Lecture 5

Lecture 5 - The Nature of Life on Earth Defining Life What...

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Unformatted text preview: The Nature of Life on Earth Defining Life What is life? A seemingly straightforward question but has plagued biologists, philosophers and theologians for centuries. What life should we be searching for and where should we look? What is Life? Needs energy to function, can move at varying speeds and can turn corners, expel waste. But the cat is definitely alive and the car is not Why? What separates a rock from a living organism? Does life contain some kind of spirit or vital force? What is alive and what is dead? 6 Key Properties of Life Materials in living organisms always exhibit some kind of order. Books and rock crystals have order but are not alive. Oder is a necessary condition for life, but alone does not make life! Living organisms reproduce or are products of reproduction . Mules are alive but cannot reproduce, and are products of reproduction (horse + donkey). Viruses cannot reproduce alone, need host alive or not? Living organisms grow and develop at some point in their life.-Heredity! Fire grows and develops not alive. e.g. Fire Is fire alive? Grow and Spread Self sustaining from a flow of energy Consume fuel Excrete waste products by the same oxidation reactions that run a cell The ordered pattern of atoms in a crystal is able to reproduce itself 6 Key Properties of Life Living organisms use energy to create and maintain order within cells, reproduce and to grow. A fridge utilises energy! nd All living organisms interact with their surroundings and respond to changes in the environment.-Sweating, panting, blood flow to maintain temperature. Thermostat also does this! Life evolves over (geologic) time new organisms evolve better suited to environments new species form. Species and Genus Species A group of organisms that share some set of common characteristics and are capable of interbreeding with one another to produce fertile offspring?->Horses and donkeys considered different species as they produce an infertile mule. Works well for most plants and animals, but not for organisms that reproduce asexually i.e. microorganisms. So species recognised as groups of organisms that are genetically distinct from other groups. Given a name comprised of two parts: Genus = first part, the generic catagory to which the organism belongs. The second part distinguishes multiple species within the same genus....
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Lecture 5 - The Nature of Life on Earth Defining Life What...

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