Cellular Respiration Part 1: Introduction & Glycolysis
Summary
TLDRThis video is the first in a three-part series on cellular respiration, focusing on glycolysis. It encourages active learning with notes, questions, and teaching others. The video explains how cells break down glucose to produce energy in the form of ATP, starting with glycolysis in the cytoplasm. It introduces substrate-level phosphorylation and electron transport phosphorylation, describing how glucose is split into pyruvate, producing a net gain of 2 ATP. The video sets up the next stages—Krebs cycle and electron transport chain—to complete the process of generating approximately 36 ATP.
Takeaways
- 📝 Be an active learner: take notes, pause, rewatch, and explain concepts in your own words to reinforce understanding.
- 📚 The video is part of a three-part series on cellular respiration, focusing on glycolysis, the Krebs cycle, and electron transport phosphorylation.
- 🌱 Cellular respiration is the process of breaking down glucose in the presence of oxygen to produce ATP, carbon dioxide, and water.
- ⚡ Glycolysis is the first stage of cellular respiration, taking place in the cytoplasm, and does not require oxygen (anaerobic).
- 🔬 Glycolysis splits glucose into two molecules of phosphoglyceraldehyde (PGL), consuming 2 ATP in the process (energy investment phase).
- 💡 In the energy return phase, 4 ATP are produced through substrate-level phosphorylation, leading to a net gain of 2 ATP.
- 🚀 NAD+ is reduced to NADH during glycolysis, carrying high-energy electrons to the electron transport chain for later ATP production.
- 🧬 Glycolysis ends with two pyruvate molecules, which will enter the mitochondria for further processing in the Krebs cycle.
- 🔗 ATP can be produced through substrate-level phosphorylation (direct transfer of phosphate) and electron transport phosphorylation (driven by chemiosmosis).
- 🧮 In glycolysis, a net profit of 2 ATP is produced, along with 2 NADH molecules and 2 pyruvate molecules that will fuel the next stages of cellular respiration.
Q & A
What is the main focus of this video series?
-The video series focuses on cellular respiration, with part 1 discussing glycolysis, part 2 covering the Krebs cycle, and part 3 explaining electron transport phosphorylation.
What are the three stages of cellular respiration mentioned?
-The three stages are glycolysis, the Krebs cycle, and electron transport phosphorylation.
What is the primary function of cellular respiration?
-The primary function of cellular respiration is to break down glucose in the presence of oxygen to produce ATP, the cell’s energy currency, along with carbon dioxide and water as byproducts.
Where does glycolysis occur in the cell?
-Glycolysis occurs in the cytoplasm of the cell.
What is ATP, and why is it important in cellular respiration?
-ATP (adenosine triphosphate) is a molecule that stores and transfers energy within cells, and it is the main energy source produced during cellular respiration.
How many ATP molecules are produced during glycolysis, and what is the net gain?
-A total of 4 ATP molecules are produced during glycolysis, but since 2 ATP are used in the process, the net gain is 2 ATP molecules.
What happens to the NADH produced in glycolysis?
-The NADH produced in glycolysis carries high-energy electrons that are later used in the electron transport chain to generate more ATP.
What is substrate-level phosphorylation?
-Substrate-level phosphorylation is a process where a substrate directly transfers a phosphate group to ADP, forming ATP.
What is the preparatory step before the Krebs cycle, and where does it occur?
-Before the Krebs cycle, pyruvate produced from glycolysis is converted in a preparatory step that occurs inside the mitochondria.
Why is the mitochondria referred to as the cell’s power plant?
-Mitochondria are referred to as the cell’s power plant because they are the primary site of cellular respiration, where ATP is generated from glucose.
Outlines
📝 Tips for Active Learning and Series Introduction
The introduction encourages active learning, suggesting viewers use paper and pencil, pause, re-watch, and draw their own pictures. It emphasizes teaching the concepts to others to reinforce understanding. The speaker introduces the video series on cellular respiration, dividing it into three parts: an overview of cellular respiration and glycolysis (Part 1), the Krebs cycle (Part 2), and electron transport phosphorylation (Part 3). The video will cover how energy from glucose is converted into ATP through cellular respiration, starting with glycolysis, a process that occurs in the cytoplasm before entering the mitochondria.
🔬 Overview of Cellular Respiration and Its Three Stages
Cellular respiration involves breaking down glucose in the presence of oxygen to release energy as ATP. The process occurs in three stages: glycolysis, the Krebs cycle, and electron transport phosphorylation. Glycolysis takes place in the cytoplasm and is anaerobic, while the Krebs cycle and electron transport occur in the mitochondria. The latter stages are aerobic and produce the majority of ATP. The mitochondria, often referred to as the cell’s power plant, is a double membrane-bound organelle where most of the energy extraction happens across the inner membrane.
Mindmap
Keywords
💡Cellular Respiration
💡Glycolysis
💡ATP (Adenosine Triphosphate)
💡Mitochondria
💡Krebs Cycle
💡Electron Transport Chain
💡Substrate-Level Phosphorylation
💡Electron Transport Phosphorylation
💡NADH
💡Pyruvate
Highlights
Introduction to the cellular respiration video series, emphasizing the importance of active learning.
Overview of the three-part series: Part 1 covers glycolysis, Part 2 covers the Krebs cycle, and Part 3 focuses on electron transport phosphorylation.
Explanation of how photosynthesis stores energy in glucose, and how cellular respiration releases this energy to form ATP.
Cellular respiration is broken into three stages: glycolysis, the Krebs cycle, and electron transport phosphorylation.
The first stage, glycolysis, is anaerobic and occurs in the cytoplasm.
Glycolysis starts with glucose, which is broken down into two molecules of phosphoglyceraldehyde (PGL) using ATP.
Glycolysis involves an 'energy investment' stage where 2 ATP are consumed, followed by an 'energy return' stage where 4 ATP are produced.
NAD+ is reduced to NADH during glycolysis, and these molecules will carry high-energy electrons to the electron transport chain.
Substrate-level phosphorylation is explained as the direct transfer of a phosphate group from a substrate to ADP, producing ATP.
In electron transport phosphorylation, ATP is produced by a chemiosmotic gradient involving ATP synthase.
The end products of glycolysis are 2 pyruvate molecules, 2 NADH, and a net gain of 2 ATP.
The pyruvate and NADH produced in glycolysis will be used in subsequent stages of cellular respiration.
Mitochondria are described as the cell's power plants, with the inner membrane being the site of significant respiration activity.
Cellular respiration in its entirety will produce approximately 36 ATP molecules from one glucose molecule.
Recap of glycolysis and a preview of what’s to come in the Krebs cycle and electron transport chain.
Transcripts
welcome to our video series on cellular
respiration before we get started I'm
going to ask you to do a few things
don't be a passive learner have paper
and pencil handy pause the video
frequently rewind and re-watch draw your
own pictures because as you know
pictures are your friends and ask
questions go ahead write them down
research the answers and to really test
your understanding teach it to someone
else in your own words and if you want
you can leave questions in the comment
sections below and only instrument as I
can now let's get started I decided to
make this a three part series in part 1
we'll do an introduction or cell
respiration and the details of
glycolysis that's what you're watching
now then in part 2 we'll take a closer
look at the Krebs cycle and in part 3
we'll look at electron transport
phosphorylation watch these three videos
in sequence I'll have links for these
second two at the end of this video and
after it finished with that series check
out my video on fermentation we'll look
at a different way of getting the energy
out of glucose all right now our last
video series we looked at photosynthesis
how we could take the energy of sunlight
and put into the bonds of glucose to
make our cellular fuel so what we need
to do in this video is figure out how we
get this energy back out we need to turn
photosynthesis around so we can see
respiration we're going to get the
energy back out of glucose in a form
called ATP so when we look at this
overall equation we're taking glucose in
the presence of oxygen and we're going
to break it apart into carbon dioxide
and water to liberate energy in the form
of molecule ATP approximately 36 of them
so the respiration is going to occur in
three stages
the first stage is called glycolysis
it's an inter robic stage that takes
place in the cytoplasm
the products of glycolysis will enter
the mitochondria where the second third
stages of respiration occur the second
stage of respiration is called the Krebs
cycle is preceded by a preparatory step
and it's a series of reactions that
occur in the mitochondria that are often
referred to as a citric acid cycle
because the first intermediate made is
citrate or citric acid in the final
stage of respiration is electron
transport phosphorylation it takes place
deep inside the mitochondria it's a
series of enzymes embedded in the inner
membrane called the electron transport
chain it's this stage of respiration
that's aerobic and that will produce the
majority of our ATP now let's take a
look at where this occurs here we have a
cell you want to zoom in on some
important organelles the mitochondria
whoops there we go the mitochondria
let's take a closer look at these
mitochondria the mitochondria is often
referred to as a cell's power plant it's
the primary site of cellular respiration
where we're going to recapture the
energy from those high energy bonds of
glucose and you'll notice that the
mitochondria is a double membrane-bound
organelle and it's across this inner
membrane where a lot of our action is
going to occur we'll come back to the
mitochondria later because the first
stages of respiration glycolysis occurs
out here in the cytoplasm now let's keep
in mind what it is we're trying to do
we're trying to make ATP
so we need to talk about how ATP is
actually made it turns out there are two
ways to make ATP substrate-level
phosphorylation and electron transport
phosphorylation which is driven by
chemiosmosis now let's look at what
substrate level phosphorylation looks
like in substrate level phosphorylation
is substrate directly hands an adp a
phosphate to become ATP let's watch that
again
we have substrate level phosphorylation
8 DP was phosphorylated into ATP with a
direct transfer of a phosphate group so
we call this substrate level
phosphorylation that substrate donates
the phosphate in electron transport
phosphorylation ATP is driven production
is driven by chemiosmotic gradient the
flow of protons through a special
channel protein that we call ATP
synthase so let's get start with
glycolysis
remember that glycolysis is an aerobic
and it occurs in the cytoplasm and we're
going to start with glucose and in the
first step of glycolysis glucose is
split with the energy from ATP and this
is interesting because we're trying to
make ATP but in the first step we
actually consume 2 ATP to split glucose
into two molecules called pgl or
phosphoglyceraldehyde so in our first
step we take a 6 carbon molecule and
split it into two three carbon PJs and
it's going to cost us two ATP we call
this our energy investment stage we
spend two ATP to make two pjo now these
two pjl molecules are used to reduce nad
plus in the NADH and in doing so the pgl
are converted into B pga or by
phosphoglycerate now these two molecules
of NADH are caring for us high-energy
electrons they're very similar to the
electron carriers NADPH that we saw in
photosynthesis but obviously minus a
phosphate so it's in ADH but these two
molecules have a lot of energy left in
them they're carrying this high energy
electrons that's energy we can tap into
later let's look at again the two pjl we
have a tin of the first step of
glycolysis reduce NAD+ to NADH NADH
which is carrying for us higher energy
electrons and hydrogen that we'll send
to the electron transport chain to get
energy out of later
we can add that to our metabolic pathway
for that next step so now we have B PGA
or by phosphoglycerate let's look what
happens as to those molecules the B PGA
will phosphorylate adp into ATP and B
PGA becomes PGA or phosphoglycerate and
these ATP were made by substrate level
phosphorylation let's add that to our
flow chart here so the B PGA
phosphorylate adp into ATP becoming
phosphoglycerate the 2-phosphoglycerate
then phosphorylate another to adp into
two more ATP again by substrate level
phosphorylation and we end with 2
molecules of pyruvate so let's finish
this out the to be the two PGA is
phosphorylate adp into ATP producing 2
pyruvate so in the second stage we have
made 4 ATP so we call this our energy
return stage we have a net profit of 2
ATP we spend 2 we make 4 we also have
these 2 nadh molecule that are carrying
energy that we've yet to tap into so
let's summarize glycolysis again it's
anaerobic doesn't require action it
takes place in the cytoplasm we have an
energy investment step 2 ATP but energy
return of 4 for a net yield or profit of
2 ATP we also produce 2 NADH molecules
which will go onto the electron
transport chain and we end with 2
pyruvate molecules which will go onto
the Crypt so again we're looking at our
flow chart the products of glycolysis
besides this 4 ATP that we're after act
our profit of 2 the other two products
the NADH and the per rate we're not done
with these per rate still have energy in
them that we're going to get in tap into
in the Krebs cycle and the nadh have
energy in them that will tap into and
the electron transport chain
finally let's finish with a little
accounting let's see here's the overall
reaction for respiration and we've
accomplished so far just glycolysis so
let's take into account what we
have and have not done yet and then grab
a pin here so we use glucose check we're
done with that we've yet to use oxygen
and we've yet to make carbon dioxide and
we've yet to make water but we have made
some ATP but only two so we have
approximately 34 ATP left to make so
where's the energy for those ATP well
hopefully you can see that we've yet to
tap into these molecules and so that's
where we're going to go next we
obviously still have a long way to go to
get through this whole process so that
does it for our first part glycolysis
click on this link right here for the
Krebs cycle as we move through this
series on cellular respiration
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