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okay so the topic of this video is going
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to be some of the characteristics of the
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lipids and then eventually saturated
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versus unsaturated fatty acids
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all right so just a question depending
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how do organisms store energy ponder
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that and we're going to move on
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but we're going to talk about lipids
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today and again lipids are a type of
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organic molecules along with proteins
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and carbohydrates and nucleic acids so
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that means they're they're molecules
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that are really built around carbon
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all right so when it comes to lipids
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we're really talking about you know the
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fats the oils the waxes you know like
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you know beeswax you know the wax that
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makes up Honeycombs uh butter would be
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an example uh the cooking oils that
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you're familiar with you know lipids one
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of the more defining features is that
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they're insoluble in water that just
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means they don't mix so here's a layer
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of vegetable oil floating on top of
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water and even if we were to get a spoon
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and stir this up uh the two would never
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mix and eventually the vegetable oil
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would just separate out on top like you
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see in the picture
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so when it comes to lipids let's talk
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about the two building blocks the two
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parts there's a head that we call the
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glycerol molecule and then attached to
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the glycerol dangling down are some
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Tails called fatty acids so here's a
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very generic drawing of a lipid but a
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more realistic drawing might look might
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look a little bit like this this is a
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lipid and there's the glycerol head and
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there's fatty acid one fatty acid two
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fatty acid three
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now if we look at the molecular
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structure of the glycerol there's the
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glycerol right there and here's a fatty
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acid notice uh in red there's two h's
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and an O well that's going to be water
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in a moment in in a in a dehydration
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synthesis reaction water is removed and
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the fatty acid bonded to the to the
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glycerol let's do that two more times
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here's another fatty acid and then water
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is removed and the second fatty acid
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bonded to the glycerol and here's a
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third fatty acid and water is removed
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and notice how we now have one gigantic
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molecule made from the glycerol head and
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then in this case One Two Three fatty
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acid Tails attached
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and so here's a triglyceride again and
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if we look at the function of
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triglycerides this is really an energy
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storage molecule there's energy stored
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in the bonds of the atoms that make up a
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triglyceride
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and so if we look at one of the fatty
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acids here you know flashing in red are
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the bonds in between the carbons and the
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carbons and the carbons and in that in
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those bonds there our energy or is
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energy that the cell can use for its
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needs
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a secondary function of lipids is
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insulation you know if you're a whale or
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you're an elephant seal and you're
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swimming through you know the chilly
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ocean waters having a thick layer of
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blubber helps to absorb or helps to
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sorry trap heat uh to you know to keep
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you warm and it's a great form of
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insulation for organisms that live in
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cold environments
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and another function for lipids is in
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the structure of our cells you know
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here's a cell right here if we zoom on
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into the cell membrane
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and when we zoom into the cell membrane
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here we see the basic units of the cell
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membrane a phospholipid so you might
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remember from learning about cells that
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the phospholipids and the cell membrane
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the phospholipids are the foundation of
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the cell membrane
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and the cell membrane regulates a what
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can enter and exit within the cell
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also there's another lipid in the cell
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membrane embedded within the cell
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membrane are cholesterol molecules these
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are very important in adding flexibility
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to the cell membrane so I know lipids
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often have a negative
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stereotype to them because we associate
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lipids with fats but here's two examples
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of lipids that are the very Foundation
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of our cells
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so let's start to focus now on the
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difference between saturated and
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unsaturated fatty acids here is the
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backbone of a saturated fatty acid
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flashing in red you'll notice a single
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bond in between every carbon and carbon
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there's a single bond this is
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characteristic of a saturated fatty acid
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and the reason it's called saturated
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because when I add the rest of the atoms
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the carbons are filled with hydrogens
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and the word saturated just as a fancy
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word that means to be filled with so
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saturated fatty acids are these chains
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of carbons that are filled with
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hydrogens
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and so notice how the chain is basically
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in a straight line the chain is
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therefore very densely compacted and
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these saturated fatty acids fatty acids
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tend to be solid at room temperature
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hence butter be in solid at room
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temperature and lard being solid at room
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temperature saturated fatty acids tend
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to be most of the animal fats and so
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again butter is made from cow's milk and
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lard is made from Pig fats now there are
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exceptions to this but that's just a
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general characteristic that saturated
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fatty acids tend to be animal fats
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but if we look at unsaturated fatty
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acids notice in between a couple you can
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see it blinking red in between a couple
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of the carbons is a what looks like an
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equal sign or a Double Dash This is
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called a double bond that double bond
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creates a little crooked kink in the
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chain of carbons
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and the reason it's called an
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unsaturated fat is because there's just
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a few less hydrogens than normal if you
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look right here
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are hydrogens needed in those two gaps
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right there do I need to draw in two
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more hydrogens I hope you see the answer
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is no
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carbon can only Bond four times right
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now all those carbons have four bonds
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attached to them there's no space for
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two more hydrogens
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and so this Kink the double bond right
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there causes the a kink in the chain and
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that causes the molecule to be less
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dense and liquidy at room temperature
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hence vegetable oil and another example
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would be some things like corn oil and
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peanut oil and avocado oil again oils
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that come from plants and also fish fats
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tend to be unsaturated fatty acids
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well if we look at you know digesting
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and breaking down lipids well that
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involves a hydrolysis reaction and so
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Hydro implies water and lysis means to
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break down and in a hydrolysis reaction
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with the additional water a lipid can be
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broken down and so here's a water
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molecule and enzymes along with water
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will break off one of the fatty acids
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let's do that again here's another water
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molecule that breaks off the middle
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fatty acid let's do that one more time
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here's another water molecule breaks off
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the third fatty acid so notice the lipid
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has been broken down into the glycerol
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which is the part on top and then the
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Three fatty acids which are the three on
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the bottom
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and so let's talk about a medical
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condition known as arterial sclerosis so
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normally here's an artery with red blood
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cells traveling through them
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and so normally blood will flow freely
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however Arthur artherosclerosis is a
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medical condition where there's a
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buildup of cholesterol and and and
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plaque that builds up in the arteries
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and you can see it can cause blockages
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and ultimately this can have some
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negative side effects like reduced
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circulation blood clots high blood
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pressure and this can be attributed to
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you know a a diet with you know high
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amounts of cholesterol or a high amounts
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of lipids
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when you get older you might have to you
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know check your cholesterol levels and
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so the red level high green level
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desirable and the picture on the bottom
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again just sums up arterial sclerosis
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the top picture shows a normal artery
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wide open so blood can flow freely the
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bottom picture shows the plaque and how
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the artery is kind of partially closed
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and so these are a little some of the
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characteristics of lipids here
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and so here's a little practice quiz for
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you pause the video try to answer these
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questions if you're in my biology class
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I'm happy to check your answers thanks
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for watching
