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Biological Molecules - You Are What You Eat: Crash Course Biology #3


Biological Molecules - You Are What You Eat: Crash Course Biology #3

Hank talks about the molecules that make up every living thing - carbohydrates, lipids, and proteins - and how we find them in our environment and in the food that we eat.

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TAGS: biological molecules, carbohydrates, lipids, proteins, nucleic acids, food, biolography, william prout, urea, energy, monosaccharides, glucose, fructose, disaccharides, sucrose, polysaccharides, simple sugars, cellulose, starch, glycogen, glycerol, fatty acid, triglyceride, phospholipid, steroid, cholesterol, enzymes, antibodies, hormones, amino acids, nitrogen, polypeptides, protein synthesis, biology, molecule, crashcourse, hank green Support CrashCourse on Patreon:

CrashCourse Macromolecules


Biomolecules (Updated)

Updated video on biomolecules (macromolecules): carbohydrates, lipids, proteins, and nucleic acids by the Amoeba Sisters including examples, functions, monomers, and structures! Expand details for table of contents. 👇 This video has a handout here: (Note: The old version of this video was called biomolecule band.)

Table of Contents:
What are Biomolecules? 0:22
Monomers 0:40
Carbohydrates 1:08
Lipids 2:04
Proteins 4:09
Nucleic Acids 5:14

Video Notes:

Video mentions that many do not consider lipids to have true monomers. This is due to the fact that their building blocks are made of two different substances (glycerol and fatty acids) that attach to each other--rather than attaching as one type of monomer to another. Also, due the the diversity of lipids, there are lipids that have a very different structure than discussed in this video.

We've seen a few comments attempt to use or critique parts of this video for human dietary guidelines. But this video, as stated in the description, focuses on general functions of biomolecules. The biomolecules: carbs, lipids, proteins, and nucleic acids, can all can have important functions in the body. However, this video is *not* giving human dietary guidelines and should *not* be used in any attempt to do so. *This is a video about the biomolecules. For your dietary needs, consult with a dietitian or medical doctor.*

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The Amoeba Sisters videos demystify science with humor and relevance. The videos center on Pinky's certification and experience in teaching science at the high school level. Pinky's teacher certification is in grades 4-8 science and 8-12 composite science (encompassing biology, chemistry, and physics). Amoeba Sisters videos only cover concepts that Pinky is certified to teach, and they focus on her specialty: secondary life science. For more information about The Amoeba Sisters, visit:

We cover the basics in biology concepts at the secondary level. If you are looking to discover more about biology and go into depth beyond these basics, our recommended reference is the FREE, peer reviewed, open source OpenStax biology textbook:

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Biological Molecules - You Are What You Eat: Crash Course Biology #3 !!.

In this video I discussed more about carbodydtrates.

Carbohydrates 1st Part:

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#Understanding Carbs #Dietary Guidelines : Define Carbohydrates #Effect of Carbohydrates on Blood Sugars #Biological Molecules - You Are What You Eat: Crash Course Biology

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Nucleic Acids | Biological Molecules Simplified #3

Learn about all the macromolecules and more at

Nucleic Acids are possibly the most underrated macromolecule known to man. They are the monomers of RNA and DNA, and without them, our cells would struggle...

Image Credit: OpenStax Biology

Thanks for stopping by, this is 2 minute classroom and today we’re talking about nucleic acids.

You may have heard about nucleic acids when talking about DNA or RNA because the “NA literally stands for “nucleic acid” This is where genetic information is stored and allows cells to produce all the necessary protein structures in living organisms.

I’m going to introduce the basic structure of nucleic acids first, and then talk about the variations for structure and how that relates to their function.

Monomers of nucleic acids are called nucleotides, these are the basics units of nucleic acids that bond together to form RNA and DNA.

All nucleotides are made up of three main components. A phosphate group, a sugar, and a nitrogenous base. In RNA and DNA, the phosphate group is the same, but they have slightly different sugars. In RNA, the sugar is ribose, and in DNA, the sugar is also a ribose, but with one less oxygen. Hence, RNA is ribonucleic acid, and DNA is Deoxyribonucleic acid. Because the ribose has been deoxygenated.

Finally, we have the nitrogenous base, and if you have studied DNA at all, you probably remember these. The nitrogenous bases in DNA are Guanine, Adenine, Cytosine, and Thymine. RNA also has Guanine, Adenine, and Cytosine, but instead of Thymine, RNA contains Uracil.

The phosphate of nucleic acids bond together to form long polynucleotide chains, like RNA and DNA. The nitrogenous bases can form weaker hydrogen bonds as they do between two strands of DNA. This bonding gives DNA its helical structure and allows it to perform many important functions.

Nucleic acids are an underrated macromolecule in my opinion. Carbohydrates, proteins, and fats seem to get all the attention, but nucleic acids store all the genetic information for your cells, without them, your body wouldn’t build the necessary machinery to carry out all cellular functions.

I hope this video answered any questions you had. If you still have some, I love to reply to my comments, so send additional questions there. You should also check out my video on DNA vs RNA, which goes into more detail. Don’t forget to smash that like button and subscribe for more quality content.

I’ll catch you next time.

Biological Molecules A Level

An overview of biological molecules for a level.

K-Bio Matter 3: Biological Molecules 1- Carbohydrates & Lipids

There may be nothing all that special about the elements we find in living systems, but there sure is something special about the way those elements are put together. In this video (part 1 of 2), Mr. Knuffke discusses two of the four major types of biological molecules: Carbohydrates and Lipids. An introduction to their structures and functions is provided, with examples from both groups to illustrate how differences in their structures leads to differences in their functions for life.

Thanks for watching! Do you still have questions? Would you like to make a request, or a correction? Leave a comment, send an email ( or check out the other resources available at

Slide handouts for this unit:

AP Curriculum Framework Video Correlations:
Link to standalone image credits:

Image Credits:
All images are licensed under creative commons and public domain licensing, except where otherwise noted. Attribution credit where applicable:
Dhatfield, derivative work: English: The Cell Membrane, Also Called the Plasma Membrane or Plasmalemma, Is a Semipermeable Lipid Bilayer Common to All Living Cells. It Contains a Variety of Biological Molecules, Primarily Proteins and Lipids, Which Are Involved in a Vast Array of Cellular Processes. It Also Serves as the Attachment Point for Both the Intracellular Cytoskeleton And, If Present, the Cell Wall., June 16, 2008. Cell_membrane_detailed_diagram_3.svg.
“File:5alpha-Dihydroprogesterone 3D Ball.png.” Wikipedia, the Free Encyclopedia. Accessed August 4, 2016.
“File:Beta-D-Glucose-3D-Balls.png - Wikimedia Commons.” Accessed August 4, 2016.
“File:Common Lipids Lmaps.png.” Wikipedia, the Free Encyclopedia. Accessed August 4, 2016.
“File:Estradiol.svg.” Wikipedia, the Free Encyclopedia. Accessed August 4, 2016.
“File:Glycerol-3D-Balls.png.” Wikipedia, the Free Encyclopedia. Accessed August 4, 2016.
“File:Glycogen Spacefilling Model.jpg.” Wikipedia, the Free Encyclopedia, March 21, 2012.
“File:Glycogen Structure.svg.” Wikipedia, the Free Encyclopedia. Accessed August 4, 2016.
“File:Oleic-Acid-3D-Ball-&-Stick.png - Wikimedia Commons.” Accessed August 4, 2016.
“File:Sucrose-3D-Balls.png - Wikimedia Commons.” Accessed August 4, 2016.
“File:Testosteron.svg.” Wikipedia, the Free Encyclopedia. Accessed August 4, 2016.
“File:Trimyristin-3D-vdW.png - Wikimedia Commons.” Accessed August 4, 2016.
Jonathunder. English: A Pat of Butter, Served on a Leaf, with a Butter Knife and Bread, January 15, 2011. Own work.
Jynto. Ball-and-Stick Model of the α-Linolenic Acid Molecule, an Unsaturated Fatty Acid., June 9, 2011. Own work This chemical image was created with Discovery Studio Visualizer.
LHcheM. English: Sample of Urea in the Form of Granules, March 12, 2012. Own work.
Mills, Ben. Ball-and-Stick Model of the Water Molecule, H2O., April 29, 2008. Own work.
Mills, Jynto and Ben. Ball-and-Stick Model of the Palmitic Acid Molecule (also Known as Hexadecanoic Acid), a Saturated Fatty Acid with 16 Carbon Atoms., August 1, 2010. Derived from File:Caproic-acid-3D-balls.png.
———. Ball and Stick Model of the Urea Molecule., November 9, 2009. Derived from File:Acetamide-3D-balls.png.

Lipids | Fats, Steroids, and Phospholipids | Biological Molecules Simplified #4

Learn about all the macromolecules and more at

Lipids are more then just fats! And Fats are more then just the excess weight we gain as we make poor diet choices. Ironically steroids are also a lipid, and they make people buff...

Image Credit: OpenStax Biology

Thanks for stopping by, this is 2 Minute Classroom and today we are talking about lipids. If you’ve learned about lipids before, you probably associate them with fats, and while fats are a lipid, so are waxes, oils, steroids and phospholipids.

Lipids are macromolecules made up of long hydrocarbon chains, thus named because they are made up exclusively of hydrogen and carbon. These long hydrocarbon chains give lipids their non-polar property, which means they are not soluble in water. This is why oil separates out from water when mixed.

One of the most common components of certain lipids is the fatty acid. Three fatty acids come together with glycerol to form a larger molecule called a triglycerol or triglyceride. Triglycerides have various functions in the body, but a primary one is energy storage as fat or adipose.

Fatty acids also include saturated and unsaturated fats, trans fats, and the omega fatty acids, but we won’t go into their detailed differences in this video.

Another molecule that incorporates the fatty acid chain is the phospholipid, most famous for its formation of the phospholipid bilayer which protects a cell from outside intrusion. Phospholipids contain two non-polar fatty acid tails bound to a polar phosphoglycerol head. This is why they form a bilayer, because the nonpolar tails are attracted to each other and the heads are attracted to water solutions in and out of the cell. At some point I’ll make a video discussing just how awesome this cell membrane is.

Let’s talk about steroids next. And yes, this includes these type of steroids, but that is not the focus of this video. Steroids are hydrophobic and not water soluble like the other lipids, but they do not contain fatty acids. Instead, they have four cyclic rings linked together. This basic structure is then added to to give us common steroids like cholesterol and cortisol. Steroids have many functions throughout the body, including the presence of hormone steroids like progesterone and testosterone, both formed from cholesterol.

Finally, lets not forget about waxes. Waxes have a variety of unique structures, and are found in the feathers of some birds and leaf structures of many plants. This is why water beads up or runs off certain plants.

There is a lot more to lipids, we didn’t even talk about soaps and detergents, but this was a great overview. If you have additional questions about lipids or just want to show some love, comment below!

Then watch these videos and don’t forget to subscribe to reap all my latest content.
I’ll catch you next time.

Proteins | Biological Molecules Simplified #2

Learn about all the macromolecules and more at

The simplest explanation of protein structure and function to help you understand just how important this macromolecule is!

Image Credit: OpenStax Biology

Thanks for stopping by, this is 2 Minute Classroom and today we are talking about proteins, and their structure and function in living organisms.

Proteins are macromolecules made primarily of Carbon, Hydrogen, Oxygen, and Nitrogen, but can have other atoms for certain proteins. Proteins are so abundant in the body and crucial to cell function that they are often called the building blocks of life. Let’s first talk about protein structure and then we’ll talk about many of their fantastic functions.

The basic subunits of all proteins are called Amino Acids, and there are 20 main amino acids in living organisms. These amino acids all have the same basic structure with a carboxyl group and an amino group, but differ in their R group or side chain. The resulting amino acid may be polar, non-polar, negatively charged, positively charged, or aromatic.

If that all went way over your head, that’s okay for this video. Just know that there are 20 amino acids with subtle differences resulting in a variety of chemical behaviors.

These amino acids bond with each other through a peptide bond and form long chains referred to as polypeptide chains. These chains then fold and bond with themselves form a complete protein, and sometimes they combine with other proteins to make a more complex protein structure.

Hemoglobin is a great example of this. Hemoglobin is the structure in red blood cells responsible for carrying oxygen to the cells. It is made of four globin protein subunits, each with an iron containing heme group. In other words, amino acids form polypeptide chains that can become complex quickly.

Along with carrying oxygen through the body, proteins have many other important functions.

Enzymes are proteins that assist in most chemical reactions in living organisms. Lactase that was mentioned in my last video is the enzyme responsible for breaking down the carbohydrate lactose. In addition to digestion, enzymes also metabolic energy pathways, genetic functions like transcription and translation, and signaling communication between cells, and the list continues.

Proteins are also crucial in forming the interior structure of the cell (the cytoskeleton) and are responsible for transporting materials both within the cell and between cells. And of course, our muscles are densely packed with proteins that facilitate the movement of our entire body.

Proteins also include antibodies involved in our immune response and hormones used to communicate specific actions in cells throughout the body.

That was quite the crash course into proteins. If you enjoyed this video let me know by hitting that like button and if you have additional comments or questions throw those below.
Don’t forget to check out my other videos and I’ll catch you next time!

Biological Molecules Summary

A summary video of what you need to know for the Biological Molecules topic of Year 12 AQA Biology.
Please comment any requests of videos you have.

Carbohydrates, Lipids, Proteins (IB Biology)

Water - Liquid Awesome: Crash Course Biology #2

Hank teaches us why water is one of the most fascinating and important substances in the universe.

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Re-watch = 00:00
Introduction = 00:42
Molecular structure & hydrogen bonds = 01:38
Cohesion & surface tension = 02:46
Adhesion = 03:31
Hydrophilic substances = 04:42
Hydrophobic substances = 05:14
Henry Cavendish = 05:49
Ice Density = 07:45
Heat Capacity = 09:10

Crash Course Biology is now available on DVD!


TAGS: water, hydrogen, oxygen, molecule, covalent bond, cohesion, adhesion, polarity, hydrogen bond, surface tension, capillary action, hydrophilic, hydrophobic, ionic bond, ion, universal solvent, henry cavendish, chemistry, specific gravity, density, heat capacity, evaporation, biology, crashcourse, crash course, hank green Support CrashCourse on Patreon:

AQA Alevel quick Biology - Episode 1 Biological molecules

A quick, accurate and succinct guide to biological molecules, for if you need to quickly revise the topic or even if you want to look ahead a little bit before class :)

Molecules of Life - Part 3: Proteins

Carbohydrates & sugars - biochemistry

What are carbohydrates & sugars? Carbohydrates simple sugars as well as complex carbohydrates and provide us with calories, or energy. Find more videos at

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DNA Structure and Replication: Crash Course Biology #10

Hank introduces us to that wondrous molecule deoxyribonucleic acid - also known as DNA - and explains how it replicates itself in our cells.

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References for this episode can be found in the Google document here:

1:41 link to Biological Molecules

Table of Contents:
1) Nucleic Acids 1:30
2) DNA
-A) Polymers 1:53
-B) Three Ingredients 2:12
-C) Base Pairs 3:45
-D) Base Sequences 4:13
3) Pop Quiz 5:07
4) RNA 5:36
-A) Three Differences from DNA 5:43
5) Biolography 6:16
6) Replication 8:49
-A) Helicase and Unzipping 9:22
-B) Leading Strand 9:38
-C) DNA Polymerase 10:08
-D) RNA Primase 10:24
-E) Lagging Strand 10:46
-F) Okazaki Fragments 11:07
-F) DNA Ligase 11:47

DNA, deoxyribonucleic acid, chromosome, nucleic acid, ribonucleic acid, RNA, polymer, nucleotide, double helix, nucleotide base, base pair, base sequence, friedrich miescher, rosalind franklin, replication, helicase, leading strand, lagging strand, rna primase, dna polymerase, okazaki fragment Support CrashCourse on Patreon:


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This video, tightly integrated with a tutorial at explains the chemistry of carbohydrates. It's designed for use with college-level freshman biology classes, or AP/Honors Biology at the high school level. Topics covered include:
1. What is a carbohydrate
2. Monosaccharides
3. Disaccharides (glucose, fructose, lactose, including lactose intolerance)
4. Polysaccharides (starch, amylose, amylopectin, glycogen, cellulose)
Link to Monomers and Polymers:

Biomolecules: The Proteins

Explore what proteins are, their structure, and their functions.

Polymers: Crash Course Chemistry #45

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Did you know that Polymers save the lives of Elephants? Well, now you do! The world of Polymers is so amazingly integrated into our daily lives that we sometimes forget how amazing they are. Here, Hank talks about how they were developed an the different types of Polymers that are common in the world today, including some that may surprise you.

Table of Contents

Commercial Polymers & Saved Elephants 0:00
Ethene AKA Ethylene 2:29
Addition Reactions 3:08
Ethene Based Polymers 4:44
Addition Polymerization & Condensation Reactions 6:32
Proteins & Other Natural Polymers 8:33
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Topic 1 of the new spec AQA A Level Biology covering Biological Molecules - specifically Carbohydrates (saccharides)



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