetyl

co a the third step and this is where

this the krebs cycle also gets its name

of the citric acid cycle acetyl co a is

going to be converted and broken down

into citric acid that happens when a

four carbon molecule from the previous

krebs cycle bonds to the acetyl co a and

i have it flashing for a reason I hope

you all understand why it's flashing

when we get to the end I wanted to do

something for you to member out to

remember this four carbon molecule from

the previous krebs cycle so an enzyme

will bond that four carbon molecule to

the acetyl co a and the coenzyme a

breaks away and what you're left with is

citric acid citric acid being a six

carbon molecule okay so the six carbon

citric acid will be broken down into a

five carbon molecule and in the process

of doing this NADH is created so here's

a molecule of nad nad along with an

enzyme will help to break down the

citric acid notice how NADH was created

also some carbon dioxide waste was

generated this is why citric acid went

from a six carbon to a five carbon

molecule so what about this five carbon

molecule this five carbon molecule is

again an intermediate it's gonna be

broken down into a four carbon molecule

and in the break down a couple things

happen

number one another molecule of NADH is

created so there's nad with the help of

an enzyme nad will strip off a hydrogen

but that's not the only thing that

happens a molecule of ATP will be

created because in the matrix of the

mitochondria there are various solutes

and molecules dissolved within the

matrix and here's a molecule of adp and

a phosphate and

bring these molecules together and in

the breakdown of this five carbon

molecule into a four carbon molecule the

ATP is bonded together and also in the

act of doing this carbon dioxide waste

is created so that's how it goes from a

five carbon to a four carbon molecule

now this four carbon molecule is again

an intermediate enzymes will rearrange

the four carbon molecule into another

four carbon molecule and in the process

of doing this a molecule of NADH is

created that means we have to have nad

come along and strip off a hydrogen and

then another molecule very similar to

nad called

F ad is gonna come on in and strip off

not one but two hydrogen's forming fadh2

now all of these NADH is in this fadh2

they have a role to play we just haven't

seen it yet their role is coming up in a

few moments well what happens with this

four carbon molecule that's just been

rearranged notice how it's flashing now

that's because this is the same flashing

four carbon molecule we saw earlier

remember the Krebs cycle is a cycle so I

wanted to do something for you to

realize when the krebs cycle was

beginning its next turn and what happens

with this four carbon molecule it will

bond with acetyl co a that really big

molecule we saw earlier so enzymes will

bind it together the coenzyme a breaks

away and what we're left with is the six

carbon molecule known as citric acid and

the process repeats itself well when we

look at what's created an overview of

the Krebs cycle this always frustrated

me because I always thought that you

know cellular respiration is purpose is

to make a lot of ATP and only two

molecules of ATP were created one

molecule of ATP from the pyruvate on the

left one molecule of ATP from the

pyruvate on the right but the big prize

of the krebs cycle is not the two

molecules of ATP it's all the nad

and fadh2 that was created those are

really important in the electron

transport chain so let's look at that

next so as we move on into the electron

transport chain what we're gonna do is

we're gonna zoom in to the membrane of

the matrix and when we zoom on in here

here we are so now that we've zoomed in

we can see embedded in the inner

mitochondrial membrane are some great

herbs and cylinders these are symbolic

of the protein complexes that are

embedded inside this membrane here and

these are gonna help to kind of drive

the electron transport chain

now we're gonna see why all the nadh and

fadh2 is created well here's a molecule

of NADH enzymes of course are going to

help break this down and notice how a

couple of electrons are now embedded in

the inner mitochondrial membrane and one

of the hydrogen ions has positioned

itself at one of those protein tubes

well this happens repeatedly another

NADH is broken down couple more

electrons embed in the inner

mitochondrial membrane another hydrogen

is positioned itself at one of the

protein tubes and here's an fadh2 that's

broken down and what we're seeing is the

beginning of the electron transport

chain those electrons are going to start

a chain reaction which we've called the

electron transport chain well what

happens with with these electrons this

is why it's called the electron

transport chain these electrons are

going to start a chain reaction of

events where those hydrogen's are going

to be transported out of the matrix and

so the electrons as they transfer from

protein channel to protein channel by

protein channel as they transfer from

the protein channels they provide the

energy to pull these hydrogens out of

the matrix and this will set up the next

step of the electron transport chain

so once all the hydrogens have been

pulled out of the matriot out of the

matrix they have accumulated in a very

large amount now and this is going to

lead to really rapid diffusion through

the molecule labeled ATP synthase and so

those hydrogen ions are going to

activate this enzyme this molecule

called ATP synthase and notice how ATP

synthase has an adp and a P attached to

it they just need the ATP synthase just

needs something to bond the phosphate

with the ADP and that's the job of the

hydrogen ion so what the hydrogen does

is it loads itself into ATP synthase

simple diffusion from a high

concentration to a low and as the

hydrogen diffuses through the mechanical

forces bring together the adp and the P

to create ATP and this happens

repeatedly over and over and over so

here's another adp and another phosphate

here's another hydrogen and as the

hydrogen diffuses through ATP is created

and this happens repeatedly over and

over and over up to 34 times well as we

wind down notice how there are some

hydrogens and electrons that are now

regather incide the matrix there has to

be a way to clean these up in order to

keep the process moving and this is

where the water is formed if you look at

the chemical formula of cellular

respiration one of the one of the

products that's formed as water

well oxygen from the air that we breathe

well bond with two of the hydrogen's and

two of the electrons to form a molecule

of water this is where we get the water

in the chemical reaction of of cellular

respiration it comes from the end of the

electron transport chain

so if you're in my class we'll talk

about this essay in more detail well as

I wrap this up I want to thank you for

watching and you know pause the video

here try to have try to answer these

questions for review practice and you

know leave your comments in the box

below thanks for watching