Captioning is on! To turn off, click CC button at bottom right!
Follow the amoebas on Twitter (@AmoebaSisters) and on Facebook.
I want you to think for a moment about your very favorite food. What is it? Pizza? Macaroni
and cheese? Chicken Salad? Sushi? Well we all have different food preferences, but food
is a source of large molecules that are needed for life called biomolecules. There are 4
major biomolecules that make up all of life, and this will be the focus of this video.
Before we get into details about the 4 biomolecules, we need to talk about one very important vocabulary
word. The word monomer. A monomer is a building block – if I had some large
substance, the parts that make up that substance are called monomers. Just like building blocks.
We're going to talk a lot about monomers today, because we need to understand what the biomolecules are made of.
And we need to understand biomolecules, because they're building components of life.
So let’s introduce the 4 biomolecules now and talk a little bit about their functions. We'll start with carbohydrates.
Carbs. Well carbs are something you have probably heard about when people are talking
about diets. You know, they try to go low carb or maybe they want a lot of carbs...diets
always come and go. Pasta and breads are examples of foods heavy in carbohydrates. Carbs are
actually a very important source of energy. In fact, that's one big function of carbs.
They are a great, fast source of energy. If you were a marathon runner, you might want
to eat a lot of carbs the night before a race. Lots of marathon runners do this. It's called
pasta loading. They eat a big pasta dinner the night before they go out on their marathon.
Now carbs have a monomer- again, remember, monomers are building blocks. The monomer
for a carb is called a monosaccharide. I know that's a big mouthful but monosaccharides
make up carbohydrates.
Next one up is a diverse group known as lipids. Lipids are better known as fats.
They have 2 different types of building blocks. One type of building block is called a fatty acid and the other type is called a glycerol.
Now examples of lipids include butter, oil, and cholesterol. Lipids, though, they have a lot of great functions. You
may think well that's fat...how good can fat be? Well it just depends when you put it into
context. For example, you know those really adorable seals that you see on calendars?
They have this fluffy white hair. They're actually called a harp seal. Well they
actually only look like that when they're babies. When they get older, they're not quite
as cute. But in their little baby stage, they actually have a lot of this hair that they're born
with that help keep them warm. But over time, they have to develop blubber. It's fat and
it helps keep them warm. Lipids are great for insulating. Also you might not think about
fats as being related to energy, but fats are a great source of long term energy. They
can store energy for a long, long time. Say for example you wanted to swim the English
Channel. That's like 21 miles of swimming. The fastest swimmers might be able to do that
in 7 or 8 hours but it might take a lot longer than that for the average swimmer. More like
25 hours, and that's a lot of swimming. Well you would want to make sure that your body
has enough lipids- enough stored fat- that it can pull upon. Because after you burn off those
carbohydrates (remember carbs are the fast source of energy), you might not have enough energy
storage unless you have some lipids on hand. Lipids also make up cell membranes so they
are very important for life because all living things are made of cells. Of course an excessive amount of lipids could be a bad
thing for your health. Remember it's all about moderation.
Ok, next, proteins! When you hear about proteins, a lot of times you might think about protein
bars. They say they have lots of protein in them and that they help with muscle building.
Well protein is great for muscle building. Examples of foods that are high in protein include
meats and many types of beans. The monomers of protein are amino acids. So sometimes you
see these labels that say, "This has 20 amino acids in this food." Really they're just trying
to say that it has protein, and proteins are made up of amino acids so that's just some
fancy advertising for you. But in addition to it being important for muscle development, protein
is also very important in other functions such as working in the immune system and acting
as enzymes. Remember enzymes are made of proteins so proteins are important for the body.
Now when we start talking about genes - the DNA genes not the jeans you wear- the DNA codes
for proteins that are very important for structure and function in the body.
The last big biomolecule is known as a nucleic acid. Nucleic acids include DNA and RNA, which
we'll get to when we get to genetics. They have a monomer called a nucleotide. That's
going to be an easy one for you to remember because nucleotide sounds a lot like nucleic acid.
If considering DNA and RNA, both of these are involved in genetic information for the
coding of your traits. They are found in a lot of your food, because whenever you eat
something that came from something once living, it can still contain the DNA. For example,
when you eat a strawberry, you're actually consuming all the cells that make up that
strawberry. In the nucleus of all of those strawberry cells is DNA. Plants and animals
both have DNA. In fact, any type of life must contain nucleic acids like DNA to direct the cells'
activities.
So we just powered through introducing the 4 biomolecules by providing examples, exploring
their monomers, and giving some general functions. One last very important part to mention is
the structure of these biomolecules. Understanding the structure can help with predicting their
properties and easily being able to identify them. One thing I like to tell students to
do is to write the 4 biomolecules in this same order we went through: carbs, lipids,
proteins, and nucleic acids. Then remember this mnemonic device that goes with these
4 biomolecules. CHO, CHO, CHON, CHONP. Instead of chomp at the end with a "m," it's chomp with an "n.”
The c stands for carbon, the h stands for hydrogen, the o for oxygen. So carbs, lipids,
proteins, and nucleic acids all have that CHO in there. It's just that proteins and
nucleic acids also have an N which is nitrogen and nucleic acids additionally have a P which
is for phosphorous. So again CHO, CHO, CHON, CHONP---the major elements in the 4 biomolecules.
Now these elements are arranged differently in the 4 biomolecules---such as a ring arrangement
or a chain arrangement. It’s important to explore the arrangement of the elements in
biomolecules, because the structure of that arrangement greatly impacts the biomolecule
function. So to the Google to discover some biomolecule arrangement illustrations. Well
that's it for the Amoeba Sisters and we remind you to stay curious.