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Biomolecules of Life
Carbohydrates
Carbohydrates include sugars and the
polymers of sugars. The monomers of
carbohydrates are monosaccharides, or
simple sugars. Carbohydrate polymers are
called polysaccharides.
Monosaccharide
Polysaccharide
Carbohydrates are made of CHO:
carbon, hydrogen, and oxygen.
Monosaccharide
Polysaccharide
Monosaccharides have molecular
formulas that are usually multiples of
CH2O. Glucose (C6H12O6) is the most
common monosaccharide.
Glucose
Polysaccharides have storage and structural roles.
The structure and function of a polysaccharide are
determined by its sugar monomers and the positions
of glycosidic linkages (the bonds that hold polymers
together).
Starch, a storage polysaccharide of
plants, is constructed of monomers of
 (alpha) glucose. Plants store starch
within chloroplasts and other plastids.
 glucose
Starch, made from 1-4  glycosidic linkages
Glycogen, a storage polysaccharide in
animals, is made from highly branched
chains of  glucose . Glycogen is stored
mainly in liver and muscle cells.
Cellulose is a polysaccharide that is a major
component of plant cell walls. Cellulose is
a polymer of  glucose, and is not
digestible by animals.
 glucose
Cellulose, made from 1-4  glycosidic linkages
Starch vs. Cellulose
Starch, made from 1-4  glycosidic linkages
Cellulose, made from 1-4  glycosidic linkages
Chitin, a structural polysaccharide, is
found in the exoskeleton of arthropods
and the cell walls of many fungi.
Directionality influences structure and function
of polymers. An example is the directionality of
DNA that determines the direction in which
complementary nucleotides are added during
DNA synthesis.
Directionality influences structure and function
of polymers. Think of directionality like the
“head” and “feet” of a person- you have specific
ends. Molecules have specific ends, too, and
some have special names.
The type of bonds between monosaccharides
determines their relative orientation in a
carbohydrate. This then determines the secondary
structure of the carbohydrate. Beyond this, there is no
special directionality to know about.
So, carbohydrates are mainly for: quick energy, storage,
and structure.
Monomers include things like glucose, fructose, galactose.
Polymers include starch, chitin, glycogen, cellulose.
Carbohydrates
• Stop and review the information to make sure
you have it all before moving on!
Proteins
Proteins are
derived from
polypeptides,
which are
polymers built
from the same
set of 20 amino
acids (protein
monomers).
Proteins are
made of CHON:
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
*They can have other
elements too, depending on
what their R-groups are
made of (more on that
soon).
In proteins, the specific order of amino
acid monomers in a polypeptide interacts
with the environment to determine the
overall shape of the protein.
An amino acid monomer contains an
amino group, a carboxyl group, and an R
group attached to a central carbon.
(I would probably draw this in your notes…)
Amino
Group
Carboxyl
Group
The main part of the amino acid is shared
between all 20 kinds. However, the “R
group” is what makes each amino acid
unique.
Amino Acids with Electrically Charged Side Chains
Aspartic acid
Glutamic acid
Lysine
Arginine
Histidine
Amino acids differ in their properties
due to differences in their R groups,
also called side chains. (p79)
Amino Acids with Electrically Charged Side Chains
Aspartic acid
Glutamic acid
Lysine
Arginine
Histidine
As amino acids link up, a
polypeptide chain forms. This is
what is known as the primary
structure of the protein. (There
are 4 levels of protein structure.
This is the first. See pg.82 for
more info).
In any given protein, some amino acids in the polypeptide
chain will interact and form hydrogen bonds. This is called the
secondary structure of the protein. Typical secondary
structures are a coil called an  helix and a folded structure
called a  pleated sheet. (pg 82)
 pleated sheet
 helix
Tertiary structure (the 3rd level of how a protein folds) is
determined by interactions between R groups/side chains.
These interactions include hydrogen bonds, ionic bonds,
hydrophobic interactions, and van der Waals interactions.
Strong covalent bonds called disulfide bridges may reinforce
the protein’s structure.
Quaternary structure results when two or
more polypeptide chains form one
macromolecule.
A functional protein consists of one or
more polypeptides twisted, folded, and
coiled into a unique shape.
After reading this and checking out the book, does
protein folding still confuse you? Then watch the first
video and take a look at the second animation.
https://www.youtube.com/watch?v=qBRFIMcxZNM
http://www.stolaf.edu/people/giannini/flashanimat
/proteins/protein%20structure.swf
Amino acids are linked by peptide
bonds.
Peptide bonds form from condensation, or
dehydration synthesis, reactions.
Proteins have an amino end and a
carboxyl end.
Proteins have many functions- almost too many to list. They
do everything from transport molecules in organisms, speed
up reactions (enzymes), form body structures (like hair and
nails), and much more. We will learn a ton more about
proteins this year.
Some examples:
Collagen is a fibrous protein consisting of three
polypeptides coiled like a rope.
Some examples:
Hemoglobin is a globular protein consisting of
four polypeptides: two alpha and two beta
chains.
Important to know:
Most proteins probably go through several states on
their way to a stable structure. Chaperonins are
protein molecules that assist the proper folding of
other proteins.
Important to know:
This loss of a protein’s native structure is called
denaturation.A denatured protein is biologically inactive. This
can be caused by the things listed in the table.
Proteins are affected
by changes in:
•
•
•
•
pH
Salt concentration
Temperature
Other environmental
Before moving on…
• Compare carbohydrates and proteins.
– How are their structures different?
– How are their functions different?
Nucleic Acids
In nucleic acids (polymers), biological
information is encoded in sequences of
monomers called nucleotides.
Nucleic acids consist of CHONP: carbon,
hydrogen, oxygen, nitrogen, and phosphorous.
Each nucleotide has the following structural
components:
• a five-carbon sugar
• a phosphate group
• a nitrogen base
Deoxyribose sugar is in DNA and
ribose sugar is in RNA.
The polymers of nucleic acids (called “nucleic acids,” ooo,
fancy!) consist of DNA and RNA. Nucleic acids carry genetic
information, which is used to assemble proteins.
The bonds that connect nucleotides
are called phosphodiester bonds.
Phosphodiester bonds form by
condensation reactions.
Directionality: nucleic acids have a 5’ end
and a 3’ end. We will talk more about
which is which later on.
DNA and RNA differ in function and differ
slightly in structure. These structural
differences account for the differing functions.
•
•
•
•
DNA
Deoxyribose sugar
Thymine
Shape: double helix
Code for genetic
information
•
•
•
•
RNA
Ribose sugar
Uracil
Shape: single strand
Copy DNA so protein can be
made
Lipids
Lipids are the one class of large biological
molecules that do not form polymers. They
are mostly made of carbon and hydrogen.
The most biologically important lipids are
fats, phospholipids, and steroids.
In general, lipids are nonpolar, having little or no
affinity for water. Lipids are hydrophobic
because they consist mostly of hydrocarbons
(they are mostly C and H), which form nonpolar
covalent bonds.
Fats are constructed from two types of
smaller molecules: glycerol and fatty acids.
Fatty acids are bonded to the glycerol
molecule by ester bonds.
The formation of ester linkages is a
dehydration synthesis reaction.
Differences in saturation determine
the structure and function of lipids.
Saturated fatty acids have the maximum
number of hydrogen atoms possible and no
double bonds. (solid at room temp- can
pack close)
Unsaturated fatty acids have one or more
double bonds. This results in a bent structure.
(liquid at room temp- “kink”- can’t pack)
Trans fats (hydrogenated oils)- unsaturated fats
that have been synthetically converted to
saturated fats by adding hydrogen.
These kinds of lipids are great for long-term energy
storage (they provide more energy per gram, when
compared to the other biomolecules). They are also
great for insulation.
Phospholipids have polar regions that
interact with other polar molecules such as
water. They also have nonpolar regions
that do not interact with water.
Phospholipids are found in cell
membranes and help serve as barriers
to keep things in or out of cells.
Steroid lipids include cholesterol,
steroid hormones (derived from
cholesterol), and bile salts.
Cholesterol (seen below) is important in
cell membranes and helps keep them fluid.
Note its ring-shaped structure.
Steroid hormones are derived from
cholesterol. In humans, sex hormones like
testosterone and estrogen are steroid
hormones.
Steroid hormones are special because they
are able to pass through the cell
membrane and get inside a cell (most
other chemical messengers cannot do this).
Bile salts, also cholesterol-derived, are
used to help digest lipids in the body.
Wrap up!
• Remember, if you have questions/confusions,
you have options.
– Try to find your answers in the book. It’s giant but it’s actually a really
good resource. See if you can answer things yourself.
– If the book fails you, try to find your answers online. You have a
plethora of resources available to you through Google and
YouTube…more than I ever had in school. Lucky you!
– Finally, you can always jot your ponderings down! Ask in class! If you
are confused, someone else probably is too. Asking helps everyone,
not just yourself. You can even ask “extension” questions if you just
want to know more about something.
And finally…
• Remember, how much you learn (and how
well you do on the final test) is ultimately
up to you.
• How can you ensure learning? Immerse
yourself in content. Review often.
• Here’s an example…seek out videos. Bozeman
and Crash Course are always fantastic. See
next slide.
And finally…
• There’s a GREAT Crash Course video on this topic. I’m
not going to require it, but honestly, it would be a
really good idea for you to watch it. Why?
– The more ways you reinforce the topic, the more likely you
are to transfer it to long-term memory.
– You might pick up something from him that you didn’t
from me.
– Yeah, it looks long, but the “meat” of the video doesn’t
really start until 3:43. Can you spare ~10 minutes?
– And besides…he’s hilarious, so it’s worth it. I can’t watch
one of these videos without cracking up!
And finally (again)…
• There are “test yourself” questions that you
can use to see if you’re “getting it.” Go back to
my dropbox folder and open PPT 6.