This collection is being developed for the revised MCAT® exam that will first be administered in April 2015. The collection contains more than 900 videos and 2000 practice questions. Content will be added to the collection through 2015. All content in this collection has been created under the direction of the Khan Academy and has been reviewed under the direction of the AAMC (Association of American Medical Colleges). All materials are categorized according to the pre-health competencies tested by the new MCAT exam; however, the content in this collection is not intended to prescribe a program of study for the new MCAT exam. The content is also included in the Pre-health Collection within MedEdPORTAL’s iCollaborative sponsored by the AAMC: *MCAT® is a program of the AAMC and related trademarks owned by the Association include Medical College Admission Test, MCAT, and MCAT2015. For more information about the MCAT exam visit
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Biological and Biochemical Foundations of Living Systems Passages

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Chemical and Physical Foundations of Biological Systems Passages

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Psychological, Social, and Biological Foundations of Behaviors Passages

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Foundational Concept 1: Biomolecules have unique properties that determine how they contribute to the structure and function of cells, and how they participate in the processes necessary to maintain life.


Foundational Concept 2: Highly-organized assemblies of molecules, cells, and organs interact to carry out the functions of living organisms

Organ systems

Foundational Concept 3: Complex systems of tissues and organs sense the internal and external environments of multicellular organisms, and through integrated functioning, maintain a stable internal environment within an ever-changing external environment.

Physical processes

Foundational Concept 4: Complex living organisms transport materials, sense their environment, process signals, and respond to changes using processes that can be understood in terms of physical principles.

Chemical processes

Foundational Concept 5: The principles that govern chemical interactions and reactions form the basis for a broader understanding of the molecular dynamics of living systems.

Processing the environment

Foundational Concept 6: Biological, psychological, and socio-cultural factors influence the ways that individuals perceive, think about, and react to the world.


Foundational Concept 7: Biological, psychological, and socio-cultural factors influence behavior and behavior change.

Individuals and society

Foundational Concept 8: Psychological, socio-cultural, and biological factors influence the way we think about ourselves and others.

Society and culture

Foundational Concept 9: Cultural and social differences influence well-being.

Social inequality

Foundational concept 10: Social stratification and access to resources influence well-being.

Chemical processes

Foundational Concept 5: The principles that govern chemical interactions and reactions form the basis for a broader understanding of the molecular dynamics of living systems.
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All content in “Chemical processes”


Skrillex loved titrating solutions because he got to drop the base. Titrations are a technique that allow us to determine the concentration of an unknown by adding a known element to it until a specific change occurs. For instance, finding the acidity of a solution by adding standard base until the solution turns pink. Learn more about titrations and indicators by watching these examples.

Solubility equilibria

When fresh water runs over a rock a little bit of the rock dissolves. When this mineral rich water dries a little, the rock can be redeposited. Reactants and products are always in equilibrium with each other. Learn how to calculate equilibrium constants and by watching these videos!

Dot structures

5B: We can’t always see molecules, but we can always simplify and draw depictions of them with simply pen and paper. It is the language of chemistry that we want you to get acquainted with. You will learn to draw Lewis dot structures and resonance structures, assign formal charges, and analyze the geometry of molecules and ions.


5B: Even molecules with the same chemical formula can have different shapes even though they may be comprised of the same atoms. For instance, with one sheet of paper, you can make origami swans of so many different shapes - similarly molecules can come in different conformations. We will walk through the concepts of structural and conformational isomers as well as stereoisomers and diastereomers

Covalent bonds

5B: Eating popcorn alone at a movie theater can be quite lonely - but sharing with someone special can feel...well, special! Sharing is caring is caring with atoms too! In a covalent bond, two atoms share electron pairs in their orbitals. We will discuss the mechanism of this bonding as well as the idea of electron orbital hybridization in this tutorial.

Separations and purifications

5C: Did you know that digitalis, one of the oldest medicines used to increase cardiac contractility, is derived from the foxglove plant? When you are in the Amazon rainforest searching for a cure for cancer in a new exotic plant, your potential miracle drug of interest is not originally pure - it must be separated from the other contaminating components. Through these tutorials you will learn how to separate and purify chemical compounds using organic chemistry lab techniques such as extraction, distillation, chromatography, and gel electrophoresis.


5D: DNA makes RNA, and RNA makes proteins,, which are one of the most important biomolecules of our bodies. They are comprised of even smaller amino acids, which are held together by peptide bonds to form proteins. You will discover the structure and functions of proteins at the cellular level in this tutorial.


Table sugar and corn syrup have the same chemical formula, so why do they taste different? The answer is in their stereochemistry. Learn how to assign chirality, interpret Fischer projections, and differentiate between different mono- and poly-saccharides in the following videos.

Alpha-carbon chemistry

5D: Aldol condensations are one of the most important, frequently seen reactions in biochemistry. In fact, the very first reaction of the Krebs (TCA) cycle is an aldol condensation in which acetyl CoA condenses with oxaloacetate, forming citrate. You will learn the mechanism of these reactions formed as we extend this concept to predict the products of aldol condensations.

Alcohols and phenols

5D: If you’ve ever walked through the wards of a hospital, you’ve probably noticed dozens of alcohol-based hand sanitizer dispensers, which quickly clean the hands of healthcare workers between seeing patients. Alcohols serve many other functions. You will gain a strong understanding of the nomenclature, properties and reactions of alcohols and phenols, along with the criteria for determining aromaticity in heterocyles. By the way, if you’re wondering where the term “aromaticity” comes from, many of the earliest aromatic compounds, like benzene and toluene, were noted to have pleasant odors, and the name for this structural class has stuck ever since.

Carboxylic acids

5D: Have you ever used vinegar to make succulent barbecue wings? Then carboxylic acids are your friends. Vinegar, also known as acetic acid, is one of the simplest carboxylic acids. You will discover the important nomenclature, properties, and reactions of carboxylic acids in this tutorial.

Carboxylic acid derivatives

5D: As the name would suggest, carboxylic acid derivatives are quite similar to carboxylic acids in their structure and function. If you’ve ever used soap to wash your hand, you have experienced firsthand (pun intended!) the lavatory effects of an ester, one of the many classes of carboxylic acid derivatives. In this tutorial, we will discuss the important nomenclature, properties, and reactions of carboxylic acids.


5D - The multitude of reactions within our cells are sped up by enzymes. Without these biomolecules, these biochemical pathways would be as slow as a turtle. For instance, without enzymes, your body may never be able to break down and absorb the hamburger you just had for lunch. The hamburger would simply sit there, a lump in your stomach, until reactions slowly started to happen on their own - enzymes speed that up!


The bane of the pharmaceutical industry is that reactions don’t go from 100% reactants to 100% products. They end in equilibrium with each other. Learn how to calculate equilibrium constants and push reactions further towards products by watching these videos!


Wouldn’t it be terrifying if our clothes, food, and houses spontaneously combusted? Molecular bonds store tremendous amounts of energy, but generally are very stable. In order to release the energy, you have to add more first - like applying a match to a firework. These videos will overview standard enthalpy, entropy, and how to find out if a reaction is spontaneous.