Biomolecules

This course is a part of MCAT, a 14-course Topic series from Khan Academy.

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.

This course contains 18 segments:

Amino acids and proteins

1A: We will come to an understanding of the central dogma of molecular biology: DNA makes RNA, and RNA makes protein. You will learn about how we classify the different amino acids and how they come together to form the building blocks of complex proteins.

Enzyme structure and function

1A: 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!

Enzyme kinetics

1A: You’ll come to understand how enzymes, biomolecular catalysts, speed up reactions in cells as well as interact with one another. With just a little algebra, we’ll come to a mathematical understanding of this fundamental process.

DNA

1B: DNA makes RNA, and RNA makes protein - in a nutshell, this is the central dogma of molecular biology. Let’s delve into that simple notion here so we can come to a better understand of the flow of genetic information.

Gene control

1B: Cells have many intricate mechanisms which regulate expression of genetic material - from transcription of RNA to translation of protein. At every point in this process, enzymes in your body can step in to modulate how much or how little RNA, or protein is produced from the genome. Sometimes, these genetic controls go awry, and so cells grow without inhibition - this is often how tumors develop, a pathogenic process we will also explore.

Genetic mutations

1C: Mutations are not always a bad thing - they give rise to much of the spice and flavor of life. But sometimes they are a result of environmental injury and can give rise to malignant disease processes like cancer. We will look at the causes and types of genetics mutations in this series as we also examine their effect on biological systems.

Mendelian genetics

1C: Why do some people have blue eyes and others brown? What determines your blood type? You will be able to answer questions like these as you have some fun with Punnett squares and discover the mechanisms of inheritance (and what all this has to do with a 19th-century German monk).

DNA technology

Thanks to advances in DNA technology, we can now clone genes, control gene expression, and sequence entire genomes. How is this possible? These videos will cover the techniques that revolutionized molecular biology and continue to be used almost daily in research labs around the world.

Chromosomal inheritance

Between 1856 and 1863, Gregor Mendel did a series of experiments with pea plants that established much of our fundamental understanding of heredity. In this section you will learn how traits are passed down from parents to their offspring and how genetic recombination can produce organisms with new gene combinations.

Evolution and population dynamics

1C: Charles Darwin inaugurated the field of evolutionary biology 150 years ago with the publication of “On the Origin of Species.” You will learn about the driving forces of evolution beyond natural selection and the relationship between populations and their environments. The story of Darwin’s finches will make a lot more sense.

Principles of bioenergetics

1D: When you light a candle, energy in the form of heat is dissipated into the surroundings. Without energy transfer, frogs wouldn’t jump, and cheetahs wouldn’t run. We will discuss Gibbs free energy, enthalpy, and Le Chatelier’s principles, thermodynamic concepts governing energy transfer as we examine their relationship to metabolism. After this tutorial, you will understand what it really means to “burn calories” during exercise.

Overview of metabolism

1D: You are breathing, your heart is beating, and you are reading this sentence. All these processes would be impossible were it not for the chemical energy produce within our cells. In this tutorial, we will integrate the biology and chemistry of metabolism as we walk you through the electron transport chain and the production of ATP, the ultimate energy currency in our bodies.

Carbohydrates

1D: Sugars are more than a prelude to a trip to the dentist - they makes life itself possible. This tutorial will describe the structure of these vital biomolecules.

Carbohydrate Metabolism

1D: The glucose in the bread of the ham and cheese sandwich you just had for lunch goes on a productive journey within your cells after it is absorbed - the glucose in the bread is involved in several interlinked pathways. Your body has a decision to make - it can either break down the glucose for energy or store it for later. We will delve into the metabolic pathways of glucose - glycolysis, gluconeogenesis, and the pentose phosphate shunt.

Krebs (citric acid) cycle and oxidative phosphorylation

1D: You will learn about the latter steps in cellular respiration - the citric acid cycle and oxidative phosphorylation. It is through these elegant processes that your cells produce energy from sugars, fats, and proteins.

Fat and protein metabolism

1D: The ham and cheese sandwich you just enjoyed need to be processed by the cells of your body. In addition to the sweet glucose we happily consume, we also take in fat (great for storing energy compactly) and proteins (which can be metabolized to produce energy or used as building blocks for innumerable parts of your body). These tutorials will shed light on the key metabolic pathways governing the metabolism of fats and proteins.

Endocrine system

1D: Glands are special organs that secrete chemical messages called hormones, which seep into the blood - it’s like putting a tea bag in hot water. As the heart pumps, this blood carries these chemical messages throughout the body, allowing the hormones to interact with specific target cells and organs. Endocrine glands help us to maintain our appetites, grow up, metabolize molecules, concentrate urine,- and oh, so much more! We will examine how these variegated hormones play a role in homeostasis as the body responds to a changing environment.

Hormonal regulation