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Course: MCAT > Unit 5
Lesson 12: Overview of metabolism- Overview of metabolism questions
- MCAT training passage: Thermodynamics of ATP hydrolysis in living cells
- Overview of metabolism: Anabolism and catabolism
- ATP: Adenosine triphosphate
- ATP hydrolysis: Gibbs free energy
- ATP hydrolysis: Transfer of a phosphate group
- Oxidation and reduction review from biological point-of-view
- Oxidation and reduction in metabolism
- Electron carrier molecules
- ATP hydrolysis mechanism
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Overview of metabolism: Anabolism and catabolism
What is the purpose of metabolism? Learn about the two major divisions in metabolism: anabolism (building up) and catabolism (breaking down). By Jasmine Rana. Created by Jasmine Rana.
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- At about4:40, the definition of catabolism anabolism is discussed. I am curious to know what the suffix(?) "bolic" means. e.g. Anabolic, metabolic, catabolic. I tried looking it up myself but could not find a solid answer.
Thanks in advance!(6 votes)- The suffix "bolism" comes from the Greek "ballein" = "to throw". The prefixes "ana" and "cata" come Greek as well (Greek "kata" = "down", Greek "ana" = "up").
Hope this helps.(20 votes)
- So would it be fair to say that; catabolism ATP is used and ADP produced, and Anabolism ADP is used and ATP produces?(2 votes)
- I believe is the opposite. The process of catabolism releases energy that can be used to produced ATP. The process of anabolism requires ATP, thus producing ADP at the end. However, catabolism requires the investment of ATP at the beginning (glycolysis), but at the end it results in a net gain.(17 votes)
- so you can say that anabolism is the reversal of catabolism?(5 votes)
- Yes, seeing how anabolism makes complex substances out of basic one, and catabolism breaks down larger structures into smaller one, the two processes could very accurately be described as the opposite of each other.(4 votes)
- At time5:56. So cellular respiration is using all of the monomers to make ATP once again? Where does the energy come from and does it use any enzyme to do this?
Thank you!(2 votes)- The small monomers are broken down and ultimately fuel the process of oxidative phosphorylation. During these processes (glycolysis, Kreb cycle, etc.), which utilize a plethora of enzymes, reduced species are produced (NADH, FADH2) and these are used to pump protons across the electron transport chain (ETC) in mitochondria. This provides energy for the ATP synthase to create ATP as H+ ions flow back. All of this is also described and in other videos in the Biology section of Khan videos.(8 votes)
- Isn't energy released when a bond forms and energy absorbed when a bond breaks?(5 votes)
- yes, energy is needed when a bond is broken and energy is released when a bond is formed to overcome force of attraction.(1 vote)
- What is primarily responsible for the release of energy: the ATP's loss of a phosphate group, the breaking down of the food as a result of the ATP, or a combination of both?(3 votes)
- Food isn't broken down as a result of ATP. Food is broken down as a result of ENZYMES. You can see this fact at work in glycolysis (sugar is broken down in steps, with each step having an enzyme associated with it). ATP hydrolysis is an EXERGONIC process....the cleavage of the terminal phosphate releases a huge amount of energy. There ya go.(3 votes)
- how is the digestion of food compared to metabolism.(1 vote)
- Digestion of food is a form of metabolism. Specifically, it is a catabolic reaction (a subset of metabolism)(2 votes)
- Not sure if this was already asked but can I get an example of both Anabolism & Catabolism?(1 vote)
- Anabolism is the building of complex molecules from numerous simple ones. Think of protein synthesis. Catabolism is the breakdown of complex molecules into numerous simple ones. Think the break down of glucose.(2 votes)
- Are fats and lipids the same thing?(1 vote)
- 'Lipid' is the larger category including fats, waxes, and oils.(2 votes)
- From what I understand:
Catabolism = beaking down. Anabolism = building up
You said that catabolism fuels anabolism.
I am confused because I thought that the formation of bonds (between amino acids for example) leads to the release of energy. SO how does catabolism fuel anabolism?(1 vote)- Both catabolism and anabolism are constantly paired. By breaking down molecules (catabolism) the freed energy is then available to be "invested" in creating new bonds. (anabolism).. does that help? I think your confusion may be from also thinking that the formation of bonds leads to a release of energy. The newly formed molecule may be at a lower energy state but energy had to be invested to get over the "hump" that is activation energy.(2 votes)
Video transcript
Textbooks define metabolism,
a topic in biochemistry, as a series of
chemical reactions that take place inside of
our bodies to sustain life. Now, this is a pretty broad
definition of metabolism. So in this video, I really
want to break this definition down to a more workable
understanding of what metabolism really is. So first, I'm going to introduce
another arrow in this diagram, like this, and say that really,
the requirements of life, let's say in a human
being, such as maintaining a constant internal temperature,
reproducing, growing, and all that jazz, all of that
ultimately boils down to the body's ability to utilize
four essential biomolecules. And these four essential
biomolecules, or as they're sometimes known
as macromolecules, are proteins, fats,
carbohydrates, or carbs, and nucleic
acids, like DNA and RNA. And ultimately, all
of these biomolecules perform different
life-sustaining reactions inside of all of the
cells in our body to ultimately promote life. So as you can see,
we've already begun to break down this
definition of metabolism. Essentially what
we're saying here is that metabolism is really
the study of how we're able to obtain these important
biomolecules to sustain life. So how do we obtain
these biomolecules? Now, a simple answer
to this question is, of course, that
we eat food to obtain all of these important
biomolecules. But there is an
important word of caution here, which is that
since most food comes from living organisms
like plants and animals, these plants and animals also
contain an array of proteins, fats, carbohydrates, nucleic
acids, but not necessarily in the same flavor
or configuration that our bodies would prefer. So what do our
bodies do instead? Well, in our bodies, we
go ahead and eat the food. That's a very large head
there, but you get the idea. And in our bodies, we
break down this food through a process
called digestion into the component parts of
all of these biomolecules. So what do I mean
by component parts? Well, the smallest
subunit of proteins is called an amino acid. And our body breaks down
all the different types of proteins that we digest
into individual amino acids. And the same pattern
continues for the rest of the biomolecules. So in the case of
fats, we're talking about fatty acids, which are
the smallest subunits of fats. And then for
carbohydrates, which are long chains of sugars. One of the most common
subunits of carbohydrates that our body loves
is called glucose. So I'll go ahead
and write that here, since you'll be seeing it
a lot in the discussion of metabolism. And then finally,
for nucleic acids were talking about nucleotides. So at this point, you're
probably thinking, well, OK. I understand that our body can't
use the same macromolecules found in food
because maybe they're not in the right configuration. But how does breaking them
down do anything for us? Now the key here is to
recognize that in our body there is actually a
delicate balance going on between the processes
of breaking down molecules, such as in the
process of digestion, and then taking these products
and building them back up. So essentially, you can see all
of these subunits, or monomers, as LEGO pieces that we're
essentially reconstructing to build the right
configurations of proteins, fats, carbs, and nucleic
acids that our body needs. So that's really
the key idea here, which is that metabolism is a
balance between breaking things down and building them
back up in our body so that we can
customize, so to say, what type of macromolecules
that we create. And just to throw
in some vocab words, biochemists call the
process of breaking down molecules in our
body catabolism. And similar sounding
word called anabolism is used to describe the process
of building molecules back up. And the way I like to
remember this is looking at the first letter of each
of these words, I think of C, I think of cutting molecules
up into tiny pieces, so breaking them down. And then for anabolism,
A, I think of as like the apex of a
building, for example. So we're building something up. Now this seems all
fine and elegant, but there's one more issue
that we need to contend with, which is a consequence of having
to balance breaking things down and building them back up. And that is that this
process of building molecules back up requires energy. Which I'm kind of
indicating here by these yellow
lightening bolt stars. So the question I want to answer
in this last part of the video is where does this
energy come from? Now, the answer to this
question is that, well, we also get this energy
by eating food. So how does that work? So first, recall that the energy
currency of the cell-- and I'm going to go ahead
and erase this just to give us some more space. The energy currency
of our bodies is a molecule called ATP,
or adenosine triphosphate. And this high energy
molecule, as it's often referred to, when it is broken
down into ADP, so it loses a phosphate group, it releases
usable chemical energy that can fuel energy requiring
processes in our body, such as the building up
process of anabolism. Now, in order for this
process to continue non-stop in our bodies, ADP must
be regenerated into ATP. And that is where food comes in. So remember that
we digest our food into all of these subunits. And some of these subunits,
such as glucose and fatty acids mainly, but occasionally
amino acids-- I'm going to put
that in parentheses-- can essentially be used
as fuels in our body. So just like wood,
for example, is a fuel for a burning
fire, which produces heat, these fuels in our
body can essentially be broken down even further
to produce the energy that's necessary to convert
ADP back into ATP and thus allowing this
cycle to continue. And just to throw in
another vocabulary word that you'll probably
see, this process of taking these
fuels, which I've indicated with this
asterisk, and breaking them down into usable
energy is a process that's referred to as
cellular respiration. And recall that because
cellular respiration involves breaking down
things even further, it's also a catabolic process. So it falls under this
category of catabolism. And just to tie everything
here together at the end, notice here that
another way to interpret this cycling between
ATP and ADP is to say that catabolism
fuels anabolism. So what do I mean by this? Well, essentially, catabolism,
such as the process of breaking things down
and extracting energy through processes of
cellular respiration, is coupled with this process
of building things back up. And so in essence, one
relies on the other. And as you can probably
guess, these processes are really tightly
regulated in our bodies. Because obviously
you wouldn't want to be breaking down something
while you're building something back up. And in fact, just to give
you a preview forward, catabolism and anabolism are
often regulated, so controlled, through the use of hormones. So I'm going to write
here that hormones are a form of regulation, and
tell the body whether it should be in a catabolic
or anabolic state.