Introduction to Biology

The Death of Spontaneous Generation The Experiments of Francesco Redi and Louis Pasteur

In the Past… People used to think that life could spring from nonliving things This idea is known as the concept of spontaneous generation Mice from hay Frogs and toads from the mud Flies from a steak

Francesco Redi Mid-1600s. Attempted to show that flies do not “spring” from meat Placed three pieces of meat in three different jars Covered one with paper and sealed it Covered the second with cheesecloth Left the third open

Francesco Redi Redi’s experiment led to the conclusion that large organisms do not appear from nonliving material however, people were not sure about microorganisms…

Louis Pasteur Mid-1800s Conducted an experiment to show that even bacteria and other microorganisms do not come from nonliving material. Two flasks filled with broth (food for bacteria) Boil them both Seal one. Leave the other open. Wait three or four days… Bacteria grow in the open one, not the sealed one

Louis Pasteur Problems… Other scientists say that by sealing the container, Pasteur kept out the “life-giving” air and his experiment was not valid Pasteur came up with a solution SWAN-NECKED FLASKS Boil the broth in the swan-neck flask. Allow to cool. Air can enter and leave, but no bacteria grow

Louis Pasteur Conclusions: Experiment supported the idea that even microorganisms DO NOT appear from nonliving materials SPONTAEOUS GENERATION IS SHOWN TO BE A FALSE HYPOTHESIS

Redi & Pasteur Both of these scientists helped to disprove spontaneous generation. They helped to establish the principle of Biogenesis. Biogenesis is the idea that living organisms come from other living organisms. This is the cornerstone of Biology.

Characteristics of Life An introduction to Biology Characteristics of Life

What is Biology? Biology is the scientific study of life. Scientists use biological principles to solve real-world problems. Preserving the environment Improving the food supply Understanding the human genome A Genome is the complete genetic material contained in an individual. Fighting diseases with vaccines and gene therapy (HIV, cancer, cystic fibrosis) Biology is rooted in the human spirit. What is Biology? What does Bio mean? Biology is the scientific extension of the human tendency to connect to and be curious about life. The adventure of Biology takes us into many environments, into laboratories, into the microscopic world, and back in time. We currently have the largest and best-equipped community of scientists in history, who are beginning to solve problems that once seemed unsolvable. Ecology is helping to evaluate environmental issues such as global warming, acid rain, and species loss. Genetics and cell biology are revolutionizing agriculture with things like “Flavor Save” tomatoes. We have mapped the human genome and can now start to cure illnesses such as cancer.

Some Properties of Life Properties and processes that we associate with life: 1. Organization 2. Regulation 3. Energy Processing/Metabolism 4. Response to the Environment 5. Reproduction 6. Growth and Development 7. Evolutionary Adaptation Living things all share some similar characteristics. These are:

Organization Highly organized structure characterizes life The basic unit of order for life is a cell. All living things are made up of one or more cells. Life is based on a high degree of order. Each level is built on the one below. One of the most important units of life’s levels is the cell. Cells can be considered the leggo blocks of life. All living things are made up of cells.

Regulation Living things must maintain a stable internal environment to survive. Homeostasis: The maintenance of stable internal conditions in spite of changes in the external environment.

Energy Processing Living things need energy to do work. Metabolism: Chemical reactions in the body that release or use energy. Living things release energy from food Living things use energy to grow and move

Response to the Environment In order to survive, organisms must be able to respond to changes in their environment. How do you respond when it gets too hot? How do you respond when it gets dark?

Reproduction All living things have a life cycle of growth, development and death. Species must reproduce to continue to exist. Reproduction- is the process by which organisms make more of their own kind from one generation to the next.

Growth & Development All living things are able to pass on traits to their offspring through genes. Genes are the basic units of heredity (found on DNA). Heredity: the passing of traits from parents to offspring. Sometimes damage causes genes to change. A mutation is a change in the DNA of a gene.

Evolutionary Adaptation The diversity of life on Earth is the result of a long history of change. Evolution is the change in inherited traits of a species over generations. Over time, organisms with favorable genes are more likely to survive and reproduce, a process called natural selection. Evolution: Biology can be viewed as having two dimensions: a “vertical” dimension covering the size scale from atoms to the biosphere and a “horizontal” dimension that stretches across the diversity of life. And not just species that are alive today! The history of life on Earth is a story that has been unfolding for billions of years and has had a huge cast of different characters. This cast of characters is revealed through fossils and other evidence. And, we are life is still evolving today. All life is connected through evolution.