Hi, I'm Sarah Maurer
And today, I'm going to tell you about the similarity between biological organisms
and how that relates to the origins of life
We use what's called a top down approach
And in this approach, we examine all living organisms
and the commonalities between them
to better understand what the requirements are for first life, or the origins of life
The first thing that all living things have in common is that we use L-amino acids in our proteins, and that we use D-sugars in our sugars and in our nucleic acids.
This was first discovered a very long time ago when scientists took purified forms of biomolecules,
placed them into a container and saw how they rotated
polarized light.
When they rotate to the left, they are called L-molecules and when they rotate to the right, they're called D-molecules.
and you can see that the molecules are mirror images of each other between the left handed version ad the right handed version. the next thing that all living organisms have in common
is that they use membranes to seperate themselves from the enviroment
and these membranes are composed of amphiphilic molecules which have a hydrophobic head, a hydrophobic tail that aggregates between itself and a hydrophilic head group that interact with the water ohae. the creates a barrier to the environment and also helps to keep
important molecules inside the cell
many/membranes are used to seperate cells from one another they are also used
to eperate organelles from other parts of the cell
one organelle is the nuclear membrane which separates the nucleic acid from the cytosol. and the nucleic acids are another component that all living things have in common. the small chemical structures that you see here are very highly consevered between all nucleic acids.. they're composod of and dna forms into these secondary structures like the double helix, but rna