Yeast can reproduce sexually through a signaling pathway known as the mating factor pathway. In this process, two haploid yeast cells combine to form a diploid cell. Yeast cells secrete a signal molecule called mating factor that attracts them to their mates. Once the mating factor of one yeast binds to the receptor on another yeast, an outgrowth called a "shmoo" forms, which allows the yeast cells to fuse together.

Thinking about the limiting factors of cell size. Focus on volume to surface area ratio.

Introduction to cell theory. Roles of Hooke, Leeuwenhoek and others in its development.

What cellular evidence do we have to construct evolutionary trees and believe that all life on Earth shares a common ancestry?

Introduction to cellular respiration, including glycolysis, the Krebs Cycle, and the electron transport chain. Created by Sal Khan.

Introduction to cellular respiration, including glycolysis, the Krebs Cycle, and the electron transport chain. Created by Sal Khan.

Sal gives a conceptual understanding of what center of mass means. Created by Sal Khan.

Learn how to use 'chaining', a common technique in jQuery for chaining a sequence of method calls together.

What challenges do immigrants face in the naturalization process? Created by Kimberly Kutz.

A worked example finding the change in centripetal acceleration from the change in linear speed, and an example finding the change in centripetal acceleration from the change in radius.

In this video we illustrate and explain the differences between a change in the quantity demanded for a good (which causes a movement along a demand curve) and the change in a good's demand (which causes the entire demand curve to shift).

A demand shifter is a change that shifts the demand curve for a product. One of the demand shifters is buyers' expectations. If a buyer expects the price of a good to go down in the future, they hold off buying it today, so the demand for that good today decreases. On the other hand, if a buyer expects the price to go up in the future, the demand for the good today increases. Explore the role of buyers' expectations as a determinant of demand in this video. Created by Sal Khan.

A worked example finding the change in the period from the change in angular velocity, and an example finding the change in frequency from the change in angular velocity.

A common error new economic students make is confusing changes in supply with changes in quantity supplied. A change in quantity supplied is a movement along the supply curve in response to a change in price. A change in supply is a shift of the entire supply curve in response to something besides price.

Previously we looked at what happens to the equilibrium price and quantity in a market if supply or demand change. In this video, we explore what happens when BOTH supply and demand are changing at the same time.

In this video, we explore how changes in a few factors affect the demand curve. Changes in income, population, and consumer preferences cause the entire demand curve to shift. Created by Sal Khan.

Changes in the supply of labor have an effect on the wage rate. The supply of labor shifts when there are changes in the population, changes in preferences and social norms, and changes in wage rates and opportunities in other markets. Learn how to show the effects of changes in labor supply on wage rates in this video.

When supply or demand change, the price and quantity in the market changes. See how a change in demand or supply affects price and quantity in this video. Created by Sal Khan.

Economists who studied the relationship between inflation and unemployment made an important modification to the Phillips curve model with the addition of the long-run Phillips curve (LRPC). When expectations are factored in, and there is enough time to adjust, the Phillips curve is vertical. Explore why in this video.