Cells: Living Building Blocks

Cells: Living Building Blocks

Subject: Physics    / General Physics
Question

Cells: Living Building Blocks
Why do we consider some things to be living and some things not? Can you imagine what Anton Leeuwenhoek must have thought when he looked at a drop of water for the very first time with his primitive microscope? A sea of cells in a drop of water; living, replicating, going about their business in a world that no one had ever envisioned. From where did these cells come? What were the functions of the various components that he was able to barely see? What were their sources of energy? How did they reproduce themselves? Our discussions for this week will focus on just how far we have come in answering these questions.
Ecosystems and Interactions
‘Global Warming!’ Regardless of your position on the subject, it makes sense that the more we understand about how ecological systems are organized, how energy flows through ecosystems, how materials are cycled through ecosystems, and the interactions that occur between the diverse communities that make up ecosystems, the better we can make decisions concerning the various factors (including increased carbon dioxide emissions) that impact these ecosystems. The purpose of this thread is to discuss each of these issues within the broader perspective of man’s influence on the environment.

DNA and Genetics
When Gregor Mendel formulated his three laws of inheritance, he opened the door to a long line of research that has produced a deep understanding of how genetic traits are transmitted from one generation to the next. Our understanding of the nature of the gene began with his work. And in a triumph no less profound than landing a human being on the moon, his research has led us to point where we have mapped the entire genome of the human being. During the course of this discussion, we will explore the nature of the gene. What are alleles? What are the various models of inheritance? What is the structure of DNA, the material from which genes are constructed? How is the information in DNA transmitted from one generation to the next? How does it regulate the functions of cells? And finally, where does mutation fit into the overall picture?

Evolution and Change Over Time
It’s difficult to look at a modern bird and fossils of some theropod dinosaurs and not see a connection. It’s equally difficult to imagine the changes in the Earth’s crust that must have occurred in order to lift a marine fossil to a mountain top. The Earth is over 4.5 billion years old. The possibilities for change over that period of time are enormous. During the course of this thread, we will discuss how our understanding of the origin of life has changed. We will examine the role played by natural selection and look into those factors that influence natural selection. How do species change over time? What kinds of conditions need to exist in order for change to occur? What is the role of mutation in the process?