History of the Scientific Thought and Origins of Life

Spontaneous Generation?

Thought his experimentation supported Spontaneous Generation John Needham – 1713-1781

Repeated and modified Needham experiment Repeated and modified Needham experiment. Spallanzani’s work refuted the idea of Spontaneous Generation Lorenzo Spallanzani – 1729 - 1799

Father of the “Germ Theory” Louis Pasteur – 1822-1895

1876: Robert Koch – Koch’s Postulates Koch’s work supports the Germ Theory – “many diseases come from microbes.

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becomes oxidized becomes reduced Fig. 9-UN2 becomes oxidized becomes reduced

becomes oxidized (loses electron) becomes reduced (gains electron) Fig. 9-UN1 becomes oxidized (loses electron) becomes reduced (gains electron)

Fig. 9-UN3 becomes oxidized becomes reduced

Stanley Miller and Harold Urey experiment - 1953

Stromatolites: Click image for video

The 7 Characteristics of Life (textbook pp 16-20):  1. Living Things are Composed of Cells: Single-cell organisms have everything they need to be self-sufficient. In multicellular organisms, specialization increases until some cells do only certain things.

2. Living things have Levels of Organization (and are highly organized): Both molecular and cellular organization. Living things must be able to organize simple substances into complex ones. Living things organize cells at several levels:   Tissue - a group of cells that perform a common function. Organ - a group of tissues that perform a common function. Organ system - a group of organs that perform a common function. (p. 21 in textbook)

Living Things Obtain and Use Energy: Living things take in energy and use it for maintenance and growth.

Living Things Grow and Develop: Cell division - the orderly formation of new cells. Cell enlargement - the increase in size of a cell. Cells grow to a certain size and then divide. An organism gets larger as the number of its cells increases. Development – change in form or function

All living things reproduce in one of the following ways: Asexual repoduction - Producing offspring without the use of gametes. Sexual reproduction - Producing offspring by the joining of sex cells. Reproduction is not essential for the survival of individual organisms, but must occur for a species to survive.

Living Things Adapt To Their Environment: Adaptations are traits giving an organism an advantage in a certain environment. Variation of individuals is important for a healthy species.

Living things react to a stimuli -

Maintain homeostasis