- [Instructor] Lecture
five quiz review on organic
molecules primarily covers
these four groups right here,
carbohydrates, lipids,
proteins, nucleic acids,
that's eight out of the 10 questions.
But there are two other
questions regarding
these organic molecules that
you've been learning about,
that will play into the
other two questions,
which are on dehydration
synthesis and hydrolysis,
you basically have one
on each one of those.
And you won't just have
definition questions on these,
those are possible questions
but you'll also have questions
that relate to all the
monomers and polymers
that we discussed in this lecture.
So you'll need to make sure
that you have this list
of monomers in this list of polymers
familiar because as I discussed
dehydration synthesis,
I may ask the question which
of the following molecules
is made through dehydration synthesis.
Now that's why I've given
you this is to show you that,
monomers are assembled
through dehydration synthesis
into polymers.
So if I say which of the following is made
through dehydration synthesis?
You're gonna look for a polymer
'cause all the other answers
will have monomers, and
those are not the ones
you want to choose.
Now the other question is the
reverse of this, hydrolysis.
Same concept though, if
I ask you which it's made
through hydrolysis you'll
look for a monomer,
you won't look for any of the polymers.
So some questions may just be definition,
others are application,
so make sure you know
both of those aspects.
Now as far as the four organic groups,
most of the questions are
going to be very particular
to each group.
So let's go through those again.
Carbohydrates, you mainly need
to know that monosaccharides
are used for energy,
disaccharides are used for energy,
and be familiar with their names.
You do not have to know
the different structures
of them between glucose
and fructose and galactose
and all of that.
Oligosaccharides we'll get
back to that one in a second.
Polysaccharides, this is the
one where you not only need
to know the name but
what organism uses it,
and what it's used for.
For example, starch is
what plants use to store
carbohydrates for energy.
Glycogen is what animals
and fungi use to store
carbohydrates for energy.
Cellulose is what plants
use to use for structure,
but it's not used for energy.
And chitin again is something
used by animals and fungi
as a structural carbohydrate,
but not used for energy.
'Cause I'm gonna describe
their, what species,
what type animal, plant, fungi,
and what they're used for
and you need to tell me,
Oh, that's starch, that's glycogen
or that cellulose.
So you do need to know
these because they come up
time and time again.
Monosaccharides and
disaccharides just make sure
you know those are
examples of carbohydrates
used for energy and they're
the building blocks.
Oligosaccharides is another one,
again this is not used
for structure or energy,
it's used for recognition,
like your blood type,
or other cellular recognition.
These are the sugars that
are found on the surface
of your cells that your
body recognizes as self,
so that if something foreign comes in
you're like, Oh, I don't recognize
that and you'll attack it
and fight it off like a
bacteria or something like that.
So these oligosaccharides,
these are proteins embedded
in your cell membrane is we're gonna get
to in the next lecture, and the glyco
that's the carbohydrate part,
that's the oligosaccharide
portion of the recognition, okay.
As far as lipids go make
sure you know the difference
between triglycerides
phospholipids and sterols.
Basically I'm going to
differentiate between
these in the questions,
make sure you know that
triglycerides come in two forms
saturated and unsaturated,
and that you can describe the difference
between the two.
Phospholipids make sure you
understand that it's the unique
polar head that they have
that give them their ability
to form these membrane structures in water
that's so critical for life.
And as far as sterols
go make sure you know
that there are these four fused
hydrocarbon ring structures
that are belonging to the fat
group but have a wide variety
of different functions, but
the reason why they belong
to the lipids group is
because they're non-polar.
Waxes will not show up on the quiz,
so don't worry about that one.
Proteins because it's
such a complex group,
there are two main
questions you're gonna have,
the first one is protein folding,
so make sure you know
all four of these levels
of folding 'cause I'm gonna
describe some level and you
tell me which one that is.
The second question is on denaturation
which is protein unfolding
'cause that comes up all the time.
Make sure you know that
heat change in salinity
and change in pH, it's not
salt or pH it's not acids
it's not alkaline it's not high salt,
because there are a lot
of proteins that work
in high salt concentrations or high,
low pH or high pH concentrations,
it's about a change in what
they're designed to work in.
So some things that
don't denature proteins
are things like light or freezing,
those things don't cause the
protein to lose their function.
We freeze proteins all the
time and then we thaw them out
and they're still perfectly viable.
Some proteins are designed
to absorb light like UV light
that's one of the proteins in your skin
that we talked about that absorbs UV light
to protect your DNA.
So make sure you know what
can denature your proteins
and what doesn't.
For nucleic acids make sure
that you know the difference
between nucleotides and then DNA and RNA.
Nucleotides are the monomers
these are the building blocks
made up of a phosphate sugar and a base,
and then DNA and RNA,
these are the polymers.
DNA some of the shortest
strands of DNA in your body
or millions of nucleotides long,
that's a long polymer.
RNA usually hundreds to
thousands of nucleotides long,
so those are still actually
really long polymers,
you don't need to memorize
the names of the bases yet,
that's for lecture 10.
But you do need to know
some of the basic properties
of DNA and RNA, DNA is the
hereditary information,
RNA is the transient information.
Generally when you see
something like information,
you need to, that's gonna
be the nucleic acid group.
Now the only nucleotide you need
to be aware of in addition
to DNA and RNA is ATP.
This is gonna come up in future lectures
and is really vital to biology.
Basically just know that
this is a short term battery,
this is short term energy that belongs
to the nucleic acid group.
Why does it belong in
the nucleic acid group?
Because of the phosphate
sugar and the base.
This is a nucleotide right here.
We're gonna talk more
about these phosphates
in a future lecture, but know that ATP
is also a monomer, it is
a small building block,
and it is used for as short term energy.
Now the reason for that is
because one of the most difficult
questions on this quiz,
fundamentally come down
to everyone's gonna get
one of these questions,
and it's going to say which
of the following groups
am I describing.
And I'll describe the carbohydrate group,
or I'll describe the lipid group,
or I'll say which of the
following is not a characteristic
of any molecule in the carbohydrate group.
So this is why you need
to be familiar with all
of the different functions
of some of the things
we've talked about in here.
Carbohydrates are used for energy,
for structure, and for recognition.
Lipids are hydrophobic
they're not very large
they don't form these huge long polymers,
and they're used for energy,
and they're used for structure.
Proteins, basically are
everything that work in the cell,
everything all the work that
the cells do is proteins.
They are used for energy,
they're used for structure,
they're used for so many different things,
but they're not used for
hereditary information.
So for example if I say
which of the following
is not a function of any of the molecules
in the protein group and used
if I say used for hereditary
information that's passed
on from cell to cell,
that's the nucleic acids group, right?
So same thing with nucleic acids,
they're used for information,
long term hereditary information,
they're used for short term information.
They're also used for short term energy,
that's why I brought up the ATP,
'cause that's the one
that throws people off
on the nucleic acids question.
So they're generally very obvious
once I've just gone through
what I've gone through,
for example if in the
lipids group it says,
that they can form
monomers that form hundreds
of thousands of different of structures,
no that's not the lipids group
that's the protein group,
proteins form hundreds of
thousands of different structures
that are necessary for biology to work.
The complexity of this group is immense.
So usually there will
be something from one
of the other groups thrown in
there, that should be the most
obvious difference, and you're like,
Oh, that's not belonging
to that group.
So that's the only difficult
question I think of all
of these, but there's
a lot of information,
a lot of things that you
got to be familiar with
just to make sure you
have all of that together.
So about two questions per group,
but in that is one of
those really big questions
that everyone's gonna get
on all four of the groups.
So you're not guaranteed two
on each one but somewhere
in those two on each
one you're going to get,
everyone's gonna get one
of those big questions
on the functions of each of these groups.
So look out for that one.
