It's getting its oxygenįrom the mother's blood. When a fetus is in the mother's womb, it's not directly breathing. Now you might say, well, why do we have this variation in the type of hemoglobin? And the answer is, that those are two different environments. Out of our mothers' wombs the hemoglobin F stops getting produced and we go to hemoglobin A. You see here four heme groups that each bind two oxygen, and when you're a fetus the primary type of hemoglobin is hemoglobin F, and then once we come So, this right over here is a picture of a hemoglobin molecule.

Hemoglobin changes from when we are inside our mothers' wombs to when we become independent beings. It turns out that hemoglobin, which you might recognize as the protein complex that binds to oxygen in our red blood cells, that the type of predominant And there's several very interesting examples of this.

Those environmentalįactors might influence what part of the DNA is being transcribed into mRNA, which then is translated into proteins at different times. In other circumstances based on environmental factors. Some of these proteins more under certain circumstances and other proteins more Now, it turns out that our DNA will encode for not only multiple proteins but multiple types of the same protein, and it can encode for And these proteins are a major way of expressing what is encoded in our DNA. They go to the ribosomes to be translated into proteins. We know that we have genes in our DNA that code eventually, they go from DNA to messenger RNA, and then That we all have DNA, all organisms, living organisms that we know about, they have DNA. But even within an organism you have variation in the types of molecules that an organism can produce and when they produce them. You are probably familiar with the idea that you have a variation of genetic makeups in a population. We are now going to discuss molecular variation in cells.

Cell and molecular biology khan academy