Given my level of education, I hardly think that I need to sit through a 53 minute presentation by a medical doctor (whose knowledge of biochemistry is probably undergraduate level) to find out what saturated and unsaturated fats are, when I've already extensively studied the subject and can draw not only the structures of lipids, but their biological synthesis, from memory.
Triglycerides of any chain length are fat molecules; the word "triglyceride" itself does not give any indication of degree of saturation. "Saturation" refers to the number of single bonds between the carbons in the triglyceride side chains; a fully saturated fat contains no double bonds in the side chains. A fully saturated fat is solid at room temperature (for example, vegetable shortening). It is meaningless to talk about a fully unsaturated fat, because the number of double bonds in the side chains is variable, so we just say that it is unsaturated, even if there is only one double bond in one of the three side chains. An unsaturated fat is *not* a solid at room temperature.
If you have access to non-homogenized milk, take a look at the cream floating on top. Or take a look at heavy whipping cream. They are not solid. Therefore, by definition, they are not saturated. Because milk fat is a complex mixture of lipids, there is very likely a fraction of fully saturated lipids (triglycerides) in the mixture. However, by definition, milk fat is *not* saturated.
The prefixes "cis" and "trans" refer to the chemical nature of the double bond in an unsaturated fat. Rather than try to describe the meaning, I'll just refer you to the Wikipedia article and draw your attention to the diagrams on the right.
I just love when I give a layperson's definition of a highly technical concept, and someone suddenly exhibits the Dunning-Kruger effect and tries to trip me up...
Fat composition differs between mammals.
Cow milk != people milk. It’s one reason you can’t really feed human babies on just cow milk and expect them to be healthy.
I had a refrigerator door full of those little breast milk containers when I was pumping for my middle baby. They got a hard shell of fat congealed on the top.
Accidentally left one out overnight and the little shell of fat was still there in the morning. Temp in my house was around 70, it was winter.
When we carefully stir the cream until the fat globules stick together and water separates out we get butter. It is stands as a solid and is known to be a mixture of fats, largely saturated. So the fat in milk is also. Or does magic occur?