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Your Objectives • Learn how plants and animals evolved from protists • Learn examples of how organisms maintain homeostasis • Learn how plants and animals use chloroplasts and mitochondria for energy • Learn how enzymes are important for cellular reactions • Learn how cells copy their DNA and divide as the cell grows • Learn how plants have adapted to different conditions to become different from one another A Trip Through Geologic Time 3.5 Billion years ago (how many human lifetimes is this?) Average human lifespan? About 70 years How many lives would this be? 3,500,000,000 years = 50,000,000 human lifespans 50,000,000 human lives Doesn’t sound like a lot? OK, the typical lifespan of a bacteria is a few hours to a few days at most… so if you think about how many “lives” bacteria have had to evolve, you have to multiply 3,500,000,000 by 365 (if you assume a cell lives for an entire day) That’s 12,775,000,000,000,000 times During that time… • Anyway, we have fossils that show photosynthetic, prokaryotic cells existed 3.5 billion years ago. • Later, actually, about 7 hundred million years later, there was a sudden increase in diversity, and It seems that some large Prokaryotes made the first big leap into more complex life Here’s how we think it happened… Cells, like amoeba, eat other cells all the time. It is likely that one cell ate another, and the other cell was never destroyed, simply continued life, ADAPTING to the new environment. This would mean that one organism… • Lives inside another organism… • Endo = inside • Sybiont = together • Incredibly, that other organism continued life inside the other…even reproducing itself? How do we know? • Scientific research has shown that chloroplasts and mitochondria have their own ribosomes – NOT the ribosomes of the “host” cell that are similar to the ribosomes in prokaryotes. • IN ADDITION, both chloroplasts and mitochondria reproduce INDEPENDENTLY of the cells that contain them. Evidence continues to mount So… • The evidence shows that there were organisms that behaved like mitochondria, that lived in an oxygen-free environment, and organisms that behaved like chloroplasts that released the oxygen we breathe into the atmosphere. • They live on in our cells, a part of them, but still have the characteristics of the original organism… Making Coacervates • In the next lab we are going to simulate a “primordial soup”.