Lesson 3: From Chemistry to Biology
Key Learning Objectives:
Understand the likely sources of chemicals on early Earth.
Explain the role of self-assembly in the origins of life.
In this lesson you'll find...
Intro to Prebiotic Chemistry
Self-assembly and the Origins of Life
Ongoing Research
Intro to Prebiotic Chemistry
Now that we have identified some molecules required for life, let's try to understand where those molecules came from. Prebiotic chemistry is the field of research that tries to figure out what molecules could have existed prior to the first living organisms.
Recently, the notion that life started in the oceans has been challenged. One of the reasons for this is that UV light has been shown, time and time again, to be critical for chemical reactions to proceed (this type of chemistry is known as photochemistry). UV light, however, does not travel very far into water, making the ocean an unlikely place for this type of photochemistry. Such reactions could thus only have taken place in shallow water features.
Activity
Read one of the articles below and complete the following tasks:
Summarise each paragraph of the article in one sentence
Identify two key points of the article
Identify a chemistry concept related to the article
Create a tweet (about 2 sentences) to share with your class on the potential role of Earth's surface in the origins of life.
Self-assembly and the Origins of Life
Self-assembly in the context of the origins of life refers to the process by which simple molecules or components come together spontaneously to form more complex structures without external guidance. This concept is often discussed in the context of abiogenesis, the origin of life from non-living matter.
The idea is that the basic building blocks of life, such as amino acids, nucleotides, and other organic molecules, could have self-assembled into more complex structures like proteins, RNA, and membranes. These structures, in turn, could have led to the formation of early protocells (a hypothetical, simplified, and primitive cell-like structure that is thought to have played a crucial role in the early stages of the origin of life) or prebiotic entities with some characteristics of living cells.
Watch the video below to understand why self-assembly is important for creating complex objects, and how it would have been necessary at life's origins for simple molecules to become life.
Ongoing Research
Understanding where the chemistry needed for life to start comes from, and how these molecules self-assemble into the first cells are active areas of research. The videos below present Dr Anna Wang (from 29:15 to 45:25) and Dr Albert Fahrenbach (from 0 to min 14:45) talking about their research on the origins of life.
The sticking together of lipid layers is super important for many biological activities, like moving stuff around in cells and building multicellular structures. When membranes with opposite charges meet, they easily stick together, but when they have the same charge, it usually needs special conditions. This research shows that by using a new method to create flexible membrane layers, even same-charged lipid bubbles can join up and stay together in pairs, hinting that these pairings might last without using extra substances like glues or special agents.
The challenge of dealing with complex chemical mixtures, often seen as a nightmare for prebiotic chemists, is discussed in this presentation. The idea is that embracing complexity could lead us from this nightmare to a "molecular biologist's dream." Albert introduces a continuous reaction network, a process that mimics a natural environment by avoiding excessive manipulation, aiming to understand how RNA, a key molecule for life, might spontaneously form from a complex mixture with minimal human intervention.
Activity
Based on what of the videos above:
Identify a chemistry or self-assembly concept related to the videos.
Create a tweet (about 2 sentences) to share with your class on the topic of how complexity (either in chemistry or self-assembled structures) could have increased on early Earth